WorldWideScience

Sample records for anaerobic degradation processes

  1. Stabilization of degradable wastes by anaerobic process

    International Nuclear Information System (INIS)

    Within the framework of a modern waste management concept, separate collection and recycling of garden wastes and degradable wastes from households and trade are indispensable and correspond to a principle enshrined in law. The ''bion-stab'' technique is a closed-cycle process for anaerobic stabilization of degradable wastes which causes few emissions and is thus extremely environmentally friendly. Latent energy contained in degradable waste is liberated by this process. This energy is environmentally friendly, as the cycle process involves the release of bonded CO2 only for a short period of time. Thus it contributes, along with the high economic efficiency of the plant, to a positive overall result both in terms of energy and with regard to environmental problems. (orig.)

  2. Anaerobic-Aerobic Process for Microbial Degradation of Tetrabromobisphenol A

    OpenAIRE

    Ronen, Zeev; Abeliovich, Aharon

    2000-01-01

    Tetrabromobisphenol A (TBBPA) is a flame retardant that is used as an additive during manufacturing of plastic polymers and electronic circuit boards. Little is known about the fate of this compound in the environment. In the current study we investigated biodegradation of TBBPA, as well as 2,4,6-tribromophenol (TBP), in slurry of anaerobic sediment from a wet ephemeral desert stream bed contaminated with chemical industry waste. Anaerobic incubation of the sediment with TBBPA and peptone-try...

  3. Anaerobic Digestion: Process

    DEFF Research Database (Denmark)

    Angelidaki, Irini; Batstone, Damien J.

    2011-01-01

    Organic waste may degrade anaerobically in nature as well as in engineered systems. The latter is called anaerobic digestion or biogasification. Anaerobic digestion produces two main outputs: An energy-rich gas called biogas and an effluent. The effluent, which may be a solid as well as liquid with...... very little dry matter may also be called a digest. The digest should not be termed compost unless it specifically has been composted in an aerated step. This chapter describes the basic processes of anaerobic digestion. Chapter 9.5 describes the anaerobic treatment technologies, and Chapter 9.......6 addresses the mass balances and environmental aspects of anaerobic digestion....

  4. DECOLORIZATION AND BIOLOGICAL DEGRADATION OF AZO DYE REACTIVE RED2 BY ANAEROBIC/AEROBIC SEQUENTIAL PROCESS

    OpenAIRE

    A. Naimabadi ، H. Movahedian Attar ، A. Shahsavani

    2009-01-01

    This study investigates the anaerobic treatability of reactive Red2 in an anaerobic/aerobic sequential process. Laboratory scale anaerobic baffled reactor and fixed activated sludge reactor were operated at different organic loadings and hydraulic retention times. The effects of shock dye concentration on the chemical oxygen demand and color removal efficiencies were investigated in the anaerobic baffled reactor. The effect of hydraulic retention time on the color and chemical oxygen demand r...

  5. Mathematic modelling of anaerobic degradation processes in biogas plants; Mathematische Modellierung der anaeroben Abbauprozesse in Biogasanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Weinrich, Soeren [Rostock Univ. (Germany). Agrar- und Umweltwissenschaftliche Fakultaet; Mauky, Eric [DBFZ - Deutsches BiomasseForschungsZentrum gGmbH, Leipzig (Germany). Fachbereich Biochemische Konversion; Nelles, Michael

    2011-07-01

    In view of the ongoing political discussion on the enhanced utilization of renewable energy sources biogas technologies continue to gain significance. To develop economic plant concepts and guaranty high energy efficiency the knowledge of the dynamic degradation of various substrates at different operating conditions are of crucial importance. Within the field of modelling the dynamic changes in concentration of substantial components (mass balance) are commonly described by known physical laws or empirical observations. On the basis of a dynamic process model by the German Biomass Research Centre (DBFZ) the main functional principles and capabilities of a simulation of a real biogas plant are described exemplarily. Besides the choice of appropriate kinetic and stoichiometric parameters the model output depends significantly on the quality of the (measured) input variables. Thus the implementation of continuous accurate data logging and the development of important process parameters are also major research topics for modelling and parameter identification of the anaerobic digestion process. (orig.)

  6. DECOLORIZATION AND BIOLOGICAL DEGRADATION OF AZO DYE REACTIVE RED2 BY ANAEROBIC/AEROBIC SEQUENTIAL PROCESS

    Directory of Open Access Journals (Sweden)

    A. Naimabadi ، H. Movahedian Attar ، A. Shahsavani

    2009-04-01

    Full Text Available This study investigates the anaerobic treatability of reactive Red2 in an anaerobic/aerobic sequential process. Laboratory scale anaerobic baffled reactor and fixed activated sludge reactor were operated at different organic loadings and hydraulic retention times. The effects of shock dye concentration on the chemical oxygen demand and color removal efficiencies were investigated in the anaerobic baffled reactor. The effect of hydraulic retention time on the color and chemical oxygen demand removal efficiencies were also investigated in the aerobic reactor. The studies were carried out in continuous mode and the effluent of the anaerobic baffled reactor was used as feed for the fixed activated sludge reactor. Chemical oxygen demand removal efficiency of 54.5% was obtained at HRT =1 day in the anaerobic reactor. The average color removal was 89.5%. Chemical oxygen demand removal efficiency of 69% was obtained at HRT =7 h in the aerobic fixed activated sludge reactor. A slight decrease of the color was also observed in the aerobic reactor. This investigation has shown that successful treatment of a highly colored wastewater is possible in the anaerobic baffled reactor. Also the results showed that, anaerobic biological system has higher efficiency in dye removal than fixed activated sludge system, while aerobic system has higher efficiency in chemical oxygen demand removal comparing with the anaerobic baffled reactor.

  7. The anaerobic degradation of gaseous, nonmethane alkanes — From in situ processes to microorganisms

    OpenAIRE

    Florin Musat

    2015-01-01

    The short chain, gaseous alkanes ethane, propane, n- and iso-butane are released in significant amounts into the atmosphere, where they contribute to tropospheric chemistry and ozone formation. Biodegradation of gaseous alkanes by aerobic microorganisms, mostly bacteria and fungi isolated from terrestrial environments, has been known for several decades. The first indications for short chain alkane anaerobic degradation were provided by geochemical studies of deep-sea environments around hydr...

  8. The anaerobic digestion process

    Energy Technology Data Exchange (ETDEWEB)

    Rivard, C.J. [National Renewable Energy Lab., Golden, CO (United States); Boone, D.R. [Oregon Graduate Inst., Portland, OR (United States)

    1996-01-01

    The microbial process of converting organic matter into methane and carbon dioxide is so complex that anaerobic digesters have long been treated as {open_quotes}black boxes.{close_quotes} Research into this process during the past few decades has gradually unraveled this complexity, but many questions remain. The major biochemical reactions for forming methane by methanogens are largely understood, and evolutionary studies indicate that these microbes are as different from bacteria as they are from plants and animals. In anaerobic digesters, methanogens are at the terminus of a metabolic web, in which the reactions of myriads of other microbes produce a very limited range of compounds - mainly acetate, hydrogen, and formate - on which the methanogens grow and from which they form methane. {open_quotes}Interspecies hydrogen-transfer{close_quotes} and {open_quotes}interspecies formate-transfer{close_quotes} are major mechanisms by which methanogens obtain their substrates and by which volatile fatty acids are degraded. Present understanding of these reactions and other complex interactions among the bacteria involved in anaerobic digestion is only now to the point where anaerobic digesters need no longer be treated as black boxes.

  9. Anaerobic degradation of linear alkylbenzene sulfonate

    DEFF Research Database (Denmark)

    Mogensen, Anders Skibsted; Haagensen, Frank; Ahring, Birgitte Kiær

    2003-01-01

    increases during anaerobic stabilization due to transformation of easily degradable organic matter. Hence, LAS is regarded as resistant to biodegradation under anaerobic conditions. We present data from a lab-scale semi-continuously stirred tank reactor (CSTR) spiked with linear dodecylbenzene sulfonate (C...

  10. Determining anaerobic degradation kinetics from batch tests.

    Science.gov (United States)

    Moreda, Iván López

    2016-01-01

    Data obtained from a biomethane potential (BMP) test were used in order to obtain the parameters of a kinetic model of solid wastes anaerobic degradation. The proposed model considers a hydrolysis step with a first order kinetic, a Monod kinetic for the soluble organic substrate degradation and a first order decay of microorganisms. The instantaneous release of methane was assumed. The parameters of the model are determined following a direct search optimization procedure. A 'multiple-shooting' technique was used as a first step of the optimization process. The confidence interval of the parameters was determined by using Monte Carlo simulations. Also, the distribution functions of the parameters were determined. Only the hydrolysis first order constant shows a normal distribution. PMID:27191569

  11. Anaerobic methanethiol degradation and methanogenic community analysis in an alkaline (pH 10) biological process for liquefied petroleum gas desulfurization.

    Science.gov (United States)

    van Leerdam, Robin C; Bonilla-Salinas, Monica; de Bok, Frank A M; Bruning, H; Lens, Piet N L; Stams, Alfons J M; Janssen, Albert J H

    2008-11-01

    Anaerobic methanethiol (MT) degradation by mesophilic (30 degrees C) alkaliphilic (pH 10) communities was studied in a lab-scale Upflow Anaerobic Sludge Bed (UASB) reactor inoculated with a mixture of sediments from the Wadden Sea (The Netherlands), Soap Lake (Central Washington), and Russian soda lakes. MT degradation started after 32 days of incubation. During the first 252 days, complete degradation was achieved till a volumetric loading rate of 7.5 mmol MT/L/day, and sulfide, methane, and carbon dioxide were the main reaction products. Temporary inhibition of MT degradation occurred after MT peak loads and in the presence of dimethyl disulfide (DMDS), which is the autooxidation product of MT. From day 252 onwards, methanol was dosed to the reactor as co-substrate at a loading rate of 3-6 mmol/L/day to stimulate growth of methylotrophic methanogens. Methanol was completely degraded and also a complete MT degradation was achieved till a volumetric loading rate of 13 mmol MT/L/day (0.77 mmol MT/gVSS/day). However, from day 354 till the end of the experimental run (day 365), acetate was formed and MT was not completely degraded anymore, indicating that methanol-degrading homoacetogenic bacteria had partially outcompeted the methanogenic MT-degrading archea. The archeal community in the reactor sludge was analyzed by DGGE and sequencing of 16S rRNA genes. The methanogenic archea responsible for the degradation of MT in the reactor were related to Methanolobus oregonensis. A pure culture, named strain SODA, was obtained by serial dilutions in medium containing both trimethyl amine and dimethyl sulfide (DMS). Strain SODA degraded MT, DMS, trimethyl amine, and methanol. Flow sheet simulations revealed that for sufficient MT removal from liquefied petroleum gas, the extraction and biological degradation process should be operated above pH 9. PMID:18814290

  12. Post-treatment of anaerobically degraded azo dye Acid Red 18 using aerobic moving bed biofilm process: Enhanced removal of aromatic amines

    International Nuclear Information System (INIS)

    Highlights: → Biofilm process was applied as post-treatment of anaerobically degraded an azo dye. → More than 65% of the dye total metabolites was completely mineralized. → Based on HPLC analysis, more than 80% of 1-naphthylamine-4-sulfonate was removed. → Inhibition of biofilm growth was increased with increasing the initial dye concentration. → Considerable porous morphology was observed in the SEM photographs of the biofilm. - Abstract: The application of aerobic moving bed biofilm process as post-treatment of anaerobically degraded azo dye Acid Red 18 was investigated in this study. The main objective of this work was to enhance removal of anaerobically formed the dye aromatic metabolites. Three separate sequential treatment systems were operated with different initial dye concentrations of 100, 500 and 1000 mg/L. Each treatment system consisted of an anaerobic sequencing batch reactor (An-SBR) followed by an aerobic moving bed sequencing batch biofilm reactor (MB-SBBR). Up to 98% of the dye decolorization and more than 80% of the COD removal occurred anaerobically. The obtained results suggested no significant difference in COD removal as well as the dye decolorization efficiency using three An-SBRs receiving different initial dye concentrations. Monitoring the dye metabolites through HPLC suggested that more than 80% of anaerobically formed 1-naphthylamine-4-sulfonate was completely removed in the aerobic biofilm reactors. Based on COD analysis results, at least 65-72% of the dye total metabolites were mineralized during the applied treatment systems. According to the measured biofilm mass and also based on respiration-inhibition test results, increasing the initial dye concentration inhibited the growth and final mass of the attached-growth biofilm in MB-SBBRs.

  13. Anaerobic lipid degradation through acidification and methanization.

    Science.gov (United States)

    Kim, Ijung; Kim, Sang-Hyoun; Shin, Hang-Sik; Jung, Jin-Young

    2010-01-01

    In biological wastewater treatment high lipid concentration is known to inhibit microorganisms and cause active biomass flotation. To reduce lipid inhibition, a two-phase anaerobic system, consisting of an anaerobic sequencing batch reactor (ASBR) and an upflow anaerobic sludge blanket (UASB) reactor, was applied to synthetic dairy wastewater. During 153 days of operation, the two-phase system showed stable performance in lipid degradation. In the ASBR, a 13% lipid removal efficiency and 10% double bond removal efficiency were maintained. In the UASB, the chemical oxygen demand (COD), lipid and volatile fatty acid (VFA) removal efficiencies were more than 80%, 70% and 95%, respectively, up to organic loading rate 6.5 g COD/L/day. There were no operational problems such as serious scum formation or sludge washout. Protein degradation occurred prior to degradation during acidogenesis. PMID:20134250

  14. Anaerobic degradation of linear alkylbenzene sulfonate

    DEFF Research Database (Denmark)

    Mogensen, Anders Skibsted; Haagensen, Frank; Ahring, Birgitte Kiær

    2003-01-01

    increases during anaerobic stabilization due to transformation of easily degradable organic matter. Hence, LAS is regarded as resistant to biodegradation under anaerobic conditions. We present data from a lab-scale semi-continuously stirred tank reactor (CSTR) spiked with linear dodecylbenzene sulfonate (C......% of the added C-12 LAS was bioavailable and 20% was biotransformed when spiking with 100 mg/L of C-12 LAS and a TS concentration of 14.2 mg/L. Enhanced bioavailability of C-12 LAS was obtained in an upflow anaerobic sludge blanket (UASB) reactor inoculated with granular sludge and sewage sludge. Biodegradation......Linear alkylbenzene sulfonate (LAS) found in wastewater is removed in the wastewater treatment facilities by sorption and aerobic biodegradation. The anaerobic digestion of sewage sludge has not been shown to contribute to the removal. The concentration of LAS based on dry matter typically...

  15. Combined Anaerobic-Aerobic Bacterial Degradation of Dyes

    OpenAIRE

    R. Wilfred Sugumar; Sandhya Sadanandan

    2010-01-01

    Wastewaters from the dye baths of a non-formal textile-dyeing unit containing C.I. Acid Orange 7 and C.I. Reactive Red 2 were subjected to degradation in a sequential anaerobic-aerobic treatment process based on mixed culture of bacteria. The technical samples of the dyestuffs and the dye bath wastes were treated in an anaerobic reactor, using an adapted mixed culture of anaerobic microorganisms. The dyestuffs were biotransformed into colourless substituted amine metabolites in the reactor. T...

  16. Anaerobic microbial LCFA degradation in bioreactors

    OpenAIRE

    Sousa, D.Z.; Pereira, M.A.; Alves, J.I.; Smidt, Hauke; Stams, A.J.M.; Alves, M. M.

    2008-01-01

    This paper reviews recent results obtained on long-chain fatty acids (LCFA) anaerobic degradation. Two LCFA were used as model substrates: oleate, a mono-unsaturated LCFA, and palmitate, a saturated LCFA, both abundant in LCFA-rich wastewaters. 16S rRNA gene analysis of sludge samples submitted to continuous oleate- and palmitate-feeding followed by batch degradation of the accumulated LCFA demonstrated that bacterial communities were dominated by members of the Clostridiaceae and Sy...

  17. Terminal Processes in the Anaerobic Degradation of an Algal-Bacterial Mat in a High-Sulfate Hot Spring

    OpenAIRE

    Ward, David M.; Olson, Gregory J.

    1980-01-01

    The algal-bacterial mat of a high-sulfate hot spring (Bath Lake) provided an environment in which to compare terminal processes involved in anaerobic decomposition. Sulfate reduction was found to dominate methane production, as indicated by comparison of initial electron flow through the two processes, rapid conversion of [2-14C]acetate to 14CO2 and not to 14CH4, and the lack of rapid reduction of NaH14CO3 to 14CH4. Sulfate reduction was the dominant process at all depth intervals, but a mark...

  18. Terminal processes in the anaerobic degradation of an algal-bacterial mat in a high-sulfate hot spring

    International Nuclear Information System (INIS)

    The algal-bacterial mat of a high-sulfate hot spring (Bath Lake) provided an environment in which to compare terminal processes involved in anaerobic decomposition. Sulfate reduction was found to dominate methane production, as indicated by comparison of initial electron flow through the two processes, rapid conversion of [2-14C]acetate to 14CO2 and not to 14CH4, and the lack of rapid reduction of NaH14CO3 to 14CH4. Sulfate reduction was the dominant process at all depth intervals, but a marked decrease of sulfate reduction and sulfate-reducing bacteria was observed with depth. Concurrent methanogenesis was indicated by the presence of viable methanogenic bacteria and very low but detectable rates of methane production. A marked increase in methane production was observed after sulfate depletion despite high concentrations of sulfide (>1.25 mM), indicating that methanogenesis was not inhibited by sulfide in the natural environment. Although a sulfate minimum and sulfide maximum occurred in the region of maximal sulfate reduction, the absence of sulfate depletion in interstitial water suggests that methanogenesis is always severely limited in Bath Lake sediments. Low initial methanogenesis was not due to anaerobic methane oxidation

  19. Anaerobic methanethiol degradation and methanogenic community analysis in an alkaline (pH 10) biological process for liquefied petroleum gas desulfurization

    NARCIS (Netherlands)

    Leerdam, van R.C.; Bonilla-Salinas, M.; Bok, de F.A.M.; Bruning, H.; Lens, P.N.L.; Stams, A.J.M.; Janssen, A.J.H.

    2008-01-01

    Anaerobic methanethiol (MT) degradation by mesophilic (30 degrees C) alkaliphilic (pH 10) communities was studied in a lab-scale Upflow Anaerobic Sludge Bed (UASB) reactor inoculated with a mixture of sediments from the Wadden Sea (The Netherlands), Soap Lake (Central Washington), and Russian soda l

  20. Anaerobic degradation kinetics of a cholesteryl ester.

    Science.gov (United States)

    Gutiérrez, S; Viñas, M

    2003-01-01

    The most important components of wool scouring effluent grease are esters of sterols. Cholesteryl palmitate (CP) is the main ester in this grease. In this paper, the influence of the ester concentration in the anaerobic digestion and the relative rate of the different degradation steps, are studied. The experiment was carried out to measure methane production in the anaerobic degradation of acetate, palmitic acid (PA) and CP. A first-order kinetic model was assumed for hydrolysis and Monod models were assumed for both the methanogenic and acetogenic steps. Maximum hydrolysis rate was found to be around 20 times faster than the maximum methanogenic reaction rate during the experience. The lanolin emulsion drop size effect was also evaluated employing fine and coarse stock lanolin emulsions and no adapted sludge. Concentrations of 13.7 to 4.6 gCOD x l(-1) were employed. In a previous study, the effect of palmitic acid emulsion size was found important when similar sludge was tested. When esters are degraded, a significant effect of drop size on the degradation rate was not found. The difference between CP and PA emulsions behavior could be due to the fact that cholesterol produced during the ester degradation has a protective effect on the sludge. PMID:14640211

  1. Microbial degradation of 4-monobrominated diphenyl ether with anaerobic sludge

    International Nuclear Information System (INIS)

    Highlights: ► BDE-3 was degraded with two anaerobes in different rates. ► Glucose addition augment the debromination efficiencies. ► Hydrogen gas was detected and relative microbes were identified. ► Extra-carbon source enhanced degradation partial due to H2-generation bacteria. - Abstract: Polybrominated diphenyl ethers (PBDEs) are widely used flame retardant additives for many plastic and electronic products. Owing to their ubiquitous distribution in the environment, multiple toxicity to humans, and increasing accumulation in the environment, the fate of PBDEs is of serious concern for public safety. In this study, the degradation of 4-monobrominated diphenyl ether (BDE-3) in anaerobic sludge and the effect of carbon source addition were investigated. BDE-3 can be degraded by two different anaerobic sludge samples. The by-products, diphenyl ether (DE) and bromide ions, were monitored, indicating the reaction of debromination within these anaerobic samples. Co-metabolism with glucose facilitated BDE-3 biodegradation in terms of kinetics and efficiency in the Jhongsing sludge. Through the pattern of amplified 16S rRNA gene fragments in denatured gradient gel electrophoresis (DGGE), the composition of the microbial community was analyzed. Most of the predominant microbes were novel species. The fragments enriched in BDE-3-degrading anaerobic sludge samples are presumably Clostridium sp. This enrichment coincides with the H2 gas generation and the facilitation of debromination during the degradation process. Findings of this study provide better understanding of the biodegradation of brominated DEs and can facilitate the prediction of the fate of PBDEs in the environment.

  2. The Role of Benzoate in Anaerobic Degradation of Terephthalate

    OpenAIRE

    Kleerebezem, Robbert; Pol, Look W. Hulshoff; Lettinga, Gatze

    1999-01-01

    The effects of acetate, benzoate, and periods without substrate on the anaerobic degradation of terephthalate (1,4-benzene-dicarboxylate) by a syntrophic methanogenic culture were studied. The culture had been enriched on terephthalate and was capable of benzoate degradation without a lag phase. When incubated with a mixture of benzoate and terephthalate, subsequent degradation with preference for benzoate was observed. Both benzoate and acetate inhibited the anaerobic degradation of terephth...

  3. Stable Isotope Probing Approaches to Study Anaerobic Hydrocarbon Degradation and Degraders.

    Science.gov (United States)

    Vogt, Carsten; Lueders, Tillmann; Richnow, Hans H; Krüger, Martin; von Bergen, Martin; Seifert, Jana

    2016-01-01

    Stable isotope probing (SIP) techniques have become state-of-the-art in microbial ecology over the last 10 years, allowing for the targeted detection and identification of organisms, metabolic pathways and elemental fluxes active in specific processes within complex microbial communities. For studying anaerobic hydrocarbon-degrading microbial communities, four stable isotope techniques have been used so far: DNA/RNA-SIP, PLFA (phospholipid-derived fatty acids)-SIP, protein-SIP, and single-cell-SIP by nanoSIMS (nanoscale secondary ion mass spectrometry) or confocal Raman microscopy. DNA/RNA-SIP techniques are most frequently applied due to their most meaningful phylogenetic resolution. Especially using 13C-labeled benzene and toluene as model substrates, many new hydrocarbon degraders have been identified by SIP under various electron acceptor conditions. This has extended the current perspective of the true diversity of anaerobic hydrocarbon degraders relevant in the environment. Syntrophic hydrocarbon degradation was found to be a common mechanism for various electron acceptors. Fundamental concepts and recent advances in SIP are reflected here. A discussion is presented concerning how these techniques generate direct insights into intrinsic hydrocarbon degrader populations in environmental systems and how useful they are for more integrated approaches in the monitoring of contaminated sites and for bioremediation. PMID:26959525

  4. Kinetics and modeling of anaerobic digestion process

    DEFF Research Database (Denmark)

    Gavala, Hariklia N.; Angelidaki, Irini; Ahring, Birgitte Kiær

    2003-01-01

    Anaerobic digestion modeling started in the early 1970s when the need for design and efficient operation of anaerobic systems became evident. At that time not only was the knowledge about the complex process of anaerobic digestion inadequate but also there were computational limitations. Thus...

  5. Degradation of formaldehyde in anaerobic sequencing batch biofilm reactor (ASBBR)

    International Nuclear Information System (INIS)

    The present study evaluated the degradation of formaldehyde in a bench-scale anaerobic sequencing batch reactor, which contained biomass immobilized in polyurethane foam matrices. The reactor was operated for 212 days at 35 deg. C with 8 h sequential cycles, under different affluent formaldehyde concentrations ranging from 31.6 to 1104.4 mg/L (formaldehyde loading rates from 0.08 to 2.78 kg/m3 day). The results indicate excellent reactor stability and over 99% efficiency in formaldehyde removal, with average effluent formaldehyde concentration of 3.6 ± 1.7 mg/L. Formaldehyde degradation rates increased from 204.9 to 698.3 mg/L h as the initial concentration of formaldehyde was increased from around 100 to around 1100 mg/L. However, accumulation of organic matter was observed in the effluent (chemical oxygen demand (COD) values above 500 mg/L) due to the presence of non-degraded organic acids, especially acetic and propionic acids. This observation poses an important question regarding the anaerobic route of formaldehyde degradation, which might differ substantially from that reported in the literature. The anaerobic degradation pathway can be associated with the formation of long-chain oligomers from formaldehyde. Such long- or short-chain polymers are probably the precursors of organic acid formation by means of acidogenic anaerobic microorganisms

  6. Limited degradation of chlorophenols by anaerobic sludge granules.

    OpenAIRE

    Mohn, W W; Kennedy, K J

    1992-01-01

    To better understand the fate of chlorophenols treated in upflow anaerobic sludge bed reactors, we examined the ability of sludge granules from such bioreactors to degrade two trichlorophenols and one dichlorophenol in batch incubations under controlled conditions. Biodegradation was primarily limited to two distinct activities, reductive dehalogenation of ortho- and of meta-chlorine substituents. Both 3- and 4-monochlorophenol were persistent degradation products, while 2-monochlorophenol wa...

  7. Anaerobic/aerobic degradation of a textile dye wastewater

    OpenAIRE

    Loyd, Chapman Kemper

    1992-01-01

    Consumer demands have led to the development of new, more stable textile dyes. These dyes, many of the azo type, are often incompletely degraded/removed in wastewater treatment plants, leading to the discharge of highlycolored effluents to rivers and streams. Concerns by downstream users of that water have led to enactment of effluent color and toxicity standards for plants that treat textile dye wastewater. Both anaerobic and aerobic biological degradation of a...

  8. Assessment of the ability of sludge to degrade PCP under anaerobic conditions

    Directory of Open Access Journals (Sweden)

    R. M. L. Bolaños

    2005-12-01

    Full Text Available The capacity of sludge from different sources to degrade pentachlorophenol (PCP was evaluated. Three 2.5 liter reactors (R1, R2, and R3 were inoculated with different anaerobic sludges, semi continuously fed and maintained in orbital motion at 30±1°C. R1 was inoculated with aerobic sludge and river sediment collected downstream from a pulp and paper plant. R2 received sludge from an anaerobic reactor treating effluents from a paper recycling plant and R3 received anaerobic sludge from a biodigestor treating industrial and domestic effluents. The sludges were first acclimatized to a culture medium generally recommended for organochloride anaerobic degradation studies. The reactors were then subjected to increasing concentrations of PCP from 0.05 to 10.0 mg.l-1. PCP degradation and metabolite formation were monitored using gas chromatography, and the effects of PCP on the anaerobic process were verified by monitoring pH, volatile fatty acids, alkalinity, total suspended solids, and chemical oxygen demand. It was found that PCP did not affect reactor performance. All the sludges displayed the best PCP degradation capacity at a concentration of 0.2 mg.l-1, producing fewer chlorinated metabolites than when higher PCP concentrations were applied. R1 consistently produced fewer chlorinated metabolites, confirming the hypothesis that pre exposure to chlorinated compounds improves the sludge's capacity to degrade PCP.

  9. Xylan degradation by the anaerobic bacterium Bacteroides xylanolyticus.

    OpenAIRE

    Schyns, P.J.Y.M.J.

    1997-01-01

    Plant cell walls are the major reservoir of fixed carbon in nature. The mineralization of the fiber material, the so called lignocellulosic complex, proceeds almost exclusively by microbial processes in both aerobic and anaerobic environments. In anaerobic microbial processes the energy of the plant polymers can be conserved in fermentation products. The valorization of agricultural waste plant materials can consist of low and high technological processes. These include the production of biog...

  10. Aerobic and anaerobic microbial degradation of crude (4-methylcyclohexyl)methanol in river sediments.

    Science.gov (United States)

    Yuan, Li; Zhi, Wei; Liu, Yangsheng; Smiley, Elizabeth; Gallagher, Daniel; Chen, Xi; Dietrich, Andrea; Zhang, Husen

    2016-03-15

    Cyclohexane and some of its derivatives have been a major concern because of their significant adverse human health effects and widespread occurrence in the environment. The 2014 West Virginia chemical spill has raised public attention to (4-methylcyclohexyl)methanol (4-MCHM), one cyclohexane derivative, which is widely used in coal processing but largely ignored. In particular, the environmental fate of its primary components, cis- and trans-4-MCHM, remains largely unexplored. This study aimed to investigate the degradation kinetics and mineralization of cis- and trans-4-MCHM by sediment microorganisms under aerobic and anaerobic conditions. We found the removal of cis- and trans-4-MCHM was mainly attributed to biodegradation with little contribution from sorption. A nearly complete aerobic degradation of 4-MCHM occurred within 14days, whereas the anaerobic degradation was reluctant with residual percentages of 62.6% of cis-4-MCHM and 85.0% of trans-4-MCHM after 16-day incubation. The cis-4-MCHM was degraded faster than the trans under both aerobic and anaerobic conditions, indicating an isomer-specific degradation could occur during the 4-MCHM degradation. Nitrate addition enhanced 4-MCHM mineralization by about 50% under both aerobic and anaerobic conditions. Both cis- and trans-4-MCHM fit well with the first-order kinetic model with respective degradation rates of 0.46-0.52 and 0.19-0.31day(-)(1) under aerobic condition. Respective degradation rates of 0.041-0.095 and 0.013-0.052day(-)(1) occurred under anaerobic condition. One bacterial strain capable of effectively degrading 4-MCHM isomers was isolated from river sediments and identified as Bacillus pumilus at the species level based on 16S rRNA gene sequence and 97% identity. Our findings will provide critical information for improving the prediction of the environmental fate of 4-MCHM and other cyclohexane derivatives with similar structure as well as enhancing the development of feasible treatment

  11. Anaerobic degradation of tetrachloroethylene; Anaerober Abbau von Tetrachlorethylen

    Energy Technology Data Exchange (ETDEWEB)

    Diekert, G. [Stuttgart Univ. (Germany). Inst. fuer Mikrobiologie; Scholz-Muramatsu, H. [Stuttgart Univ. (Germany). Inst. fuer Siedlungswasserbau

    1996-12-31

    Dehalospirillum multivorans, a tetrachloroethylene-dechlorinating bacterium, was isolated in activated sludge. This organism is able to grow on a defined medium with hydrogen and tetrachloroethylene (PCE) as its only energy source. The organism was characterised and the physiology of dechlorination was studied. In this process PCE is dechlorinated to cis-1,2-dichloroethene (DCE) via trichloroethene (TCE). A fluidized-bed reactor which reduces PCE to DCE at a high rate (15 nmol/min/mg of protein at 5 {mu}M PCE) was inoculated with the bacterium. Meanwhile a reactor inoculated with D. multivorans and a fully dechlorinating mixed culture has become available which catalyses the complete dechlorination of PCE to ethene at just as high rates. Tetrachloroethene dehalogenase was purified from D. multivorans (unpublished results) and characterised. (orig./SR) [Deutsch] Aus Belebtschlamm wurde ein Tetrachlorethen-dechlorierendes Bakterium, Dehalospirillum multivorans, isoliert. Der Organismus waechst auf definiertem Medium mit Wasserstoff und Tetrachlorethen (PCE) als einziger Energiequelle. Der Organismus wurde charakterisiert und die Physiologie der Dechlorierung wurde untersucht. PCE wird dabei ueber Trichlorethen (TCE) bis zum cis-1,2-Dichlorethen (DCE) dechloriert. Mit diesem Bakterium wurde ein Wirbelschichtreaktor inokuliert, der mit hohen Raten (15 nmol/min/mg Protein bei 5 {mu}M PCE) PCE zu DCE reduziert. Inzwischen steht ein Reaktor zur Verfuegung, der mit D. multivorans und einer voellig dechlorierenden Mischkultur inokuliert wurde und der mit ebenso hohen Raten eine vollstaendige Dechlorierung von PCE bis zum Ethen katalysiert. Aus D. multivorans wurde die Tetrachlorethen-Dehalogenase gereinigt (unveroeffentlichte Ergebnisse) und charakterisiert. (orig./SR)

  12. Anaerobic Degradation of Chlorinated Hydrocarbons in Groundwater Aquifers or "Chlorinated Hydrocarbon Degradation"

    OpenAIRE

    Nielsen, R. Brent; Jay D Keasling

    1997-01-01

    Groundwater contamination by chlorinated hydrocarbons, such as tetrachloroethene (PCE) or trichloroethene (TCE), is a major concern throughout the United States. A developing strategy for the remediation of PCE and TCE contaminated aquifers is anaerobic biodegradation. From a TCE contaminated groundwater site, microorganisms were enriched with the ability to anaerobically convert PCE and TCE completely to ethene. Kinetic studies performed with this culture showed that degradation of PCE, TCE...

  13. Relating BTEX degradation to the biogeochemistry of an anaerobic aquifer

    International Nuclear Information System (INIS)

    Trends in chemical and microbiological parameters in a petroleum hydrocarbon plume within anaerobic groundwater have been studied. Previously, microbial degradation of the hydrocarbon compounds had been substantiated by the use of deuterated hydrocarbons to determine natural (intrinsic) degradation rates within the contaminant plume. Here, sulfate concentration decreases, Eh decreases, and hydrogen sulfide and bicarbonate concentration increases are shown to be associated with the contaminant plume. These trends indicate microbial degradation of the benzene, toluene, ethylbenzene, and xylene (BTEX) compounds by sulfate-reducing bacteria. Stoichiometry indicates that other consortia of bacteria play a role in the degradation of the hydrocarbons. Total microbial cell numbers were higher within the plume than in the uncontaminated groundwater. There is, however, no direct correlation between total microbial cell numbers, and BTEX, sulfate, bicarbonate, and hydrogen sulfide concentrations within the plume

  14. Biomarkers of Microbial Metabolism for Monitoring in-situ Anaerobic PAH Degradation

    Science.gov (United States)

    Young, L.; Phelps, C.; Battistelli, J.

    2002-12-01

    Monoaromatic and polycyclic aromatic compounds found in petroleum and its products are subject to biodegradation in the absence of oxygen. These anaerobic pathways reveal novel mechanism of microbial transformation through a series of metabolites and intermediates which are unique to the anaerobic degradation process. The presence of these compounds in-situ, then conceptually can serve as indicators that anaerobic degradation is taking place. We have laboratory studies and field samples which support this concept for BTX and PAH compounds. Environments in which these anaerobic degradation processes have been observed include freshwater and estuarine sediments, groundwater from impacted aquifers at a former manufactured gas plant and gasoline station, and a creosote-contaminated aquifer. Analytical protocols were developed to detect nanomolar concentrations from soil slurries and groundwater samples and microcosm studies verified their formation from field samples and use as biomarkers of activity. Recent studies on the mechanisms of anaerobic naphthalene and methylnaphthalene metabolism have identified several unusual compounds that can serve as biomarkers for monitoring in situ PAH biodegradation. For naphthalene these include 2-naphthoic acid (2-NA), tetrahydro-2-naphthoic acid (TH-2-NA), hexahydro-2-naphthoic acid (HH-2-NA) and methylnaphthoic acid (MNA) generated by sulfate-reducing bacteria degrading naphthalene or methylnaphthalene. Groundwater samples were analyzed from wells distributed throughout an anaerobic, creosote-contaminated aquifer and also from a leaking underground storage site. Samples were extracted, derivatized and analyzed by GC/MS. The concentration of 2-NA at each monitoring well was quantified and correlated to the zones of naphthalene contamination. Taken together with measurements of the aquifer's physical characteristics, these biomarker data can be used to describe the extent of naphthalene biodegradation at these site.

  15. Anaerobic degradation of alkylated benzenes in denitrifying laboratory aquifer columns

    International Nuclear Information System (INIS)

    Toluene and m-xylene were rapidly mineralized in an anaerobic laboratory aquifer column operated under continuous-flow conditions with nitrate as an electron acceptor. The oxidation of toluene and m-xylene was coupled with the reduction of nitrate, and mineralization was confirmed by trapping 14CO2 evolved from 14C-ring-labeled substrates. Substrate degradation also took place when nitrous oxide replaced nitrate as an electron acceptor, but decomposition was inhibited in the presence of molecular oxygen or after the substitution of nitrate by nitrite. The m-xylene-adapted microorganisms in the aquifer column degraded toluene, benzaldehyde, benzoate, m-toluylaldehyde, m-toluate, m-cresol, p-cresol, and p-hydroxybenzoate but were unable to metabolize benzene, naphthalene, methylcyclohexane, and 1,3-dimethylcyclohexane. Isotope-dilution experiments suggested benzoate as an intermediate formed during anaerobic toluene metabolism. The finding that the highly water-soluble nitrous oxide served as electron acceptor for the anaerobic mineralization of some aromatic hydrocarbons may offer attractive options for the in situ restoration of polluted aquifers

  16. Anaerobic Microbial Degradation of Hydrocarbons: From Enzymatic Reactions to the Environment.

    Science.gov (United States)

    Rabus, Ralf; Boll, Matthias; Heider, Johann; Meckenstock, Rainer U; Buckel, Wolfgang; Einsle, Oliver; Ermler, Ulrich; Golding, Bernard T; Gunsalus, Robert P; Kroneck, Peter M H; Krüger, Martin; Lueders, Tillmann; Martins, Berta M; Musat, Florin; Richnow, Hans H; Schink, Bernhard; Seifert, Jana; Szaleniec, Maciej; Treude, Tina; Ullmann, G Matthias; Vogt, Carsten; von Bergen, Martin; Wilkes, Heinz

    2016-01-01

    Hydrocarbons are abundant in anoxic environments and pose biochemical challenges to their anaerobic degradation by microorganisms. Within the framework of the Priority Program 1319, investigations funded by the Deutsche Forschungsgemeinschaft on the anaerobic microbial degradation of hydrocarbons ranged from isolation and enrichment of hitherto unknown hydrocarbon-degrading anaerobic microorganisms, discovery of novel reactions, detailed studies of enzyme mechanisms and structures to process-oriented in situ studies. Selected highlights from this program are collected in this synopsis, with more detailed information provided by theme-focused reviews of the special topic issue on 'Anaerobic biodegradation of hydrocarbons' [this issue, pp. 1-244]. The interdisciplinary character of the program, involving microbiologists, biochemists, organic chemists and environmental scientists, is best exemplified by the studies on alkyl-/arylalkylsuccinate synthases. Here, research topics ranged from in-depth mechanistic studies of archetypical toluene-activating benzylsuccinate synthase, substrate-specific phylogenetic clustering of alkyl-/arylalkylsuccinate synthases (toluene plus xylenes, p-cymene, p-cresol, 2-methylnaphthalene, n-alkanes), stereochemical and co-metabolic insights into n-alkane-activating (methylalkyl)succinate synthases to the discovery of bacterial groups previously unknown to possess alkyl-/arylalkylsuccinate synthases by means of functional gene markers and in situ field studies enabled by state-of-the-art stable isotope probing and fractionation approaches. Other topics are Mo-cofactor-dependent dehydrogenases performing O2-independent hydroxylation of hydrocarbons and alkyl side chains (ethylbenzene, p-cymene, cholesterol, n-hexadecane), degradation of p-alkylated benzoates and toluenes, glycyl radical-bearing 4-hydroxyphenylacetate decarboxylase, novel types of carboxylation reactions (for acetophenone, acetone, and potentially also benzene and

  17. Effect of Volatile Fatty Acid Concentration on Anaerobic Degradation Rate from Field Anaerobic Digestion Facilities Treating Food Waste Leachate in South Korea

    Directory of Open Access Journals (Sweden)

    Dong-Jin Lee

    2015-01-01

    Full Text Available The purpose of this study was to investigate the effect of volatile fatty acid concentration on anaerobic degradation rate of food waste leachate in the anaerobic digestion facilities. The anaerobic digestion facilities treating food waste leachate (FWL, codigestion with food leachate and animal manure (A-MIX, and codigestion with food waste leachate and sewage sludge (S-MIX were selected for this study. In accordance with the regulation under Wastes Control Act in South Korea, the guideline of volatile solid removal rate for anaerobic digestion facility is set as 65% for anaerobic degradation efficiency. Highest volatile solids removal rates were achieved from FWL (63.5% than A-MIX (56.4% and S-MIX (41.2%. Four out of eight FWLs met the guidelines. The concentration of volatile fatty acids, therefore, was analyzed to determine the relationship with volatile solid removal rate. The results showed that, in order to meet the Korean guideline of 65% volatile solid removal rate, volatile fatty acid concentrations should remain below 4,000 mg/L on the field anaerobic digestion facilities treating FWL. Volatile fatty acid concentrations should be used along with others as an operational parameter to control and manage the anaerobic digestion process.

  18. Anaerobic degradation of carbon capture reclaimer MEA waste.

    Science.gov (United States)

    Wang, S; Hovland, J; Bakke, R

    2013-01-01

    The anaerobic biodegradation of reclaimer MEA (monoethanolamine) waste (MEAw) with easily degradable co-substrates was investigated in a laboratory-scale bioreactor at room temperature during a 160 d experimental run. The reactor that was constructed with three phases to facilitate attached biofilm and suspended biomass retention for degradation of the complex and challenging MEAw performed well. A feed strategy of step-wise increasing organic loading rate (OLR) by either increasing feed MEAw concentration or the hydraulic loading rate was applied. The system performance was evaluated by chemical oxygen demand (COD) removal efficiency, methane yield, MEA removal, and the accumulation of ammonia and volatile fatty acid (VFA). The total COD removal efficiency initially was 93% when the feed was mainly easily degradable co-substrate. The total removal dropped to 75% at the end when MEAw constituted 60% of the feed COD. Ion chromatography results show that the MEA and some unidentified feed chemicals were almost completely consumed. The main products of MEAw degradation were ammonia, VFAs and biogas. The ammonia nitrogen concentration reached about 2.0 g/L, which may explain the observed inhibition of acetoclastic methanogenesis leading to acetate accumulation. Methane accounted for up to 80% of the biogas generated. The highest methane yield was 0.34 L/g-COD while the yield was 0.16 L/g-COD at the highest load. This study shows that more than 80% reclaimer MEAw COD degradation with a co-substrate can be maintained in a hybrid anaerobic bioreactor operated in a wide loading range. PMID:23752388

  19. Two-phase anaerobic digestion of coffee wet wastewater: Effect of recycle on anaerobic process performance

    Directory of Open Access Journals (Sweden)

    Yans Guardia Puebla

    2014-01-01

    Full Text Available The present work shows the results of the two-phase anaerobic digestion assessment for the treatment of coffee wet wastewater. The effect of recycle on the anaerobic digestion process was studied. Twooverall organic loading rate (OLR values of 4,2 and 5,7 kgCOD·m -3 ·d -1 , with same overall hydraulic retention time (HRT of 21,5 h was evaluated.In a two-phase system wereapplied two recycle rate of 0,4 and 1,0, of the effluent of an UASB-UAF methanogenic hybrid reactor towards an UASB acidogenic reactor. In the anaerobic system with a recycle rate of 1,0 the total chemical oxygen demand (COD removal was 90%. The introduction of the recycle decreased the concentration of total volatile fatty acids (VFA, but it did not affect their composition, suggesting that the degradation pattern did not change. The presence of the acidogenic reactor in the two-phase system improved the stability of the anaerobic digestion process and increased the efficiency of methanogenic digester.

  20. Kinetics and modeling of anaerobic digestion process

    DEFF Research Database (Denmark)

    Gavala, Hariklia N.; Angelidaki, Irini; Ahring, Birgitte Kiær

    Anaerobic digestion modeling started in the early 1970s when the need for design and efficient operation of anaerobic systems became evident. At that time not only was the knowledge about the complex process of anaerobic digestion inadequate but also there were computational limitations. Thus, the...... first models were very simple and consisted of a limited number of equations. During the past thirty years much research has been conducted on the peculiarities of the process and on the factors that influence it on the one hand while an enormous progress took place in computer science on the other. The...... combination of both parameters resulted in the development of more and more concise and complex models. In this chapter the most important models found in the literature are described starting from the simplest and oldest to the more recent and complex ones....

  1. Effect of Disinfectant on Anaerobic Degradation of Wastewater

    Directory of Open Access Journals (Sweden)

    Prof. J.C Agunwamba1 ,

    2014-08-01

    Full Text Available A field experiment to investigate the effects of disinfectant on anaerobic degradation of sewage was carried out using wastewater. It was found that disinfectant is not completely favorable to degradation of sewage. Sewage was collected from the University Of Nigeria Nsukka treatment plant and transferred into six (6 clean four (4 Litre white bucket with mouth covered and black polythene bag to prevent the interference of sun-light and oxygen. To five (5 of the samples contained in the four (4 litre buckets , 0.5ml, 1.0ml, 1.5m, 2.0ml, 2.5ml, of each of the two (2 disinfectants (Izal and Dettol were added with the last serving as a control sample, stirred initially and covered all through the experiment which lasted for one (1 month each. The experimental run was divided into two set, set A with Dettol dosed and set B with Izal dosed. Samples collected twice a week for analysis and the parameters checked for included: Biochemical Oxygen Demand (BOD, Chemical Oxygen Demand (COD, and Fecal Coliform (FC. It was observed that addition of disinfectant on sewage can make wastewater characteristic increase the organic content present in sewage and may later decrease the degradation or make the bacteria weak.

  2. Applications of the anaerobic digestion process

    DEFF Research Database (Denmark)

    Angelidaki, Irini; Ellegaard, L.; Ahring, Birgitte Kiær

    2003-01-01

    and resource/energy recovery have been developed. Treatment of biowastes by anaerobic digestion processes is in many cases the optimal way to convert organic waste into useful products such as energy (in the form of biogas) and a fertilizer product. Other waste management options, such as land filling...

  3. Anaerobic degradation of aircraft deicing fluid (ADF) in upflow anaerobic sludge blanket (UASB) reactors and the fate of ADF additives

    Science.gov (United States)

    Pham, Thi Tham

    2002-11-01

    A central composite design was employed to methodically investigate anaerobic treatment of aircraft deicing fluid (ADF) in bench-scale Upflow Anaerobic Sludge Blanket (UASB) reactors. A total of 23 runs at 17 different operating conditions were conducted in continuous mode. The development of four empirical models describing process responses (i.e., chemical oxygen demand (COD) removal efficiency, biomass specific acetoclastic activity, methane production rate, and methane production potential) as functions of ADF concentration, hydraulic retention time (HRT), and biomass concentration is presented. Model verification indicated that predicted responses (COD removal efficiencies, biomass specific acetoclastic activity, and methane production rates and potential) were in good agreement with experimental results. Biomass specific acetoclastic activity was improved by almost two-fold during ADF treatment in UASB reactors. For the design window, COD removal efficiencies were higher than 90%. Predicted methane production potentials were close to theoretical values, and methane production rates increased as the organic loading rate (OLR) was increased. ADF toxicity effects were evident for 1.6% ADF at medium specific organic loadings (SOLR above 0.5 g COD/g VSS/d). In contrast, good reactor stability and excellent removal efficiencies were achieved at 1.2% ADF for reactor loadings approaching that of highly loaded systems (0.73 g COD/g VSS/d). Acclimation to ADF resulted in an initial reduction in the biomass settling velocity. The fate of ADF additives was also investigated. There was minimal sorption of benzotriazole (BT), 5-methyl-1 H-benzotriazole (MeBT), and 5,6-dimethyl-1 H-benzotriazole (DiMeBT) to anaerobic granules. A higher sorption capacity was measured for NP. Active transport may be one of the mechanisms for NP sorption. Ethylene glycol degradation experiments indicated that BT, MeBT, DiMeBT, and the nonionic surfactant Tergitol NP-4 had no significant

  4. New anaerobic process of nitrogen removal.

    Science.gov (United States)

    Kalyuzhnyi, S; Gladchenko, M; Mulder, A; Versprille, B

    2006-01-01

    This paper reports on successful laboratory testing of a new nitrogen removal process called DEAMOX (DEnitrifying AMmonium OXidation) for the treatment of strong nitrogenous wastewater such as baker's yeast effluent. The concept of this process combines the recently discovered ANAMMOX (ANaerobic AMMonium OXidation) reaction with autotrophic denitrifying conditions using sulfide as an electron donor for the production of nitrite within an anaerobic biofilm. The achieved results with a nitrogen loading rate of higher than 1,000 mg/L/d and nitrogen removal of around 90% look very promising because they exceed (by 9-18 times) the corresponding nitrogen removal rates of conventional activated sludge systems. The paper describes also some characteristics of DEAMOX sludge, as well as the preliminary results of its microbiological characterization. PMID:17163025

  5. Robust regulation of anaerobic digestion processes.

    Science.gov (United States)

    Mailleret, L; Bernard, O; Steyer, J P

    2003-01-01

    This paper deals with the problem of controlling anaerobic digestion processes. A two-step (i.e. acidogenesis-methanization) mass balance model is considered for a 1 m3 fixed bed digester treating industrial wine distillery wastewater. The control law aims at regulating the organic pollution level while avoiding washout of biomass. To this end, a simple output feedback controller is considered which regulates a variable strongly related to the Chemical Oxygen Demand (COD). Numerical simulations assuming noisy measurements first illustrate the robustness of this control procedure. Then, the regulating procedure is implemented on the considered anaerobic digestion process in order to validate and demonstrate its efficiency in real life experiments. PMID:14640204

  6. Functional Gene Markers for Fumarate-Adding and Dearomatizing Key Enzymes in Anaerobic Aromatic Hydrocarbon Degradation in Terrestrial Environments.

    Science.gov (United States)

    von Netzer, Frederick; Kuntze, Kevin; Vogt, Carsten; Richnow, Hans H; Boll, Matthias; Lueders, Tillmann

    2016-01-01

    Anaerobic degradation is a key process in many environments either naturally or anthropogenically exposed to petroleum hydrocarbons. Considerable advances into the biochemistry and physiology of selected anaerobic degraders have been achieved over the last decades, especially for the degradation of aromatic hydrocarbons. However, researchers have only recently begun to explore the ecology of complex anaerobic hydrocarbon degrader communities directly in their natural habitats, as well as in complex laboratory systems using tools of molecular biology. These approaches have mainly been facilitated by the establishment of a suite of targeted marker gene assays, allowing for rapid and directed insights into the diversity as well as the identity of intrinsic degrader populations and degradation potentials established at hydrocarbon-impacted sites. These are based on genes encoding either peripheral or central key enzymes in aromatic compound breakdown, such as fumarate-adding benzylsuccinate synthases or dearomatizing aryl-coenzyme A reductases, or on aromatic ring-cleaving hydrolases. Here, we review recent advances in this field, explain the different detection methodologies applied, and discuss how the detection of site-specific catabolic gene markers has improved the understanding of processes at contaminated sites. Functional marker gene-based strategies may be vital for the development of a more elaborate population-based assessment and prediction of aromatic degradation potentials in hydrocarbon-impacted environments. PMID:26959523

  7. Biological degradation of triclocarban and triclosan in a soil under aerobic and anaerobic conditions and comparison with environmental fate modelling

    International Nuclear Information System (INIS)

    Triclocarban and triclosan are two antimicrobial agents widely used in many personal care products. Their biodegradation behaviour in soil was investigated by laboratory degradation experiments and environmental fate modelling. Quantitative structure-activity relationship (QSAR) analyses showed that triclocarban and triclosan had a tendency to partition into soil or sediment in the environment. Fate modelling suggests that either triclocarban or triclosan 'does not degrade fast' with its primary biodegradation half-life of 'weeks' and ultimate biodegradation half-life of 'months'. Laboratory experiments showed that triclocarban and triclosan were degraded in the aerobic soil with half-life of 108 days and 18 days, respectively. No negative effect of these two antimicrobial agents on soil microbial activity was observed in the aerobic soil samples during the experiments. But these two compounds persisted in the anaerobic soil within 70 days of the experimental period. - Triclocarban and triclosan can be degraded by microbial processes in aerobic soil, but will persist in anaerobic soil

  8. Anaerobic Digestion. Student Manual. Biological Treatment Process Control.

    Science.gov (United States)

    Carnegie, John W., Ed.

    This student manual contains the textual material for a four-lesson unit on anaerobic digestion control. Areas addressed include: (1) anaerobic sludge digestion (considering the nature of raw sludge, purposes of anaerobic digestion, the results of digestion, types of equipment, and other topics); (2) digester process control (considering feeding…

  9. Evidence of hydrolytic route for anaerobic cyanide degradation.

    OpenAIRE

    Fallon, R. D.

    1992-01-01

    Products observed during anaerobic cyanide transformation are consistent with a hydrolytic pathway (HCN + H2O HCONH2 + H2O HCOOH + NH3). Formate, the most frequently observed product, was generally converted to bicarbonate. Formamide was rapidly hydrolyzed to formate upon exposure to the anaerobic consortium but was not detected as an intermediate of cyanide transformation.

  10. Anaerobic Degradation of Chloroaromatic Compounds in Aquatic Sediments under a Variety of Enrichment Conditions †

    OpenAIRE

    Genthner, Barbara R. Sharak; Price, W. Allen; Pritchard, P H

    1989-01-01

    Anaerobic degradation of monochlorophenols and monochlorobenzoates in a variety of aquatic sediments was compared under four enrichment conditions. A broader range of compounds was degraded in enrichments inoculated with sediment exposed to industrial effluents. Degradation of chloroaromatic compounds was observed most often in methanogenic enrichments and in enrichments amended with 1 mM bromoethane sulfonic acid. Degradation was observed least often in enrichments with added nitrate or sulf...

  11. Anaerobic aniline degradation via reductive deamination of 4-aminobenzoyl-CoA in Desulfobacterium anilini

    OpenAIRE

    Schnell, Sylvia; Schink, Bernhard

    1991-01-01

    The initial reactions involved in anaerobic aniline degradation by the sulfate-reducing Desulfobacterium anilini were studied. Experiments for substrate induction indicated the presence of a common pathway for aniline and 4-aminobenzoate, different from that for degradation of 2-aminobenzoate, 2-hydroxybenzoate, 4-hydroxybenzoate, or phenol. Degradation of aniline by dense cell suspensions depended on CO2 whereas 4-aminobenzoate degradation did not. If acetyl-CoA oxidation was inhibited by cy...

  12. Polychlorinated biphenyl (PCB) anaerobic degradation in marine sediments: microcosm study and role of autochthonous microbial communities.

    Science.gov (United States)

    Matturro, Bruna; Ubaldi, Carla; Grenni, Paola; Caracciolo, Anna Barra; Rossetti, Simona

    2016-07-01

    Polychlorobiphenyl (PCB) biodegradation was followed for 1 year in microcosms containing marine sediments collected from Mar Piccolo (Taranto, Italy) chronically contaminated by this class of hazardous compounds. The microcosms were performed under strictly anaerobic conditions with or without the addition of Dehalococcoides mccartyi, the main microorganism known to degrade PCBs through the anaerobic reductive dechlorination process. Thirty PCB congeners were monitored during the experiments revealing that the biodegradation occurred in all microcosms with a decrease in hepta-, hexa-, and penta-chlorobiphenyls (CBs) and a parallel increase in low chlorinated PCBs (tri-CBs and tetra-CBs). The concentrations of the most representative congeners detected in the original sediment, such as 245-245-CB and 2345-245-CB, and of the mixture 2356-34-CB+234-245-CB, decreased by 32.5, 23.8, and 46.7 %, respectively, after only 70 days of anaerobic incubation without any bioaugmentation treatment. Additionally, the structure and population dynamics of the microbial key players involved in the biodegradative process and of the entire mixed microbial community were accurately defined by Catalyzed Reporter Deposition Fluorescence In Situ Hybridization (CARD-FISH) in both the original sediment and during the operation of the microcosm. The reductive dehalogenase genes of D. mccartyi, specifically involved in PCB dechlorination, were also quantified using real-time PCR (qPCR). Our results demonstrated that the autochthonous microbial community living in the marine sediment, including D. mccartyi (6.32E+06 16S rRNA gene copy numbers g(-1) sediment), was able to efficiently sustain the biodegradation of PCBs when controlled anaerobic conditions were imposed. PMID:26162439

  13. Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

    International Nuclear Information System (INIS)

    Highlights: → Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. → Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. → Several species from classes β-, δ- and γ-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 μM of benzene were degraded, which corresponds to 279 ± 27 micro-electron equivalents (μEq) L-1, linked to the reduction of 619 ± 81 μEq L-1 of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two γ-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes β-, δ- and γ-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

  14. Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, Francisco J., E-mail: fjcervantes@ipicyt.edu.mx [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Mancilla, Ana Rosa; Toro, E. Emilia Rios-del [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia [Division de Biologia Molecular, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico)

    2011-11-15

    Highlights: {yields} Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. {yields} Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. {yields} Several species from classes {beta}-, {delta}- and {gamma}-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 {mu}M of benzene were degraded, which corresponds to 279 {+-} 27 micro-electron equivalents ({mu}Eq) L{sup -1}, linked to the reduction of 619 {+-} 81 {mu}Eq L{sup -1} of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two {gamma}-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes {beta}-, {delta}- and {gamma}-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

  15. An investigation of inhibition effect of metronidazole before and after using advanced oxidation process (UV254/H2O2 on specific methanogenic activity of anaerobic biomass

    Directory of Open Access Journals (Sweden)

    S. A. Mirzaee

    2014-07-01

    Conclusion: Different concentrations of metronidazole had an inhibition effect on anaerobic digestions and therefore the efficient pretreatment method is needed to reduce this inhibition effect. The UV254/H2O2 process is an effective method for degradation and conversion of metronidazole to more biodegradable compounds for anaerobic bacteria consumption and, in turn, to increase biogasproduction in anaerobic digestions.

  16. Microbial dynamics in anaerobic enrichment cultures degrading di-n-butyl phthalic acid ester

    DEFF Research Database (Denmark)

    Trably, Eric; Batstone, Damien J.; Christensen, Nina;

    2008-01-01

    enrichment cultures degrading phthalic acid esters under methanogenic conditions. A selection pressure was applied by adding DBP at 10 and 200 mg L(-1) in semi-continuous anaerobic reactors. The microbial dynamics were monitored using single strand conformation polymorphism (SSCP). While only limited abiotic...... microorganism described previously as an anaerobic benzaldehyde degrader. Within the archaeal community, there was a shift between two different species of the genus Methanosaeta sp., indicating a highly specific impact of DBP or degradation products on archaeal species. RNA-directed probes were designed from...

  17. Solid-, Solution-, and Gas-state NMR Monitoring of 13C-Cellulose Degradation in an Anaerobic Microbial Ecosystem

    Directory of Open Access Journals (Sweden)

    Yasuhiro Date

    2013-07-01

    Full Text Available Anaerobic digestion of biomacromolecules in various microbial ecosystems is influenced by the variations in types, qualities, and quantities of chemical components. Nuclear magnetic resonance (NMR spectroscopy is a powerful tool for characterizing the degradation of solids to gases in anaerobic digestion processes. Here we describe a characterization strategy using NMR spectroscopy for targeting the input solid insoluble biomass, catabolized soluble metabolites, and produced gases. 13C-labeled cellulose produced by Gluconacetobacter xylinus was added as a substrate to stirred tank reactors and gradually degraded for 120 h. The time-course variations in structural heterogeneity of cellulose catabolism were determined using solid-state NMR, and soluble metabolites produced by cellulose degradation were monitored using solution-state NMR. In particular, cooperative changes between the solid NMR signal and 13C-13C/13C-12C isotopomers in the microbial degradation of 13C-cellulose were revealed by a correlation heat map. The triple phase NMR measurements demonstrated that cellulose was anaerobically degraded, fermented, and converted to methane gas from organic acids such as acetic acid and butyric acid.

  18. Anaerobic degradation of inedible crop residues produced in a Controlled Ecological Life Support System

    Science.gov (United States)

    Schwingel, W. R.; Sager, J. C.

    1996-01-01

    An anaerobic reactor seeded with organisms from an anaerobic lagoon was used to study the degradation of inedible crop residues from potato and wheat crops grown in a closed environment. Conversion of this biomass into other products was also evaluated. Degradation of wheat volatile solids was about 25% where that of potato was about 50%. The main product of the anaerobic fermentation of both crops was acetic acid with smaller quantities of propionate and butyrate produced. Nitrate, known to be high in concentration in inedible potato and wheat biomass grown hydroponically, was converted to ammonia in the anaerobic reactor. Both volatile fatty acid and ammonia production may have implications in a crop production system.

  19. Anaerobic degradation of inedible crop residues produced in a Controlled Ecological Life Support System.

    Science.gov (United States)

    Schwingel, W R; Sager, J C

    1996-01-01

    An anaerobic reactor seeded with organisms from an anaerobic lagoon was used to study the degradation of inedible crop residues from potato and wheat crops grown in a closed environment. Conversion of this biomass into other products was also evaluated. Degradation of wheat volatile solids was about 25% where that of potato was about 50%. The main product of the anaerobic fermentation of both crops was acetic acid with smaller quantities of propionate and butyrate produced. Nitrate, known to be high in concentration in inedible potato and wheat biomass grown hydroponically, was converted to ammonia in the anaerobic reactor. Both volatile fatty acid and ammonia production may have implications in a crop production system. PMID:11538974

  20. Hydroxylation and Carboxylation—Two Crucial Steps of Anaerobic Benzene Degradation by Dechloromonas Strain RCB

    OpenAIRE

    Chakraborty, Romy; Coates, John D.

    2005-01-01

    Benzene is a highly toxic industrial compound that is essential to the production of various chemicals, drugs, and fuel oils. Due to its toxicity and carcinogenicity, much recent attention has been focused on benzene biodegradation, especially in the absence of molecular oxygen. However, the mechanism by which anaerobic benzene biodegradation occurs is still unclear. This is because until the recent isolation of Dechloromonas strains JJ and RCB no organism that anaerobically degraded benzene ...

  1. Isolation and characterization of an anaerobic ruminal bacterium capable of degrading hydrolyzable tannins.

    OpenAIRE

    Nelson, K E; A. N. Pell; Schofield, P; Zinder, S

    1995-01-01

    An anaerobic diplococcoid bacterium able to degrade hydrolyzable tannins was isolated from the ruminal fluid of a goat fed desmodium (Desmodium ovalifolium), a tropical legume which contains levels as high as 17% condensed tannins. This strain grew under anaerobic conditions in the presence of up to 30 g of tannic acid per liter and tolerated a range of phenolic monomers, including gallic, ferulic, and p-coumaric acids. The predominant fermentation product from tannic acid breakdown was pyrog...

  2. Assessment of the ability of sludge to degrade PCP under anaerobic conditions

    OpenAIRE

    R. M. L. Bolaños; M. H. R. Z. Damianovic; ZAIAT M.; E. Foresti

    2005-01-01

    The capacity of sludge from different sources to degrade pentachlorophenol (PCP) was evaluated. Three 2.5 liter reactors (R1, R2, and R3) were inoculated with different anaerobic sludges, semi continuously fed and maintained in orbital motion at 30±1°C. R1 was inoculated with aerobic sludge and river sediment collected downstream from a pulp and paper plant. R2 received sludge from an anaerobic reactor treating effluents from a paper recycling plant and R3 received anaerobic sludge...

  3. Degradation Action of the Anaerobic Bacteria and Oxygen to the Polymer

    Institute of Scientific and Technical Information of China (English)

    LU Xiang-Guo; ZHANG Ke

    2008-01-01

    Oxygen could prohibit anaerobic bacterium in the produced water and degrade the polymer molecular chains.Aiming at problems making up aerobic polymer solution by the produced water in Daqing Oil Field, some evaluations were done on the viscosity characteristics of polymer solution and bactericide in anaerobic and aerobic environments. Reasonable aerobic concentration of the produced water was obtained. The experimental results indicate that the viscosity of polymer solution confected by the produced water in the aerobic environment is higher than that of the polymer solution confected by the produced water in the anaerobic environment, and the reasonable ments, but the sterilization effect is better in the aerobic environment.

  4. Degradation of a mono sulfonated azo dye by an integrated bio sorption and anaerobic system

    International Nuclear Information System (INIS)

    A simulated textile effluent containing a mono sulphonated azo dye was fed to an anaerobic bioreactor in which a natural adsorbent, spent brewery grains (SBG), was incorporated. SABG is a by-product of the brewing industry and could act as adsorbent as well an electron shuttle (lignin fraction) in the dye degradation mechanism. Furthermore, it can also work as a conditioner for the anaerobic biomass. The influence of the dye (Acid Orange 7, AO7) concentration (60 and 150 mg/L) and the presence of SBG in the performance of upflow anaerobic sludge blanket reactor (UASB) was evaluated. (Author)

  5. Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

    Science.gov (United States)

    Chapatwala, Kirit D.; Babu, G. R. V.; Baresi, Larry; Trunzo, Richard M.

    1995-01-01

    Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

  6. Removal and Degradation Pathways of Sulfamethoxazole Present in Synthetic Municipal Wastewater via an Anaerobic Membrane Bioreactor

    KAUST Repository

    Sanchez Huerta, Claudia

    2016-05-01

    The current global water crisis in addition to continues contamination of natural water bodies with harmful organic micropollutants (OMPs) have driven the development of new water treatment technologies that allow the efficient removal of such compounds. Among a long list of OMPs, antibiotics are considered as top priority pollutants to be treated due to their great resistance to biological treatments and their potential to develop bacterial resistance. Different approaches, such as membrane-based and advance oxidation processes have been proposed to alleviate or minimize antibiotics discharge into aquatic environments. However most of these processes are costly and generate either matrices with high concentration of OMPs or intermediate products with potentially greater toxicity or persistence. Therefore, this thesis proposes the study of an anaerobic membrane bioreactor (AnMBR) for the treatment of synthetic municipal wastewater containing sulfamethoxazole (SMX), a world widely used antibiotic. Besides the general evaluation of AnMBR performance in the COD removal and biogas production, this research mainly focuses on the SMX removal and its degradation pathway. Thus 5 SMX quantification was performed through solid phase extraction-liquid chromatography/mass spectrometry and the identification of its transformation products (TPs) was assessed by gas chromatography/mass spectrometry technique. The results achieved showed that, working under optimal conditions (35°C, pH 7 and ORP around -380 to -420 mV) and after a biomass adaptation period (maintaining 0.85 VSS/TSS ratio), the AnMBR process provided over 95% COD removal and 95-98% SMX removal, while allowing stable biogas composition and methane production (≈130 mL CH4/g CODremoved). Kinetic analysis through a batch test showed that after 24 h of biological reaction, AnMBR process achieved around 94% SMX removal, indicating a first order kinetic reaction with K= 0.119, which highlights the high degradation

  7. Degradation of BTEX by anaerobic bacteria: physiology and application

    OpenAIRE

    Weelink, S.A.B.; Eekert, van, M.H.A.; Stams, A.J.M.

    2010-01-01

    Pollution of the environment with aromatic hydrocarbons, such as benzene, toluene, ethylbenzene and xylene (so-called BTEX) is often observed. The cleanup of these toxic compounds has gained much attention in the last decades. In situ bioremediation of aromatic hydrocarbons contaminated soils and groundwater by naturally occurring microorganisms or microorganisms that are introduced is possible. Anaerobic bioremediation is an attractive technology as these compounds are often present in the a...

  8. Mathematical modelling of anaerobic digestion processes: applications and future needs

    DEFF Research Database (Denmark)

    Batstone, Damien J.; Puyol, Daniel; Flores Alsina, Xavier;

    2015-01-01

    of the role of the central carbon catabolic metabolism in anaerobic digestion, with an increased importance of phosphorous, sulfur, and metals as electron source and sink, and consideration of hydrogen and methane as potential electron sources. The paradigm of anaerobic digestion is challenged by anoxygenic...... phototrophism, where energy is relatively cheap, but electron transfer is expensive. These new processes are commonly not compatible with the existing structure of anaerobic digestion models. These core issues extend to application of anaerobic digestion in domestic plant-wide modelling, with the need......Anaerobic process modelling is a mature and well-established field, largely guided by a mechanistic model structure that is defined by our understanding of underlying processes. This led to publication of the IWA ADM1, and strong supporting, analytical, and extension research in the 15 years since...

  9. Inhibition of the anaerobic digestion process by linear alkylbenzene sulfonates

    DEFF Research Database (Denmark)

    Gavala, Hariklia N.; Ahring, Birgitte Kiær

    2002-01-01

    it is important to investigate the effect of these xenobiotic compounds on an anaerobic environment. The inhibitory effect of Linear Alkylbenzene Sulfonates (LAS) on the acetogenic and methanogenic step of the anaerobic digestion process was studied. LAS inhibit both acetogenesis from propionate...... of the anaerobic digestion process should be seriously taken into consideration when wastewater from a surfactant producing industry is to be treated biologically or enter a municipal wastewater treatment plant that employs anaerobic technology. The upper allowable biomass specific LAS concentration should be 14......Linear Alkylbenzene Sulfonates (LAS) are the most widely used synthetic anionic surfactants. They are anthropogenic, toxic compounds and are found in the primary sludge generated in municipal wastewater treatment plants. Primary sludge is usually stabilized anaerobically and therefore...

  10. Distribution of Digoxin-reducing, Oxalate-degrading, and Total Anaerobic Bacteria in the Human Colon

    OpenAIRE

    Weaver, G A; Krause, J A; Allison, M J; Lindenbaum, J.

    2011-01-01

    Samples of the mucosal surface of the caecum and sigmoid colon were obtained from 33 colonoscopy subjects for microbiol studies using a microbiology brush system. Faecal samples and caecal lumen aspirates were also obtained. Estimated numbers of digoxin-reducing, oxalate-degrading and total anaerobic bacteria from the caecal brush samples correlated significantly with the respective concentrations of these organisms from the sigmoid area. The concentrations of oxalate-degrading bacteria and t...

  11. Electron beam/biological processing of anaerobic and aerobic sludge

    International Nuclear Information System (INIS)

    Besides common chemical and biological methods, the radiation technology is a promising way of sludge treatment. The paper describes possibilities of combined accelerated electrons/biological processing of both anaerobic and aerobic sludge. Besides one-shot experiments, experimental reactors for the simulation of anaerobic processes have been used. Main effort has been aimed to decrease organic compounds concentration and overall volume of solids, to improve some physico-chemical parameters of sludge, to validate hygienisation effects of the ionising radiation, and in the case of anaerobic sludge, to increase the volume of the produced biogas. Positive effects of the electron beam processing have been observed on all previously named parameters. (author)

  12. A novel denitrifying bacterial isolate that degrades trimethylamine both aerobically and anaerobically via two different pathways.

    Science.gov (United States)

    Kim, S G; Bae, H S; Lee, S T

    2001-10-01

    The aerobic and anaerobic degradation of trimethylamine by a newly isolated denitrifying bacterium from an enrichment culture with trimethylamine inoculated with activated sludge was studied. Based on 16S rDNA analysis, this strain was identified as a Paracoccus sp. The isolate, strain T231, aerobically degraded trimethylamine, dimethylamine and methylamine and released a stoichiometric amount of ammonium ion into the culture fluid as a metabolic product, indicating that these methylated amines were completely degraded to formaldehyde and ammonia. The strain degraded trimethylamine also under denitrifying conditions and consumed a stoichiometric amount of nitrate, demonstrating that complete degradation of trimethylamine was coupled with nitrate reduction. Cell-free extract prepared from cells grown aerobically on trimethylamine exhibited activities of trimethylamine mono-oxygenase, trimethylamine N-oxide demethylase, dimethylamine mono-oxygenase, and methylamine mono-oxygenase. Cell-free extract from cells grown anaerobically on trimethylamine and nitrate exhibited activities of trimethylamine dehydrogenase and dimethylamine dehydrogenase. These results indicate that strain T231 had two different pathways for aerobic and anaerobic degradation of trimethylamine. This is a new feature for trimethylamine metabolism in denitrifying bacteria. PMID:11685371

  13. Anaerobic degradation of landfill leachate using an upflow anaerobic fixed-bed reactor with microbial sulfate reduction

    International Nuclear Information System (INIS)

    This study evaluated the anaerobic degradation of landfill leachate and sulfate reduction as a function of COD/(SO42-) ratio in an upflow anaerobic fixed-bed reactor. The reactor, which was inoculated with a mixed consortium, was operated under a constant hydraulic retention time (HRT) of 5 days. We investigated the effect of COD/(SO42-) ratio variation on the sulfate reduction efficiency, hydrogen sulfide production, chemical oxygen demand (COD) removal, conductivity, and pH variation. The best reactor performance, with significant sulfate reduction efficiency and COD removal efficiency of 91% and 87%, respectively, was reached under a COD/(SO42-) ratio of 1.17. Under these conditions, microscopic analysis showed the abundance of vibrios and rod-shaped bacterial cells. Two anaerobic bacteria were isolated from the reactor sludge. Phylogenetic studies performed on these strains identified strain A1 as affiliated to Clostridium genus and strain H1 as a new species of sulfate-reducing bacteria affiliated to the Desulfovibrio genus. The closest phylogenetic relative of strain H1 was Desulfovibrio desulfuricans, at 96% similarity for partial 16S RNA gene sequence data. Physiological and metabolic characterization was performed for this strain.

  14. Initiation of Anaerobic Degradation of p-Cresol by Formation of 4-Hydroxybenzylsuccinate in Desulfobacterium cetonicum

    OpenAIRE

    Müller, Jochen A.; Galushko, Alexander S.; Kappler, Andreas; Bernhard SCHINK

    2001-01-01

    The anaerobic bacterium Desulfobacterium cetonicum oxidized p-cresol completely to CO2 with sulfate as the electron acceptor. During growth, 4-hydroxybenzylsuccinate accumulated in the medium. This finding indicated that the methyl group of p-cresol is activated by addition to fumarate, analogous to anaerobic toluene, m-xylene, and m-cresol degradation. In cell extracts, the formation of 4-hydroxybenzylsuccinate from p-cresol and fumarate was detected at an initial rate of 0.57 nmol min21 (mg...

  15. Improved ADM1 model for anaerobic digestion process considering physico-chemical reactions.

    Science.gov (United States)

    Zhang, Yang; Piccard, Sarah; Zhou, Wen

    2015-11-01

    The "Anaerobic Digestion Model No. 1" (ADM1) was modified in the study by improving the bio-chemical framework and integrating a more detailed physico-chemical framework. Inorganic carbon and nitrogen balance terms were introduced to resolve the discrepancies in the original bio-chemical framework between the carbon and nitrogen contents in the degraders and substrates. More inorganic components and solids precipitation processes were included in the physico-chemical framework of ADM1. The modified ADM1 was validated with the experimental data and used to investigate the effects of calcium ions, magnesium ions, inorganic phosphorus and inorganic nitrogen on anaerobic digestion in batch reactor. It was found that the entire anaerobic digestion process might exist an optimal initial concentration of inorganic nitrogen for methane gas production in the presence of calcium ions, magnesium ions and inorganic phosphorus. PMID:26253912

  16. Biological degradation of triclocarban and triclosan in a soil under aerobic and anaerobic conditions and comparison with environmental fate modelling

    Energy Technology Data Exchange (ETDEWEB)

    Ying Guangguo [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); CSIRO Land and Water, Adelaide Laboratory, PMB2, Glen Osmond SA 5064 (Australia)], E-mail: guang-guo.ying@gig.ac.cn; Yu Xiangyang [CSIRO Land and Water, Adelaide Laboratory, PMB2, Glen Osmond SA 5064 (Australia); Food Safety Research Institute, Jiangsu Academy of Agricultural Sciences, Nanjing 210014 (China); Kookana, Rai S. [CSIRO Land and Water, Adelaide Laboratory, PMB2, Glen Osmond SA 5064 (Australia)

    2007-12-15

    Triclocarban and triclosan are two antimicrobial agents widely used in many personal care products. Their biodegradation behaviour in soil was investigated by laboratory degradation experiments and environmental fate modelling. Quantitative structure-activity relationship (QSAR) analyses showed that triclocarban and triclosan had a tendency to partition into soil or sediment in the environment. Fate modelling suggests that either triclocarban or triclosan 'does not degrade fast' with its primary biodegradation half-life of 'weeks' and ultimate biodegradation half-life of 'months'. Laboratory experiments showed that triclocarban and triclosan were degraded in the aerobic soil with half-life of 108 days and 18 days, respectively. No negative effect of these two antimicrobial agents on soil microbial activity was observed in the aerobic soil samples during the experiments. But these two compounds persisted in the anaerobic soil within 70 days of the experimental period. - Triclocarban and triclosan can be degraded by microbial processes in aerobic soil, but will persist in anaerobic soil.

  17. Phenols in anaerobic digestion processes and inhibition of ammonia oxidising bacteria (AOB) in soil

    International Nuclear Information System (INIS)

    This study focuses on the presence of phenols in digestate from seven Swedish large-scale anaerobic digestion processes and their impact on the activity of ammonia oxidising bacteria (AOB) in soil. In addition, the importance of feedstock composition and phenol degradation capacity for the occurrence of phenols in the digestate was investigated in the same processes. The results revealed that the content of phenols in the digestate was related to the inhibition of the activity of AOB in soil (EC5 = 26 μg phenols g-1 d.w. soil). In addition, five pure phenols (phenol, o-, p-, m-cresol and 4-ethylphenol) inhibited the AOB to a similar extent (EC5 = 43-110 μg g-1 d.w. soil). The phenol content in the digestate was mainly dependent on the composition of the feedstock, but also to some extent by the degradation capacity in the anaerobic digestion process. Swine manure in the feedstock resulted in digestate containing higher amounts of phenols than digestate from reactors with less or no swine manure in the feedstock. The degradation capacity of phenol and p-cresol was studied in diluted small-scale batch cultures and revealed that anaerobic digestion at mesophilic temperatures generally exhibited a higher degradation capacity compared to digestion at thermophilic temperature. Although phenol, p-cresol and 4-ethylphenol were quickly degraded in soil, the phenols added with the digestate constitute an environmental risk according to the guideline values for contaminated soils set by the Swedish Environmental Protection Agency. In conclusion, the management of anaerobic digestion processes is of decisive importance for the production of digestate with low amounts of phenols, and thereby little risks for negative effects of the phenols on the soil ecosystem

  18. Increased temperature in the thermophilic stage in temperature phased anaerobic digestion (TPAD) improves degradability of waste activated sludge.

    Science.gov (United States)

    Ge, Huoqing; Jensen, Paul D; Batstone, Damien J

    2011-03-15

    Two-stage temperature phased anaerobic digestion (TPAD) is an increasingly popular method to improve stabilisation of sewage waste activated sludge, which normally has inherently poor and slow degradation. However, there has been limited systematic analysis of the impact of the initial thermophilic stage (temperature, pH and retention time) on performance in the main mesophilic stage. In this study, we demonstrate a novel two-stage batch test method for TPAD processes, and use it to optimize operating conditions of the thermophilic stage in terms of degradation extent and methane production. The method determines overall degradability and apparent hydrolysis coefficient in both stages. The overall process was more effective with short pre-treatment retention times (1-2 days) and neutral pH compared to longer retention time (4 days) and low pH (4-5). Degradabilities and apparent hydrolysis coefficients were 0.3-0.5 (fraction degradable) and 0.1-0.4d(-1), respectively, with a margin of error in each measurement of approximately 20% relative (95% confidence). Pre-treatment temperature had a strong impact on the whole process, increasing overall degradability from 0.3 to 0.5 as temperature increased from 50 to 65 °C, with apparent hydrolysis coefficient increasing from 0.1 to 0.4d(-1). PMID:21277081

  19. Characteristics, Process Parameters, and Inner Components of Anaerobic Bioreactors

    Directory of Open Access Journals (Sweden)

    Awad Abdelgadir

    2014-01-01

    Full Text Available The anaerobic bioreactor applies the principles of biotechnology and microbiology, and nowadays it has been used widely in the wastewater treatment plants due to their high efficiency, low energy use, and green energy generation. Advantages and disadvantages of anaerobic process were shown, and three main characteristics of anaerobic bioreactor (AB, namely, inhomogeneous system, time instability, and space instability were also discussed in this work. For high efficiency of wastewater treatment, the process parameters of anaerobic digestion, such as temperature, pH, Hydraulic retention time (HRT, Organic Loading Rate (OLR, and sludge retention time (SRT were introduced to take into account the optimum conditions for living, growth, and multiplication of bacteria. The inner components, which can improve SRT, and even enhance mass transfer, were also explained and have been divided into transverse inner components, longitudinal inner components, and biofilm-packing material. At last, the newly developed special inner components were discussed and found more efficient and productive.

  20. Application of natural zeolites in anaerobic digestion processes: A review

    OpenAIRE

    Montalvo, Silvio; Borja Padilla, Rafael; Sánchez, Enrique; Milán, Zhenia; Cortés, Isel; Rubia, M. Ángeles de la

    2012-01-01

    This paper reviews the most relevant uses and applications of zeolites in anaerobic digestion processes. The feasibility of using natural zeolites as support media for the immobilization of microorganisms in different high-rate reactor configurations (fixed bed, fluidized bed, etc.) is also reviewed. Zeolite, with its favorable characteristics for microorganism adhesion, has also been widely used as an ion exchanger for the removal of ammonium in anaerobic digestion due to the presence of Na ...

  1. Anaerobic degradation of naphthalene by the mixed bacteria under nitrate reducing conditions

    International Nuclear Information System (INIS)

    Mixed bacteria were enriched from soil samples contaminated with polycyclic aromatic hydrocarbons (PAHs). The anaerobic degradation characteristics by the enriched bacteria with different initial naphthalene concentrations were investigated under nitrate reducing conditions. The results showed that the mixed bacteria could degrade nearly all the naphthalene over the incubations of 25 days when the initial naphthalene concentration was below 30 mg/L. The degradation rates of naphthalene increased with increasing initial concentrations. A high naphthalene concentration of 30 mg/L did not inhibit neither on the bacterial growth nor on the naphthalene degradation ability. The accumulation of nitrite was occurred during the reduction of nitrate, and a nitrite concentration of 50 mg/L had no inhibition effect on the degradation of naphthalene. The calculation of electron balances revealed that most of the naphthalene was oxidized whereas a small proportion was used for cell synthesis.

  2. A bio-electrochemical system for removing inhibitors of anaerobic digestion processes from anaerobic reactors

    DEFF Research Database (Denmark)

    2014-01-01

    reactor to recover ammonia from anaerobic digestion reactor, and thereby alleviate or counteract ammonia inhibition and enhance the conversion of ammonia-rich wastes to biogas. The invention may further reduce overall cost, giving synergistic advantages for both ammonia recycling and biogas plants......Inhibition of anaerobic digestion process by high level of ammonia (NH4 +/I\\IH3) is the most serious problem existing in biogas plants. No viable/applicable method to overcome this problem has been found up to now. This invention proposes an innovative submersible bio-electrochemical membrane...

  3. Two-phase anaerobic digestion of coffee wet wastewater: Effect of recycle on anaerobic process performance

    OpenAIRE

    Yans Guardia Puebla; Suyén Rodríguez Pérez; Yennys Cuscó Varona; Janet Jiménez Hernández; Víctor Sánchez Girón

    2014-01-01

    The present work shows the results of the two-phase anaerobic digestion assessment for the treatment of coffee wet wastewater. The effect of recycle on the anaerobic digestion process was studied. Twooverall organic loading rate (OLR) values of 4,2 and 5,7 kgCOD·m -3 ·d -1 , with same overall hydraulic retention time (HRT) of 21,5 h was evaluated.In a two-phase system wereapplied two recycle rate of 0,4 and 1,0, of the effluent of an UASB-UAF methanogenic hybrid reactor towards an UASB acidog...

  4. A comprehensive review of the process on hexachlorobenzene degradation

    Directory of Open Access Journals (Sweden)

    Ji Xiyan

    2015-01-01

    Full Text Available This paper describes the chemical, physical property of the pollution source along with its perniciousness. In addition, with the recent treatment or degradation of the hexachlorobenzene (HCB, it talks about the research developments on the HCB. Of the many options available for treatment of municipal and industrial HCB pollution, the anaerobic biological treatment process is unique because of its potential for producing usable energy. It focuses on the biodegradation pathway which is intent to finish the steps of dechlorination. Moreover, the future study on the HCB degradation is prospected in this paper from the author’s angle.

  5. Impact of agricultural activities on anaerobic processes in stream sediments

    Science.gov (United States)

    Schade, J. D.; Ludwig, S.; Nelson, L. C.; Porterfield, J.; Sather, K. L.; Songpitak, M.; Spawn, S.; Weigel, B.

    2013-12-01

    Streams draining agriculture watersheds are subject to significant anthropogenic impacts, including sedimentation from soil erosion and high nitrate input from heavy fertilizer application. Sedimentation degrades habitat and can reduce hydrologic exchange between surface and subsurface waters. Disconnecting surface and subsurface flow reduces oxygen input to hyporheic water, increasing the extent of anoxic zones in stream sediments and creating hotspots for anaerobic processes like denitrification and methanogenesis that can be important sources of nitrous oxide and methane, both powerful greenhouse gases. Increased nitrate input may influence greenhouse gas fluxes from stream sediments by stimulating rates of denitrification and potentially reducing rates of methanogenesis, either through direct inhibition or by increasing competition for organic substrates from denitrifying bacteria. We hypothesized that accumulation of fine sediments in stream channels would result in high rates of methanogenesis in stream sediments, and that increased nitrate input from agricultural runoff would stimulate denitrification and reduce rates of methane production. Our work focused on streams in northern and central Minnesota, in particular on Rice Creek, a small stream draining an agricultural watershed. We used a variety of approaches to test our hypotheses, including surveys of methane concentrations in surface waters of streams ranging in sediment type and nitrate concentration, bottle incubations of sediment from several sites in Rice Creek, and the use of functional gene probes and RNA analyses to determine if genes for these processes are present and being expressed in stream sediments. We found higher methane concentrations in surface water from streams with large deposits of fine sediments, but significantly less methane in these streams when nitrate concentrations were high. We also found high potential for both methanogenesis and denitrification in sediment incubations

  6. Microbial communities involved in anaerobic degradation of unsaturated or saturated long chain fatty acids

    OpenAIRE

    Sousa, D.Z.; Pereira, M.A.; Stams, A.J.M.; Alves, M. M.; Smidt, H.

    2007-01-01

    Anaerobic long-chain fatty acid (LCFA)-degrading bacteria were identified by combining selective enrichment studies with molecular approaches. Two distinct enrichment cultures growing on unsaturated and saturated LCFAs were obtained by successive transfers in medium containing oleate and palmitate, respectively, as the sole carbon and energy sources. Changes in the microbial composition during enrichment were analyzed by denaturing gradient gel electrophoresis (DGGE) profiling of PCR...

  7. Enrichment and characterization of microbial consortia degrading soluble microbial products discharged from anaerobic methanogenic bioreactors.

    Science.gov (United States)

    Kim, Na-Kyung; Oh, Seungdae; Liu, Wen-Tso

    2016-03-01

    Soluble microbial products (SMP) produced in bioprocesses have been known as a main cause to decrease treatment efficiency, lower effluent quality, and promote membrane fouling in water reclamation plants. In this study, biological degradation of SMP using selectively enriched microbial consortia in a down-flow hanging sponge (DHS) reactor was introduced to remove SMP discharged from anaerobic methanogenic reactors. On average, 68.9-87.5% SMP removal was achieved by the enriched microbial consortia in the DHS reactor for >800 days. The influent SMP fed to the DHS reactor exhibited a bimodal molecular weight (MW) distribution with 14-20 kDa and <4 kDa. Between these two types of SMP, the small MW SMP were biodegraded in the upper part of the reactor, together with most of the large MW SMP. Using 16S rRNA gene pyrosequencing technology, the microbial community composition and structure were characterized and correlated with operational factors, such as hydraulic retention time, organic loading rate, and removal of soluble chemical oxygen demand at different depths of the reactor, by performing network and redundancy analyses. The results revealed that Saprospiraceae was strongly correlated to the increasing SMP loading condition, indicating positive co-occurrences with neighboring bacterial populations. Different microbial diversity along with the depth of the reactor implies that stratified microbial communities could participate in the process of SMP degradation. Taken together, these observations indicate that the spatial and temporal variability of the enriched microbial community in the DHS reactor could effectively treat SMP with respect to changes in the operational factors. PMID:26771162

  8. Degradation of fipronil in anaerobic sediments and the effect on porewater concentrations.

    Science.gov (United States)

    Brennan, Amanda A; Harwood, Amanda D; You, Jing; Landrum, Peter F; Lydy, Michael J

    2009-09-01

    The current study measured the degradation of fipronil in laboratory-spiked silt loam sediment under anaerobic conditions at different aging times. The half-life of fipronil in anaerobic sediments spiked at 5.8+/-0.049 and 21+/-1.4microg/kg dry weight (dw) was 21+/-0.22 and 15+/-0.11d, respectively. Fipronil-sulfide was the primary degradation product with fipronil-sulfone detected at lower concentrations. No degradation occurred to fipronil-sulfide and fipronil-sulfone over 200d in separate systems. A concurrent decline in sediment concentrations resulted in a decline of fipronil in sediment porewater with an increase in fipronil-sulfide and fipronil-sulfone measured by matrix-solid phase microextraction (matrix-SPME). Equilibrium among sediment, porewater, and matrix-SPME fiber occurred within 138d for fipronil and fipronil-sulfone; however, fipronil-sulfide did not reach equilibrium during the test, and modeling predicted upwards of 1083d to reach equilibrium. Regardless of the time to reach equilibrium, the rapid degradation of fipronil has little ecological significance given that fipronil-sulfide and fipronil-sulfone have equal or greater toxicity, and exhibit greater environmental stability in both the sediment and porewater, thereby becoming bioavailable. PMID:19576615

  9. Anaerobic testosterone degradation in Steroidobacter denitrificans - Identification of transformation products

    Energy Technology Data Exchange (ETDEWEB)

    Fahrbach, Michael, E-mail: michael.fahrbach@web.d [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Uberlandstrasse 133, P.O. Box 611, CH-8600 Duebendorf (Switzerland); Krauss, Martin, E-mail: martin.krauss@eawag.c [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Uberlandstrasse 133, P.O. Box 611, CH-8600 Duebendorf (Switzerland); Preiss, Alfred, E-mail: alfred.preiss@item.fraunhofer.d [Fraunhofer Institute of Toxicology and Experimental Medicine (ITEM), Nikolai-Fuchs-Strasse 1, D-30625 Hannover (Germany); Kohler, Hans-Peter E., E-mail: hkohler@eawag.c [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Uberlandstrasse 133, P.O. Box 611, CH-8600 Duebendorf (Switzerland); Hollender, Juliane, E-mail: juliane.hollender@eawag.c [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Uberlandstrasse 133, P.O. Box 611, CH-8600 Duebendorf (Switzerland)

    2010-08-15

    The transformation of the androgenic steroid testosterone by gammaproteobacterium Steroidobacter denitrificans was studied under denitrifying conditions. For the first time, growth experiments showed that testosterone was mineralized under consumption of nitrate and concurrent biomass production. Experiments with cell suspensions using [4-{sup 14}C]-testosterone revealed the intermediate production of several transformation products (TPs). Characterisation of ten TPs was carried out by means of HPLC coupled to high resolution mass spectrometry with atmospheric pressure chemical ionization as well as {sup 1}H and {sup 13}C NMR spectroscopy. 3{beta}-hydroxy-5{alpha}-androstan-17-one (trans-androsterone) was formed in the highest amount followed by 5{alpha}-androstan-3,17-dione. The data suggests that several dehydrogenation and hydrogenation processes take place concurrently in ring A and D because no consistent time-resolved pattern of TP peaks was observed and assays using 2 TPs as substrates resulted in essentially the same TPs. The further transformation of testosterone in S. denitrificans seems to be very efficient and fast without formation of detectable intermediates. - Testosterone is completely mineralized by Steroidobacter denitrificans under denitrifying conditions with initial formation of several reduced and oxidized transformation products.

  10. Evaluation of anaerobic degradation, biogas and digestate production of cereal silages using nylon-bags.

    Science.gov (United States)

    Negri, Marco; Bacenetti, Jacopo; Fiala, Marco; Bocchi, Stefano

    2016-06-01

    In this study, the degradation efficiency and the biogas and digestate production during anaerobic digestion were evaluated for the cereal silages most used to feed biogas plants. To this purpose, silages of: maize from the whole plant, maize from the ear, triticale and wheat were digested, inside of nylon bags, in laboratory scale digesters, for 75days. Overall, the test involved 288 nylon bags. After 75days of digestion, the maize ear silage shows the highest degradation efficiency (about 98%) while wheat silage the lowest (about 83%). The biogas production ranges from 438 to 852Nm(3)/t of dry matter for wheat and ear maize silage, respectively. For all the cereal silages, the degradation as well as the biogas production are faster at the beginning of the digestion time. Digestate mass, expressed as percentage of the fresh matter, ranges from 38% to 84% for wheat and maize ear silage, respectively. PMID:26946439

  11. Structure and function of enzymes involved in the anaerobic degradation of L-threonine to propionate

    Indian Academy of Sciences (India)

    Dhirendra K Simanshu; Sagar Chittori; H S Savithri; M R N Murthy

    2007-09-01

    In Escherichia coli and Salmonella typhimurium, L-threonine is cleaved non-oxidatively to propionate via 2-ketobutyrate by biodegradative threonine deaminase, 2-ketobutyrate formate-lyase (or pyruvate formate-lyase), phosphotransacetylase and propionate kinase. In the anaerobic condition, L-threonine is converted to the energy-rich keto acid and this is subsequently catabolised to produce ATP via substrate-level phosphorylation, providing a source of energy to the cells. Most of the enzymes involved in the degradation of L-threonine to propionate are encoded by the anaerobically regulated tdc operon. In the recent past, extensive structural and biochemical studies have been carried out on these enzymes by various groups. Besides detailed structural and functional insights, these studies have also shown the similarities and differences between the other related enzymes present in the metabolic network. In this paper, we review the structural and biochemical studies carried out on these enzymes.

  12. Dynamics of the anaerobic process: Effects of volatile fatty acids

    DEFF Research Database (Denmark)

    Pind, Peter Frode; Angelidaki, Irini; Ahring, Birgitte Kiær

    2003-01-01

    A complex and fast dynamic response of the anaerobic biogas system was observed when the system was subjected to pulses of volatile fatty acids (VFAs). It was shown that a pulse of specific VFAs into a well-functioning continuous stirred tank reactor (CSTR) system operating on cow manure affected...... history of the reactor process. It should be pointed out that the observed dynamics of VFA responses were based on hourly measurements, meaning that the response duration was much lower than the hydraulic retention time, which exceeds several days in anaerobic CSTR systems....

  13. Thermophilic anaerobic waste water treatment, temperature aspects and process stability.

    NARCIS (Netherlands)

    Lier, van J.B.

    1995-01-01

    The main objective of this thesis was to assess the thermostability of thermophilic anaerobic wastewater treatment processes and the possibility to optimize the performance of thermophilic high-rate systems.Experiments were conducted to study the suitability of two types of seed material to start a

  14. Anaerobic Metabolism: Linkages to Trace Gases and Aerobic Processes

    Science.gov (United States)

    Megonigal, J. P.; Hines, M. E.; Visscher, P. T.

    2003-12-01

    's surface area, they have a profound influence on the biogeochemistry of the planet. This is evident from the observation that the O2 and CH4 content of Earth's atmosphere are in extreme disequilibrium (Sagan et al., 1993). The combination of high aerobic primary production and anoxic sediments provided the large deposits of fossil fuels that have become vital and contentious sources of energy for modern industrialized societies. Anaerobic metabolism is responsible for the abundance of N2 in the atmosphere; otherwise N2-fixing bacteria would have consumed most of the N2 pool long ago (Schlesinger, 1997). Anaerobic microorganisms are common symbionts of termites, cattle, and many other animals, where they aid digestion. Nutrient and pollutant chemistry are strongly modified by the reduced conditions that prevail in wetland and aquatic ecosystems.This review of anaerobic metabolism emphasizes aerobic oxidation, because the two processes cannot be separated in a complete treatment of the topic. It is process oriented and highlights the fascinating microorganisms that mediate anaerobic biogeochemistry. We begin this review with a brief discussion of CO2 assimilation by autotrophs, the source of most of the reducing power on Earth, and then consider the biological processes that harness this potential energy. Energy liberation begins with the decomposition of organic macromolecules to relatively simple compounds, which are simplified further by fermentation. Methanogenesis is considered next because CH4 is a product of acetate fermentation, and thus completes the catabolism of organic matter, particularly in the absence of inorganic electron acceptors. Finally, the organisms that use nitrogen, manganese, iron, and sulfur for terminal electron acceptors are considered in order of decreasing free-energy yield of the reactions.

  15. Biodegradability and toxicity of styrene in the anaerobic digestion process

    OpenAIRE

    Araya-Kroff, P.; Chamy, Rolando; M. Mota; Alves, M.M.

    2000-01-01

    Start-up and operation of an Upflow Anaerobic Sludge Blanket (UASB) reactor fed with an industrial effluent from a polymer synthesis plant containing 6 mg styrene 1ˉ¹ was unstable. In batch assays with 200 mg styrene 1ˉ¹, 74% of styrene was degraded at a rate of 7 ml methane gˉ¹ volatile suspended solids.day, without a lag phase. The toxicity limit (IC50) of styrene was 1.4 mM for the acetoclastic activity, 0.45 and 1.6 mM for the methanogenic activity in the presence of 30 mM of ...

  16. Morphological observation and microbial population dynamics in anaerobic polyurethane foam biofilm degrading gelatin

    Directory of Open Access Journals (Sweden)

    Tommaso G.

    2002-01-01

    Full Text Available This work reports on a preliminary study of anaerobic degradation of gelatin with emphasis on the development of the proteolytic biofilm in polyurethane foam matrices in differential reactors. The evolution of the biofilm was observed during 22 days by optical and scanning electron microscopy (SEM analyses. Three distinct immobilization patterns could be observed in the polyurethane foam: cell aggregates entrapped in matrix pores, thin biofilms attached to inner polyurethane foam surfaces and individual cells that have adhered to the support. Rods, cocci and vibrios were observed as the predominant morphologies of bacterial cells. Methane was produced mainly by hydrogenothrophic reactions during the operation of the reactors.

  17. Anaerobic microbial processes in a petroleum plume in fractured rock, northern Canada

    International Nuclear Information System (INIS)

    Fuel plumes are among the most common groundwater pollution problems at polluted sites throughout Canada, including the Canadian Shield region. However, the microbial processes that occur under cold climate conditions in fuel-contaminated groundwater are poorly understood. This study focused on evidence for anaerobic microbial processes in fuel plumes in groundwater at a Canadian Shield site in the Northwest Territories, within a zone mapped as having extensive discontinuous permafrost. In particular, the study examined redox-sensitive species in the groundwater, specifically iron, manganese, sulfate and nitrate. The data reported in the paper were based on a sampling program conducted in September 2007. The data showed strong evidence that anaerobic microorganisms are active in fuel-contaminated groundwater in fractured rock at the study site. The microbial processes include the reduction of electron acceptors, notably sulfate, ferric iron, manganese and possibly nitrate. It is possible that such anaerobic processes play an important role in the biodegradation of dissolved petroleum hydrocarbons in the groundwater at this site. However, it was concluded that additional analysis is needed in order to infer rates of these processes in the groundwater and to understand the relationship of these processes to degradation of the fuel plume. 14 refs., 8 figs.

  18. Anaerobic Methyl tert-Butyl Ether-Degrading Microorganisms Identified in Wastewater Treatment Plant Samples by Stable Isotope Probing

    OpenAIRE

    Sun, Weimin; Sun, Xiaoxu; Cupples, Alison M.

    2012-01-01

    Anaerobic methyl tert-butyl ether (MTBE) degradation potential was investigated in samples from a range of sources. From these 22 experimental variations, only one source (from wastewater treatment plant samples) exhibited MTBE degradation. These microcosms were methanogenic and were subjected to DNA-based stable isotope probing (SIP) targeted to both bacteria and archaea to identify the putative MTBE degraders. For this purpose, DNA was extracted at two time points, subjected to ultracentrif...

  19. Evaluation of an Anaerobic Digestion System for Processing CELSS Crop Residues for Resource Recovery

    Science.gov (United States)

    Strayer, R. F.; Finger, B. W.; Alazraki, M. P.

    1997-01-01

    Three bioreactors, connected in series, were used to process CELSS potato residues for recovery of resources. The first stage was an anaerobic digestor (8 L working volume; cow rumen contents inoculum; fed-batch; 8 day retention time; feed rate 25 gdw/day) that converted 33% of feed (dry weight loss) to CO2 and "volatile fatty acids" (vfa, 83:8:8 mmolar ratio acetic:propionic:butyric). High nitrate-N in the potato residue feed was absent in the anaerobic effluent, with a high portion converted to NH4(+)-N and the remainder unaccounted and probably lost to denitrification and NH4(+) volatilization. Liquid anaerobic effluent was fed to an aerobic, yeast biomass production vessel (2 L volume; Candida ingens inoculum; batch [pellicle] growth; 2 day retention time) where the VFAs and some NH4(+)-N were converted into yeast biomass. Yeast yields accounted for up to 8% of potato residue fed into the anaerobic bioreactor. The third bioreactor (0.5 L liquid working volume; commercial nitrifier inoculum; packed-bed biofilm; continuous yeast effluent feed; recirculating; constant volume; 2 day hydraulic retention time) was used to convert successfully the remaining NH4(+)-N into nitrate-N (preferred form of N for CELSS crop production) and to remove the remaining degradable soluble organic carbon. Effluents from the last two stages were used for partial replenishment of minerals for hydroponic potato production.

  20. Comparative study of stability and half-life of enzymes and enzyme aggregates implemented in anaerobic biogas processes

    Energy Technology Data Exchange (ETDEWEB)

    Binner, Roman; Schmack, Doris; Reuter, Monika [Research and Development Department, Schmack Biogas GmbH, Schwandorf (Germany); Menath, Veronika; Huber, Harald; Thomm, Michael [University of Regensburg, Department of Microbiology, Regensburg (Germany); Bischof, Franz [University of Applied Sciences Amberg-Weiden, Faculty of Mechanical Engineering/Environmental Engineering, Amberg (Germany)

    2011-03-15

    Anaerobic digestion of mainly energy crops gains more and more importance in developing a sustainable energy supply. Therefore, the optimization of gas yield plays a major role in specific research attempts and economical considerations. One possibility to increase natural polymer degradation and concomitantly energy efficiency is the addition of exoenzymes to biogas facilities to enforce the primary degradation steps for biogas production. Therefore, in the present study, the stability and activity of five externally added enzyme mixtures to anaerobic biogas processes were investigated. Protein assays using soluble fractions of different biogas plants incubated together with the enzyme mixtures revealed that, within about 10 min, the externally added enzymes were mostly degraded. This very low stability in biogas reactors makes it unlikely that the addition of enzymes contributes significantly to degradation of macromolecules in the biogas process. Even the addition of protease inhibitors did not protect the added enzyme mixtures from degradation in most experiments. Furthermore, the influence of added enzymes on the viscosity of the biomass was tested. Only a marginal effect was obtained, when applying a tenfold higher concentration of added enzymes as proposed for practical use. The same result was achieved when commercially available enzymes were added to technical-scale fermentations using corn silage as monosubstrate. Therefore, these studies did not provide evidence that the addition of external enzymes into anaerobic degradation systems increases the methane yield in biogas facilities. (orig.)

  1. ANAEROBIC DIGESTION POTENTIAL FOR ETHANOL PROCESSING RESIDUES

    Science.gov (United States)

    The production of corn-based ethanol in the U.S. is dramatically increasing, and consequently so is the quantity of byproduct materials generated from this processing sector. These coproduct streams are currently solely utilized as livestock feed, which is a route that provides ethanol processors w...

  2. Nitrogen in the Process of Waste Activated Sludge Anaerobic Digestion

    Directory of Open Access Journals (Sweden)

    Suschka Jan

    2014-07-01

    Full Text Available Primary or secondary sewage sludge in medium and large WWTP are most often processed by anaerobic digestion, as a method of conditioning, sludge quantity minimization and biogas production. With the aim to achieve the best results of sludge processing several modifications of technologies were suggested, investigated and introduced in the full technical scale. Various sludge pretreatment technologies before anaerobic treatment have been widely investigated and partially introduced. Obviously, there are always some limitations and some negative side effects. Selected aspects have been presented and discussed. The problem of nitrogen has been highlighted on the basis of the carried out investigations. The single and two step - mesophilic and thermophilic - anaerobic waste activated sludge digestion processes, preceded by preliminary hydrolysis were investigated. The aim of lab-scale experiments was pre-treatment of the sludge by means of low intensive alkaline and hydrodynamic disintegration. Depending on the pretreatment technologies and the digestion temperature large ammonia concentrations, up to 1800 mg NH4/dm3 have been measured. Return of the sludge liquor to the main sewage treatment line means additional nitrogen removal costs. Possible solutions are discussed.

  3. Microbial diversity and anaerobic hydrocarbon degradation potential in an oil-contaminated mangrove sediment

    Directory of Open Access Journals (Sweden)

    Andrade Luiza L

    2012-08-01

    Full Text Available Abstract Background Mangrove forests are coastal wetlands that provide vital ecosystem services and serve as barriers against natural disasters like tsunamis, hurricanes and tropical storms. Mangroves harbour a large diversity of organisms, including microorganisms with important roles in nutrient cycling and availability. Due to tidal influence, mangroves are sites where crude oil from spills farther away can accumulate. The relationship between mangrove bacterial diversity and oil degradation in mangrove sediments remains poorly understood. Results Mangrove sediment was sampled from 0–5, 15–20 and 35–40 cm depth intervals from the Suruí River mangrove (Rio de Janeiro, Brazil, which has a history of oil contamination. DGGE fingerprinting for bamA, dsr and 16S rRNA encoding fragment genes, and qPCR analysis using dsr and 16S rRNA gene fragment revealed differences with sediment depth. Conclusions Analysis of bacterial 16S rRNA gene diversity revealed changes with depth. DGGE for bamA and dsr genes shows that the anaerobic hydrocarbon-degrading community profile also changed between 5 and 15 cm depth, and is similar in the two deeper sediments, indicating that below 15 cm the anaerobic hydrocarbon-degrading community appears to be well established and homogeneous in this mangrove sediment. qPCR analysis revealed differences with sediment depth, with general bacterial abundance in the top layer (0–5 cm being greater than in both deeper sediment layers (15–20 and 35–40 cm, which were similar to each other.

  4. Targeted modification of organic components of municipal solid waste by short-term pre-aeration and its enhancement on anaerobic degradation in simulated landfill bioreactors.

    Science.gov (United States)

    Ni, Zhe; Liu, Jianguo; Girotto, Francesca; Cossu, Raffaello; Qi, Guangxia

    2016-09-01

    Pre-aeration is effective on regulating subsequent anaerobic degradation of municipal solid waste (MSW) with high organic fractions during landfilling. The strength of pre-aeration should be optimized to intentionally remove some easily biodegradable fractions while conserve bio-methane potential as much as possible. This study investigates the evolution of organic components in MSW during 2-14days pre-aeration process and its impacts on subsequent anaerobic degradation in simulated landfill bioreactors. Results showed that a 6-day pre-aeration enabled to develop a thermophilic stage, which significantly accelerated biodegradation of organics except lignocelluloses, with removal rates of 42.8%, 76.7% and 25.1% for proteins, carbohydrates and lipids, respectively. Particularly, ammonia from accelerated ammonification in the thermophilic stage neutralized VFAs generated from anaerobic landfilling. As a result, the MSW with 6-day pre-aeration obtained the highest methane yield 123.4NL/kg dry matter. Therefore, it is recommended to interrupt pre-aeration before its cooling stage to switch to anaerobic landfilling. PMID:27243602

  5. Modeling multi-component transport and enhanced anaerobic dechlorination processes in a single fracture-clay matrix system

    DEFF Research Database (Denmark)

    Chambon, Julie Claire Claudia; Broholm, Mette Martina; Binning, Philip John;

    2010-01-01

    Clayey tills contaminated with chlorinated solvents are a threat to groundwater and are difficult to remediate. A numerical model is developed for assessing leaching processes and for simulating the remediation via enhanced anaerobic dechlorination. The model simulates the transport...... to the physical processes, mainly diffusion in the matrix, than to the biogeochemical processes, when dechlorination is assumed to take place in a limited reaction zone only. The inclusion of sequential dechlorination in clay fracture transport models is crucial, as the contaminant flux to the aquifer...... of a contaminant in a single fracture-clay matrix system coupled with a reactive model for anaerobic dechlorination. The model takes into account microbially driven anaerobic dechlorination, where sequential Monod kinetics with competitive inhibition is used to model the reaction rates, and degradation...

  6. ANAMMOX process start up and stabilization with an anaerobic seed in Anaerobic Membrane Bioreactor (AnMBR).

    Science.gov (United States)

    Suneethi, S; Joseph, Kurian

    2011-10-01

    ANaerobic AMMonium OXidation (ANAMMOX) process, an advanced biological nitrogen removal alternative to traditional nitrification--denitrification removes ammonia using nitrite as the electron acceptor without oxygen. The feasibility of enriching anammox bacteria from anaerobic seed culture to start up an Anaerobic Membrane Bioreactor (AnMBR) for N-removal is reported in this paper. The Anammox activity was established in the AnMBR with anaerobic digester seed culture from a Sewage Treatment Plant in batch mode with recirculation followed by semi continuous process and continuous modes of operation. The AnMBR performance under varying Nitrogen Loading Rates (NLR) and HRTs is reported for a year, in terms of nitrogen transformations to ammoniacal nitrogen, nitrite and nitrate along with hydrazine and hydroxylamine. Interestingly ANAMMOX process was evident from simultaneous Amm-N and nitrite reduction, consistent nitrate production, hydrazine and hydroxylamine presence, notable organic load reduction and bicarbonate consumption. PMID:21775136

  7. Degradation of Reactive Black 5 dye using anaerobic/aerobic membrane bioreactor (MBR) and photochemical membrane reactor

    International Nuclear Information System (INIS)

    Three different types of advance treatment methods were evaluated for the degradation of Reactive Black 5 (RB5). The performance of two stage anaerobic SBR-aerobic MBR, anaerobic MBR with immobilized and suspended biocells and an integrated membrane photocatalytic reactor (MPR) using slurry UV/TiO2 system were investigated. The results suggest that, nearly 99.9% color removal and 80-95% organic COD and TOC removal can be achieved using different reactor systems. Considering the Taiwan EPA effluent standard discharge criteria for COD/TOC, the degree of treatment achieved by combining the anaerobic-aerobic system was found to be acceptable. Anew, Bacilluscereus, high color removal bacterium was isolated from Anaerobic SBR. Furthermore, when this immobilized into PVA-calcium alginate pellets, and suspended in the anaerobic MBR was able to achieve high removal efficiencies, similar to the suspended biocells system. However, the immobilized cell Anaerobic MBR was found to be more advantageous, due to lower fouling rates in the membrane unit. Results from slurry type MPR system showed that this system was capable of mineralizing RB5 dyes with faster degradation rate as compared to other systems. The reactor was also able to separate the catalyst effectively and perform efficiently without much loss of catalyst activity.

  8. Comparison of static, in-vessel composting of MSW with thermophilic anaerobic digestion and combinations of the two processes.

    Science.gov (United States)

    Walker, Lee; Charles, Wipa; Cord-Ruwisch, Ralf

    2009-08-01

    The biological stabilisation of the organic fraction of municipal solid waste (OFMSW) into a form stable enough for land application can be achieved via aerobic or anaerobic treatments. To investigate the rates of degradation (e.g. via electron equivalents removed, or via carbon emitted) of aerobic and anaerobic treatment, OFMSW samples were exposed to computer controlled laboratory-scale aerobic (static in-vessel composting), and anaerobic (thermophilic anaerobic digestion with liquor recycle) treatment individually and in combination. A comparison of the degradation rates, based on electron flow revealed that provided a suitable inoculum was used, anaerobic digestion was the faster of the two waste conversion process. In addition to faster maximum substrate oxidation rates, anaerobic digestion (followed by post-treatment aerobic maturation), when compared to static composting alone, converted a larger fraction of the organics to gaseous end-products (CO2 and CH4), leading to improved end-product stability and maturity, as measured by compost self-heating and root elongation tests, respectively. While not comparable to windrow and other mixed, highly aerated compost systems, our results show that in the thermophilic, in-vessel treatment investigated here, the inclusion of a anaerobic phase, rather than using composting alone, improved hydrolysis rates as well as oxidation rates and product stability. The combination of the two methods, as used in the DiCOM process, was also tested allowing heat generation to thermophilic operating temperature, biogas recovery and a low odour stable end-product within 19 days of operation. PMID:19345576

  9. Reductive transformation and detoxification mechanism of 2,4-dinitrochlorobenzene in combined zero valent iron and anaerobic-aerobic process

    Institute of Scientific and Technical Information of China (English)

    Jinyou Shen; Zongyuan Zhou; Changjin Ou; Xiuyun Sun; Jiansheng Li; Weiqing Han; Lin Zhou; Lianjun Wang

    2012-01-01

    A combined zero valent iron (ZVI) and anaerobic-aerobic process was adopted for the treatment of 2,4-dinitrochlorobenzene (DNCB)-containing wastewater.The transformation pathway,reduction of acute toxicity and enhancement of biodegradability were investigated.After pretreatment by ZVI,DNCB in wastewater could be completely converted into 2,4-diaminochlorobenzene (DACB).The ratio of BOD5/COD increased from 0.005 ± 0.001 to 0.168 ± 0.007,while EC50,48 hr (V/V) increased from 0.65% to 5.20%,indicating the enhancement of biodegradability and reduction of acute toxicity with the pretreatment by ZVI.DACB was further dechlorinated to m-phenylenediamine during the anaerobic process using methanol as electron donor,with EC50,48 hr increasing from 5.20% to 48.2%.After the subsequent anaerobic-aerobic process,m-phenylenediamine was degraded completely,with effluent COD of 67.5 ± 10.8 mg/L.This effluent of the subsequent anaerobic-aerobic process was not toxic to zebrafish.The combined ZVI and anaerobic-aerobic process offers bright prospects for the treatment of chlorinated nitroaromatic compound-containing wastewater.

  10. Thermophilic degradation of phenolic compounds in lab scale hybrid up flow anaerobic sludge blanket reactors

    International Nuclear Information System (INIS)

    This Study describes the feasibility of anaerobic degradation of United States Environmental Protection Agency (USEPA) listed 4-chloro-2-nitrophenol (4C-2-NP), 2-chloro-4-nitrophenol (2C-4-NP), 2-chloro-5-methylphenol (2C-5-MP) from a simulated wastewater using four identical 7L bench scale hybrid up flow anaerobic sludge blankets (HUASBs) at five different hydraulic retention times (HRTs) under thermophilic condition (55 ± 3 deg. C). The substrate to co-substrate ratios were maintained between 1:33.3 and 1:166.6. Continuous monitoring of parameters like pH, volatile fatty acids (VFAs) accumulation, oxidation reduction potential, chemical oxygen demand (COD), alkalinity, gas productions, methane percentages were carried out along with compound reduction to asses the efficiency of biodegradation. The compound reduction was estimated by using spectrophotometric methods and further validated with high-performance liquid chromatography (HPLC). Optimum HRT values were observed at 24 h. Optimum ratio of substrate (phenolic compounds) to co-substrate (glucose) was 1:100. Scanning electron micrographs show that the granules were composed of thermophilic Methanobrevibacter and thermophilic Methanothrix like bacteria.

  11. Succession of lignocellulolytic bacterial consortia bred anaerobically from lake sediment

    NARCIS (Netherlands)

    Korenblum, Elisa; Jiménez Avella, Diego; van Elsas, Jan

    2016-01-01

    Anaerobic bacteria degrade lignocellulose in various anoxic and organically rich environments, often in a syntrophic process. Anaerobic enrichments of bacterial communities on a recalcitrant lignocellulose source were studied combining polymerase chain reaction–denaturing gradient gel electrophoresi

  12. Phenol degradation in an anaerobic fluidized bed reactor packed with low density support materials

    Directory of Open Access Journals (Sweden)

    G. P. Sancinetti

    2012-03-01

    Full Text Available The objective of this research was to study phenol degradation in anaerobic fluidized bed reactors (AFBR packed with polymeric particulate supports (polystyrene - PS, polyethylene terephthalate - PET, and polyvinyl chloride - PVC. The reactors were operated with a hydraulic retention time (HRT of 24 h. The influent phenol concentration in the AFBR varied from 100 to 400 mg L-1, resulting in phenol removal efficiencies of ~100%. The formation of extracellular polymeric substances yielded better results with the PVC particles; however, deformations in these particles proved detrimental to reactor operation. PS was found to be the best support for biomass attachment in an AFBR for phenol removal. The AFBR loaded with PS was operated to analyze the performance and stability for phenol removal at feed concentrations ranging from 50 to 500 mg L-1. The phenol removal efficiency ranged from 90-100%.

  13. Degradation of weathered diesel fuel by microorganisms from a contaminated aquifer in aerobic and anaerobic microcosms

    International Nuclear Information System (INIS)

    A diesel fuel-contaminated aquifer in Menziken, Canton of Aargau, Switzerland, was in situ bioremediated from 1989 to 1994 by adding O2, NO3-, PO43-, and NH4+ through an infiltration well. After a remediation time of 3.5 years, aquifer material from the contaminated zone was excavated and found to contain > 106 hydrocarbon-degrading microorganisms/g and 1.15 ± 0.15 mg/g weathered diesel fuel comprising mainly isoprenoid alkanes and an unresolved complex mixture (UCM) of unknown components. Samples of this material were incubated for up to 470 days in aerobic and anaerobic microcosms. The microbial activity was determined by measuring the production of inorganic carbon and the consumption of O2 and NO3-. The degradation of the weathered diesel fuel was quantified by infrared spectroscopy and by capillary gas chromatography. In aerobic microcosms, all isoprenoid alkanes and most of the UCM were biodegraded as long as a nitrogen source was present. The O2 consumption could be stimulated by adding KH2PO4 and by elevating the temperature to 22 C. In anaerobic microcosms with KNO3, NO3- was consumed, inorganic carbon was produced, and the isoprenoid alkanes and the UCM were partially metabolized. In some selected microcosms, the NO3- consumption rate was stimulated by adding external substrates such as toluene, o-xylene, m-xylene, p-xylene, n-alkanes, or fatty acids. Mineralization of toluene, naphthalene, and hexadecane to CO2 under denitrifying conditions was confirmed by using [14C]-labelled substrates

  14. The physicochemical characteristics and anaerobic degradability of desiccated coconut industry waste water.

    Science.gov (United States)

    Chanakya, H N; Khuntia, Himanshu Kumar; Mukherjee, Niranjan; Aniruddha, R; Mudakavi, J R; Thimmaraju, Preeti

    2015-12-01

    Desiccated coconut industries (DCI) create various intermediates from fresh coconut kernel for cosmetic, pharmaceutical and food industries. The mechanized and non-mechanized DCI process between 10,000 and 100,000 nuts/day to discharge 6-150 m(3) of malodorous waste water leading to a discharge of 264-6642 kg chemical oxygen demand (COD) daily. In these units, three main types of waste water streams are coconut kernel water, kernel wash water and virgin oil waste water. The effluent streams contain lipids (1-55 g/l), suspended solids (6-80 g/l) and volatile fatty acids (VFA) at concentrations that are inhibitory to anaerobic bacteria. Coconut water contributes to 20-50% of the total volume and 50-60% of the total organic loads and causes higher inhibition of anaerobic bacteria with an initial lag phase of 30 days. The lagooning method of treatment widely adopted failed to appreciably treat the waste water and often led to the accumulation of volatile fatty acids (propionic acid) along with long-chain unsaturated free fatty acids. Biogas generation during biological methane potential (BMP) assay required a 15-day adaptation time, and gas production occurred at low concentrations of coconut water while the other two streams did not appear to be inhibitory. The anaerobic bacteria can mineralize coconut lipids at concentrations of 175 mg/l; however; they are severely inhibited at a lipid level of ≥350 mg/g bacterial inoculum. The modified Gompertz model showed a good fit with the BMP data with a simple sigmoid pattern. However, it failed to fit experimental BMP data either possessing a longer lag phase and/or diauxic biogas production suggesting inhibition of anaerobic bacteria. PMID:26612563

  15. Physiology of deletion mutants in the anaerobic β-myrcene degradation pathway in Castellaniella defragrans

    Directory of Open Access Journals (Sweden)

    Lüddeke Frauke

    2012-09-01

    Full Text Available Abstract Background Monoterpenes present a large and versatile group of unsaturated hydrocarbons of plant origin with widespread use in the fragrance as well as food industry. The anaerobic β-myrcene degradation pathway in Castellaniella defragrans strain 65Phen differs from well known aerobic, monooxygenase-containing pathways. The initial enzyme linalool dehydratase-isomerase ldi/LDI catalyzes the hydration of β-myrcene to (S-(+-linalool and its isomerization to geraniol. A high-affinity geraniol dehydrogenase geoA/GeDH and a geranial dehydrogenase geoB/GaDH contribute to the formation of geranic acid. A genetic system was for the first time applied for the betaproteobacterium to prove in vivo the relevance of the linalool dehydratase-isomerase and the geraniol dehydrogenase. In-frame deletion cassettes were introduced by conjugation and two homologous recombination events. Results Polar effects were absent in the in-frame deletion mutants C. defragrans Δldi and C. defragrans ΔgeoA. The physiological characterization of the strains demonstrated a requirement of the linalool dehydratase-isomerase for growth on acyclic monoterpenes, but not on cyclic monoterpenes. The deletion of geoA resulted in a phenotype with hampered growth rate on monoterpenes as sole carbon and energy source as well as reduced biomass yields. Enzyme assays revealed the presence of a second geraniol dehydrogenase. The deletion mutants were in trans complemented with the broad-host range expression vector pBBR1MCS-4ldi and pBBR1MCS-2geoA, restoring in both cases the wild type phenotype. Conclusions In-frame deletion mutants of genes in the anaerobic β-myrcene degradation revealed novel insights in the in vivo function. The deletion of a high-affinity geraniol dehydrogenase hampered, but did not preclude growth on monoterpenes. A second geraniol dehydrogenase activity was present that contributes to the β-myrcene degradation pathway. Growth on cyclic monoterpenes

  16. Anaerobic biodegradation of oleate by a highly loaded biomass before and after degrading the associated substrate

    OpenAIRE

    Salvador, A. F.; M. A. PEREIRA; Alves, M.M.

    2007-01-01

    Oleic Acid (C18:1) is an unsaturated Long Chain Fatty Acid (LCFA), described as especially problematic in anaerobic digestion processes. In this work, a sludge heavily loaded with 5985 mgCOD.gVSˉ¹ was studied in terms of its capability to biodegrade oleic acid in batch assays, in concentrations ranging from 100 to 1500 mg.lˉ¹. Lag phases before the onset of methane production increased with the oleic acid concentration, up to 17 days for 1500 mg.lˉ¹and methane production did no...

  17. Succession of microbial community and enhanced mechanism of a ZVI-based anaerobic granular sludge process treating chloronitrobenzenes wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Liang, E-mail: felix79cn@hotmail.com [Department of Environmental Engineering, Zhejiang University, Hangzhou 310058 (China); Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou 310058 (China); Jin, Jie [Department of Environmental Engineering, Zhejiang University, Hangzhou 310058 (China); Lin, Haizhuan [Department of Environmental Engineering, Zhejiang University, Hangzhou 310058 (China); Wenzhou Environmental Protection Design Scientific Institute, Wenzhou 325000 (China); Gao, Kaituo [Department of Environmental Engineering, Zhejiang University, Hangzhou 310058 (China); Xu, Xiangyang, E-mail: xuxy@zju.edu.cn [Department of Environmental Engineering, Zhejiang University, Hangzhou 310058 (China); Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou 310058 (China)

    2015-03-21

    Highlights: • The combined ZVI–UASB process was established for the degradation of chloronitrobenzenes. • There were the better shock resistance and buffering capacity for anaerobic acidification in the combined process. • Novel ZVI-based anaerobic granular sludge (ZVI–AGS) was successfully developed. • Adaptive shift of microbial community was significant in ZVI-based anaerobic granular sludge system. - Abstract: The combined zero-valent iron (ZVI) and upflow anaerobic sludge blanket (UASB) process is established for the treatment of chloronitrobenzenes (ClNBs) wastewater, and the succession of microbial community and its enhanced mechanism are investigated in the study. Results showed that compared with the control UASB (R1), the stable COD removal, ClNBs transformation, and dechlorination occurred in the combined system (R2) when operated at influent COD and 3,4-Dichloronitrobenzene (3,4-DClNB) loading rates of 4200–7700 g m{sup −3} d{sup −1} and 6.0–70.0 g m{sup −3} d{sup −1}, and R2 had the better shock resistance and buffering capacity for the anaerobic acidification. The dechlorination for the intermediate products of p-chloroanaline (p-ClAn) to analine (AN) occurred in R2 reactor after 45 days, whereas it did not occur in R1 after a long-term operation. The novel ZVI-based anaerobic granular sludge (ZVI–AGS) was successfully developed in the combined system, and higher microbial activities including ClNB transformation and H{sub 2}/CH{sub 4} production were achieved simultaneously. The dominant bacteria were closely related to the groups of Megasphaera, Chloroflexi, and Clostridium, and the majority of archaea were correlated with the groups of Methanosarcinalesarchaeon, Methanosaetaconcilii, and Methanothrixsoehngenii, which are capable of reductively dechlorinating PCB, HCB, and TCE in anaerobic niche and EPS secretion.

  18. Succession of microbial community and enhanced mechanism of a ZVI-based anaerobic granular sludge process treating chloronitrobenzenes wastewater

    International Nuclear Information System (INIS)

    Highlights: • The combined ZVI–UASB process was established for the degradation of chloronitrobenzenes. • There were the better shock resistance and buffering capacity for anaerobic acidification in the combined process. • Novel ZVI-based anaerobic granular sludge (ZVI–AGS) was successfully developed. • Adaptive shift of microbial community was significant in ZVI-based anaerobic granular sludge system. - Abstract: The combined zero-valent iron (ZVI) and upflow anaerobic sludge blanket (UASB) process is established for the treatment of chloronitrobenzenes (ClNBs) wastewater, and the succession of microbial community and its enhanced mechanism are investigated in the study. Results showed that compared with the control UASB (R1), the stable COD removal, ClNBs transformation, and dechlorination occurred in the combined system (R2) when operated at influent COD and 3,4-Dichloronitrobenzene (3,4-DClNB) loading rates of 4200–7700 g m−3 d−1 and 6.0–70.0 g m−3 d−1, and R2 had the better shock resistance and buffering capacity for the anaerobic acidification. The dechlorination for the intermediate products of p-chloroanaline (p-ClAn) to analine (AN) occurred in R2 reactor after 45 days, whereas it did not occur in R1 after a long-term operation. The novel ZVI-based anaerobic granular sludge (ZVI–AGS) was successfully developed in the combined system, and higher microbial activities including ClNB transformation and H2/CH4 production were achieved simultaneously. The dominant bacteria were closely related to the groups of Megasphaera, Chloroflexi, and Clostridium, and the majority of archaea were correlated with the groups of Methanosarcinalesarchaeon, Methanosaetaconcilii, and Methanothrixsoehngenii, which are capable of reductively dechlorinating PCB, HCB, and TCE in anaerobic niche and EPS secretion

  19. Hybrid alkali-hydrodynamic disintegration of waste-activated sludge before two-stage anaerobic digestion process

    OpenAIRE

    Grübel, Klaudiusz; Suschka, Jan

    2014-01-01

    The first step of anaerobic digestion, the hydrolysis, is regarded as the rate-limiting step in the degradation of complex organic compounds, such as waste-activated sludge (WAS). The aim of lab-scale experiments was to pre-hydrolyze the sludge by means of low intensive alkaline sludge conditioning before applying hydrodynamic disintegration, as the pre-treatment procedure. Application of both processes as a hybrid disintegration sludge technology resulted in a higher organic matter release (...

  20. Anaerobic digestion of buffalo dung: simulation of process kinetics

    International Nuclear Information System (INIS)

    Assessment of kinetic of AD (Anaerobic Digestion) is a beneficial practice to forecast the performance of the process. It is helpful in the design of AD vessels, substrate feeding and digestate exit systems. The aim of this work was to assess the kinetics of anaerobically digested buffalo dung at different quantities of water added. It comprises the assessment of the specific methane production on the basis of VS (Volatile Solids) added in each reactor by using three first order models, i.e. the modified Gompertz model, the Cone model and the Exponential Curve Factor model. The analysis was tested by using the three statistical parameters, i.e. the coefficient of multiple determinations, the standard deviation of residuals and the Akaike's Information Criteria. The result reveals that the Exponential Curve Factor model was the best model that described the experimental data well. Moreover, there was not a direct or indirect relation between the kinetic coefficients of the AD process with the varying total or volatile solid content. (author)

  1. Anaerobic Digestion of Buffalo Dung: Simulation of Process Kinetics

    Directory of Open Access Journals (Sweden)

    Abdul Razaque Sahito

    2015-01-01

    Full Text Available Assessment of kinetic of AD (Anaerobic Digestion is a beneficial practice to forecast the performance of the process. It is helpful in the design of AD vessels, substrate feeding and digestate exit systems. The aim of this work was to assess the kinetics of anaerobically digested buffalo dung at different quantities of water added. It comprises the assessment of the specific methane production on the basis of VS (Volatile Solids added in each reactor by using three first order models, i.e. the modified Gompertz model, the Cone model and the Exponential Curve Factor model. The analysis was tested by using the three statistical parameters, i.e. the coefficient of multiple determinations, the standard deviation of residuals and the Akaike?s Information Criteria. The result reveals that the Exponential Curve Factor model was the best model that described the experimental data well. Moreover, there was not a direct or indirect relation between the kinetic coefficients of the AD process with the varying total or volatile solid content

  2. Anaerobic digestion of crop and waste biomass: Impact of feedstock characteristics on process performance

    OpenAIRE

    Ivo Achu, Nges

    2012-01-01

    Anaerobic digestion provides an array of positive environmental benefits such as reducing greenhouse gas emissions, replacing mineral fertilizers, producing renewable energy and treating waste. However, pitfalls in anaerobic digestion such as poor methane yields, process instability, process failure and regional shortages of feedstock have limited the full exploitation of the anaerobic digestion process. The research presented in this thesis deals with the assessment of the possible n...

  3. In-Situ Anaerobic Biosurfactant Production Process For Remediation Of DNAPL Contamination In Subsurface Aquifers

    Science.gov (United States)

    Albino, J. D.; Nambi, I. M.

    2009-12-01

    Microbial Enhanced Oil Recovery (MEOR) and remediation of aquifers contaminated with hydrophobic contaminants require insitu production of biosurfactants for mobilization of entrapped hydrophobic liquids. Most of the biosurfactant producing microorganisms produce them under aerobic condition and hence surfactant production is limited in subsurface condition due to lack of oxygen. Currently bioremediation involves expensive air sparging or excavation followed by exsitu biodegradation. Use of microorganisms which can produce biosurfactants under anaerobic conditions can cost effectively expedite the process of insitu bioremediation or mobilization. In this work, the feasibility of anaerobic biosurfactant production in three mixed anaerobic cultures prepared from groundwater and soil contaminated with chlorinated compounds and municipal sewage sludge was investigated. The cultures were previously enriched under complete anaerobic conditions in the presence of Tetrachloroethylene (PCE) for more than a year before they were studied for biosurfactant production. Biosurfactant production under anaerobic conditions was simulated using two methods: i) induction of starvation in the microbial cultures and ii) addition of complex fermentable substrates. Positive result for biosurfactant production was not observed when the cultures were induced with starvation by adding PCE as blobs which served as the only terminal electron acceptor. However, slight reduction in interfacial tension was noticed which was caused by the adherence of microbes to water-PCE interface. Biosurfactant production was observed in all the three cultures when they were fed with complex fermentable substrates and surface tension of the liquid medium was lowered below 35 mN/m. Among the fermentable substrates tested, vegetable oil yielded highest amount of biosurfactant in all the cultures. Complete biodegradation of PCE to ethylene at a faster rate was also observed when vegetable oil was amended to the

  4. Bench-scale Analysis of Surrogates for Anaerobic Digestion Processes.

    Science.gov (United States)

    Carroll, Zachary S; Long, Sharon C

    2016-05-01

    Frequent monitoring of anaerobic digestion processes for pathogen destruction is both cost and time prohibitive. The use of surrogates to supplement regulatory monitoring may be one solution. To evaluate surrogates, a semi-batch bench-scale anaerobic digester design was tested. Bench-scale reactors were operated under mesophilic (36 °C) and thermophilic (53-55 °C) conditions, with a 15 day solids retention time. Biosolids from different facilities and during different seasons were examined. USEPA regulated pathogens and surrogate organisms were enumerated at different times throughout each experiment. The surrogate organisms included fecal coliforms, E. coli, enterococci, male-specific and somatic coliphages, Clostridium perfringens, and bacterial spores. Male-specific coliphages tested well as a potential surrogate organism for virus inactivation. None of the tested surrogate organisms correlated well with helminth inactivation under the conditions studied. There were statistically significant differences in the inactivation rates between the facilities in this study, but not between seasons. PMID:27131309

  5. A two-stage anaerobic system for biodegrading wastewater containing terephthalic acid and high strength easily degradable pollutants

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The high strength easily biodegradable pollutants(represented by CODE) are strong inhibitors of terephthalic acid(TA) anaerobic biodegradation. At the same time, TA can inhibiteasily biodegradable pollutants removal under anaerobic conditionsto a limited extent. This mutual inhibition could happen and causea low removal efficiency of both TA and CODE, when the effluentfrom TA workshops containing TA and easily biodegradable pollutantsare treated by a single anaerobic reactor system. Based upon thetreatment kinetics analysis of both TA degradation and CODEremoval, a two-stage up-flow anaerobic sludge blanket and up-flowfixed film reactor(UASB-UAFF) system for dealing with this kind ofwastewater was developed and run successfully at laboratory scale.An UASB reactor with the methanogenic consortium as the first stageremoves the easily biodegradable pollutants(CODE). An UAFF reactor as the second stage is mainly in charge of TA degradation. At aHRT 18.5h, the CODE and TA removal rate of the system reached 89.2% and 71.6%, respectively.

  6. Characterization of Anaerobic Degradability and Kinetics of Harvested Submerged Aquatic Weeds Used for Nutrient Phytoremediation

    Directory of Open Access Journals (Sweden)

    Takuro Kobayashi

    2014-12-01

    Full Text Available In this study, eight different submerged aquatic species were screened by batch biochemical methane potential and anaerobic degradability tests to identify a promising/suitable feedstock. Kinetics of the best-screened substrate were studied in a mesophilic semi-continuous experiment. The aquatic species Myriophyllum aquaticum, Egeria densa and Potamogeton perfoliatus showed relatively higher methane yields of over 400 NmL/g-VS (volatile solids. Semi-continuous operation was carried out by feeding E. densa for over 400 days. The achieved results were 33%–53% chemical oxygen demand (COD reduction and methane yield of 126–231 NmL/g-VS with a short hydraulic retention time (HRT. Additionally, the NH4+ and PO43− releases from the biomass to water were found to be low (18%–27% and 2.5%–3.9% throughout the experiment. Hydrolysis was the limiting step in the digestion of E. densa, regardless of changes in HRT (15–45 days. The acid-phase model indicated that the hydrolysis rate constant (kh of E. densa was 0.058 one/day, which was one third lower the kh value of food waste, but quite similar to cow manure.

  7. Effects of nature organic matters and hydrated metal oxides on the anaerobic degradation of lindane,p,p'-DDT and HCB in sediments

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xu; QUAN Xie; ZHAO Hui-min; CHEN Jing-wen; CHEN Shou; ZHAO Ya-zhi

    2003-01-01

    Effects of natural organic matters(NOM) and hydrated metal oxides(HMO) in sediments on the anaerobic degradation of γ-666, p,p'-DDT and HCB were investigated by means of removing NOM and HMO in Liaohe River sediments sequentially. The results showed that the anaerobic degradation of γ-666, p,p'-DDT and HCB followed pseudo-first-order kinetics in different sediments; But, the extents and rates of degradation were different, even the other conditions remained the same. Anaerobic degradation rates of γ-666, p,p'-DDT and HCB were 0.020 d-1, 0.009 d-1 and 0.035 month-1 respectively for the sediments without additional carbon resources. However, with addition of carbon resources, the anaerobic degradation rates of γ-666, p, p'-DDT and HCB were 0.071d-1, 0.054d-1 and 0.088 month-1 in the original sediments respectively. After removing NOM, the rates were decreased to 0.047 d-1, 0.037 d-1 and 0.066 month-1; in the sediments removed NOM and HMO, the rates were increased to 0.067d-1, 0.059 d-1 and 0.086 month-1. These results indicated that NOM in the sediments accelerated the anaerobic degradation of γ-666, p,p'-DDT and HCB; the HMO inhibited the anaerobic degradation of γ-666, p,p'-DDT and HCB.

  8. Degradation of n-Hexadecane and Its Metabolites by Pseudomonas aeruginosa under Microaerobic and Anaerobic Denitrifying Conditions

    OpenAIRE

    Chayabutra, Chawala; Ju, Lu-Kwang

    2000-01-01

    A strategy for sequential hydrocarbon bioremediation is proposed. The initial O2-requiring transformation is effected by aerobic resting cells, thus avoiding a high oxygen demand. The oxygenated metabolites can then be degraded even under anaerobic conditions when supplemented with a highly water-soluble alternative electron acceptor, such as nitrate. To develop the new strategy, some phenomena were studied by examining Pseudomonas aeruginosa fermentation. The effects of dissolved oxygen (DO)...

  9. Thermophilic anaerobic fermentation of olive pulp for hydrogen and methane production: modelling of the anaerobic digestion process

    DEFF Research Database (Denmark)

    Gavala, Hariklia N.; Skiadas, Ioannis V.; Ahring, Birgitte Kiær;

    2006-01-01

    The present study investigates the thermophilic biohydrogen and methane production from olive pulp, which is the semi-solid. residue coming from the two-phase processing of olives. It focussed on: a) production of methane from the raw olive pulp; b) anaerobic bio-production of hydrogen from the...

  10. Atomistic Processes of Catalyst Degradation

    Energy Technology Data Exchange (ETDEWEB)

    None

    2004-11-27

    The purpose of this cooperative research and development agreement (CRADA) between Sasol North America, Inc., and the oak Ridge National Laboratory (ORNL) was to improve the stability of alumina-based industrial catalysts through the combination of aberration-corrected scanning transmission electron microscopy (STEM) at ORNL and innovative sample preparation techniques at Sasol. Outstanding progress has been made in task 1, 'Atomistic processes of La stabilization'. STEM investigations provided structural information with single-atom precision, showing the lattice location of La dopant atoms, thus enabling first-principles calculations of binding energies, which were performed in collaboration with Vanderbilt University. The stabilization mechanism turns out to be entirely due to a particularly strong binding energy of the La tom to the {gamma}-alumina surface. The large size of the La atom precludes incorporation of La into the bulk alumina and also strains the surface, thus preventing any clustering of La atoms. Thus highly disperse distribution is achieved and confirmed by STEM images. la also affects relative stability of the exposed surfaces of {gamma}-alumina, making the 100 surface more stable for the doped case, unlike the 110 surface for pure {gamma}-alumina. From the first-principles calculations, they can estimate the increase in transition temperature for the 3% loading of La used commercially, and it is in excellent agreement with experiment. This task was further pursued aiming to generate useable recommendations for the optimization of the preparation techniques for La-doped aluminas. The effort was primarily concentrated on the connection between the boehmitre-{gamma}-Al{sub 2}O{sub 3} phase transition (i.e. catalyst preparation) and the resulting dispersion of La on the {gamma}-Al{sub 2}O{sub 3} surface. It was determined that the La distribution on boehmite was non-uniform and different from that on the {gamma}-Al{sub 2}O{sub 3} and thus

  11. Performance and dye-degrading bacteria isolation of a hybrid membrane process

    International Nuclear Information System (INIS)

    Textile dyeing wastewater contains harmful compounds, which are toxic to both marine organisms and human beings if it discharged into an aquatic environmental without suitable treatment. In this study, the wastewater containing the azo dye, Reactive Black 5 (RB5), was partially treated in an anaerobic sequencing batch reactor which was further treated either in an aerobic membrane bioreactors (AOMBR) or in combined aerobic membrane bioreactor/reverse osmosis (AOMBR/RO) process. The results showed that in the anaerobic sequencing batch reactor the RB5 dye was degraded to form aromatic amine intermediate metabolites, which were further mineralized in the AOMBR. It was also observed that although all effluents from the AOMBR and AOMBR/RO processes met the Taiwan EPA's effluent criteria, irrespective of which membranes were used in the aerobic tank, the effluent from the AOMBR/RO process met the criteria for reuse for toilet flushing, landscaping, irrigation, and cooling water purposes, where as the AOMBR effluent only met the criteria for cooling water due to incomplete color removal. Five anaerobic high dye-degrading bacteria were isolated, which were identified to be the same species of Lactococcus lactis by 16S rRNA sequencing. The L. lactis showed complete degradation of RB5 and further studies showed that it can also able to degrade Reactive Red 120 and Reactive Yellow 84 efficiently within 6 h.

  12. Is the continuous two-stage anaerobic digestion process well suited for all substrates?

    Science.gov (United States)

    Lindner, Jonas; Zielonka, Simon; Oechsner, Hans; Lemmer, Andreas

    2016-01-01

    Two-stage anaerobic digestion systems are often considered to be advantageous compared to one-stage processes. Although process conditions and fermenter setups are well examined, overall substrate degradation in these systems is controversially discussed. Therefore, the aim of this study was to investigate how substrates with different fibre and sugar contents (hay/straw, maize silage, sugar beet) influence the degradation rate and methane production. Intermediates and gas compositions, as well as methane yields and VS-degradation degrees were recorded. The sugar beet substrate lead to a higher pH-value drop 5.67 in the acidification reactor, which resulted in a six time higher hydrogen production in comparison to the hay/straw substrate (pH-value drop 5.34). As the achieved yields in the two-stage system showed a difference of 70.6% for the hay/straw substrate, and only 7.8% for the sugar beet substrate. Therefore two-stage systems seem to be only recommendable for digesting sugar rich substrates. PMID:26519699

  13. IMPORTANT DEGRADATIONS IN POLYETHYLENE TERAPHTALATE EXTRUSION PROCESS

    Directory of Open Access Journals (Sweden)

    Şule ALTUN

    2003-01-01

    Full Text Available Polyethylene terephthalate (PET is one of the most used thermo-plastic polymers. The total consumption of PET has been about 30 million tons in the year 2000. Polyester fibers constitute about 60 % of total synthetic fibers consumption. During extrusion, PET polymer is faced to thermal, thermo-oxidative and hydrolytic degradation, which result in severe reduction in its molecular weight, thereby adversely affecting its subsequent melt processability. Therefore, it is essential to understand degradation processes of PET during melt extrusion.

  14. Instrumentation and control of anaerobic digestion processes: A review and some research challenges

    NARCIS (Netherlands)

    Jimenez, J.; Latrille, E.; Harmand, J.; Robles, A.; Ferrer, J.; Gaida, D.; Wolf, C.; Mairet, F.; Bernard, O.; Alcaraz-Gonzalez, V.; Mendez-Acosta, H.; Zitomer, D.; Totzke, D.; Spanjers, H.; Jacobi, F.; Guwy, A.; Dinsdale, R.; Premier, G.; Mazhegrane, S.; Ruiz-Filippi, G.; Seco, A.; Ribeiro, T.; Pauss, A.; Steyer, J.P.

    2015-01-01

    To enhance energy production from methane or resource recovery from digestate, anaerobic digestion processes require advanced instrumentation and control tools. Over the years, research on these topics has evolved and followed the main fields of application of anaerobic digestion processes: from mun

  15. INDUCTION OF ANAEROBIC PROCESSES IN BAIKAL ENDEMICS EULIMNOGAMMARUS VITTATUS (DYB. AND E. VERRUCOSUS (DYB. (AMPHIPODA, CRUSTACEA

    Directory of Open Access Journals (Sweden)

    Timofeyev M.A.

    2006-03-01

    Full Text Available The data confirming the ability of Baikalian endemic species Eulimnogammarus vittatus (Dyb. and E. verrucosus (Dyb. to activate anaerobic glycolysis under hypoxia are presented. The differences in the degree and the rate of lactic acid accumulation and remetabolisation in returning to aerobiosis are noted in the species concerned. On the example of E. vittatus the ability of Baikalian endemics to activate anaerobic lipolysis and process of anaerobic formation of succinate is shown

  16. INDUCTION OF ANAEROBIC PROCESSES IN BAIKAL ENDEMICS EULIMNOGAMMARUS VITTATUS (DYB.) AND E. VERRUCOSUS (DYB.) (AMPHIPODA, CRUSTACEA)

    OpenAIRE

    Timofeyev M.A; Kirichenko K.A.; Rokhin A.V.; Bedulina D.S.; Chernyshova K.P.; Pobezhimova T.P.

    2006-01-01

    The data confirming the ability of Baikalian endemic species Eulimnogammarus vittatus (Dyb.) and E. verrucosus (Dyb.) to activate anaerobic glycolysis under hypoxia are presented. The differences in the degree and the rate of lactic acid accumulation and remetabolisation in returning to aerobiosis are noted in the species concerned. On the example of E. vittatus the ability of Baikalian endemics to activate anaerobic lipolysis and process of anaerobic formation of succinate is shown

  17. [Detection of anaerobic processes and microorganisms in immobilized activated sludge of a wastewater treatment plant with intense aeration].

    Science.gov (United States)

    Litti, Iu V; Nekrasova, V K; Kulikov, N I; Siman'kova, M V; Nozhevnikova, A N

    2013-01-01

    Attached activated sludge from the Krasnaya Polyana (Sochi) wastewater treatment plant was studied after the reconstruction by increased aeration and water recycle, as well as by the installation of a bristle carrier for activated sludge immobilization. The activated sludge biofilms developing under conditions of intense aeration were shown to contain both aerobic and anaerobic microorganisms. Activity of a strictly anaerobic methanogenic community was revealed, which degraded organic compounds to methane, further oxidized by aerobic methanotrophs. Volatile fatty acids, the intermediates of anaerobic degradation of complex organic compounds, were used by both aerobic and anaerobic microorganisms. Anaerobic oxidation of ammonium with nitrite (anammox) and the presence of obligate anammox bacteria were revealed in attached activated sludge biofilms. Simultaneous aerobic and anaerobic degradation of organic contaminants by attached activated sludge provides for high rates of water treatment, stability of the activated sludge under variable environmental conditions, and decreased excess sludge formation. PMID:25509405

  18. The effect of thermal hydrolysis pretreatment on the anaerobic degradation of nonylphenol and short-chain nonylphenol ethoxylates in digested biosolids.

    Science.gov (United States)

    McNamara, P J; Wilson, C A; Wogen, M T; Murthy, S N; Novak, J T; Novak, P J

    2012-06-01

    The presence of micropollutants can be a concern for land application of biosolids. Of particular interest are nonylphenol diethoxylate (NP(2)EO), nonylphenol monoethoxylate (NP(1)EO), and nonylphenol (NP), collectively referred to as NPE, which accumulate in anaerobically digested biosolids and are subject to regulation based on the environmental risks associated with them. Because biosolids are a valuable nutrient resource, it is essential that we understand how various treatment processes impact the fate of NPE in biosolids. Thermal hydrolysis (TH) coupled with mesophilic anaerobic digestion (MAD) is an advanced digestion process that destroys pathogens in biosolids and increases methane yields and volatile solids destruction. We investigated the impact of thermal hydrolysis pretreatment on the subsequent biodegradation of NPE in digested biosolids. Biosolids were treated with TH, anaerobic digestion, and aerobic digestion in laboratory-scale reactors, and NPE were analyzed in the influent and effluent of the digesters. NP(2)EO and NP(1)EO have been observed to degrade to the more estrogenic NP under anaerobic conditions; therefore, changes in the ratio of NP:NPE were of interest. The increase in NP:NPE following MAD was 56%; the average increase of this ratio in four sets of TH-MAD samples, however, was only 24.6 ± 3.1%. In addition, TH experiments performed in pure water verified that, during TH, the high temperature and pressure alone did not directly destroy NPE; TH experiments with NP added to sludge also showed that NP was not destroyed by the high temperature and pressure of TH when in a more complex sludge matrix. The post-aerobic digestion phases removed NPE, regardless of whether TH pretreatment occurred. This research indicates that changes in biosolids processing can have impacts beyond just gas production and solids destruction. PMID:22494493

  19. Modeling of Degradation Processes in Historical Mortars

    OpenAIRE

    Sýkora, J

    2014-01-01

    The aim of presented paper is modeling of degradation processes in historical mortars exposed to moisture impact during freezing. Internal damage caused by ice crystallization in pores is one of the most important factors limiting the service life of historical structures. Coupling the transport processes with the mechanical part will allow us to address the impact of moisture on the durability, strength and stiffness of mortars. This should be accomplished with the help of a complex thermo-h...

  20. Innovative two-stage mesophilic/thermophilic anaerobic degradation of sonicated sludge: performances and energy balance.

    Science.gov (United States)

    Gianico, A; Braguglia, C M; Gallipoli, A; Mininni, G

    2015-05-01

    This study investigates for the first time, on laboratory scale, the possible application of an innovative enhanced stabilization process based on sequential mesophilic/thermophilic anaerobic digestion of waste-activated sludge, with low-energy sonication pretreatment. The first mesophilic digestion step was conducted at short hydraulic retention time (3-5 days), in order to favor volatile fatty acid production, followed by a longer thermophilic step of 10 days to enhance the bioconversion kinetics, assuring a complete pathogen removal. The high volatile solid removals, up to 55%, noticeably higher compared to the performances of a single-stage process carried out in same conditions, can guarantee the stability of the final digestate for land application. The ultrasonic pretreatment influenced significantly the fatty acid formation and composition during the first mesophilic step, improving consequently the thermophilic conversion of these compounds into methane. Methane yield from sonicated sludge digestion reached values up to 0.2 Nm(3)/kgVSfed. Positive energy balances highlighted the possible exploitation of this innovative two-stage digestion in place of conventional single-stage processes. PMID:24906832

  1. Degradation of a model azo dye in submerged anaerobic membrane bioreactor (SAMBR) operated with powdered activated carbon (PAC).

    Science.gov (United States)

    Baêta, B E L; Luna, H J; Sanson, A L; Silva, S Q; Aquino, S F

    2013-10-15

    This work investigated the anaerobic degradation of the model azo dye Remazol Yellow Gold RNL in an upflow anaerobic sludge blanket reactor (UASB) and two submerged anaerobic membrane (SAMBR) bioreactors, one of which (SAMBR-1) was operated with powdered activated carbon (PAC) in its interior. The reactors were operated at 35 °C with a hydraulic retention time of 24 h in three operational phases, aimed to assess the effect of external sources of carbon (glucose) or redox mediator (yeast extract) on the removal or color and organic matter. The results showed that removal efficiencies of COD (73-94%) and color (90-94%) were higher for SAMBR-1 when compared to SAMBR-2 (operated without PAC) and UASB reactors. In addition, the presence of PAC in SAMBR-1 increased reactor stability, thereby leading to a lower accumulation of volatile fatty acids (VFA). The microfiltration membrane was responsible for an additional removal of ~50% of soluble residual COD in the form of VFA, thus improving permeate quality. On its turn, PAC exhibited the ability to adsorb byproducts (aromatic amines) of azo dye degradation as well as to act as source of immobilized redox mediator (quinone groups on its surface), thereby enhancing color removal. PMID:23810998

  2. IMPORTANT DEGRADATIONS IN POLYETHYLENE TERAPHTALATE EXTRUSION PROCESS

    OpenAIRE

    Şule ALTUN; ULCAY, Yusuf

    2003-01-01

    Polyethylene terephthalate (PET) is one of the most used thermo-plastic polymers. The total consumption of PET has been about 30 million tons in the year 2000. Polyester fibers constitute about 60 % of total synthetic fibers consumption. During extrusion, PET polymer is faced to thermal, thermo-oxidative and hydrolytic degradation, which result in severe reduction in its molecular weight, thereby adversely affecting its subsequent melt processability. Therefore, it is essential to understan...

  3. Assessing the correlation between anaerobic toluene degradation activity and bssA concentrations in hydrocarbon-contaminated aquifer material.

    Science.gov (United States)

    Kazy, Sufia K; Monier, Amy L; Alvarez, Pedro J J

    2010-09-01

    The assessment of biodegradation activity in contaminated aquifers is critical to demonstrate the performance of bioremediation and natural attenuation and to parameterize models of contaminant plume dynamics. Real time quantitative PCR (qPCR) was used to target the catabolic bssA gene (coding for benzylsuccinate synthase) and a 16S rDNA phylogenetic gene (for total Bacteria) as potential biomarkers to infer on anaerobic toluene degradation rates. A significant correlation (P = 0.0003) was found over a wide range of initial toluene concentrations (1-100 mg/l) between toluene degradation rates and bssA concentrations in anaerobic microcosms prepared with aquifer material from a hydrocarbon contaminated site. In contrast, the correlation between toluene degradation activity and total Bacteria concentrations was not significant (P = 0.1125). This suggests that qPCR targeting of functional genes might offer a simple approach to estimate in situ biodegradation activity, which would enhance site investigation and modeling of natural attenuation at hydrocarbon-contaminated sites. PMID:20204467

  4. A novel application of an anaerobic membrane process in wastewater treatment.

    Science.gov (United States)

    You, H S; Tseng, C C; Peng, M J; Chang, S H; Chen, Y C; Peng, S H

    2005-01-01

    The applications of membrane processes in anaerobic biological wastewater treatment still have some limitations due to severe membrane scaling and fouling, although they have been proven to achieve superior COD removal and biomass retention. An innovative anaerobic membrane process for wastewater treatment was conducted to control the membrane scaling problems. The process comprises an anaerobic reactor, an aerobic reactor, and a membrane separation tank. Anaerobic sludge from a full-scale UASB reactor treating food wastewater was inoculated to anaerobic and aerobic reactor to purify synthetic wastewater consisting of glucose and sodium acetate. The anaerobic reactor was operated in a sludge bed type without three-phase separator. The aerobic reactor can eliminate residual organics from the anaerobic reactor effluent using facultative microorganisms. To provide solid-liquid separation, hollow fiber ultrafiltration module was submerged in the separation tank. The results clearly show that the anaerobic membrane process combined methanogenic and aerobic COD reduction is a stable system. No fatal scaling was found after two months of operation even without chemical cleaning for the membrane. It was also found that inorganic precipitates formed in the aerobic reactor were reduced due to CO2 stripping in aerobic reactor. Another important finding was that the inorganic precipitates were entrapped into facultative aerobes floc. The ash/SS ratio of aerobes floc increased from 0.17 to 0.55 after 50 days of operation, which confirms this phenomenon. Based on our investigation, the new process can control scaling effectively to extend the membrane application in anaerobic treatment. PMID:16003960

  5. Photocatalytic Based Degradation Processes of Lignin Derivatives

    Directory of Open Access Journals (Sweden)

    Colin Awungacha Lekelefac

    2015-01-01

    Full Text Available Photocatalysis, belonging to the advanced oxidation processes (AOPs, is a potential new transformation technology for lignin derivatives to value added products (e.g., phenol, benzene, toluene, and xylene. Moreover, lignin represents the only viable source to produce aromatic compounds as fossil fuel alternative. This review covers recent advancement made in the photochemical transformation of industrial lignins. It starts with the photochemical reaction principle followed by results obtained by varying process parameters. In this context, influences of photocatalysts, metal ions, additives, lignin concentration, and illumination intensity and the influence of pH are presented and discussed. Furthermore, an overview is given on several used process analytical methods describing the results obtained from the degradation of lignin derivatives. Finally, a promising concept by coupling photocatalysis with a consecutive biocatalytic process was briefly reviewed.

  6. Study of the Process of Hydraulic Mixing in Anaerobic Digester of Biogas Plant

    Directory of Open Access Journals (Sweden)

    Karaeva Julia V.

    2015-03-01

    Full Text Available Two systems of hydraulic mixing in a vertical cylindrical anaerobic digester: standard and modernised are discussed in the paper. Numerical investigations that were carried out are focused on a study of hydrodynamic processes in an aerobic digester using two various systems of hydraulic mixing as well as on analysis of the efficiency of methane fermentation process accomplished under different geometric parameters of an anaerobic digester and systems of hydraulic mixing.

  7. Dynamics of the anaerobic process: Effects of volatile fatty acids

    DEFF Research Database (Denmark)

    Pind, Peter Frode; Angelidaki, Irini; Ahring, Birgitte Kiær

    2003-01-01

    A complex and fast dynamic response of the anaerobic biogas system was observed when the system was subjected to pulses of volatile fatty acids (VFAs). It was shown that a pulse of specific VFAs into a well-functioning continuous stirred tank reactor (CSTR) system operating on cow manure affected...

  8. Anaerobic Digestion. Instructor's Guide. Biological Treatment Process Control.

    Science.gov (United States)

    Carnegie, John W., Ed.

    This instructor's guide contains materials needed to teach a four-lesson unit on anaerobic digestion control. These materials include: (1) unit overview; (2) lesson plans; (3) lecture outlines; (4) student worksheets for each lesson (with answers); and (5) two copies of a final quiz (with and without answers). Lesson 1 is a review of the theory of…

  9. Degradation of phenol in an upflow anaerobic sludge blanket(UASB) reactor at ambient temperatureKE

    Institute of Scientific and Technical Information of China (English)

    KE Shui-zhou1; SHI Zhou; ZHANG Tong; Herbert H. P. FANG

    2004-01-01

    A synthetic wastewater containing phenol as sole substrate was treated in a 2.8 L upflow anaerobic sludge blanket(UASB) reactor at ambient temperature. The operation conditions and phenol removal efficiency were discussed, microbial population in the UASB sludge was identified based on DNA cloning, and pathway of anaerobic phenol degradation was proposed. Phenol in wastewater was degraded in an UASB reactor at loading rate up to 18 gCOD/(L·d), With a 1:1 recycle ratio, at 26(1℃, pH 7.0-7.5. An UASB reactor was able to remove 99% of phenol up to 1226 mg/L in wastewater with 24 h of hydraulic retention time(HRT). For HRT below 24 h, phenol degradation efficiency decreased with HRT, from 95.4% at 16 h to 93.8% at 12 h. It further deteriorated to 88.5% when HRT reached 8 h. When the concentration of influent phenol of the reactor was 1260 mg/L(corresponding COD 3000 mg/L), with the HRT decreasing(from 40 h to 4 h, corresponding COD loading increasing), the biomass yields tended to increase from 0.265 to 3.08 g/(L·d). While at 12 h of HRT, the biomass yield was lower. When HRT was 12 h, the methane yield was 0.308 L/(gCOD removed), which was the highest. Throughout the study, phenol was the sole organic substrate. The effluent contained only residual phenol without any detectable intermediates, such as benzoate, 4-hydrobenzoate or volatile fatty acids(VFAs). Based on DNA cloning analysis, the sludge was composed of five groups of microorganisms. Desulfotomaculum and Clostridium were likely responsible for the conversion of phenol to benzoate, which was further degraded by Syntrophus to acetate and H2/CO2. Methanogens lastly converted acetate and H2/CO2 to methane. The role of epsilon-Proteobacteria was, however, unsure.

  10. The key microorganisms for anaerobic degradation of pentachlorophenol in paddy soil as revealed by stable isotope probing

    International Nuclear Information System (INIS)

    Highlights: • SIP suggested that Dechloromonas can mineralize PCP in soil. • Methanosaeta and Methanocella acquired PCP-derived carbon. • Lactate enhanced microbial degradation of PCP in soil. - Abstract: Pentachlorophenol (PCP) is a common residual persistent pesticide in paddy soil and has resulted in harmful effect on soil ecosystem. The anaerobic microbial transformation of PCP, therefore, has been received much attentions, especially the functional microbial communities for the reductive transformation. However, the key functional microorganisms for PCP mineralization in the paddy soil still remain unknown. In this work, DNA-based stable isotope probing (SIP) was applied to explore the key microorganisms responsible for PCP mineralization in paddy soil. The SIP results indicated that the dominant bacteria responsible for PCP biodegradation belonged to the genus Dechloromonas of the class β-Proteobacteria. In addition, the increased production of 13CH4 and 13CO2 indicated that the addition of lactate enhanced the rate of biodegradation and mineralization of PCP. Two archaea classified as the genera of Methanosaeta and Methanocella of class Methanobacteria were enriched in the heavy fraction when with lactate, whereas no archaea was detected in the absence of lactate. These findings provide direct evidence for the species of bacteria and archaea responsible for anaerobic PCP or its breakdown products mineralization and reveal a new insight into the microorganisms linked with PCP degradation in paddy soil

  11. The key microorganisms for anaerobic degradation of pentachlorophenol in paddy soil as revealed by stable isotope probing

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Hui [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Chengshuai [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550009 (China); Li, Fangbai, E-mail: cefbli@soil.gd.cn [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Luo, Chunling [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Chen, Manjia; Hu, Min [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China)

    2015-11-15

    Highlights: • SIP suggested that Dechloromonas can mineralize PCP in soil. • Methanosaeta and Methanocella acquired PCP-derived carbon. • Lactate enhanced microbial degradation of PCP in soil. - Abstract: Pentachlorophenol (PCP) is a common residual persistent pesticide in paddy soil and has resulted in harmful effect on soil ecosystem. The anaerobic microbial transformation of PCP, therefore, has been received much attentions, especially the functional microbial communities for the reductive transformation. However, the key functional microorganisms for PCP mineralization in the paddy soil still remain unknown. In this work, DNA-based stable isotope probing (SIP) was applied to explore the key microorganisms responsible for PCP mineralization in paddy soil. The SIP results indicated that the dominant bacteria responsible for PCP biodegradation belonged to the genus Dechloromonas of the class β-Proteobacteria. In addition, the increased production of {sup 13}CH{sub 4} and {sup 13}CO{sub 2} indicated that the addition of lactate enhanced the rate of biodegradation and mineralization of PCP. Two archaea classified as the genera of Methanosaeta and Methanocella of class Methanobacteria were enriched in the heavy fraction when with lactate, whereas no archaea was detected in the absence of lactate. These findings provide direct evidence for the species of bacteria and archaea responsible for anaerobic PCP or its breakdown products mineralization and reveal a new insight into the microorganisms linked with PCP degradation in paddy soil.

  12. Two-stage anaerobic and post-aerobic mesophilic digestion of sewage sludge: Analysis of process performance and hygienization potential.

    Science.gov (United States)

    Tomei, M Concetta; Mosca Angelucci, Domenica; Levantesi, Caterina

    2016-03-01

    Sequential anaerobic-aerobic digestion has been demonstrated to be effective for enhanced sludge stabilization, in terms of increased solid reduction and improvement of sludge dewaterability. In this study, we propose a modified version of the sequential anaerobic-aerobic digestion process by operating the aerobic step under mesophilic conditions (T=37 °C), in order to improve the aerobic degradation kinetics of soluble and particulate chemical oxygen demand (COD). Process performance has been assessed in terms of "classical parameters" such as volatile solids (VS) removal, biogas production, COD removal, nitrogen species, and polysaccharide and protein fate. The aerobic step was operated under intermittent aeration to achieve nitrogen removal. Aerobic mesophilic conditions consistently increased VS removal, providing 32% additional removal vs. 20% at 20 °C. Similar results were obtained for nitrogen removal, increasing from 64% up to 99% at the higher temperature. Improved sludge dewaterability was also observed with a capillary suction time decrease of ~50% during the mesophilic aerobic step. This finding may be attributable to the decreased protein content in the aerobic digested sludge. The post-aerobic digestion exerted a positive effect on the reduction of microbial indicators while no consistent improvement of hygienization related to the increased temperature was observed. The techno-economic analysis of the proposed digestion layout showed a net cost saving for sludge disposal estimated in the range of 28-35% in comparison to the single-phase anaerobic digestion. PMID:26760266

  13. Effects of Electron Acceptors, Reducing Agents, and Toxic Metabolites on Anaerobic Degradation of Heterocyclic Compounds

    DEFF Research Database (Denmark)

    Licht, Dorthe; Ahring, Birgitte Kiær; Arvin, Erik

    1996-01-01

    Degradation of four heterocyclic compounds was examined under nitrate-reducing, sulphate-reducing and methanogenic conditions. Soil samples from a creosote-polluted site in Denmark were used as inoculum. Indole and quinoline were degraded under all redox conditions with the highest degradation...

  14. Isolation of a tannic acid-degrading Streptococcus sp. from an anaerobic shea cake digester.

    Science.gov (United States)

    Nitiema, L W; Dianou, D; Simpore, J; Karou, S D; Savadogo, P W; Traore, A S

    2010-01-01

    An anaerobic digester fed with shea cake rich in tannins and phenolic compounds rich-shea cake and previously inoculated with anaerobic sludge from the pit of a slaughterhouse, enabled six months acclimatization of the bacteria to aromatic compounds. Afterwards, digester waste water samples were subject to successive culture on media with 1 g L(-1) tannic acid allowing the isolation of a bacterial strain coded AB. Strain AB was facultatively anaerobic, mesophilic, non-motile, non-sporulating, catalase and oxidase negative bacterium, namely strain AB, was isolated from an anaerobic digester fed with shea cake rich in tannins and phenolic compounds, after inoculation with anaerobic sludge from the pit of a slaughterhouse and enrichment on tannic acid. The coccoid cells occurred in pair, short or long chains and stained Gram-positive. Strain AB fermented a wide range of carbohydrates including glucose, fructose, galactose, raffinose, arabinose, sucrose, maltose, lactose, starch and cellulose. Optimum growth occurred with glucose and tannic acid at 37 degrees C and pH 8. The pH, temperature and salt concentration for growth ranged from 5 to 9, 20 to 45 degrees C and 0 to 15 g L(-1), respectively. Strain AB converted tannic acid to gallic acid. These features were similar to those of the Streptococcus genus. The determination of tannic acid hydrolysis end products, ability to utilize various organic acids, alcohols and peptides, GC% of the DNA, the sequencing of 16S rRNA gene and DNA-DNA hybridization will permit to confirm this affiliation and to determine the species. PMID:20415153

  15. Impacts of trace element supplementation on the performance of anaerobic digestion process: A critical review.

    Science.gov (United States)

    Choong, Yee Yaw; Norli, Ismail; Abdullah, Ahmad Zuhairi; Yhaya, Mohd Firdaus

    2016-06-01

    This paper critically reviews the impacts of supplementing trace elements on the anaerobic digestion performance. The in-depth knowledge of trace elements as micronutrients and metalloenzyme components justifies trace element supplementation into the anaerobic digestion system. Most of the earlier studies reported that trace elements addition at (sub)optimum dosages had positive impacts mainly longer term on digester stability with greater organic matter degradation, low volatile fatty acids (VFA) concentration and higher biogas production. However, these positive impacts and element requirements are not fully understood, they are explained on a case to case basis because of the great variance of the anaerobic digestion operation. Iron (Fe), nickel (Ni) and cobalt (Co) are the most studied and desirable elements. The right combination of multi-elements supplementation can have greater positive impact. This measure is highly recommended, especially for the mono-digestion of micronutrient-deficient substrates. The future research should consider the aspect of trace element bioavailability. PMID:27005788

  16. Mechanical degradation processes: The Belgian experience

    International Nuclear Information System (INIS)

    Design life is merely used in Belgium as a requirement in the 'Design Specification' of some components subjected to known degradation processes, such as stress induced fatigue, embrittlement (irradiation or other), various types of corrosion, wear, erosion, thermal aging (electrical insulation, ...), etc. Design life is in no way directly related to the duration of the plant operation. In that sense design life for the Belgian NPP components includes the values of 20, 30 and 40 years. The oldest plant (20 years design life) has been decommissioned in 1991. The most recent units (40 years design life) have still a good time to go. The intermediate units (30 years design life) started around 1975. Consequently components of these plants need be looked at to determine whether or not deteriorations have occurred. The paper presents the various known mechanical degradation processes and how they affect various components. Emphasis is laid on prevention, mitigation or repair measures that have been or are being taken to avoid that the 'Equipment design life' be the limiting factor in the duration of the plant operation. (author)

  17. Thermophilic anaerobic fermentation of olive pulp for hydrogen and methane production: modelling of the anaerobic digestion process

    DEFF Research Database (Denmark)

    Gavala, Hariklia N.; Skiadas, Ioannis V.; Ahring, Birgitte Kiær; Lyberatos, G.

    2006-01-01

    The present study investigates the thermophilic biohydrogen and methane production from olive pulp, which is the semi-solid. residue coming from the two-phase processing of olives. It focussed on: a) production of methane from the raw olive pulp; b) anaerobic bio-production of hydrogen from the...... were performed. The hydrogen potential of the olive pulp amounted to 1.6 mmole H-2 per g TS. The methane potential of the raw olive pulp and hydrogen-effluent was as high as 19 mmole CH4 per g TS suggesting that: a) olive pulp is a suitable substrate for methane production; and b) biohydrogen...

  18. Integration of a Water Scrubbing Technique and Two-Stage Pressurized Anaerobic Digestion in One Process

    OpenAIRE

    Andreas Lemmer; Yuling Chen; Anna-Maria Wonneberger; Frank Graf; Rainer Reimert

    2015-01-01

    Two-stage pressurized anaerobic digestion is a promising technology. This technology integrates in one process biogas production with upgrading and pressure boosting for grid injection. To investigate whether the efficiency of this novel system could be further increased, a water scrubbing system was integrated into the methanogensis step. Therefore, six leach-bed reactors were used for hydrolysis/acidification and a 30-L pressurized anaerobic filter operated at 9 bar was adopted for acetogen...

  19. Modeling, Simulation and Control of Biotechnological Processes in Decentralized Anaerobic Treatment of Domestic Wastewater

    OpenAIRE

    Vega De Lille, Marisela Ix-chel

    2015-01-01

    The general objective of the present thesis is the development of less empirical methods for assessment and control of a decentralized anaerobic plant for the treatment of domestic wastewater to obtain service water quality. The reuse of treated domestic wastewater as service water (e.g. toilet flushing, irrigation, etc.) can significantly help to decrease potable water consumption. Since anaerobic treatment plants are subject to a high sensitivity to disturbances and process complexity,...

  20. Correlation between Organic Matter Degradation and the Rheological Performance of Waste Sludge During Anaerobic Digestion

    Science.gov (United States)

    Morel, Evangelina S.; Hernández-Hernándes, José A.; Méndez-Contreras, Juan M.; Cantú-Lozano, Denis

    2008-07-01

    Anaerobic digestion has demonstrated to be a good possibility to reduce the organic matter contents in waste activated sludge resulting in the effluents treatment. An anaerobic digestion was carried out in a 3.5 L reactor at 35 °C for a period of 20 days. An electronic thermostat controlled the temperature. The reactor was agitated at a rate of 200 rpm. The study of the rheological behavior of the waste activated sludge was done with an Anton Paar™ rheometer model MCR301 with a peltier plate for temperature control. Four-blade vane geometry was used with samples of 37 mL for determining rheological properties. Sampling (two samples) was taken every four days of anaerobic digestion through a peristaltic pump. The samples behavior was characterized by the Herschel-Bulkley model, with R2>0.99 for most cases. In all samples were found an apparent viscosity (ηap) and yield stress (τo) decrement when organic matter content diminishes. This demonstrates a relationship between rheological properties and organic matter concentration (% volatile solids). Also the flow activation energy (Ea) was calculated using the Ahrrenius correlation and samples of waste activated sludge before anaerobic digestion. In this case, samples were run in the rheometer at 200 rpm and a temperature range of 25 to 75 °C with an increment rate of 2 °C per minute. The yield stress observed was in a range of 0.93-0.18 Pa, the apparent viscosity was in a range of 0.0358-0.0010 Pa.s, the reduction of organic matter was in a range of 62.57-58.43% volatile solids and the average flow activation energy was 1.71 Calṡg-mol-1.

  1. Simplified mechanistic model for the two-stage anaerobic degradation of sewage sludge.

    Science.gov (United States)

    Donoso-Bravo, Andrés; Pérez-Elvira, Sara; Fdz-Polanco, Fernando

    2015-01-01

    Two-phase anaerobic systems are being increasingly implemented for the treatment of both sewage sludge and organic fraction of municipal solid waste. Despite the good amount of mathematical models in anaerobic digestion, few have been applied in two-phase systems. In this study, a three-reaction mechanistic model has been developed, implemented and validated by using experimental data from a long-term anaerobic two-phase (TPAD) digester treating sewage sludge. A sensitivity analysis shows that the most influential parameters of the model are the ones related to the hydrolysis reaction and the activity of methanogens in the thermophilic reactor. The calibration procedure highlights a noticeable growth rate of the thermophilic methanogens throughout the evaluation period. Overall, all the measured variables are properly predicted by the model during both the calibration and the cross-validation periods. The model's representation of the organic matter behaviour is quite good. The most important disagreements are observed for the biogas production especially during the validation period. The whole application procedure underlines the ability of the model to properly predict the behaviour of this bioprocess. PMID:25400016

  2. Hybrid alkali-hydrodynamic disintegration of waste-activated sludge before two-stage anaerobic digestion process.

    Science.gov (United States)

    Grübel, Klaudiusz; Suschka, Jan

    2015-05-01

    The first step of anaerobic digestion, the hydrolysis, is regarded as the rate-limiting step in the degradation of complex organic compounds, such as waste-activated sludge (WAS). The aim of lab-scale experiments was to pre-hydrolyze the sludge by means of low intensive alkaline sludge conditioning before applying hydrodynamic disintegration, as the pre-treatment procedure. Application of both processes as a hybrid disintegration sludge technology resulted in a higher organic matter release (soluble chemical oxygen demand (SCOD)) to the liquid sludge phase compared with the effects of processes conducted separately. The total SCOD after alkalization at 9 pH (pH in the range of 8.96-9.10, SCOD = 600 mg O2/L) and after hydrodynamic (SCOD = 1450 mg O2/L) disintegration equaled to 2050 mg/L. However, due to the synergistic effect, the obtained SCOD value amounted to 2800 mg/L, which constitutes an additional chemical oxygen demand (COD) dissolution of about 35 %. Similarly, the synergistic effect after alkalization at 10 pH was also obtained. The applied hybrid pre-hydrolysis technology resulted in a disintegration degree of 28-35%. The experiments aimed at selection of the most appropriate procedures in terms of optimal sludge digestion results, including high organic matter degradation (removal) and high biogas production. The analyzed soft hybrid technology influenced the effectiveness of mesophilic/thermophilic anaerobic digestion in a positive way and ensured the sludge minimization. The adopted pre-treatment technology (alkalization + hydrodynamic cavitation) resulted in 22-27% higher biogas production and 13-28% higher biogas yield. After two stages of anaerobic digestion (mesophilic conditions (MAD) + thermophilic anaerobic digestion (TAD)), the highest total solids (TS) reduction amounted to 45.6% and was received for the following sample at 7 days MAD + 17 days TAD. About 7% higher TS reduction was noticed compared with the sample after 9

  3. Monitoring of anaerobic digestion processes: A review perspective

    DEFF Research Database (Denmark)

    Madsen, Michael; Holm-Nielsen, Jens Bo; Esbensen, Kim

    2011-01-01

    The versatility of anaerobic digestion (AD) as an effective technology for solving central challenges met in applied biotechnological industry and society has been documented in numerous publications over the past many decades. Reduction of sludge volume generated from wastewater treatment...... potential is highlighted. The Danish co-digestion concept, which integrates utilisation of agricultural manure, biomass and industrial organic waste, is used as a case study. We present a first foray for the next research and development perspectives and directions for the AD bioconversion sector....

  4. Anaerobic electrochemical membrane bioreactor and process for wastewater treatment

    KAUST Repository

    Amy, Gary

    2015-07-09

    An anaerobic electrochemical membrane bioreactor (AnEMBR) can include a vessel into which wastewater can be introduced, an anode electrode in the vessel suitable for supporting electrochemically active microorganisms (EAB, also can be referred to as anode reducing bacteria, exoelectrogens, or electricigens) that oxidize organic compounds in the wastewater, and a cathode membrane electrode in the vessel, which is configured to pass a treated liquid through the membrane while retaining the electrochemically active microorganisms and the hydrogenotrophic methanogens (for example, the key functional microbial communities, including EAB, methanogens and possible synergistic fermenters) in the vessel. The cathode membrane electrode can be suitable for catalyzing the hydrogen evolution reaction to generate hydro en.

  5. Anaerobic BTEX degradation in oil sands tailings ponds: Impact of labile organic carbon and sulfate-reducing bacteria.

    Science.gov (United States)

    Stasik, Sebastian; Wick, Lukas Y; Wendt-Potthoff, Katrin

    2015-11-01

    The extraction of bitumen from oil sands in Alberta (Canada) produces volumes of tailings that are pumped into large anaerobic settling-basins. Beside bitumen, tailings comprise fractions of benzene, toluene, ethylbenzene and xylenes (BTEX) that derive from the application of industrial solvents. Due to their toxicity and volatility, BTEX pose a strong concern for gas- and water-phase environments in the vicinity of the ponds. The examination of two pond profiles showed that concentrations of indigenous BTEX decreased with depth, pointing at BTEX transformation in situ. With depth, the relative contribution of ethylbenzene and xylenes to total BTEX significantly decreased, while benzene increased relatively from 44% to 69%, indicating preferential hydrocarbon degradation. To predict BTEX turnover and residence time, we determined BTEX degradation rates in tailings of different depths in a 180-days microcosm study. In addition, we evaluated the impact of labile organic substrates (e.g. acetate) generally considered to stimulate hydrocarbon degradation and the contribution of sulfate-reducing bacteria (SRB) to BTEX turnover. In all depths, BTEX concentrations significantly decreased due to microbial activity, with degradation rates ranging between 4 and 9 μg kg(-1) d(-1). BTEX biodegradation decreased linearly in correlation with initial concentrations, suggesting a concentration-dependent BTEX transformation. SRB were not significantly involved in BTEX consumption, indicating the importance of methanogenic degradation. BTEX removal decreased to 70-90% in presence of organic substrates presumptively due to an accumulation of acetate that lowered BTEX turnover due to product inhibition. In those assays SRB slightly stimulated BTEX transformation by reducing inhibitory acetate levels. PMID:26066083

  6. Avoiding propionic acid accumulation in the anaerobic process for biohydrogen production

    International Nuclear Information System (INIS)

    The accumulation of propionic acid in the anaerobic process will result in low efficiency of the methanogenic phase due to the low acetogenic rate of propionic acid, and hence low wastewater treatment efficiency. The reasons for propionic acid accumulation in the acidogenic phase and the relationship between the accumulation and biohydrogen generation were studied and a strategy for avoiding propionic acid accumulation in the anaerobic process for biohydrogen generation is also introduced. The experimental results indicate that changing pH and oxidation-reduction potential (ORP) can result in the variation of fermentation type, and maintaining lower ORP and avoiding pH of 5.5 will reduce the accumulation of propionic acid in the anaerobic process. Higher biohydrogen generation rate is not always accompanied with the accumulation of propionic acid. In the acidogenic reactor of two-phase separated anaerobic process, ethanol type fermentation, in which pH at 4.5 below, can produce much more biohydrogen but without accumulation of propionic acid. Thus, ethanol-type fermentation is a better selection when using an acidogenic reactor of a two-phase separated anaerobic process to efficiently produce biohydrogen with simultaneous organic wastewater pre-treatment

  7. p-cresol methylhydroxylase from a denitrifying bacterium involved in anaerobic degradation of p-cresol.

    OpenAIRE

    Hopper, D. J.; Bossert, I D; Rhodes-Roberts, M E

    1991-01-01

    A bacterium, strain PC-07, previously isolated as part of a coculture capable of growing on p-cresol under anaerobic conditions with nitrate as the acceptor was identified as an Achromobacter sp. The first enzyme of the pathway, p-cresol methylhydroxylase, which converts its substrate into p-hydroxybenzyl alcohol, was purified. The enzyme had an Mr of 130,000 and the spectrum of a flavocytochrome. It was composed of flavoprotein subunits of Mr 54,000 and cytochrome subunits of Mr 12,500. The ...

  8. Characterization and single-stage denitrification anaerobic digestion of spent stream from the hydrolysis-fermentation-combustion process

    Science.gov (United States)

    Singh, Ramnik

    The demand for ethanol as an oxygenate and octane booster in automobile fuel is growing. A number of processes are being investigated for conversion of biomass to ethanol. The Hydrolysis-Fermentation-Combustion (HFC) process for fuel ethanol production developed at the University of California Forest Products Laboratory, Richmond, California is at the stage of technology transfer following over two decades of research and development. This study addresses the technology to be used in treatment of spent streams to be discharged from this process. The treatment design combines a single stage denitrification and anaerobic digestion (SSDAD) for the biological treatment of a representative stream from this process. A typical spent stream contained a wide range of soluble organic materials including: unfermented sugars, components of the feedstocks solubilized in the hydrolysis, acid degradation products of carbohydrates, cleavage products of lignin, water-soluble extractives and phenolics, terpenes and other unfermented organic material, and nitrate ion from the nitric acid used as a catalyst in the hydrolysis reaction. Three sets of experiments were conducted in laboratory scale anaerobic digesters. Commonly available anaerobic sludge from local sewage treatment plants was used as a starter seed and was successfully acclimated to the high nitrate substrate leading to enrichment of denitrifiers. Necessary nutrients and trace elements were identified and supplied to satisfy the obligatory requirements of different groups of bacterial groups present. A major finding was the unique role of ammonium hydroxide in controlling pH leading to steady-state operation of the digester. At steady state operation the reduction in COD was 65%, the nitrate reduction was 88% and the nitrite reduction was 100%. Nitrate was reduced to safe nitrogen gas without buildup of any intermediate products. Organic material was converted to useful methane gas and carbon dioxide. The SSDAD system was

  9. Energy balance of a two-phase anaerobic digestion process for energy crops

    Energy Technology Data Exchange (ETDEWEB)

    Zielonka, Simon; Lemmer, Andreas; Oechsner, Hans; Jungbluth, Thomas [University of Hohenheim, State Institute of Agricultural Engineering and Bioenergy, Stuttgart (Germany)

    2010-12-15

    This article deals with the digestion of energy crops in a two-phase biogas process based on an anaerobic leach-bed reactor combined with an anaerobic filter. The biogas process is a microbiological conversion of biomass into methane and carbon dioxide. This process is carried out by different microorganisms and can be divided into four steps which normally take place in only one digester. To be able to digest difficult energy crops by mono-digestion and to meet the different needs of the several bacteria, which take part in the four-step process of the methane production, the process was divided into two phases: (i) an anaerobic batch leach-bed phase, where the leachate was produced and (ii) an anaerobic filter, where the organic fraction of the leachate was converted into biogas. Considering the results of the experiments, the two-phase digestion of energy crops exhibited stable digestion behavior. No biological imbalance of the process, e.g. due to a sudden change of substrate, was detected either in the leach bed or in the anaerobic filter. Variation in suitability for two-phase fermentation with an anaerobic batch leach-bed reactor was observed for various substrates. The different substrates varied in their influence on acid formation and concentration as well as an influence on the course of the pH value. Therefore, an effect on the distribution of energy to the phases could be observed. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Calculation of energy recovery and greenhouse gas emission reduction from palm oil mill effluent treatment by an anaerobic granular-sludge process.

    Science.gov (United States)

    Show, K Y; Ng, C A; Faiza, A R; Wong, L P; Wong, L Y

    2011-01-01

    Conventional aerobic and low-rate anaerobic processes such as pond and open-tank systems have been widely used in wastewater treatment. In order to improve treatment efficacy and to avoid greenhouse gas emissions, conventional treatment can be upgraded to a high performance anaerobic granular-sludge system. The anaerobic granular-sludge systems are designed to capture the biogas produced, rendering a potential for claims of carbon credits under the Kyoto Protocol for reducing emissions of greenhouse gases. Certified Emission Reductions (CERs) would be issued, which can be exchanged between businesses or bought and sold in international markets at the prevailing market prices. As the advanced anaerobic granular systems are capable of handling high organic loadings concomitant with high strength wastewater and short hydraulic retention time, they render more carbon credits than other conventional anaerobic systems. In addition to efficient waste degradation, the carbon credits can be used to generate revenue and to finance the project. This paper presents a scenario on emission avoidance based on a methane recovery and utilization project. An example analysis on emission reduction and an overview of the global emission market are also outlined. PMID:22170839

  11. How to use molecular biology tools for the study of the anaerobic digestion process?

    NARCIS (Netherlands)

    Cabezas, Angela; Araujo, de Juliana Calabria; Callejas, Cecilia; Galès, Amandine; Hamelin, Jérôme; Marone, Antonella; Machado de Sousa, Diana; Trably, Eric; Etchebehere, Claudia

    2015-01-01

    Anaerobic digestion is used with success for the treatment of solid waste, urban and industrial effluents with a concomitant energy production. The process is robust and stable, but the complexity of the microbial community involved in the process is not yet fully comprehensive. Nowadays, the stu

  12. The contribution of biotic and abiotic processes during azo dye reduction in anaerobic sludge

    NARCIS (Netherlands)

    Zee, van der F.P.; Bisschops, I.A.E.; Blanchard, V.G.; Bouwman, R.H.M.; Lettinga, G.; Field, J.A.

    2003-01-01

    Azo dye reduction results from a combination of biotic and abiotic processes during the anaerobic treatment of dye containing effluents. Biotic processes are due to enzymatic reactions whereas the chemical reaction is due to sulfide. In this research, the relative impact of the different azo dye red

  13. Fate of products of degradation processes: consequences for climatic change

    NARCIS (Netherlands)

    Slanina, J.; Brink, ten H.M.; Khlystov, A.

    1999-01-01

    The end products of atmospheric degradation are not only CO2 and H2O but also sulfate and nitrate depending on the chemical composition of the substances which are subject to degradation processes. Atmospheric degradation has thus a direct influence on the radiative balance of the earth not only due

  14. Biohydrogen production from diary processing wastewater by anaerobic biofilm reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rios-Gonzalez, L.J.; Moreno-Davila, I.M.; Rodriguez-Martinez, J.; Garza-Garcia, Y. [Universidad Autonoma de Coahuila, Saltillo, Coahuila (Mexico)]. E-mail: leopoldo.rios@mail.uadec.mx

    2009-09-15

    This article describes biological hydrogen production from diary wastewater via anaerobic fermentation using pretreated heat shock (100 degrees Celsius, 30 min.) and acid (pH 3.0, 24 h) treatment procedures to selectively enrich the hydrogen producing mixed consortia prior to inoculation to batch reactors. Bioreactor used for immobilization consortia was operated at mesophilic (room) temperature (20{+-}3 degrees Celsius), under acidophilic conditions (pH 4.0-4.5), HRT (2h), and a natural support for generate hydrogen producing mixed consortia biofilm: Opuntia imbricata. Reactor was initially operated with sorbitol (5g/L) for 60 days of operation. Batch tests were conducted using 20{+-}0.02g of natural support with biofilm. Batch experiments were conducted to investigate the effect of COD (2.9-21.1 g-COD/L), at initial pH of 7.0, 32{+-}1 degrees Celsius. Maximum hydrogen yield was obtained at 21.1 g-COD/L. Experiments of pH effect were conducted using the optimal substrate concentration (21.2 g-COD/L), at pH 4 to 7 and 11.32 (pH diary wastewater) ,and 32{+-}1 degrees Celsius. Experiments results indicate the optimum initial cultivation was pH 4.0, but we can consider also a stable hydrogen production at pH 11.32 (pH diary wastewater), so we can avoid to fit the pH, and use diary wastewater as it left the process of cheese manufacture. The operational pH of 4.0 is 1.5 units below that of previously reported hydrogen producing organisms. The influence of the effect of temperature were conducted using the optimal substrate concentration (21.2 g-COD/L), two pH levels: 4.0 and 11.32, and four different temperatures: 16{+-}3 degrees Celsius (room temperature), 3 C, 45{+-}1 degrees Celsius y 55{+-}1 degrees Celsius.Optimal temperature for hydrogen production from diary wastewater at pH 4.0 was 55{+-}1 degrees Celsius, and for pH 11.32 was 16{+-}3 degrees Celsius.Therefore, the results suggests biofilm reactors in a natural support like Opuntia imbricata have good potential

  15. Investigations on degradation of nitrogen compounds by anaerobic-aerobic treatment of concentrated wastewaters with special regard to nitrogen removal via nitrite

    International Nuclear Information System (INIS)

    The main result is, that the two-stage anaerobic-aerobic treatment of high strength ammonium wastewater is an economical solution, save to operate and with high efficiency. Therefore its very important, to project and optimize the total process. On the one hand the biogas production has to be maximized, on the other hand the energy consumption for aeration and excess sludge treatment and resulting excess sludge has to be minimized. One possibility to realize this, is the nitrogen removal via nitrite. This process has been investigated in half-technical pilot plants. The carbon consumption amounts only to 63% in comparison with dentrification via nitrate. The 37% which are saved could be transformed into biogas during the anaerobic stage. The excess sludge production and the energy consumption in the aerobic stage is correspondingly lower. The essential parameter for regulating the process is the concentration of free ammonia (1-5 mg NH3/l) in the reactor (controlled by means of a continuous NH4- and pH-measurement). The inhibition of the nitrobacter amounts to 80%. - The storage of nitrifying biomass for several months (for industries working in campaigns) is possible without adding nitrogen and with an aeration intensity of e.g. 1 h/d, depending on the actual ammonium increase in the reactor (< 10 mg/l). To avoid inhibition during the reactivation of the sludge, the load has to be adapted to the actual activity (measured by means of an ammonium-degradation-test) and the dentrification has to be started at the same time. (orig.). 27 figs., 42 tabs., 104 refs

  16. A new model for anaerobic processes of up-flow anaerobic sludge blanket reactors based on cellular automata

    DEFF Research Database (Denmark)

    Skiadas, Ioannis V.; Ahring, Birgitte Kiær

    2002-01-01

    characteristics and lead to different reactor behaviour. A dynamic mathematical model has been developed for the anaerobic digestion of a glucose based synthetic wastewater in UASB reactors. Cellular automata (CA) theory has been applied to simulate the granule development process. The model takes......The advantageous performance of the UASB reactors is due to the immobilisation of the active biomass, since bacteria coagulate forming aggregates usually called granules. Changes in organic loading rate, hydraulic loading rate or influent substrate composition usually result in changes in granule...... into consideration that granule diameter and granule microbial composition are functions of the reactor operational parameters and is capable of predicting the UASB performance and the layer structure of the granules....

  17. The degradation processes in high loaded casts

    Directory of Open Access Journals (Sweden)

    E. Ďuriníková

    2010-01-01

    Full Text Available In this work are described structural changes of jet engine DV – 2 turbine blades and effect of degradation process. Turbine blades work in aggressively environs and because of that there are rate among high loaded cast stock. As an experimental material we have chose nickel superalloy ŽS6K with surface heat - resisting alitize layer. Evaluation is slant on largeness wearing over work of certain number of hour in operation. Effect working environs and overrun working temperatures is show changes measures as well as changes macrostructure of basic material blades. Evaluate is advance quantitative metallography through the medium metallographic software NIS element. Quantitative analysis evaluate thickness measures, quality control outer look and lack mixture in the seat, which is not splash, is precede by lack of near another applied protective layer. Allowance is knot on last examination in the area ratings protective heat-resisting layers and gives records for others possible ratings and experiments in this area.

  18. Anaerobic digestion and co-digestion processes of vegetable and fruit residues: process and microbial ecology.

    Science.gov (United States)

    Garcia-Peña, E I; Parameswaran, P; Kang, D W; Canul-Chan, M; Krajmalnik-Brown, R

    2011-10-01

    This study evaluated the feasibility of methane production from fruit and vegetable waste (FVW) obtained from the central food distribution market in Mexico City using an anaerobic digestion (AD) process. Batch systems showed that pH control and nitrogen addition had significant effects on biogas production, methane yield, and volatile solids (VS) removal from the FVW (0.42 m(biogas)(3)/kg VS, 50%, and 80%, respectively). Co-digestion of the FVW with meat residues (MR) enhanced the process performance and was also evaluated in a 30 L AD system. When the system reached stable operation, its methane yield was 0.25 (m(3)/kg TS), and the removal of the organic matter measured as the total chemical demand (tCOD) was 65%. The microbial population (general Bacteria and Archaea) in the 30 L system was also determined and characterized and was closely correlated with its potential function in the AD system. PMID:21865034

  19. Formation of pristane from α-tocopherol under simulated anoxic sedimentary conditions: A combination of biotic and abiotic degradative processes

    Science.gov (United States)

    Rontani, Jean-François; Nassiry, Mina; Michotey, Valérie; Guasco, Sophie; Bonin, Patricia

    2010-01-01

    Incubation of intact and oxidized α-tocopherol (vitamin E) in anaerobic sediment slurries allowed us to demonstrate that, as previously suggested by Goossens et al. (1984), the degradation of α-tocopherol in anoxic sediments results in the formation of pristane. The conversion of α-tocopherol to this isoprenoid alkane involves a combination of biotic and abiotic degradative processes, i.e. the anaerobic biodegradation (which seems to be mainly induced by denitrifying bacteria) of trimeric structures resulting from the abiotic oxidation of α-tocopherol. On the basis of the results obtained, it is proposed that in the marine environment most of the α-tocopherol present in phytoplanktonic cells should be quickly degraded within the water column and the oxic zone of sediments by way of aerobic biodegradation, photo- and autoxidation processes. Abiotic transformation of this compound mainly results in the production of trimeric oxidation products, sufficiently stable to be incorporated into anoxic sediments and whose subsequent anaerobic bacterial degradation affords pristane. These results confirm that the ratio pristane to phytane cannot be used as an indicator of the oxicity of the environment of deposition; in contrast, they support the use of PFI (Pristane Formation Index) as a proxy for the state of diagenesis of sedimentary organic matter.

  20. The influence of the temperature regime on the formation of methane in a two-phase anaerobic digestion process

    Energy Technology Data Exchange (ETDEWEB)

    Schoenberg, Mandy; Linke, Bernd

    2012-06-15

    The influence of different temperature levels on the formation of methane in a two-phase anaerobic digestion process using rye silage and barley straw as feedstocks was investigated in this study. This process comprised a leach-bed reactor (LBR), a reservoir for leachate from the LBR, and a separate downstream fixed-film anaerobic filter (AF), with immobilized micro biocoenosises. The degree of degradation of the volatile solids was similar in both studies and was almost equal at 75 Ma.-%{sub VS}. When both reactor phases were operated at thermophilic conditions, the main substrate turnover was observed in the LBR(58% of the total methane yield, with an average methane content of 41 Vol.-%). Only the excess of organic fraction in the process-liquid was transformed in the AF(42% of the total methane yield, with an average methane content of 74 Vol.-%). When the parts of the reactor system operated at different temperature regimes, thermophilic hydrolysis/acidogenesis phase and mesophilic methanization, a separation of carbon dioxide and methane production, was observed. A total methane yield of 88%, with an average methane content of 85 Vol.-%, was formed in the AF. The generated biogas with high methane concentrations is suitable for feeding the purified biomethane into the natural gas grid. Furthermore, it can be used as fuel for cars and tractors. (copyright 2012 WILEY-VCH Verlag GmbH 8 Co. KGaA, Weinheim)

  1. Anaerobic degradation of 3-aminobenzoate by a newly isolated sulfate reducer and a methanogenic enrichment culture

    OpenAIRE

    Schnell, Sylvia; Schink, Bernhard

    1992-01-01

    A new rod-shaped, gram-negative, non-sporing sulfate reducer, strain mAB1, was enriched and isolated from marine sediment samples with 3-aminobenzoate as sole electron and carbon source. Strain mAB1 degraded 3-aminobenzoate completely to CO 2 and NH 3 with stoichiometric reduction of sulfate to sulfide. Ceils contained carbon monoxide dehydrogenase, cytochromes, and sulfite reductase P582. Strain mAB1 degraded also benzoate, 4-aminobenzoate, hydroxybenzoates, and some aliphatic compounds. Bes...

  2. Anaerobic digestion of organic by-products from meat-processing industry. The effect of pre-treatments and co-digestion

    Energy Technology Data Exchange (ETDEWEB)

    Luste, S.

    2011-07-01

    Anaerobic digestion is a multi-beneficial biological treatment during which micro-organisms degrade organic material producing biogas (i.e. methane) and stabilised end-product (i.e. digestate). Methane is a versatile renewable energy source and digestate can be used as an organic fertiliser and/or soil improver. Because of the increasing consumption and tightening environment and health legislation, production of organic wastes suitable for anaerobic digestion increases. Animal by-products (ABP) from the meat-processing industry are often rendered (contaminated material), used as feedstock (in fur breeding), or composted. However, ABPs studied could not be utilised in fodder or in animal food production and have currently been rendered or directed to composting, despite being mostly considered unsuitable for composting. Many ABPs are energy-rich, wet and pasty materials and suitable for the anaerobic digestion process. Moreover, suitable pre-treatment to hydrolyse solid materials and/or co-digestion of two or several materials may improve the anaerobic digestion with ultimate goal to increase the methane production, stabilisation and reusability of digestate. The case chosen for more detailed research was that of a middle-sized Finnish meat-processing industry. The aim of the thesis was to evaluate the feasibility of different ABPs presently available for treatment as raw material for anaerobic digestion. Another objective was to enhance the anaerobic digestion process via specific pre-treatments and co-digestion cases with the ultimate aim to increase the methane production and the quality of the digestate. The general goal was to observe the overall process from the perspective of real-circumstances in Finland to rise to needs in practice and to produce exploitable information for adopting sustainable development locally and case-specifically into practice via versatile anaerobic digestion technology. The ABPs studied were highly bio-degradable and especially

  3. Recent development of anaerobic digestion processes for energy recovery from wastes.

    Science.gov (United States)

    Nishio, Naomichi; Nakashimada, Yutaka

    2007-02-01

    Anaerobic digestion leads to the overall gasification of organic wastewaters and wastes, and produces methane and carbon dioxide; this gasification contributes to reducing organic matter and recovering energy from organic carbons. Here, we propose three new processes and demonstrate the effectiveness of each process. By using complete anaerobic organic matter removal process (CARP), in which diluted wastewaters such as sewage and effluent from a methane fermentation digester were treated under anaerobic condition for post-treatment, the chemical oxygen demand (COD) in wastewater was decreased to less than 20 ppm. The dry ammonia-methane two-stage fermentation process (Am-Met process) is useful for the anaerobic treatment of nitrogen-rich wastes such as waste excess sludge, cow feces, chicken feces, and food waste without the dilution of the ammonia produced by water or carbon-rich wastes. The hydrogen-methane two-stage fermentation (Hy-Met process), in which the hydrogen produced in the first stage is used for a fuel cell system to generate electricity and the methane produced in the second stage is used to generate heat energy to heat the two reactors and satisfy heat requirements, is useful for the treatment of sugar-rich wastewaters, bread wastes, and biodiesel wastewaters. PMID:17368391

  4. Anodes Stimulate Anaerobic Toluene Degradation via Sulfur Cycling in Marine Sediments.

    Science.gov (United States)

    Daghio, Matteo; Vaiopoulou, Eleni; Patil, Sunil A; Suárez-Suárez, Ana; Head, Ian M; Franzetti, Andrea; Rabaey, Korneel

    2016-01-01

    Hydrocarbons released during oil spills are persistent in marine sediments due to the absence of suitable electron acceptors below the oxic zone. Here, we investigated an alternative bioremediation strategy to remove toluene, a model monoaromatic hydrocarbon, using a bioanode. Bioelectrochemical reactors were inoculated with sediment collected from a hydrocarbon-contaminated marine site, and anodes were polarized at 0 mV and +300 mV (versus an Ag/AgCl [3 M KCl] reference electrode). The degradation of toluene was directly linked to current generation of up to 301 mA m(-2) and 431 mA m(-2) for the bioanodes polarized at 0 mV and +300 mV, respectively. Peak currents decreased over time even after periodic spiking with toluene. The monitoring of sulfate concentrations during bioelectrochemical experiments suggested that sulfur metabolism was involved in toluene degradation at bioanodes. 16S rRNA gene-based Illumina sequencing of the bulk anolyte and anode samples revealed enrichment with electrocatalytically active microorganisms, toluene degraders, and sulfate-reducing microorganisms. Quantitative PCR targeting the α-subunit of the dissimilatory sulfite reductase (encoded by dsrA) and the α-subunit of the benzylsuccinate synthase (encoded by bssA) confirmed these findings. In particular, members of the family Desulfobulbaceae were enriched concomitantly with current production and toluene degradation. Based on these observations, we propose two mechanisms for bioelectrochemical toluene degradation: (i) direct electron transfer to the anode and/or (ii) sulfide-mediated electron transfer. PMID:26497463

  5. Anodes Stimulate Anaerobic Toluene Degradation via Sulfur Cycling in Marine Sediments

    Science.gov (United States)

    Daghio, Matteo; Vaiopoulou, Eleni; Patil, Sunil A.; Suárez-Suárez, Ana; Head, Ian M.

    2015-01-01

    Hydrocarbons released during oil spills are persistent in marine sediments due to the absence of suitable electron acceptors below the oxic zone. Here, we investigated an alternative bioremediation strategy to remove toluene, a model monoaromatic hydrocarbon, using a bioanode. Bioelectrochemical reactors were inoculated with sediment collected from a hydrocarbon-contaminated marine site, and anodes were polarized at 0 mV and +300 mV (versus an Ag/AgCl [3 M KCl] reference electrode). The degradation of toluene was directly linked to current generation of up to 301 mA m−2 and 431 mA m−2 for the bioanodes polarized at 0 mV and +300 mV, respectively. Peak currents decreased over time even after periodic spiking with toluene. The monitoring of sulfate concentrations during bioelectrochemical experiments suggested that sulfur metabolism was involved in toluene degradation at bioanodes. 16S rRNA gene-based Illumina sequencing of the bulk anolyte and anode samples revealed enrichment with electrocatalytically active microorganisms, toluene degraders, and sulfate-reducing microorganisms. Quantitative PCR targeting the α-subunit of the dissimilatory sulfite reductase (encoded by dsrA) and the α-subunit of the benzylsuccinate synthase (encoded by bssA) confirmed these findings. In particular, members of the family Desulfobulbaceae were enriched concomitantly with current production and toluene degradation. Based on these observations, we propose two mechanisms for bioelectrochemical toluene degradation: (i) direct electron transfer to the anode and/or (ii) sulfide-mediated electron transfer. PMID:26497463

  6. Thermotoga lettingae sp. nov., a novel thermophilic, methanol-degrading bacterium isolated from a thermophilic anaerobic reactor.

    Science.gov (United States)

    Balk, Melike; Weijma, Jan; Stams, Alfons J M

    2002-07-01

    A novel, anaerobic, non-spore-forming, mobile, Gram-negative, thermophilic bacterium, strain TMOT, was isolated from a thermophilic sulfate-reducing bioreactor operated at 65 C with methanol as the sole substrate. The G+C content of the DNA of strain TMOT was 39.2 mol%. The optimum pH, NaCl concentration, and temperature for growth were 7.0, 1.0%, and 65 degrees C, respectively. Strain TMOT was able to degrade methanol to CO2 and H2 in syntrophic culture with Methanothermobacter thermautotrophicus AH or Thermodesulfovibrio yellowstonii. Thiosulfate, elemental sulfur, Fe(III) and anthraquinone-2,6-disulfonate were able to serve as electron acceptors during methanol degradation. In the presence of thiosulfate or elemental sulfur, methanol was converted to CO2 and partly to alanine. In pure culture, strain TMOT was also able to ferment methanol to acetate, CO2 and H2. However, this degradation occurred slower than in syntrophic cultures or in the presence of electron acceptors. Yeast extract was required for growth. Besides growing on methanol, strain TMOT grew by fermentation on a variety of carbohydrates including monomeric and oligomeric sugars, starch and xylan. Acetate, alanine, CO2, H2, and traces of ethanol, lactate and alpha-aminobutyrate were produced during glucose fermentation. Comparison of 16S rDNA genes revealed that strain TMOT is related to Thermotoga subterranea (98%) and Thermotoga elfii (98%). The type strain is TMOT (= DSM 14385T = ATCC BAA-301T). On the basis of the fact that these organisms differ physiologically from strain TMOT, it is proposed that strain TMOT be classified as a new species, within the genus Thermotoga, as Thermotoga lettingae. PMID:12148651

  7. Process Evolution of Dry Anaerobic Co-digestion of Cattle Manure with Kitchen Waste

    OpenAIRE

    Li, H. L.; X. L. GUO; Cao, F. F.; Wang, Y.

    2014-01-01

    Knowledge of the effect of kitchen waste on dry anaerobic mesophilic digestion of cattle manure is important for understanding and controlling the anaerobic co-digestion process. In this study, laboratory scale (Volume = 5 L) performance was evaluated using six different ratios of cattle manure to kitchen waste: 1:0, 11:1, 9:1, 7:1, 5:1 and 3:1. The selected conditions were: 10 % inoculum, 20 % total solids, and 35 °C temperature, optimum in the mesophilic range. The six ratios showed an init...

  8. Anaerobic digestion for simultaneous sewage sludge treatment and CO biomethanation: process performance and microbial ecology

    DEFF Research Database (Denmark)

    Luo, Gang; Wang, Wen; Angelidaki, Irini

    2013-01-01

    in an anaerobic reactor was presented. Batch experiments showed that CO was inhibitory to methanogens, but not to bacteria, at CO partial pressure between 0.25 and 1 atm under thermophilic conditions. During anaerobic digestion of sewage sludge supplemented with CO added through a hollow fiber...... membrane (HFM) module in continuous thermophilic reactors, CO did not inhibit the process even at a pressure as high as 1.58 atm inside the HFM, due to the low dissolved CO concentration in the liquid. Complete consumption of CO was achieved with CO gas retention time of 0.2 d. Results from high...

  9. Degradation of atrazine by microbial consortium in an anaerobic submerged biological filter.

    Science.gov (United States)

    Nasseri, Simin; Baghapour, Mohammad Ali; Derakhshan, Zahra; Faramarzian, Mohammad

    2014-09-01

    Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) (ATZ) is one of the components of S-triazine. Due to its certain characteristics, ATZ causes pollution in various ecosystems and has been of concern for its probable carcinogenic effects on humans. Researchers have used chemical and physical methods for removing ATZ from the environment. Although these methods are quick, they have not been capable of complete mineralization. Therefore, researchers are looking for methods with lower energy consumption and cost and higher efficiency. In this study, biodegradation of ATZ by microbial consortium was evaluated in the aquatic environment. The present study aimed to evaluate the efficiency of ATZ removal from aqueous environments by using an anaerobic submerged biological filter in four concentration levels of atrazine and three hydraulic retention times. The maximum efficiencies of ATZ and soluble chemical oxygen demand (SCOD) were 51.1 and 45.6%, respectively. There was no accumulation of ATZ in the biofilm and the loss of ATZ in the control reactor was negligible. This shows that ATZ removal in this system was due to biodegradation. Furthermore, the results of modeling showed that the Stover-Kincannon model had desirable fitness (R² > 99%) in loading ATZ in this biofilter. PMID:25252353

  10. Biogas and biohydrogen production potential of high strength automobile industry wastewater during anaerobic degradation.

    Science.gov (United States)

    Bajaj, Mini; Winter, Josef

    2013-10-15

    High strength automobile industry wastewater, collected from decanters (DECA) of the pre-treatment plant after oil, grease and sludge separation, was investigated for production of methane in the absence and presence of glucose or excess aerobic sludge (AS) from a lab scale suspension reactor as co-substrates. The highest methane production from DECA wastewater was 335.4 L CH4/kg CODsoluble removal which decreased in the presence of the co-substrates to 232.5 (with 2 g/L glucose) and to 179 (with 40% AS) L CH4/kg CODsoluble removal, respectively. Around 95% of total methane was produced within 5 days of incubation of DECA at 37 °C when no co-substrate was added. Addition of co-substrates did not improve biodegradation of DECA but overall methane production from DECA + co-substrates was increased due to co-substrate biodegradation. The anaerobic inoculum, capable of producing 2.4 mol of hydrogen/mol of glucose under zinc induced inhibitory conditions, was unable to produce hydrogen from DECA as substrate under the same conditions. PMID:23831674

  11. Anaerobic sulfamethoxazole degradation is driven by homoacetogenesis coupled with hydrogenotrophic methanogenesis.

    Science.gov (United States)

    Cetecioglu, Z; Ince, B; Orhon, D; Ince, O

    2016-03-01

    In this study, microbial community dynamics were assessed in two lab-scale anaerobic sequencing batch reactors (ASBRs). One of the reactors was fed by synthetic pharmaceutical industry wastewater with sulfamethoxazole (SMX) as the test reactor and the other without sulfamethoxazole as the control reactor. DNA based DGGE results indicated that Clostiridum sp. became dominant in the SMX reactor while the inoculum was dominated with Firmicutes (61%) and Methanomicrobiales (28%). However their abundances in active community decreased through the last phase. Also the abundance of hydrogenotrophs was high in each phase, while acetoclastic methanogens disappeared in the last phase. Q-PCR analysis revealed that there is a significant reduction in the bacterial community approximately 84%, while methanogens increased to 97% through the operation. Additionally an increase in the expression level of bacterial and methanogenic 16S rRNA (60% and 20%, respectively) was detected. Significant correlation between microbial community and the reactor operation data was found. The study demonstrated that the microbial community maintains the system stability under high antibiotic concentration and long-term operation by homoacetogenesis coupled with hydrogenotrophic methanogenesis. PMID:26724442

  12. Modelling phosphorus (P), sulphur (S) and iron (Fe) interactions during the simulation of anaerobic digestion processes

    DEFF Research Database (Denmark)

    Flores-Alsina, Xavier; Solon, Kimberly; Kazadi-Mbamba, Christian;

    2015-01-01

    This paper examines the effects of different model formulations when describing sludge stabilization processes in wastewater treatment plants by the Anaerobic Digestion Model No. 1 (ADM1). The proposed model extensions describe the interactions amongst phosphorus (P), sulfur (S), iron (Fe...

  13. Biohydrogen Production from Cheese Processing Wastewater by Anaerobic Fermentation Using Mixed Microbial Communities

    Science.gov (United States)

    Hydrogen (H2) production from simulated cheese processing wastewater via anaerobic fermentation was conducted using mixed microbial communities under mesophilic conditions. In batch H2 fermentation experiments H2 yields of 8 and 10 mM/g-COD fed were achieved at food-to-microorganism (F/M) ratios of ...

  14. Anaerobic Digestion of the Organic Fraction of Municipal Solid Waste With Recirculation of Process Water

    DEFF Research Database (Denmark)

    Hartmann, H.; Angelidaki, Irini; Ahring, Birgitte Kiær

    2001-01-01

    A new concept of a wet anaerobic digestion treatment of the organic fraction of municipal solid waste (OFMSW) is investigated. Once the waste is diluted with water, the entire liquid fraction of the effluent is recirculated and used as process water for dilution of the waste. This enables a well...

  15. North American Soil Degradation: Processes, Practices, and Mitigating Strategies

    OpenAIRE

    Baumhardt, R.L.; Stewart, B.A.; U. M. Sainju

    2015-01-01

    Soil can be degraded by several natural or human-mediated processes, including wind, water, or tillage erosion, and formation of undesirable physical, chemical, or biological properties due to industrialization or use of inappropriate farming practices. Soil degradation occurs whenever these processes supersede natural soil regeneration and, generally, reflects unsustainable resource management that is global in scope and compromises world food security. In North America, soil degradation pre...

  16. Fate and degradation of nonylphenolic compounds during wastewater treatment process.

    Science.gov (United States)

    Lian, Jing; Liu, Junxin

    2013-08-01

    In order to explore the biodegradation behavior of nonylphenolic compounds during wastewater treatment processing, two full-scale wastewater treatment plants were investigated and batch biodegradation experiments were conducted. The biodegradation pathways under the various operational conditions were identified from batch experiments: shortening of ethoxy-chains dominated under the anaerobic condition, whereas oxidizing of the terminal alcoholic group prevailed over the other routes under the aerobic condition. Results showed that the anoxic condition could accelerate the biodegradation rates of nonylphenolic compounds, but had no influence on the biodegradation pathway. The biodegradation rates of nonylphenol (NP) and short-chain nonylphenol polyethoxylates (NPnEOs, n: number of ethoxy units) increased from the anaerobic condition, then the anoxic, finally to the aerobic condition, while those of long-chain NPnEOs and nonylphenoxy carboxylates (NPECs) seemed similar under the various conditions. Under every operational condition, long-chain NPnEOs showed the highest biodegradation activity, followed by NPECs and short-chain NPnEOs, whereas NP showed relatively recalcitrant characteristics especially under the anaerobic condition. In addition, introducing sulfate and nitrate to the anaerobic condition could enhance the biodegradation of NP and short-chain NPnEOs by supplying more positive redox potentials. PMID:24520688

  17. Anaerobic biological treatment

    International Nuclear Information System (INIS)

    The Enso-Fenox process has been very successfully used to remove chlorinated phenolic compounds from pulp bleaching effluents. It is a two-stage anaerobic/aerobic process consisting of a nonmethanogenic anaerobic fluidized bed followed by a trickling filter. Studies have been conducted on reductive dechlorination of chlorinated aromatic compounds under anaerobic conditions with chlorinated phenols as the sole carbon and energy source. Approximately 40% of the added chlorophenols was converted to CH4 and CO2. Substrate loading rates were 20 mg/L/d at hydraulic detention times of 2-4 days with 90% substrate conversion efficiency. Reductive dechlorination of mono, di-, tri-, and pentachlorophenols has been demonstrated in anaerobic sewage sludge. The following constituents were tested in the laboratory at their approximate concentrations in coal conversion wastewater (CCWW) and were anaerobically degraded in serum bottles: 1,000 mg/L phenol; 500 mg/L resorcinol; 1,000 mg/L benzoic acid; 500 mg/L p-cresol; 200 mg/L pyridine; 2,000 mg/L benzoic acid; 250 mg/L 40 methylcatechol; 500 mg/L 4-ethylpyridine; and 2,000 mg/L hexanoic acid. A petrochemical may initially exhibit toxicity to an unacclimated population of methane-fermenting bacteria, but with acclimation the toxicity may be greatly reduced or disappear. In addition, the microorganisms may develop the capacity to actually degrade compounds which showed initial toxicity. Since biomass digestion requires a complete consortium of bacteria, it is relevant to study the effect of a given process as well as to individual steps within the process. A toxicant can inhibit the rate-limiting step and/or change the step that is rate-limiting. Both manifestations of toxicity can severely affect the overall process

  18. Methane and carbon dioxide production from simulated anaerobic degradation of cattle carcasses

    International Nuclear Information System (INIS)

    Highlights: ► This study evaluates methane and carbon dioxide production after land burial of cattle carcasses. ► Disposal of animal mortalities is often overlooked in evaluating the environmental impacts of animal production. ► we quantify annual emissions from cattle carcass disposal in the United States as 1.6 Tg CO2 equivalents. - Abstract: Approximately 2.2 million cattle carcasses require disposal annually in the United States. Land burial is a convenient disposal method that has been widely used in animal production for disposal of both daily mortalities as well as during catastrophic mortality events. To date, greenhouse gas production after mortality burial has not been quantified, and this study represents the first attempt to quantify greenhouse gas emissions from land burial of animal carcasses. In this study, anaerobic decomposition of both homogenized and unhomogenized cattle carcass material was investigated using bench-scale reactors. Maximum yields of methane and carbon dioxide were 0.33 and 0.09 m3/kg dry material, respectively, a higher methane yield than that previously reported for municipal solid waste. Variability in methane production rates were observed over time and between reactors. Based on our laboratory data, annual methane emissions from burial of cattle mortalities in the United States could total 1.6 Tg CO2 equivalents. Although this represents less than 1% of total emissions produced by the agricultural sector in 2009, greenhouse gas emissions from animal carcass burial may be significant if disposal of swine and poultry carcasses is also considered.

  19. Isolation and Characterization of a Sulfate-Reducing Bacterium That Anaerobically Degrades Alkanes

    OpenAIRE

    So, Chi Ming; Young, L. Y.

    1999-01-01

    An alkane-degrading, sulfate-reducing bacterial strain, AK-01, was isolated from an estuarine sediment with a history of chronic petroleum contamination. The bacterium is a short, nonmotile, non-spore-forming, gram-negative rod. It is mesophilic and grows optimally at pH 6.9 to 7.0 and at an NaCl concentration of 1%. Formate, fatty acids (C4 to C16) and hydrogen were readily utilized as electron donors. Sulfate, sulfite, and thiosulfate were used as electron acceptors, but sulfur, nitrite, an...

  20. Anaerobic Digestion of Paper Mill Wastewater

    OpenAIRE

    Shreeshivadasan Chelliapan; Siti Baizura Mahat; Md. Fadjil Md. Din; A. Yuzir; Othman, N.

    2012-01-01

    In general, paper mill wastewater contains complex organic substances which could not be treated completely using conventional treatment processes, e.g. aerobic processes. As a result, anaerobic technology is a promising alternative for paper mill wastewater treatment due to its ability to degrade hard organic compounds. In the present study, treatment of paper mill wastewater using a stage anaerobic reactor was investigated. The more specific objectives of this study were to confirm whether ...

  1. Modelling and estimating degradation processes with application in structural reliability

    International Nuclear Information System (INIS)

    The characteristic level of degradation of a given structure is modeled through a stochastic process called the degradation process. The random evolution of the degradation process is governed by a differential system with Markovian environment. We put the associated reliability framework by considering the failure of the structure once the degradation process reaches a critical threshold. A closed form solution of the reliability function is obtained thanks to Markov renewal theory. Then, we build an estimation methodology for the parameters of the stochastic processes involved. The estimation methods and the theoretical results, as well as the associated numerical algorithms, are validated on simulated data sets. Our method is applied to the modelling of a real degradation mechanism, known as crack growth, for which an experimental data set is considered. (authors)

  2. The anaerobic degradation of organic matter in Danish coastal sediments - Iron reduction, manganese reduction, and sulfate reduction

    Science.gov (United States)

    Canfield, Donald E.; Thamdrup, BO; Hansen, Jens W.

    1993-01-01

    A combination of porewater and solid phase analysis as well as a series of sediment incubations are used to quantify organic carbon oxidation by dissimilatory Fe reduction, Mn reduction, and sulfate reduction, in sediments from the Skagerrak (located off the northeast coast of Jutland, Denmark). Solid phase data are integrated with incubation results to define the zones of the various oxidation processes. At S(9), surface Mn enrichments of up to 3.5 wt pct were found, and with such a ready source of Mn, dissimilatory Mn reduction was the only significant anaerobic process of carbon oxidation in the surface 10 cm of the sediment. At S(4) and S(6), active Mn reduction occurred; however, most of the Mn reduction may have resulted from the oxidation of acid volatile sulfides and Fe(2+) rather than by a dissimilatory sulfate. Dissolved Mn(2+) was found to completely adsorb onto sediment containing fully oxidized Mn oxides.

  3. Predicting parameters of degradation succession processes of Tibetan Kobresia grasslands

    Science.gov (United States)

    Lin, L.; Li, Y. K.; Xu, X. L.; Zhang, F. W.; Du, Y. G.; Liu, S. L.; Guo, X. W.; Cao, G. M.

    2015-11-01

    In the past two decades, increasing human activity (i.e., overgrazing) in the Tibetan Plateau has strongly influenced plant succession processes, resulting in the degradation of alpine grasslands. Therefore, it is necessary to diagnose the degree of degradation to enable implementation of appropriate management for sustainable exploitation and protection of alpine grasslands. Here, we investigated environmental factors and plant functional group (PFG) quantity factors during the alpine grassland succession processes. Principal component analysis (PCA) was used to identify the parameters indicative of degradation. We divided the entire degradation process into six stages. PFG types shifted from rhizome bunchgrasses to rhizome plexus and dense-plexus grasses during the degradation process. Leguminosae and Gramineae plants were replaced by sedges during the advanced stages of degradation. The PFGs were classified into two reaction groups: the grazing-sensitive group, containing Kobresia humilis Mey, and Gramineae and Leguminosae plants, and the grazing-insensitive group, containing Kobresia pygmaea Clarke. The first group was correlated with live root biomass in the surface soil (0-10 cm), whereas the second group was strongly correlated with mattic epipedon thickness and K. pygmaea characteristics. The degree of degradation of alpine meadows may be delineated by development of mattic epipedon and PFG composition. Thus, meadows could be easily graded and their use adjusted based on our scaling system, which would help prevent irreversible degradation of important grasslands. Because relatively few environmental factors are investigated, this approach can save time and labor to formulate a conservation management plan for degraded alpine meadows.

  4. Citrus essential oils and their influence on the anaerobic digestion process: an overview.

    Science.gov (United States)

    Ruiz, B; Flotats, X

    2014-11-01

    Citrus waste accounts for more than half of the whole fruit when processed for juice extraction. Among valorisation possibilities, anaerobic digestion for methane generation appears to be the most technically feasible and environmentally friendly alternative. However, citrus essential oils can inhibit this biological process. In this paper, the characteristics of citrus essential oils, as well as the mechanisms of their antimicrobial effects and potential adaptation mechanisms are reviewed. Previous studies of anaerobic digestion of citrus waste under different conditions are presented; however, some controversy exists regarding the limiting dosage of limonene for a stable process (24-192 mg of citrus essential oil per liter of digester and day). Successful strategies to avoid process inhibition by citrus essential oils are based either on recovery or removal of the limonene, by extraction or fungal pre-treatment respectively. PMID:25081855

  5. Anaerobic digestion of olive oil mill effluents together with swine manure in UASB reactors

    DEFF Research Database (Denmark)

    Angelidaki, Irini; Ahring, Birgitte Kiær; Deng, H.; Schmidt, Jens Ejbye

    2002-01-01

    Combined anaerobic digestion of olive oil mill effluent (OME) with swine manure, was investigated. In batch experiments was shown that for anaerobic degradation of OME alone nitrogen addition was needed. A COD:N ratio in the range of 65:1 to 126:1 was necessary for the optimal degradation process...

  6. Comprehensive microbial analysis of combined mesophilic anaerobic-thermophilic aerobic process treating high-strength food wastewater

    DEFF Research Database (Denmark)

    Jang, Hyun Min; Ha, Jeong Hyub; Park, Jong Moon;

    2015-01-01

    A combined mesophilic anaerobic-thermophilic aerobic process was used to treat high-strength food wastewater in this study. During the experimental period, most of solid residue from the mesophilic anaerobic reactor (R1) was separated by centrifugation and introduced into the thermophilic aerobic...

  7. Mathematical interpretation of mass transfer process in anaerobic bioreactors

    OpenAIRE

    Ружинская, Людмила Ивановна; Фоменкова, Анастасия Алексеевна

    2013-01-01

    The article considers the methanogenesis in bioreactors with immobilized microflora on fixed media. The processes of decomposition of organic pollution of the wastewater and the formation of metabolic products are analyzed. At the same time, the decomposition of organic pollution is considered from the standpoint of a two-stage process. As the first stage, the hydrolysis and acid production is considered, as the second - methanogenesis. On the basis of this process the spatial distribution of...

  8. Citrus essential oils and their influence on the anaerobic digestion process: An overview

    OpenAIRE

    RUIZ FUERTES, BEGOÑA; Flotats Ripoll, Xavier

    2014-01-01

    Citrus waste accounts for more than half of the whole fruit when processed for juice extraction. Among valorisation possibilities, anaerobic digestion for methane generation appears to be the most technically feasible and environmentally friendly alternative. However, citrus essential oils can inhibit this biological process. In this paper, the characteristics of citrus essential oils, as well as the mechanisms of their antimicrobial effects and potential adaptation mechanisms are reviewed. P...

  9. Metabolic analysis of the soil microbe Dechloromonas aromatica str. RCB: indications of a surprisingly complex life-style and cryptic anaerobic pathways for aromatic degradation

    OpenAIRE

    Feil Helene; Feil William S; Keller Keith; Salinero Kennan; Trong Stephan; Di Bartolo Genevieve; Lapidus Alla

    2009-01-01

    Abstract Background Initial interest in Dechloromonas aromatica strain RCB arose from its ability to anaerobically degrade benzene. It is also able to reduce perchlorate and oxidize chlorobenzoate, toluene, and xylene, creating interest in using this organism for bioremediation. Little physiological data has been published for this microbe. It is considered to be a free-living organism. Results The a priori prediction that the D. aromatica genome would contain previously characterized "centra...

  10. Enhanced Versus Conventional Sludge Anaerobic Processes: Performances and Techno-Economic Assessment.

    Science.gov (United States)

    Gianico, Andrea; Bertanza, Giorgio; Braguglia, Camilla M; Canato, Matteo; Gallipoli, Agata; Laera, Giuseppe; Levantesi, Caterina; Mininni, Giuseppe

    2016-05-01

    Sewage sludge processing is a key issue in water resource recovery facilities due to the inefficacy of conventional treatments to produce high quality biosolids to be safely used in agriculture. Under this framework, the performances of several enhanced stabilization processes, namely ultrasound-pretreated Mesophilic Anaerobic Digestion (US+MAD), thermophilic anaerobic digestion (TAD), thermal-pretreated TAD (TH+TAD) and ultrasound-pretreated inverse Temperature Phased Anaerobic Digestion (US+iTPAD) have been investigated. Such enhanced processes resulted in higher biogas yields and higher destruction of pathogens with respect to conventional MAD process, thus suggesting their feasibility in full-scale implementation perspectives. A procedure for technical-economic comparison of new sludge processing lines against conventional ones (benchmarking) was developed, based on the definition of technical issues (e.g. reliability, complexity, etc.) which are rated for each situation. Moreover, capital and operating costs were estimated. The enhanced processes analyzed in this work showed some potentially critical items, mainly related to energy balance and reagent consumption. PMID:27131310

  11. [Anaerobic membrane bioreactors for treating agricultural and food processing wastewater at high strength].

    Science.gov (United States)

    Wei, Yuan-Song; Yu, Da-Wei; Cao, Lei

    2014-04-01

    As the second largest amounts of COD discharged in 41 kinds of industrial wastewater, it is of great urgency for the agricultural and food processing industry to control water pollution and reduce pollutants. Generally the agricultural and food processing industrial wastewater with high strength COD of 8 000-30 000 mg x L(-1), is mainly treated with anaerobic and aerobic processes in series, but which exists some issues of long process, difficult maintenance and high operational costs. Through coupling anaerobic digestion and membrane separation together, anaerobic membrane bioreactor (AnMBR) has typical advantages of high COD removal efficiency (92%-99%), high COD organic loading rate [2.3-19.8 kg x (m3 x d)(-1)], little sludge discharged (SRT > 40 d) and low cost (HRT of 8-12 h). According to COD composition of high strength industrial wastewater, rate-limiting step of methanation could be either hydrolysis and acidification or methanogenesis. Compared with aerobic membrane bioreactor (MBR), membrane fouling of AnMBR is more complicated in characterization and more difficult in control. Measures for membrane fouling control of AnMBR are almost the same as those of MBR, including cross flow, air sparging and membrane relaxation. For meeting discharging standard of food processing wastewater with high strength, AnMBR is a promising technology with very short process, by enhancing COD removal efficiency, controlling membrane fouling and improving energy recovery. PMID:24946624

  12. Application of Hydrothermal Treatment to High Concentrated Sewage Sludge for Anaerobic Digestion Process

    Directory of Open Access Journals (Sweden)

    M. Orikawa

    2013-10-01

    Full Text Available Tomato and seaweed were produced by utilizing CO2 and heat discharged from power generation using biogas in Toyogawa biomass park, Japan. The biogas was obtained by anaerobic digestion with hydrothermal treatment. The hydrothermal treatment was applied to the high concentrated sewage sludge (22 % total solids (TS dewatered sludge. The purpose of this study is to clarify the effect of hydrothermal treatment on the qualities of high concentrated sewage sludge, by analyzing particulate organic carbon (POC and dissolved organic carbon (DOC. The hydrothermal treatment was investigated under 10-60 min of treatment time, 180-200 °C of temperature, 10-22 %-TS of sewage sludge concentration. The results showed that the DOC in each conditions increased through hydrothermal treatment. The highest DOC obtained was 67 % of total carbon concentration, when the temperature was 180 °C, treatment time was 60 min and sewage sludge concentration was 10 %-TS. Furthermore, the viscosity of treated sewage sludge was decreased by hydrothermal treatment. In batch anaerobic digestion test, methane gas production was confirmed. In addition, this study evaluated the energy balance of this system. Thus, the results of this study indicated that the possibility of application of hydrothermal treatment to high concentrated sewage sludge for anaerobic digestion process. Keywords: anaerobic reaction, hydrothermal treatment, sewage sludge, solubilization

  13. The anaerobic degradation of organic matter in Danish coastal sediments: iron reduction, manganese reduction, and sulfate reduction

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene; Thamdrup, B; Hansen, Jens Würgler

    1993-01-01

    We used a combination of porewater and solid phase analysis, as well as a series of sediment incubations, to quantify organic carbon oxidation by dissimilatory Fe reduction, Mn reduction, and sulfate reduction, in sediments from the Skagerrak (located off the northeast coast of Jutland, Denmark......). In the deep portion of the basin, surface Mn enrichments reached 3.5 wt%, and Mn reduction was the only important anaerobic carbon oxidation process in the upper 10 cm of the sediment. In the less Mn-rich sediments from intermediate depths in the basin, Fe reduction ranged from somewhat less, to far......, encouraged by bioturbation. Recycling was so rapid that the residence time of Fe and Mn oxides, with respect to reduction, ranged from 70-250 days. These results require that, on average, an atom of Fe or Mn is oxidized and reduced between 100-300 times before ultimate burial into the sediment. We observed...

  14. Hydrolysis rates, methane production and nitrogen solubilisation of grey waste components during anaerobic degradation.

    Science.gov (United States)

    Jokela, J P Y; Vavilin, V A; Rintala, J A

    2005-03-01

    Municipal grey waste (i.e. the remaining fraction in municipal waste management systems in which putrescibles (biowaste) and other recyclables (paper, metals, glass) are source-segregated) was manually sorted into six main fractions on the basis of composition and also separated by sieving (100 mm mesh size) into two fractions, oversized and undersized, respectively. In practice, in waste management plant the oversized fraction is (or will be) used to produce refuse-derived fuel and the undersized landfilled after biological stabilisation. The methane yields and nitrogen solubilisation of the grey waste and the different fractions (all studied samples were first milled to 5 mm particle samples) were determined in a 237-day methane production batch assay and in a water elution test, respectively. The grey waste was found to contained remnants of putrescibles and also a high amount of other biodegradable waste, including packaging, cartons and cardboard, newsprint, textiles and diapers. These waste fractions comprised 41%-w/w of the grey waste and produced 40-210 m3 methane (total solids (TS))(-1) and less than 0.01 g NH4-N kg TS(added)(-1) except diapers which produced 9.8 g NH4-N kg TS(added)(-1) in the batch assays. In the case of the two sieved fractions and on mass bases, most of the methane originated from the oversized fraction, whereas most of the NH4-N was solublised from the undersized fraction. The first-order kinetic model described rather well the degradation of each grey waste fraction and component, showing the different components to be in the range 0.021-0.058 d(-1), which was around one-sixth of the values reported for the source-segregated putrescible fraction of MSW. PMID:15491833

  15. Kinetic analysis of anaerobic phosphorus release during biological phosphorus removal process

    Institute of Scientific and Technical Information of China (English)

    DOU Junfeng; LUO Guyuan; LIU Xiang

    2007-01-01

    Enhanced biological phosphorus removal(EBPR)is a commonly used and sustainable method for phosphorus removal from wastewater.Poly-β-hydroxybutyrate(PHB),polyphosphate,and glycogen are three kinds of intracellular storage polymers in phosphorus accumulation organisms.The variation of these polymers under different conditions has an apparent influence on anaerobic phosphorus release,which is very important for controlling the performance of EBPR.To obtain the mechanism and kinetic character of anaerobic phosphorus release,a series of batch experiments were performed using the excessively aerated sludge from the aerobic unit of the biological phosphorus removal system in this study.The results showed that the volatile suspended solid(vss)had an increasing trend,while the mixed liquid suspended sludge(MLSS)and ashes were reduced during the anaerobic phosphorus release process.The interruption of anaerobic HAc-uptake and phosphorus-release occurs when the glycogen in the phosphorus-accumulating-organisms is exhausted.Under the condition of lower initial HAc-COD,HAc became the limiting factor after some time for anaerobic HAc uptake.Under the condition of higher initial HAc-COD,HAc uptake was stopped because of the depletion of glycogen in the microorganisms.The mean ratio of △ρP/△ρPHB,△ρGLY/△ρPHB,△ρP/△COD,and △ρPHB/△COD was 0.48,0.50,0.44.and 0.92.respectively,which was nearly the same as the theoretical value.The calibrated kinetic parameters of the HAc-uptake and phosphorus-release model were evaluated as Kgly was 0.005,and KCOD was 3 mg/L.An apparently linear correlation was observed between the ratio of △ρP/△COD and pH of the solution,and the equation between them was obtained in this study.

  16. North American Soil Degradation: Processes, Practices, and Mitigating Strategies

    Directory of Open Access Journals (Sweden)

    R. L. Baumhardt

    2015-03-01

    Full Text Available Soil can be degraded by several natural or human-mediated processes, including wind, water, or tillage erosion, and formation of undesirable physical, chemical, or biological properties due to industrialization or use of inappropriate farming practices. Soil degradation occurs whenever these processes supersede natural soil regeneration and, generally, reflects unsustainable resource management that is global in scope and compromises world food security. In North America, soil degradation preceded the catastrophic wind erosion associated with the dust bowl during the 1930s, but that event provided the impetus to improve management of soils degraded by both wind and water erosion. Chemical degradation due to site specific industrial processing and mine spoil contamination began to be addressed during the latter half of the 20th century primarily through point-source water quality concerns, but soil chemical degradation and contamination of surface and subsurface water due to on-farm non-point pesticide and nutrient management practices generally remains unresolved. Remediation or prevention of soil degradation requires integrated management solutions that, for agricultural soils, include using cover crops or crop residue management to reduce raindrop impact, maintain higher infiltration rates, increase soil water storage, and ultimately increase crop production. By increasing plant biomass, and potentially soil organic carbon (SOC concentrations, soil degradation can be mitigated by stabilizing soil aggregates, improving soil structure, enhancing air and water exchange, increasing nutrient cycling, and promoting greater soil biological activity.

  17. Hyperspectral imaging techniques applied to the monitoring of wine waste anaerobic digestion process

    Science.gov (United States)

    Serranti, Silvia; Fabbri, Andrea; Bonifazi, Giuseppe

    2012-11-01

    An anaerobic digestion process, finalized to biogas production, is characterized by different steps involving the variation of some chemical and physical parameters related to the presence of specific biomasses as: pH, chemical oxygen demand (COD), volatile solids, nitrate (NO3-) and phosphate (PO3-). A correct process characterization requires a periodical sampling of the organic mixture in the reactor and a further analysis of the samples by traditional chemical-physical methods. Such an approach is discontinuous, time-consuming and expensive. A new analytical approach based on hyperspectral imaging in the NIR field (1000 to 1700 nm) is investigated and critically evaluated, with reference to the monitoring of wine waste anaerobic digestion process. The application of the proposed technique was addressed to identify and demonstrate the correlation existing, in terms of quality and reliability of the results, between "classical" chemical-physical parameters and spectral features of the digestate samples. Good results were obtained, ranging from a R2=0.68 and a RMSECV=12.83 mg/l for nitrate to a R2=0.90 and a RMSECV=5495.16 mg O2/l for COD. The proposed approach seems very useful in setting up innovative control strategies allowing for full, continuous control of the anaerobic digestion process.

  18. Anaerobic digestion of microalgae residues resulting from the biodiesel production process

    International Nuclear Information System (INIS)

    The recovery of methane from post transesterified microalgae residues has the potential to improve the renewability of the 'microalgae biomass to biodiesel' conversion process as well as reduce its cost and environmental impact. This paper deals with the anaerobic digestion of microalgae biomass residues (post transesterification) using semi-continuously fed reactors. The influence of substrate loading concentrations and hydraulic retention times on the specific methane yield of the anaerobically digested microalgae residues was investigated. The co-digestion of the microalgae residues with glycerol as well as the influence of temperature was also examined. It was found that the hydraulic retention period was the most significant variable affecting methane production from the residues, with periods (>5 days) corresponding to higher energy recovery. The methane yield was also improved by a reduction in the substrate loading rates, with an optimum substrate carbon to nitrogen ratio of 12.44 seen to be required for the digestion process.

  19. A contribution to resource recovery from wastewater. Anaerobic processes for organic matter and nitrogen treatment

    OpenAIRE

    Basset Olivé, Núria

    2015-01-01

    Organic matter and nutrients present in urban and industrial wastewater should be removed or valorised to reduce its impact on the environment. Conventional wastewater treatments are focused on the removal of these pollution sources at the minimum cost. The idea of resource recovery from wastewater is changing the concept of the conventional wastewater treatment plants that tend to incorporate little by little processes as anaerobic digestion, MBR, biofilm, granulation, etc. However, their ap...

  20. Anaerobic Hydrogen and Methane Production from Dairy Processing Waste: Experiment and Modeling

    OpenAIRE

    Zhong, Jianming

    2016-01-01

    Dairy processing waste (DPW) can cause many environmental problems if not treated well. Various wastewater treatment technologies have been applied to reduce the organics and inorganics in DPW. The overall objective of this research was to develop cost effective anaerobic digestion technology for hydrogen and methane production from DPW. This search included three phases of studies. In phase 1, we investigated continuous fermentations of algae, lawn grass clippings and DPW, commingled and ...

  1. Fault Management: Degradation Signature Detection, Modeling, and Processing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Fault to Failure Progression (FFP) signature modeling and processing is a new method for applying condition-based signal data to detect degradation, to identify...

  2. Isolation and characterization of two novel thermophilic anaerobic bacteria from syngas - and carbon monoxide - degrading cultures

    OpenAIRE

    Alves, J.I.; Alves, M.M.; Stams, A. J. M.; Plugge, C.M.; Sousa, D. Z.

    2012-01-01

    Syn(thesis)gas is a mixture containing hydrogen, carbon monoxide and carbon dioxide, in variable ratios. Syngas is commonly produced from fossil fuels, but it can be generated from a vast array of feedstocks such as lignocellulosic biomass and carbon-based wastes, including recalcitrant wastes. Production of biofuels and bulk chemicals from syngas, both by thermochemical or microbial processes, is a field of promising technological developments. In this work, thermophilic (55ºC...

  3. Chlorella pyrenoidosa cultivation using anaerobic digested starch processing wastewater in an airlift circulation photobioreactor.

    Science.gov (United States)

    Tan, Xiaobo; Chu, Huaqiang; Zhang, Yalei; Yang, Libin; Zhao, Fangchao; Zhou, Xuefei

    2014-10-01

    To explore the integration of microalgae cultivation and anaerobic processing for wastewater treatment, we utilized an airlift circulation photobioreactor and a dynamic membrane reactor for microalgae cultivation in combination with an upflow anaerobic sludge bed (UASB) reactor for starch processing wastewater (SPW) treatment. Chlorella pyrenoidosa completely adapted to the digested SPW without any chemical additives, and it grew normally under a wide temperature range in different seasons. C. pyrenoidosa was always the dominant microorganism in the photobioreactors although bacteria and some wild type microalgae were observed. Optimal biomass growth and pollutants removal was achieved at temperatures between 35 and 38°C in summer, removing 65.99% of COD, 83.06% of TN, 96.97% of TP and a biomass productivity of 0.37gL(-1)d(-1). Temperature fluctuation significantly influenced lipid contents and FAMEs compositions in biomass. The results demonstrate the successful integration of microalgae biomass production and anaerobic processing for wastewater treatment. PMID:25164347

  4. Research on Anaerobic Digestion: Optimization and Scalability of Mixed High-strength Food Processing Wastes for Renewable Biogas Energy

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zhongtang [The Ohio State Univ., Columbus, OH (United States); Hitzhusen, Fredrick [The Ohio State Univ., Columbus, OH (United States)

    2012-12-27

    This research project developed and improved anaerobic digestion technologies, created a comprehensive Inventory of Ohio Biomass and a database of microorganisms of anaerobic digesters, and advanced knowledge and understanding of the underpinning microbiology of the anaerobic digestion process. The results and finding of this research project may be useful for future development and implementation of anaerobic digesters, especially at livestock farms. Policy makers and investors may also find the information on the biomass availability in Ohio and valuation of energy projects useful in policy making and making of investment decisions. The public may benefit from the information on biogas as an energy source and the potential impact of anaerobic digester projects on their neighborhoods.

  5. ANAEROBIC MEMBRANE BIOREACTORS FOR DOMESTIC WASTEWATER TREATMENT. PRELIMINARY STUDY

    OpenAIRE

    Luisa Vera; Ignacio Ruigómez; Enrique González; Paula Bodelón; Juan Rodríguez-Sevilla

    2014-01-01

    The operation of submerged anaerobic membrane bioreactors (SAnMBRs) for domestic wastewaters treatment was studied in laboratory scale, with the objective to define sustainable filtration conditions of the suspensions along the process. During continuous experiments, the organic matter degradation by anaerobic way showed an average DQOT removal of 85% and 93%. Indeed, the degradation generated biogas after 12 days of operation and its relative methane composition was of 60% after 25 days of o...

  6. Hydrogen and methane production from desugared molasses using a two‐stage thermophilic anaerobic process

    DEFF Research Database (Denmark)

    Kongjan, Prawit; O-Thong, Sompong; Angelidaki, Irini

    2013-01-01

    3380 mL CH4/day/L, corresponding to a yield of 239 mL CH4/g VS. Aceticlastic Methanosarcina mazei was the dominant methanogen in the methanogenesis stage. This work demonstrates that biohydrogen production can be very efficiently coupled with a subsequent step of methane production using desugared......Hydrogen and methane production from desugared molasses by a two‐stage thermophilic anaerobic process was investigated in a series of two up‐flow anaerobic sludge blanket (UASB) reactors. The first reactor that was dominated with hydrogen‐producing bacteria of Thermoanaerobacterium...... thermosaccharolyticum and Thermoanaerobacterium aciditolerans could generate a high hydrogen production rate of 5600 mL H2/day/L, corresponding to a yield of 132 mL H2/g volatile solid (VS). The effluent from the hydrogen reactor was further converted to methane in the second reactor with the optimal production rate of...

  7. The Impact of Chemical Phosphorus Removal on the Process of Anaerobic Sludge Digestion

    Directory of Open Access Journals (Sweden)

    Svetlana Ofverstrom

    2011-02-01

    Full Text Available The paper investigates the efficiency of the mixture of primary sludge and excess activated sludge in Vilnius WWTP with reference to the anaerobic digestion process. Sludge digestion was carried out under laboratory conditions using anaerobic sludge digestion model W8 (Armfield Ltd., UK. Laboratory analyses consist of two periods – the anaerobic digestion of the un-dosed and Fe-dosed sludge mixture. The results of digestion were processed using the methods of statistical analysis. The findings showed reduction in volatile solids approx. by 6% when dosing min FeCl3·6H2O and 15% when dosing max FeCl3·6H2O into feed sludge. Gas volume produced during the digestion of the un-dosed sludge was 90–160 ml/d and 60–125 ml/d in min Fe-dosed sludge and 45-95 ml/d. Also, correlation between VS loadings and biogas production was found. A rise in VS loading from 0,64 g/l/d to 1,01 g/l/d increased biogas production from 90 ml/d to 140–160 ml/d.Article in Lithuanian

  8. Characteristics of the bioreactor landfill system using an anaerobic-aerobic process for nitrogen removal.

    Science.gov (United States)

    He, Ruo; Liu, Xin-Wen; Zhang, Zhi-Jian; Shen, Dong-Sheng

    2007-09-01

    A sequential upflow anaerobic sludge blanket (UASB) and air-lift loop sludge blanket (ALSB) treatment was introduced into leachate recirculation to remove organic matter and ammonia from leachate in a lab-scale bioreactor landfill. The results showed that the sequential anaerobic-aerobic process might remove above 90% of COD and near to 100% of NH4+ -N from leachate under the optimum organic loading rate (OLR). The total COD removal efficiency was over 98% as the OLR increased to 6.8-7.7 g/l d, but the effluent COD concentration increased to 2.9-4.8 g/l in the UASB reactor, which inhibited the activity of nitrifying bacteria in the subsequent ALSB reactor. The NO3- -N concentration in recycled leachate reached 270 mg/l after treatment by the sequential anaerobic-aerobic process, but the landfill reactor could efficiently denitrify the nitrate. After 56 days operation, the leachate TN and NH4+ -N concentrations decreased to less than 200 mg/l in the bioreactor landfill system. The COD concentration was about 200 mg/l with less than 8 mg/l BOD in recycled leachate at the late stage. In addition, it was found that nitrate in recycled leachate had a negative effect on waste decomposition. PMID:17071082

  9. Degradation of 2-hydroxybenzoic acid by advanced oxidation processes

    OpenAIRE

    C. L. P. S. Zanta; Martínez-Huitle, C. A.

    2009-01-01

    In this study, advanced oxidation processes (AOPs) such as the UV/H2O2 and Fenton processes were investigated for the degradation of 2-hydroxybenzoic acid (2-HBA) in lab-scale experiments. Different [H2O2]/[2-HBA] molar ratios and pH values were used in order to establish the most favorable experimental conditions for the Fenton process. For comparison purposes, degradation of 2-HBA was carried out by the UV/H2O2 process under Fenton experimental conditions. The study showed that the Fenton p...

  10. MATHEMATICAL MODELLING OF DEGRADATION AND FLUVIAL PROCESS DOWNSTREAM RESERVOIRS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To research into the problem of degradation and fluvial process downstream reservoirs and its influence on flood control and navigation, a 1-D mathematical model of degradation and fluvial process downstream the reservoir was established in this paper. The non-equilibrium transport of non-uniform suspended load, the non-uniform bedload transport and bed material sorting were considered in the model. Some techniques were suggested for some problems in calculation, such as the effective suspended load carrying capacity of the different reaches of bed materials, the coefficient of suspended load carrying capacity, the recovering coefficient of carrying capacity, the mixed layer thickness, the bedload transport width, bifurcation and confluence of main and branch channel, and the distribution of deposition and erosion along the cross section, etc. The model was tested by the data of degradation downstream the Danjiangkou reservoir on the Hanjiang River and the data of degradation downstream the Gezhouba Project on the Yangtze River.

  11. Lactivibrio alcoholicus gen. nov., sp. nov., an anaerobic, mesophilic, lactate-, alcohol-, carbohydrate- and amino-acid-degrading bacterium in the phylum Synergistetes.

    Science.gov (United States)

    Qiu, Yan-Ling; Hanada, Satoshi; Kamagata, Yoichi; Guo, Rong-Bo; Sekiguchi, Yuji

    2014-06-01

    A mesophilic, obligately anaerobic, lactate-, alcohol-, carbohydrate- and amino-acid- degrading bacterium, designated strain 7WAY-8-7(T), was isolated from an upflow anaerobic sludge blanket reactor treating high-strength organic wastewater from isomerized sugar production processes. Cells of strain 7WAY-8-7(T) were motile, curved rods (0.7-1.0×5.0-8.0 µm). Spore formation was not observed. The strain grew optimally at 37 °C (range for growth was 25-40 °C) and pH 7.0 (pH 6.0-7.5), and could grow fermentatively on yeast extract, glucose, ribose, xylose, malate, tryptone, pyruvate, fumarate, Casamino acids, serine and cysteine. The main end-products of glucose fermentation were acetate and hydrogen. In co-culture with the hydrogenotrophic methanogen Methanospirillum hungatei DSM 864(T), strain 7WAY-8-7(T) could utilize lactate, glycerol, ethanol, 1-propanol, 1-butanol, L-glutamate, alanine, leucine, isoleucine, valine, histidine, asparagine, glutamine, arginine, lysine, threonine, 2-oxoglutarate, aspartate and methionine. A Stickland reaction was not observed with some pairs of amino acids. Yeast extract was required for growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite and Fe (III) were not used as terminal electron acceptors. The G+C content of the genomic DNA was 61.4 mol%. 16S rRNA gene sequence analysis revealed that the isolate belongs to the uncultured environmental clone clade (called 'PD-UASB-13' in the Greengenes database) in the bacterial phylum Synergistetes, showing less than 90% sequence similarity with closely related described species such as Aminivibrio pyruvatiphilus and Aminobacterium colombiense (89.7% and 88.7%, respectively). The major cellular fatty acids were iso-C(13 : 0), iso-C(15 : 0), anteiso-C(15 : 0), C(18 : 1), C(19 : 1), C(20 : 1) and C(21 : 1). A novel genus and species, Lactivibrio alcoholicus gen. nov., sp. nov. is proposed to accommodate strain 7WAY-8-7(T) ( = JCM 17151(T

  12. A new class of Wiener process models for degradation analysis

    International Nuclear Information System (INIS)

    For many products, it is not uncommon to see that a unit with a higher degradation rate has a more volatile degradation path. Motivated by this observation, we propose a new class of random effects model for the Wiener process model. We express the Wiener process in a special form and allow one of the parameters to be random across the product population so that a unit with a high degradation rate would also possess high volatility. Statistical inference of the model is discussed. By the same token, we introduce a stress–acceleration relation for the Wiener process so that both the degradation rate and the volatility of the product are increasing in the stress level. The proposed models are demonstrated by analyzing a dataset of fatigue crack growth and a dataset of head wears of hard disk drives. The applications suggest that our models perform better than existing models that ignore the positive correlation between the drift rate and the volatility. - Highlights: • We propose a new Wiener process to capture dependence between mean and variance. • Random-effects Wiener process models are developed so that the variance is increasing in the degradation mean. • Stress are incorporated into the process in a similar way. • Statistical inference methods are also developed. • The methods are applied to two real examples

  13. Soil degradation processes in the Italian agricultural and forest ecosystems

    OpenAIRE

    Edoardo A.C. Costantini; Romina Lorenzetti

    2013-01-01

    A number of processes of degradation threaten soil functions. Ten of them are acknowledged by the European Union and fifteen by the Organisation for Economic Co-operation and Development (OECD), but at least another seven have been indicated by different authors in Italy and in other parts of the world. This short review paper summarizes the nature, economic relevance, and territorial impact of soil degradation in Italy, and with reference to Europe as a whole, and highlights the most relevan...

  14. Anaerobic hydrolysis during digestion of complex substrates

    NARCIS (Netherlands)

    Sanders, W.T.M.

    2001-01-01

    Complex waste(water) such as, raw sewage, dairy wastewater, slaughterhouse wastewater, fish processing wastewater, primary sludge and the organic fraction of municipal solid waste have been proven to be degradable under anaerobic conditions. However, during the digestion process the conversion of th

  15. Integration of a Water Scrubbing Technique and Two-Stage Pressurized Anaerobic Digestion in One Process

    Directory of Open Access Journals (Sweden)

    Andreas Lemmer

    2015-03-01

    Full Text Available Two-stage pressurized anaerobic digestion is a promising technology. This technology integrates in one process biogas production with upgrading and pressure boosting for grid injection. To investigate whether the efficiency of this novel system could be further increased, a water scrubbing system was integrated into the methanogensis step. Therefore, six leach-bed reactors were used for hydrolysis/acidification and a 30-L pressurized anaerobic filter operated at 9 bar was adopted for acetogenesis/methanogenesis. The fermentation liquid of the pressurized anaerobic filter was circulated periodically via a flash tank, operating at atmospheric pressure. Due to the pressure drop, part of dissolved carbon dioxide was released from the liquid phase into the flash tank. The depressurized fermentation liquid was then recycled to the pressurized reactor. Three different flow rates (0 L·day−1, 20 L·day−1 and 40 L·day−1 were tested with three repetitions. As the daily recycled flashed liquid flow was increased from 0 to 40 L, six times as much as the daily feeding, the methane content in the biogas increased from 75 molar percent (mol% to 87 mol%. The pH value of the substrate in the methane reactor rose simultaneously from 6.5 to 6.7. The experimental data were verified by calculation.

  16. Lytic process studies on anaerobic digestion of organic wastes. Etude des activites lytiques intervenant au cours de la digestion anaerobie des dechets organiques; Rapport final

    Energy Technology Data Exchange (ETDEWEB)

    Durecu, S.; Thauront, J. (PEC Engineering, 95 - Cergy Pontoise (France). Service de Recherche et Developpement); Festino, C.; Aubart, C.; Reisinger, O. (Nancy-1 Univ., 54 - Vandoeuvre-les-Nancy (France). Lab. d' Ecologie Microbienne)

    1990-01-01

    To improve anaerobic digestion of pig manure, solubilization of the solid fraction was studied as the rate limiting step in the biomethanation process in an experimental completely mixed digester. The performance of conventional digesters should anaerobic microflora were inefficient in degrading complex biopolymers such as plant fibers. For pectin or cellulose, the use of digestible co-substrates accelerated methanation by increasing the yield of methane and a doubling of the apparent first order solubilization rate constant (Kp = 0.090/d). Lignin should methanation by decreasing methane yield and reducing the rate constant (Kp = 0.035/d). This inhibition was unrelated to volatile fatty acid accumulation. Nine strains of pectinolytic and/or cellulolytic bacteria were isolated. Chitin, a structural constituent of many final species, was effectively solubilized dining anaerobic digestion of pig manure. Seven strains of chitinolytic bacteria were isolated by high chitnese activity. The mycolytic power of fermenting manure processes acting through lytic microflora has been shown to be an effective antagonist of soil borne phytopathogenic fungi, as well as a fertilizer. In greenhouse trails, this compiled fraction demonstrated its ability to control flux unit. Keratin enhanced methane production, and increased H{sub 2}S nearly six-fold. Bacterial strains able to solubilize keratin were also used in autoclawed feather meal to extract the amino acids. (KJD)

  17. Degradation of corticosteroids during activated sludge processing.

    Science.gov (United States)

    Miyamoto, Aoi; Kitaichi, Yuko; Uchikura, Kazuo

    2014-01-01

    Laboratory tests of the decomposition of corticosteroids during activated sludge processing were investigated. Corticosteroid standards were added to activated sludge, and aliquots were regularly taken for analysis. The corticosteroids were extracted from the samples using a solid-phase extraction method and analyzed LC-MS. Ten types of corticosteroids were measured and roughly classified into three groups: 1) prednisolone, triamcinolone, betamethasone, prednisolone acetate, and hydrocortisone acetate, which decomposed within 4 h; 2) flunisolide, betamethasone valerate, and budesonide of which more than 50% remained after 4 h, but almost all of which decomposed within 24 h; and 3) triamcinolone acetonide, and fluocinolone acetonide of which more than 50% remained after 24 h. The decomposed ratio was correlated with each corticosteroid's Log P, especially groups 2) and 3). PMID:24390495

  18. Residual life estimation based on a generalized Wiener degradation process

    International Nuclear Information System (INIS)

    The issue of residual life (RL) estimation, which has been widely studied recently, plays an important role in scheduling maintenance. In this work, we present an adaptive method of RL estimation based on a generalized Wiener degradation process which subsumes several existing models as limiting cases. The nonlinearity, the temporal uncertainty, and the product-to-product variability of the degradation are jointly taken into account in the proposed degradation model. Under a mild assumption, an analytical approximation to the probability density function of the RL is derived in a closed-form, which becomes quite useful in maintenance decision making. The unknown parameters of the model that characterize the population-based degradation characteristics are obtained by using the maximum likelihood approach, while the parameters that describe the online product-specific characteristic are estimated by using the Markov chain Monte Carlo (MCMC) method. Once new degradation data information of the target product becomes available, the degradation model is first updated based on the degradation history up to the current time through a strong tracking filter, and then the RL is estimated sequentially. In this way, the RL of a product can be estimated in an adaptive manner. Finally, the validity of the proposed method is demonstrated with an illustrative example concerning fatigue cracks

  19. Iodinated contrast media electro-degradation: Process performance and degradation pathways

    Energy Technology Data Exchange (ETDEWEB)

    Del Moro, Guido; Pastore, Carlo; Di Iaconi, Claudio; Mascolo, Giuseppe, E-mail: giuseppe.mascolo@ba.irsa.cnr.it

    2015-02-15

    The electrochemical degradation of six of the most widely used iodinated contrast media was investigated. Batch experiments were performed under constant current conditions using two DSA® electrodes (titanium coated with a proprietary and patented mixed metal oxide solution of precious metals such as iridium, ruthenium, platinum, rhodium and tantalum). The degradation removal never fell below 85% (at a current density of 64 mA/cm{sup 2} with a reaction time of 150 min) when perchlorate was used as the supporting electrolyte; however, when sulphate was used, the degradation performance was above 80% (at a current density of 64 mA/cm{sup 2} with a reaction time of 150 min) for all of the compounds studied. Three main degradation pathways were identified, namely, the reductive de-iodination of the aromatic ring, the reduction of alkyl aromatic amides to simple amides and the de-acylation of N-aromatic amides to produce aromatic amines. However, as amidotrizoate is an aromatic carboxylate, this is added via the decarboxylation reaction. The investigation did not reveal toxicity except for the lower current density used, which has shown a modest toxicity, most likely for some reaction intermediates that are not further degraded. In order to obtain total removal of the contrast media, it was necessary to employ a current intensity between 118 and 182 mA/cm{sup 2} with energy consumption higher than 370 kWh/m{sup 3}. Overall, the electrochemical degradation was revealed to be a reliable process for the treatment of iodinated contrast media that can be found in contaminated waters such as hospital wastewater or pharmaceutical waste-contaminated streams. - Highlights: • The electrochemical degradation of six iodinated contrast media were investigated. • Treatment feasibility as well as reaction by-products and toxicity were investigated. • In all the investigated cases, the removal efficiency was higher than 80%. • Two main degradation pathways were identified.

  20. Iodinated contrast media electro-degradation: Process performance and degradation pathways

    International Nuclear Information System (INIS)

    The electrochemical degradation of six of the most widely used iodinated contrast media was investigated. Batch experiments were performed under constant current conditions using two DSA® electrodes (titanium coated with a proprietary and patented mixed metal oxide solution of precious metals such as iridium, ruthenium, platinum, rhodium and tantalum). The degradation removal never fell below 85% (at a current density of 64 mA/cm2 with a reaction time of 150 min) when perchlorate was used as the supporting electrolyte; however, when sulphate was used, the degradation performance was above 80% (at a current density of 64 mA/cm2 with a reaction time of 150 min) for all of the compounds studied. Three main degradation pathways were identified, namely, the reductive de-iodination of the aromatic ring, the reduction of alkyl aromatic amides to simple amides and the de-acylation of N-aromatic amides to produce aromatic amines. However, as amidotrizoate is an aromatic carboxylate, this is added via the decarboxylation reaction. The investigation did not reveal toxicity except for the lower current density used, which has shown a modest toxicity, most likely for some reaction intermediates that are not further degraded. In order to obtain total removal of the contrast media, it was necessary to employ a current intensity between 118 and 182 mA/cm2 with energy consumption higher than 370 kWh/m3. Overall, the electrochemical degradation was revealed to be a reliable process for the treatment of iodinated contrast media that can be found in contaminated waters such as hospital wastewater or pharmaceutical waste-contaminated streams. - Highlights: • The electrochemical degradation of six iodinated contrast media were investigated. • Treatment feasibility as well as reaction by-products and toxicity were investigated. • In all the investigated cases, the removal efficiency was higher than 80%. • Two main degradation pathways were identified

  1. Digestion and degradation, air for life

    NARCIS (Netherlands)

    Lettinga, G.

    2001-01-01

    Anaerobic degradation of dead biomass is a natural gasification process, an anaerobic crematorium producing a very useful end-product composed of methane and carbon dioxide, generally polluted with small amounts of some malodorous and quite toxic volatile S-compounds. It leads to the production of e

  2. Anaerobic digestion of organic waste in RDF process - an initial investigation

    International Nuclear Information System (INIS)

    Disposing of municipal solid waste (MSW) into a landfill is a method of the past and creates the negative environmental impact. Growing awareness of this negative impact induced the development of Refuse Derived Fuel (RDF) from MSW RDF is not simply converting waste into energy but also enable waste to be recycled into heat and power. However, during the production of RDF, there are some spillages or rejects consist of organic fraction that still can be recovered. One of the options to treat these wastes is by biological treatment, the anaerobic digestion (AD). AD process could occur either naturally or in a controlled environment such as a biogas plant. The process produces a flammable gas known as biogas that can be used for processing heating, power generation, and in internal combustion engines. In general, the process provides not only pollution prevention but can also convert a disposal problem into a new profit centre. This paper will highlight the use of anaerobic technology to treat rejects derived from the RDF production process. (Author)

  3. Integrating the Anaerobic Process with Ultrafiltration in Meat Industry Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    Kwarciak-Kozłowska Anna

    2014-12-01

    Full Text Available The aim of this paper was to study meat industry wastewater treatment efficiency during fermentation process in ASBR reactor and post-treatment in UF process. The anaerobic process obtained a considerable degree of the removal of organic pollutants from raw wastewater designated as COD (73.3%, BOD (71.4% and TOC (83.2%. The concentrations of COD and BOD were 435 and 443 mg/dm3, respectively. The value of TOC reached a level of 136 mg/dm3. Generated biogas in the methane fermentation process of wastewater from meat industry plants was characterized by high methane content (80.9% vol.. In the final part of the experiment, the UF process was used in order to post-treating effluent from ASBR reactor. During the UF process, COD, BOD and TOC parameters were removed at 67.2%, 68% and 70.4%, respectively.

  4. Relationships between anaerobic consortia and removal efficiencies in an UASB reactor degrading 2,4 dichlorophenol (DCP).

    Science.gov (United States)

    Sponza, Delia Teresa; Cigal, Canan

    2008-04-01

    To gain more insight into the interactions between anaerobic bacteria and reactor performances (chemical oxygen demand-COD, 2,4 dichlorophenol-2,4 DCP removals, volatile fatty acid-VFA, and methane gas productions) and how they depended on operational conditions the microbial variations in the anaerobic granular sludge from an upflow anaerobic sludge blanket (UASB) reactor treating 2,4 DCP was studied. The study was composed of two parts. In the first part, the numbers of methanogens and acedogens in the anaerobic granular sludge were counted at different COD removal efficiencies. The relationships between the numbers of methanogens, the methane gas production and VFA production were investigated. The COD removal efficiencies increased to 74% from 30% while the number of total acedogens decreased to 10 from 30 cfu ml(-1). The number of total methanogens and acedogens varied between 11 x 10(3) and 10 x 10(9)MPN g(-1) and 10 and 30 cfu ml(-1) as the 2,4 DCP removal efficiencies were obtained between 60% and 99%, respectively. It was seen that, as the number of total acedogens decreased, the COD removal efficiencies increased. However, the number of total methanogens increased as the COD removal efficiencies increased. Correlations between the bacterial number and with the removal efficiencies obtained in different operational conditions were investigated. From the results presented in this paper a high correlation between the number of bacteria, COD removals, methane gas percentage, 2,4 DCP removals and VFA was observed. In the second part, methanogen bacteria in the anaerobic granular sludge were identified. Microbial observations and biochemical tests were applied to identify the anaerobic microorganisms from the anaerobic granular sludge. In the reactor treating 2,4 DCP, Methanobacterium bryantii, Methanobacterium formicicum, Methanobrevibacter smithii, Methanococcus voltae, Methanosarcina mazei, Methanosarcina acetivorans, Methanogenium bourgense and

  5. A new concept for enhancing energy recovery from agricultural residues by coupling anaerobic digestion and pyrolysis process

    OpenAIRE

    Monlau, Florian; Sambusiti, Cécilia; Antoniou, N; Barakat, Abdellatif; Zabaniotou, A.

    2015-01-01

    In a full-scale anaerobic digestion plant, agricultural residues are generally converted into biogas and digestate, the latter usually produced in large amount. Generally, biogas is converted into heat, often lost, and electricity, which is completely valorized or it is sold to the public grid. In this context, the aim of this study was to investigate the feasibility to combine anaerobic digestion and pyrolysis processes in order to increase the energy recovery from agricultural residues and ...

  6. ANAEROBIC MEMBRANE BIOREACTORS FOR DOMESTIC WASTEWATER TREATMENT. PRELIMINARY STUDY

    Directory of Open Access Journals (Sweden)

    Luisa Vera

    2014-12-01

    Full Text Available The operation of submerged anaerobic membrane bioreactors (SAnMBRs for domestic wastewaters treatment was studied in laboratory scale, with the objective to define sustainable filtration conditions of the suspensions along the process. During continuous experiments, the organic matter degradation by anaerobic way showed an average DQOT removal of 85% and 93%. Indeed, the degradation generated biogas after 12 days of operation and its relative methane composition was of 60% after 25 days of operation. Additionally, the comparison between membrane bioreactors (MBRs performance in aerobic and anaerobic conditions in filterability terms, reported that both systems behave similarly once reached the stationary state.

  7. Analysis of aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography

    Institute of Scientific and Technical Information of China (English)

    Kazuaki ITO; Kazuhiko TANAKA; Jun SAKAMOTO; Kazuya NAGAOKA; Yohichi TAKAYAMA; Takashi KANAHORI; Hiroshi SUNAHARA; Tsuneo HAYASHI; Shinji SATO; Takeshi HIROKAWA

    2012-01-01

    The analysis of seven aliphatic carboxylic acids ( formic,acetic,propionic,iso-butyric,n-butyric,iso-valeric and n-valeric acid) in anaerobic digestion process waters for biogas production was examined by ion-exclusion chromatography with dilute acidic eluents (benzoic acid,perfluorobutyric acid (PFBA) and sulfuric acid) and non-suppressed conductivity/ultraviolet (UV) detection.The columns used were a styrene/divinylbenzene-based strongly acidic cation-exchange resin column ( TSKgel SCX) and a polymethacrylate-based weakly acidic cation-exchange resin column ( TSKgel Super IC-A/C ).Good separation was performed on the TSKgel SCX in shorter retention times.For the TSKgel Super IC-A/C,peak shape of the acids was sharp and symmetrical in spite of longer retention times.In addition,the mutual separation of the acids was good except for iso- and n-butyric acids.The better separation and good detection was achieved by using the two columns (TSKgel SCX and TSKgel Super IC-A/C connected in series),lower concentrations of PFBA and sulfuric acid as eluents,non-suppressed conductivity detection and UV detection at 210 nm.This analysis was applied to anaerobic digestion process waters.The chromatograms with conductivity detection were relatively simpler compared with those of UV detection.The use of two columns with different selectivities for the aliphatic carboxylic acids and the two detection modes was effective for the determination and identification of the analytes in anaerobic digestion process waters containing complex matrices.

  8. Anaerobic degradation of solid material: importance of initiation centers for methanogenesis, mixing intensity, and 2D distributed model.

    Science.gov (United States)

    Vavilin, V A; Angelidaki, I

    2005-01-01

    Batch anaerobic codigestion of municipal household solid waste (MHSW) and digested manure in mesophilic conditions was carried out. The different waste-to-biomass ratios and intensity of mixing were studied theoretically and experimentally. The experiments showed that when organic loading was high, intensive mixing resulted in acidification and failure of the process, while low mixing intensity was crucial for successful digestion. However, when loading was low, mixing intensity had no significant effect on the process. We hypothesized that mixing was preventing establishment of methanogenic zones in the reactor space. The methanogenic zones are important to withstand inhibition due to development of acids formed during acidogenesis. The 2D distributed models of symmetrical cylinder reactor are presented based on the hypothesis of the necessity of a minimum size of methanogenic zones that can propagate and establish a good methanogenic environment. The model showed that at high organic loading rate spatial separation of the initial methanogenic centers from active acidogenic areas is the key factor for efficient conversion of solids to methane. The initial level of methanogenic biomass in the initiation centers is a critical factor for the survival of these centers. At low mixing, most of the initiation methanogenic centers survive and expand over the reactor volume. However, at vigorous mixing the initial methanogenic centers are reduced in size, averaged over the reactor volume, and finally dissipate. Using fluorescence in situ hybridization, large irregular cocci of microorganisms were observed in the case with minimal mixing, while in the case with high stirring mainly dead cells were found. PMID:15540194

  9. Soil Degradation Processes; Procesos de Degradacion del Suelo

    Energy Technology Data Exchange (ETDEWEB)

    Nunez Crespi, S.; Perez Martinez, M.; Cuesta Santianes, M. J.; Cabrera Jimenez, J. A.

    2007-12-28

    In the European communication entitled Towards a Thematic Strategy for Soil Protection, eight main threats to soil were identified: contamination, erosion, loss of organic matter, compaction, salinization; hydro-geological risks, soil sealing, and decline in biodiversity. The main purpose of this report is to provide the current state of knowledge of the soil degradation processes both, in the European Community scale and, particularly, in the Spanish territory. Furthermore, the main research project information related to soil degradation processes is also included, identifying the main actors involved in soil scientific research and development. (Author) 66 refs.

  10. Mechanisms of granular activated carbon anaerobic fluidized-bed process for treating phenols wastewater

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Granular activated carbon (GAC) anaerobic fluidized-bed reactor was applied to treating phenols wastewater. When influent phenol concentration was 1000 mg/L, volume loadings of phenol and CODCr were 0.39 kg/(m3*d) and 0.98 kg/(m3*d), their removal rates were 99.9% and 96.4% respectively. From analyzing above results, the main mechanisms of the process are that through fluidizing GAC, its adsorption is combined with biodegradation, both activities are brought into full play, and phenol in wastewater is effectively decomposed. Meanwhile problems concerning gas-liquid separation and medium plugging are well solved.

  11. Highly organic natural media as permeable reactive barriers: TCE partitioning and anaerobic degradation profile in eucalyptus mulch and compost.

    Science.gov (United States)

    Öztürk, Zuhal; Tansel, Berrin; Katsenovich, Yelena; Sukop, Michael; Laha, Shonali

    2012-10-01

    Batch and column experiments were conducted with eucalyptus mulch and commercial compost to evaluate suitability of highly organic natural media to support anaerobic decomposition of trichloroethylene (TCE) in groundwater. Experimental data for TCE and its dechlorination byproducts were analyzed with Hydrus-1D model to estimate the partitioning and kinetic parameters for the sequential dechlorination reactions during TCE decomposition. The highly organic natural media allowed development of a bioactive zone capable of decomposing TCE under anaerobic conditions. The first order TCE biodecomposition reaction rates were 0.23 and 1.2d(-1) in eucalyptus mulch and compost media, respectively. The retardation factors in the eucalyptus mulch and compost columns for TCE were 35 and 301, respectively. The results showed that natural organic soil amendments can effectively support the anaerobic bioactive zone for remediation of TCE contaminated groundwater. The natural organic media are effective environmentally sustainable materials for use in permeable reactive barriers. PMID:22795070

  12. Characteristics of high-sulfate wastewater treatment by two-phase anaerobic digestion process with Jet-loop anaerobic fluidized bed

    Institute of Scientific and Technical Information of China (English)

    WEI Chao-hai; WANG Wen-xiang; DENG Zhi-yi; WU Chao-fei

    2007-01-01

    A new anaerobic reactor,Jet-loop anaerobic fluidized bed(JLAFB),was designed for treating high-sulfate wastewater.The treatment characteristics,including the effect of influent COD/SO42- ratio and alkalinity and sulfide inhibition in reactors,were discussed for a JLAFB and a general anaerobic fluidized bed(AFB)reactor used as sulfate-reducing phase and methane-producing phase,respectively,in two-phase anaerobic digestion process.The formation of granules in the two reactors was also examined.The results indicated that COD and sulfate removal had different demand of influent COD/S042- ratios.When total COD removal Was up to 85%,the ratio was only required up to 1.2,whereas,total sulfate removal up to 95%required it exceeding 3.0.The alkalinity in the two reactors increased linearly with the growth of influent alkalinity.Moreover,the change of influent alkalinity had no significant effect on pH and volatile fatty acids(VFA)in the two reactors.Influent alkalinity kept at 400-500 mg/t,could meet the requirement of the treating process.The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms.When sulfate loading rate was up to 8.1 kg/(m3·d),the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L,respectively.Furthermore,the granules,with offwhite color,ellipse shape and diameters of 1.0-3.0 mm,could be developed in JLAFB reactor.In granules,different groups of bacteria were distributed in different layers,and some inorganic metal compounds such as Fe,Ca,Mg etc.were found.

  13. Subsurface aeration of anaerobic groundwater : iron colloid formation and the nitrification process

    NARCIS (Netherlands)

    Wolthoorn, A.

    2003-01-01

    Keywords: Iron, anaerobic groundwater, groundwater purification, heterogeneous oxidation, iron colloid formation, electron microscopy, nitrification In anaerobic groundwater iron and ammonium can be found in relatively high concentrations. These substances need to be removed when groundwater is used

  14. Hydroponic potato production on nutrients derived from anaerobically-processed potato plant residues

    Science.gov (United States)

    Mackowiak, C. L.; Stutte, G. W.; Garland, J. L.; Finger, B. W.; Ruffe, L. M.

    1997-01-01

    Bioregenerative methods are being developed for recycling plant minerals from harvested inedible biomass as part of NASA's Advanced Life Support (ALS) research. Anaerobic processing produces secondary metabolites, a food source for yeast production, while providing a source of water soluble nutrients for plant growth. Since NH_4-N is the nitrogen product, processing the effluent through a nitrification reactor was used to convert this to NO_3-N, a more acceptable form for plants. Potato (Solanum tuberosum L.) cv. Norland plants were used to test the effects of anaerobically-produced effluent after processing through a yeast reactor or nitrification reactor. These treatments were compared to a mixed-N treatment (75:25, NO_3:NH_4) or a NO_3-N control, both containing only reagent-grade salts. Plant growth and tuber yields were greatest in the NO_3-N control and yeast reactor effluent treatments, which is noteworthy, considering the yeast reactor treatment had high organic loading in the nutrient solution and concomitant microbial activity.

  15. Biogas production and methanogenic archaeal community in mesophilic and thermophilic anaerobic co-digestion processes.

    Science.gov (United States)

    Yu, D; Kurola, J M; Lähde, K; Kymäläinen, M; Sinkkonen, A; Romantschuk, M

    2014-10-01

    Over 258 Mt of solid waste are generated annually in Europe, a large fraction of which is biowaste. Sewage sludge is another major waste fraction. In this study, biowaste and sewage sludge were co-digested in an anaerobic digestion reactor (30% and 70% of total wet weight, respectively). The purpose was to investigate the biogas production and methanogenic archaeal community composition in the anaerobic digestion reactor under meso- (35-37 °C) and thermophilic (55-57 °C) processes and an increasing organic loading rate (OLR, 1-10 kg VS m(-3) d(-1)), and also to find a feasible compromise between waste treatment capacity and biogas production without causing process instability. In summary, more biogas was produced with all OLRs by the thermophilic process. Both processes showed a limited diversity of the methanogenic archaeal community which was dominated by Methanobacteriales and Methanosarcinales (e.g. Methanosarcina) in both meso- and thermophilic processes. Methanothermobacter was detected as an additional dominant genus in the thermophilic process. In addition to operating temperatures, the OLRs, the acetate concentration, and the presence of key substrates like propionate also affected the methanogenic archaeal community composition. A bacterial cell count 6.25 times higher than archaeal cell count was observed throughout the thermophilic process, while the cell count ratio varied between 0.2 and 8.5 in the mesophilic process. This suggests that the thermophilic process is more stable, but also that the relative abundance between bacteria and archaea can vary without seriously affecting biogas production. PMID:24837280

  16. Sustainable Agro-Food Industrial Wastewater Treatment Using High Rate Anaerobic Process

    OpenAIRE

    Yung-Tse Hung; Michel Torrijos; Cata Saady, Noori M.; Rajinikanth Rajagopal; Joseph V. Thanikal

    2013-01-01

    This review article compiles the various advances made since 2008 in sustainable high-rate anaerobic technologies with emphasis on their performance enhancement when treating agro-food industrial wastewater. The review explores the generation and characteristics of different agro-food industrial wastewaters; the need for and the performance of high rate anaerobic reactors, such as an upflow anaerobic fixed bed reactor, an upflow anaerobic sludge blanket (UASB) reactor, hybrid systems etc.; op...

  17. Characterization of Arsenic Biotransformation Products from an Open Anaerobic Degradation of Fucus distichus by Hydride Generation Gas Chromatography Atomic Absorption Spectrometry and High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry

    OpenAIRE

    Abiodun A. Ojo; Onasanya, Amos

    2013-01-01

    This work reports on the isolation and determination of biotransformation products obtained from the organoarsenic compounds that are present in Fucus distichus when it was subjected to an open anaerobic decomposition by using the Hydride Generation Gas Chromatography Atomic Absorption Spectrometry (HG-GC-AAS) and High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS). The seaweed and filtrate residues obtained from the open anaerobic degradation pro...

  18. 三价铁离子促进玉米秸秆厌氧发酵%Fe3+enhanced anaerobic digestion process of corn straw

    Institute of Scientific and Technical Information of China (English)

    时昌波; 王进; 彭书传; 侯成虎; 陈天虎; 岳正波※

    2013-01-01

    %, respectively. Moreover, the degradation efficiencies were 70%, and 90%and 83%respectively. As for the control reactor with 0%FeCl3, the degradation efficiencies of neutral detergent fiber, hemicellulose, and cellulose were 62%, and 85%and 72%, respectively. This meant that the addition of 3% FeCl3 promoted the degradation of cellulose and hemicelluloses, which resulted in the higher methane yield. The major limiting factor for the anaerobic digestion of corn stover was the high recalcitrance of substrate, which was mainly caused by the lignin and crystalline structure of cellulose. Normally lignin could not be digested by the anaerobic microorganisms, and only partially was released into the digester solution during the degradation of the cellulose and hemicellulose. The crystalline structure of the anaerobic digester residues were tested by X-ray diffraction (XRD). Results showed that the crystalline of the solid digester residue in the reactor with 3%FeCl3 was lower compared to that of the residue from the control reactor. The results mentioned above showed that a synergistic effect happened between Fe3+ and anaerobic microorganisms. This resulted in the destruction of crystalline cellulose, and higher cellulose degradation efficiency and methane yield. However, the variation of Fe availability and its effect on the microbial community was not performed, which needs to be investigated in the future. In the current research, FeCl3 was used as the iron source, but its cost was higher. A cheaper iron resource needs to be found, and the iron-promoted anaerobic digestion process should be optimized to further increase the methane yield and the economic efficiency.%  厌氧消化是农业废弃物资源化利用的有效途径之一。微量元素是影响有机废弃物厌氧产沼气性能的重要生态因子,其中铁对有机废弃物的厌氧发酵过程的效率和稳定性作用最为显著,而通常秸秆的含铁量很低。因此,该试验以玉米秸秆

  19. Nitrogen removal from sludge dewatering effluent through anaerobic ammonia oxidation process

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shao-hui; ZHENG Ping; HUA Yu-mei

    2005-01-01

    Anaerobic ammonia oxidation(Anammox) process is a novel and promising wastewater nitrogen removal process. The feasibility of transition of Anammox from denitrification and the performance of lab-scale Anammox biofilm reactor were investigated with sludge dewatering effluent. The results showed that Anammox process could be successfully started up after cultivation of denitrification biofilm and using it as inoculum. The transition of Anammox from denitrification was accomplished within 85 d. Anammox process was found suitable to remove ammonia from sludge dewatering effluent. The effluent ammonia concentration was detected to be 23.11 mgN/L at HRT of 28 h when influent ammonia concentration was fed 245 mgN/L, which was less than that for the national discharge standard Ⅱ (25 mgN/L) of 243.25 mg NH4+ -N/L and 288.31 mg NO2- -N/L.

  20. Influence of compatibilizer on blends degradation during processing

    Directory of Open Access Journals (Sweden)

    Walter R. Waldman

    2013-01-01

    Full Text Available The thermomechanical degradation of blends made from polypropylene and polystyrene, with or without compatibilizer, was studied using an internal mixer coupled to a torque rheometer. The blends processed without compatibilizer presented regular and expected results regarding torque reduction, with evidence of chain scission. The blends processed with the block copolymer of styrene and butadiene, SBS, as a compatibilizer presented unchanged or less reduced variation on torque values during processing. The extraction of stabilizers from the compatibilizer before processing did not affect the results. The compatibilizer concentration in the blends was varied, with its influence still being observed in concentrations as low as 0.03 parts per hundred. Similar results were obtained in an experiment comparing the performance of a primary commercial anti-oxidant, Irganox 1076, and the compatibilizer SBS. Therefore, the compatibilizer can be considered as a processing aid agent with positive influence on avoiding thermomechanical degradation.

  1. A mechanistic kinetic model for phenol degradation by the Fenton process

    International Nuclear Information System (INIS)

    The objective of this paper is to develop and validate a mechanistic model for the degradation of phenol by the Fenton process. Experiments were performed in semi-batch operation, in which phenol, catechol and hydroquinone concentrations were measured. Using the methodology described in Pontes and Pinto [R.F.F. Pontes, J.M. Pinto, Analysis of integrated kinetic and flow models for anaerobic digesters, Chemical Engineering Journal 122 (1-2) (2006) 65-80], a stoichiometric model was first developed, with 53 reactions and 26 compounds, followed by the corresponding kinetic model. Sensitivity analysis was performed to determine the most influential kinetic parameters of the model that were estimated with the obtained experimental results. The adjusted model was used to analyze the impact of the initial concentration and flow rate of reactants on the efficiency of the Fenton process to degrade phenol. Moreover, the model was applied to evaluate the treatment cost of wastewater contaminated with phenol in order to meet environmental standards.

  2. Anaerobic degradation of 1,1,2,2-tetrachloroethane and association with microbial communities in a freshwater tidal wetland, Aberdeen Proving Ground, Maryland : laboratory experiments and comparisons to field data

    Science.gov (United States)

    Lorah, Michelle M.; Voytek, Mary A.; Kirshtein, Julie D.; Jones, Elizabeth J., (Phillips)

    2003-01-01

    Defining biodegradation rates and processes is a critical part of assessing the feasibility of monitored natural attenuation as a remediation method for ground water containing organic contaminants. During 1998?2001, the U.S. Geological Survey conducted a microbial study at a freshwater tidal wetland along the West Branch Canal Creek, Aberdeen Proving Ground, Maryland, as part of an investigation of natural attenuation of chlorinated volatile organic compounds (VOCs) in the wetland sediments. Geochemical analyses and molecular biology techniques were used to investigate factors controlling anaerobic degradation of 1,1,2,2-tetrachloroethane (TeCA), and to characterize the microbial communities that potentially are important in its degradation. Rapid TeCA and daughter product degradation observed in laboratory experiments and estimated with field data confirm that natural attenuation is a feasible remediation method at this site. The diverse microbial community that seems to be involved in TeCA degradation in the wetland sediments varies with changing spatial and seasonal conditions, allowing continued effective natural attenuation throughout the year. Rates of TeCA degradation in anaerobic microcosm experiments conducted with wetland sediment collected from two different sites (WB23 and WB30) and during three different seasons (March?April 1999, July?August 1999, and October?November 2000) showed little spatial variability but high seasonal variability. Initial first-order degradation rate constants for TeCA ranged from 0.10?0.01 to 0.16?0.05 per day (half-lives of 4.3 to 6.9 days) for March?April 1999 and October?November 2000 microcosms incubated at 19 degrees Celsius, whereas lower rate constants of 0 ? 0.03 and 0.06 ? 0.03 per day were obtained in July?August 1999 microcosms incubated at 19 degrees Celsius. Microbial community profiles showed that low microbial biomass and microbial diversity in the summer, possibly due to competition for nutrients by the

  3. Technical and operational feasibility of psychrophilic anaerobic digestion biotechnology for processing ammonia-rich waste

    International Nuclear Information System (INIS)

    Highlights: • Long-term anaerobic digestion (AD) process at high-ammonia (>5 gN/L) is limited. • PADSBR technology was validated to treat N-rich waste with 8.2 ± 0.3 gNH3-N/L. • Excess ammonia (8.2 gN/L) did not affect the digestion process with no inhibition. • VFA, an indicator for process stability, did not accumulate in PADSBR. • Biomass acclimation in PADSBR ensured a high-stabilization of the AD process. - Abstract: Ammonia nitrogen plays a critical role in the performance and stability of anaerobic digestion (AD) of ammonia rich wastes like animal manure. Nevertheless, inhibition due to high ammonia remains an acute limitation in AD process. A successful long-term operation of AD process at high ammonia (>5 gN/L) is limited. This study focused on validating technical feasibility of psychrophilic AD in sequencing batch reactor (PADSBR) to treat swine manure spiked with NH4Cl up to 8.2 ± 0.3 gN/L, as a representative of N-rich waste. CODt, CODs, VS removals of 86 ± 3, 82 ± 2 and 73 ± 3% were attained at an OLR of 3 gCOD/L.d, respectively. High-ammonia had no effect on methane yields (0.23 ± 0.04 L CH4/gTCODfed) and comparable to that of control reactors, which fed with raw swine manure alone (5.5 gN/L). Longer solids/hydraulic retention times in PADSBRs enhanced biomass acclimation even at high-ammonia. Thus VFA, an indicator for process stability, did not accumulate in PADSBR. Further investigation is essential to establish the maximum concentrations of TKN and free ammonia that the PADSBR can sustain

  4. The dominant acetate degradation pathway/methanogenic composition in full-scale anaerobic digesters operating under different ammonia levels

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Karakashev, Dimitar Borisov; Angelidaki, Irini

    2014-01-01

    Ammonia is a major environmental factor influencing biomethanation in full-scale anaerobic digesters. In this study, the effect of different ammonia levels on methanogenic pathways and methanogenic community composition of full-scale biogas plants was investigated. Eight full-scale digesters...

  5. Anaerobic digestion of food waste stabilized by lime mud from papermaking process.

    Science.gov (United States)

    Zhang, Jishi; Wang, Qinqing; Zheng, Pengwei; Wang, Yusong

    2014-10-01

    The effects of lime mud from papermaking process (LMP) addition as buffer agent and inorganic nutrient on the anaerobic digestion stability of food waste (FW) were investigated under mesophilic conditions with the aim of avoiding volatile fatty acids accumulation, and inorganic elements deficiency. When LMP concentration ranged from 6.0 to 10g/L, the FW anaerobic digestion could maintain efficient and stable state. These advantages are attributed to the existence of Ca, Na, Mg, K, Fe, and alkaline substances that favor the methanogenic process. The highest CH4 yield of 272.8mL/g-VS was obtained at LMP and VS concentrations of 10.0 and 19.8g/L, respectively, with the corresponding lag-phase time of 3.84d and final pH of 8.4. The methanogens from residue digestates mainly consisted of Methanobrevibacter, coccus-type and sarcina-type methanogens with LMP addition compared to Methanobacteria in control. However, higher concentration of LMP inhibited methanogenic activities and methane production. PMID:25151070

  6. Iodinated contrast media electro-degradation: process performance and degradation pathways.

    Science.gov (United States)

    Del Moro, Guido; Pastore, Carlo; Di Iaconi, Claudio; Mascolo, Giuseppe

    2015-02-15

    The electrochemical degradation of six of the most widely used iodinated contrast media was investigated. Batch experiments were performed under constant current conditions using two DSA® electrodes (titanium coated with a proprietary and patented mixed metal oxide solution of precious metals such as iridium, ruthenium, platinum, rhodium and tantalum). The degradation removal never fell below 85% (at a current density of 64 mA/cm(2) with a reaction time of 150 min) when perchlorate was used as the supporting electrolyte; however, when sulphate was used, the degradation performance was above 80% (at a current density of 64 mA/cm(2) with a reaction time of 150 min) for all of the compounds studied. Three main degradation pathways were identified, namely, the reductive de-iodination of the aromatic ring, the reduction of alkyl aromatic amides to simple amides and the de-acylation of N-aromatic amides to produce aromatic amines. However, as amidotrizoate is an aromatic carboxylate, this is added via the decarboxylation reaction. The investigation did not reveal toxicity except for the lower current density used, which has shown a modest toxicity, most likely for some reaction intermediates that are not further degraded. In order to obtain total removal of the contrast media, it was necessary to employ a current intensity between 118 and 182 mA/cm(2) with energy consumption higher than 370 kWh/m(3). Overall, the electrochemical degradation was revealed to be a reliable process for the treatment of iodinated contrast media that can be found in contaminated waters such as hospital wastewater or pharmaceutical waste-contaminated streams. PMID:25433384

  7. Sulfate-reducing bacteria in anaerobic bioreactors.

    NARCIS (Netherlands)

    Oude Elferink, S.J.W.H.

    1998-01-01

    The treatment of industrial wastewaters containing high amounts of easily degradable organic compounds in anaerobic bioreactors is a well-established process. Similarly, wastewaters which in addition to organic compounds also contain sulfate can be treated in this way. For a long time, the occurrenc

  8. Microbial degradation of toluene under sulfate-reducing conditions and the influence of iron on the process

    International Nuclear Information System (INIS)

    Toluene degradation occurred concomitantly with sulfate reduction in anaerobic microcosms inoculated with contaminated subsurface soil from an aviation fuel storage facility near the Patuxent River (Md.). Similar results were obtained for enrichment cultures in which toluene was the sole carbon source. Several lines of evidence suggest that toluene degradation was directly coupled to sulfate reduction in Patuxent River microcosms and enrichment cultures: (1) the two processes were synchronous and highly correlated, (2) the observed stoichiometric ratios of moles of sulfate consumed per mole of toluene consumed were consistent with the theoretical ratio for the oxidation of toluene to CO2 coupled with the reduction of sulfate to hydrogen sulfide, and (3) toluene degradation ceased when sulfate was depleted, and conversely, sulfate reduction ceased when toluene was depleted. Mineralization of toluene was confirmed in experiments with [ring-U-14C]toluene. The addition of millimolar concentrations of amorphous Fe(OH)3 to Patuxent River microcosms and enrichment cultures either greatly facilitated the onset of toluene degradation or accelerated the rate once degradation had begun. In iron-amended microcosms and enrichment cultures, ferric iron reduction proceeded concurrently with toluene degradation and sulfate reduction. Stoichiometric data and other observations indicate that ferric iron reduction was not directly coupled to toluene oxidation but was a secondary, presumably abiotic, reaction between ferric iron and biogenic hydrogen sulfide

  9. Treatment of wastewater from coffee bean processing in anaerobic fixed bed reactors with different support materials: performance and kinetic modeling.

    Science.gov (United States)

    Fia, Fátima R L; Matos, Antonio T; Borges, Alisson C; Fia, Ronaldo; Cecon, Paulo R

    2012-10-15

    An evaluation was performed of three upflow anaerobic fixed bed reactors for the treatment of wastewater from coffee bean processing (WCP). The supports used were: blast furnace cinders, polyurethane foam and crushed stone with porosities of 53, 95 and 48%, respectively. The testing of these 139.5 L reactors consisted of increasing the COD of the influent (978; 2401 and 4545 mg L(-1)), while maintaining the retention time of 1.3 days. For the maximum COD applied, the reactor filled with foam presented removals of 80% (non-filtered samples) and 83% (filtered samples). The greater performance of the reactor filled with foam is attributed to its porosity, which promoted greater collection of biomass. From the results, it could be concluded that the reactors presented satisfactory performance, especially when using the foam as a support. Furthermore, the modified Stover-Kincannon and second order for multicomponent substrate degradation models were successfully used to develop a model of the experimental data. PMID:22609965

  10. Lifetime prediction based on Gamma processes from accelerated degradation data

    Institute of Scientific and Technical Information of China (English)

    Wang Haowei; Xu Tingxue; Mi Qiaoli

    2015-01-01

    Accelerated degradation test is a useful approach to predict the product lifetime at the normal use stress level, especially for highly reliable products. Two kinds of the lifetime prediction based on Gamma processes were studied. One was to predict the lifetime of the population from accelerated degradation data, and the other was to predict the lifetime of an individual by taking the accelerated degradation data as prior information. For an extensive application, the Gamma process with a time transformation and random effects was considered. A novel contribution is that a deducing method for determining the relationships between the shape and scale parameters of Gamma processes and accelerated stresses was presented. When predicting the lifetime of an indi-vidual, Bayesian inference methods were adopted to improve the prediction accuracy, in which the conjugate prior distribution and the non-conjugate prior distribution of random parameters were studied. The conjugate prior distribution only considers the random effect of the scale parameter while the non-conjugate prior distribution considers the random effects of both the scale and shape parameter. The application and usefulness of the proposed method was demonstrated by the accelerated degradation data of carbon-film resistors.

  11. Controlling of degradation effects in radiation processing of polymers

    International Nuclear Information System (INIS)

    Radiation induced degradation technology is a new and promising application of ionizing radiation to develop viscose, pulp, paper, food preservation, pharmaceutical production, and natural bioactive agents industries. Controlling the degree of degradation, uniform molecular weight distribution, saving achieved in the chemicals (used in conventional methods) on a cost basis, and environmentally friendly process are the beneficial effects of using radiation technology in these industries. However, for some development countries such technology is not economic. Therefore, a great effort should be done to reduce the cost required for such technologies. One of the principle factors for reducing the cost is achieving the degradation at low irradiation doses. This not only reduces the cost of radiation but also improve the quality of the end use products. The end product of irradiated natural products such as carboxymethylcellulose and chitosan alginate may be used as food additive or benefited in agricultural purposes. (author)

  12. Controlling of degradation effects in radiation processing of polymers

    International Nuclear Information System (INIS)

    Radiation induced degradation technology is a new and promising application of ionizing radiation to develop viscose, pulp, paper, food preservation, pharmaceutical production, and natural bioactive agents industries. Controlling the degree of degradation, uniform molecular weight distribution, saving achieved in the chemicals (used in conventional methods) on a cost basis, and environmentally friendly process are the beneficial effects of using radiation technology in these industries. However, for some development countries such technology is not economic. Therefore, a great effort should be done to reduce the cost required for such technologies. One of the principle factors for reducing the cost is achieving the degradation at low irradiation doses. The addition of some additives such as potassium per-sulfate (KPS), ammonium per-sulfate (APS), or H2O2 to natural polymers (carboxy-methylcellulose (CMC), chitosan, carageenan and Na-alginate) during irradiation process accelerates their degradation. The highest degradation rate of polysaccharides obtained when APS was used. The end product of irradiated CMC, chitosan, carageenan and Na-alginate may be used as food additive or benefited in agricultural purposes. On the other hand, radiation crosslinking of PAAm or PNIPAAm is affected by the presence of natural polymer like CMC-Na and carageenan due to their degradability which could be controlled according to its concentration in the bulk medium and irradiation dose. Accordingly, the gel content, thermo-sensitivity (LCST) and swelling properties of PNIPAAm based natural polymers could be controlled. The swelling of the prepared copolymer hydrogels was investigated for its possible use in personal care articles particularly diapers or as carriers for drug delivery systems. The prepared crosslinked copolymers possessed high and fast swelling properties in simulated urine media and the swelling ratios of CMC-Na /PAAm gels in urine are acceptable for diaper application

  13. Anaerobic Digestion and its Applications

    Science.gov (United States)

    Anaerobic digestion is a natural biological process. The initials "AD" may refer to the process of anaerobic digestion, or the built systems of anaerobic digesters. While there are many kinds of digesters, the biology is basically the same for all. Anaerobic digesters are built...

  14. The alkaloid gramine in the anaerobic digestion process-inhibition and adaptation of the methanogenic community.

    Science.gov (United States)

    Popp, Denny; Harms, Hauke; Sträuber, Heike

    2016-08-01

    As many plant secondary metabolites have antimicrobial activity, microorganisms of the anaerobic digestion process might be affected when plant material rich in these compounds is digested. Hitherto, the effects of plant secondary metabolites on the anaerobic digestion process are poorly investigated. In this study, the alkaloid gramine, a constituent of reed canary grass, was added daily to a continuous co-digestion of grass silage and cow manure. A transient decrease of the methane yield by 17 % and a subsequent recovery was observed, but no effect on other process parameters. When gramine was infrequently spiked in higher amounts, the observed inhibitory effect was even more pronounced including a 53 % decrease of the methane yield and an increase of acetic acid concentrations up to 96 mM. However, the process recovered and the process parameters were finally at initial values (methane yield around 255 LN CH4 per gram volatile solids of substrate and acetic acid concentration lower than 2 mM). The bacterial communities of the reactors remained stable upon gramine addition. In contrast, the methanogenic community changed from a well-balanced mixture of five phylotypes towards a strong dominance of Methanosarcina (more than two thirds of the methanogenic community) while Methanosaeta disappeared. Batch inhibition assays revealed that acetic acid was only converted to methane via acetoclastic methanogenesis which was more strongly affected by gramine than hydrogenotrophic methanogenesis and acetogenesis. Hence, when acetoclastic methanogenesis is the dominant pathway, a shift of the methanogenic community is necessary to digest gramine-rich plant material. PMID:27138201

  15. Processes of malate catabolism during the anaerobic metabolism of grape berries

    International Nuclear Information System (INIS)

    In order to precise malate fate during the anaerobic metabolism of grape, malate-3-14C was injected into Carignan berries kept in darkness at 350C under carbon dioxide atmosphere. The injection of labelled malate was effected in presence or not of non-labelled oxalate which inhibits malic enzyme (EC I.I.I.40). The analyses of the samples fixed after 3 and 7 days anaerobiosis concerned the titration of various substrates, organic acids, amino-acids and glycolysis products, and the measuring of the NADP+-malic enzyme (EC I.I.I.40) and malate dehydrogenase (EC I.I.I.40). Radioactivity is mainly observed in ethanol, amino-butyrate the non-separated group glycerate-shikimate and succinate. Malic enzyme acts in the first sequence of a process leading from malate to ethanol. Alanin synthesis seems to be stimulated in presence of oxalate. The results obtained and some hypotheses presented in the literature induce to suggest a utilization scheme for malate in the anaerobic metabolism of grape

  16. Increase of the efficiency of anaerobic digestion by various pre-treatment processes of sewage sludge

    Directory of Open Access Journals (Sweden)

    Łukasz Krawczyk

    2011-09-01

    Full Text Available The aim of this paper is to demonstrate the effects of pre-treatment increase of the efficiency of anaerobic digestion on waste activated sludge. There were four methods for pre-treatment of the waste activated sludge: A – thermally treated at 121°C for 30 min, homogenized and hydrolysed by Bacillus subtilis bacteria, B – thermally treated at 121°C for 30 min and homogenized, C – thermally treated at 121°C for 30 min and hydrolysed by B. subtilis bacteria, D – thermally treated at 121°C for 30 min. The process consisted of a hydrolyses phase and anaerobic digestion phase operated at 36°C ±1°C for 35 days. It was investigated with regard to hydrolytic enzymes: amylase, cellulase, lipase and protease. Acetic acid (4.3 g∙dm-3 and butanediotic acid (0.1 g∙dm-3 were reported to appear in biggest quantities in volatile fatty acids according to measurement of VFA. The amount of carbon and nitrogen decreased while the ratio of C:N increased from 8:1 to 10:1. The highest methane yield was obtained in A method.

  17. Anaerobic acidification of sugar-beet processing wastes: Effect of operational parameters

    International Nuclear Information System (INIS)

    The objective of this study was to maximize the hydrolysis and acidification of sugar-beet processing wastewater and beet pulp for volatile fatty acid (VFA) production through acidogenic anaerobic metabolism. Experiments were conducted to determine the optimum operational conditions (HRT, waste-mixing ratio and pH) for effective acidification in daily-fed, continuously mixed anaerobic reactors. For this purpose, reactors were operated at 35 ± 1 C with different combinations of HRT (2-4 days), wastewater-pulp mixing ratios (1:0-1:1, in terms of COD) and pH ranges (5.7-7.5). Increased OLRs, resulting from pulp addition, increased the amount of acidification products (VFAs) which led to relatively low operational pH values (5.7-6.8). In this pH range, methanogenic activity was successfully inhibited and the lowest methane percentages (5.6-16.3%) were observed in the produced biogas. The optimum operational conditions were determined to be 2-day HRT and 1:1 waste mixing ratio (in terms of COD) without external alkalinity addition. These operational conditions led to the highest tVFA concentration (3635 ± 209 mg/L as H-Ac) with the acidification degree of 46.9 ± 2.1%. (author)

  18. Effects of nitrite on phosphate uptake in anaerobic-oxic process

    Institute of Scientific and Technical Information of China (English)

    LI Jie; XIONG Biyong; ZHANG Shude; YANG Hong; ZHANG Jie

    2007-01-01

    An anaerobic-oxic(A/O)biological phosphorus removal reactor was operated to study the effect of nitrite on phosphate uptake.The phosphorus uptake profile was determined under different operating conditions.The results indicated that in addition to oxygen and nitrate(DPBNa,nitrate denitrifying phosphorus removal),to some extent,nitrite could also serve as an electron acceptor to achieve nitrite denitrifying phosphorus removal(DPBNi).The quantity and rate of phosphorus uptake of DPBNi,however,were evidently lower than that of DPBNa.The experiment results revealed that nitrite would bring toxic action to phosphate accumulating organisms(PAOs)when NO2- -N≥93]7 mg/L.The nitrite existing in the anoxic reactor made no difference to the quantity and rate of denitrifying phosphorus removal,but it could reduce the consumption of nitrate.Moreover,the data showed that the aerobic phosphate uptake of DPBNi was lower than that of anaerobic phosphorus-released sludge in a traditional A/O process.However,there was not much difference between these two kinds of sludge in terms of the total phosphorus uptake quantity and the effluent quality.

  19. Anaerobic digestion of by-products of sugar beet and starch potato processing

    Energy Technology Data Exchange (ETDEWEB)

    Kryvoruchko, Vitaliy; Machmueller, Andrea; Bodiroza, Vitomir; Amon, Barbara; Amon, Thomas [Division of Agricultural Engineering, Department of Sustainable Agricultural Systems, University of Natural Resources and Applied Life Sciences, Peter-Jordan Strasse 82, A-1190 Vienna (Austria)

    2009-04-15

    Anaerobic digestion (AD) is a promising option for the environmentally friendly recycling of agricultural by-products. However, overloading of the digester with sugar, starch or protein might cause inhibition of the anaerobic processes. The aim of the present project was to investigate the AD of sugar beet, starch potato by-products and effect of pre-treatment by steam on methane yield of potatoes pulp. The investigated by-products have been: sugar beet pulp silage (SBP), sugar beet tail silage (SBT), potato pulp (PP), potato peel pulp (PPP) and potato fruit water (PFW). All by-products were digested in 1 l eudiometer-batch digesters at 37.5 C during 28-38 days. The specific methane yields of SBP and SBT were 430 and 481 l{sub N} kg{sup -1} volatile solids (VS), respectively. The specific methane yields of PP, PPP and PFW were 332, 377 and 323 l{sub N} (kg VS){sup -1}. A steam pre-treatment significantly increased the specific methane yield of PP up to 373 l{sub N} (kg VS){sup -1}. (author)

  20. Anaerobic acidification of sugar-beet processing wastes: Effect of operational parameters

    International Nuclear Information System (INIS)

    The objective of this study was to maximize the hydrolysis and acidification of sugar-beet processing wastewater and beet pulp for volatile fatty acid (VFA) production through acidogenic anaerobic metabolism. Experiments were conducted to determine the optimum operational conditions (HRT, waste-mixing ratio and pH) for effective acidification in daily-fed, continuously mixed anaerobic reactors. For this purpose, reactors were operated at 35 ± 1 oC with different combinations of HRT (2-4 days), wastewater-pulp mixing ratios (1:0-1:1, in terms of COD) and pH ranges (5.7-7.5). Increased OLRs, resulting from pulp addition, increased the amount of acidification products (VFAs) which led to relatively low operational pH values (5.7-6.8). In this pH range, methanogenic activity was successfully inhibited and the lowest methane percentages (5.6-16.3%) were observed in the produced biogas. The optimum operational conditions were determined to be 2-day HRT and 1:1 waste mixing ratio (in terms of COD) without external alkalinity addition. These operational conditions led to the highest tVFA concentration (3635 ± 209 mg/L as H-Ac) with the acidification degree of 46.9 ± 2.1%.

  1. Anaerobic acidification of sugar-beet processing wastes: Effect of operational parameters

    Energy Technology Data Exchange (ETDEWEB)

    Alkaya, Emrah; Demirer, Goeksel N. [Department of Environmental Engineering, Middle East Technical University, Inonu Bulvari, 06531 Ankara (Turkey)

    2011-01-15

    The objective of this study was to maximize the hydrolysis and acidification of sugar-beet processing wastewater and beet pulp for volatile fatty acid (VFA) production through acidogenic anaerobic metabolism. Experiments were conducted to determine the optimum operational conditions (HRT, waste-mixing ratio and pH) for effective acidification in daily-fed, continuously mixed anaerobic reactors. For this purpose, reactors were operated at 35 {+-} 1 C with different combinations of HRT (2-4 days), wastewater-pulp mixing ratios (1:0-1:1, in terms of COD) and pH ranges (5.7-7.5). Increased OLRs, resulting from pulp addition, increased the amount of acidification products (VFAs) which led to relatively low operational pH values (5.7-6.8). In this pH range, methanogenic activity was successfully inhibited and the lowest methane percentages (5.6-16.3%) were observed in the produced biogas. The optimum operational conditions were determined to be 2-day HRT and 1:1 waste mixing ratio (in terms of COD) without external alkalinity addition. These operational conditions led to the highest tVFA concentration (3635 {+-} 209 mg/L as H-Ac) with the acidification degree of 46.9 {+-} 2.1%. (author)

  2. Fate of products of degradation processes: consequences for climatic change

    International Nuclear Information System (INIS)

    The end products of atmospheric degradation are not only CO2 and H2O but also sulfate and nitrate depending on the chemical composition of the substances which are subject to degradation processes. Atmospheric degradation has thus a direct influence on the radiative balance of the earth not only due to formation of greenhouse gases but also of aerosols. Aerosols of a diameter of 0.1 to 2 micrometer, reflect short wave sunlight very efficiently leading to a radiative forcing which is estimated to be about -0.8 watt per m2 by IPCC. Aerosols also influence the radiative balance by way of cloud formation. If more aerosols are present, clouds are formed with more and smaller droplets and these clouds have a higher albedo and are more stable compared to clouds with larger droplets. Not only sulfate, but also nitrate and polar organic compounds, formed as intermediates in degradation processes, contribute to this direct and indirect aerosol effect. Estimates for the Netherlands indicate a direct effect of -4 watt m-2 and an indirect effect of as large as -5 watt m-2. About one third is caused by sulfates, one third by nitrates and last third by polar organic compounds. This large radiative forcing is obviously non-uniform and depends on local conditions. (author)

  3. Fate of products of degradation processes: consequences for climatic change.

    Science.gov (United States)

    Slanina, J; ten Brink, H M; Khlystov, A

    1999-03-01

    The end products of atmospheric degradation are not only CO2 and H2O but also sulfate and nitrate depending on the chemical composition of the substances which are subject to degradation processes. Atmospheric degradation has thus a direct influence on the radiative balance of the earth not only due to formation of greenhouse gases but also of aerosols. Aerosols of a diameter of 0.1 to 2 micrometer, reflect short wave sunlight very efficiently leading to a radiative forcing which is estimated to be about -0.8 watt per m2 by IPCC. Aerosols also influence the radiative balance by way of cloud formation. If more aerosols are present, clouds are formed with more and smaller droplets and these clouds have a higher albedo and are more stable compared to clouds with larger droplets. Not only sulfate, but also nitrate and polar organic compounds, formed as intermediates in degradation processes, contribute to this direct and indirect aerosol effect. Estimates for the Netherlands indicate a direct effect of -4 watt m-2 and an indirect effect of as large as -5 watt m-2. About one third is caused by sulfates, one third by nitrates and last third by polar organic compounds. This large radiative forcing is obviously non-uniform and depends on local conditions. PMID:10070730

  4. Does Signal Degradation Affect Top-Down Processing of Speech?

    Science.gov (United States)

    Wagner, Anita; Pals, Carina; de Blecourt, Charlotte M; Sarampalis, Anastasios; Başkent, Deniz

    2016-01-01

    Speech perception is formed based on both the acoustic signal and listeners' knowledge of the world and semantic context. Access to semantic information can facilitate interpretation of degraded speech, such as speech in background noise or the speech signal transmitted via cochlear implants (CIs). This paper focuses on the latter, and investigates the time course of understanding words, and how sentential context reduces listeners' dependency on the acoustic signal for natural and degraded speech via an acoustic CI simulation.In an eye-tracking experiment we combined recordings of listeners' gaze fixations with pupillometry, to capture effects of semantic information on both the time course and effort of speech processing. Normal-hearing listeners were presented with sentences with or without a semantically constraining verb (e.g., crawl) preceding the target (baby), and their ocular responses were recorded to four pictures, including the target, a phonological (bay) competitor and a semantic (worm) and an unrelated distractor.The results show that in natural speech, listeners' gazes reflect their uptake of acoustic information, and integration of preceding semantic context. Degradation of the signal leads to a later disambiguation of phonologically similar words, and to a delay in integration of semantic information. Complementary to this, the pupil dilation data show that early semantic integration reduces the effort in disambiguating phonologically similar words. Processing degraded speech comes with increased effort due to the impoverished nature of the signal. Delayed integration of semantic information further constrains listeners' ability to compensate for inaudible signals. PMID:27080670

  5. Anaerobes beyond anaerobic digestion

    OpenAIRE

    Sousa, D. Z.; Pereira, M A; Alves, M.M.

    2009-01-01

    Anaerobic microorganisms are widespread in nature. Sediments, gastrointestinal tracks, volcanic vents, geothermal sources are examples of habitats where anaerobic metabolism prevail, in some cases at extreme temperature, pH and pressure conditions. In such microbial ecosystems waste of some is food for others in a true integrated structure. Anaerobic microorganisms are able to use a wide variety of organic and inorganic compounds. Recalcitrant compounds, such as hydrocarbons, a...

  6. Development and optimisation of VFA driven DEAMOX process for treatment of strong nitrogenous anaerobic effluents.

    Science.gov (United States)

    Kalyuzhnyi, S V; Gladchenko, M A; Kang, Ho; Mulder, A; Versprille, A

    2008-01-01

    The recently proposed DEAMOX (DEnitrifying AMmonium OXidation) process combines the anammox reaction with autotrophic denitrifying conditions using sulphide as an electron donor for the production of nitrite from nitrate within an anaerobic biofilm. This paper firstly presents a feasibility study of the DEAMOX process using synthetic (ammonia + nitrate) wastewater where sulphide is replaced by volatile fatty acids (VFA) as a more widespread electron donor for partial denitrification. Under the influent N-NH+4/N-NO3(-) and COD/N-NO3(-) ratios of 1 and 2.3, respectively, the typical efficiencies of ammonia removal were around 40% (no matter whether a VFA mixture or only acetate were used) for nitrogen loading rates (NLR) up to 1236 mg N/l/d. This parameter increased to 80% by increasing the influent COD/N-NO3(-) ratio to 3.48 and decreasing the influent N-NH4 +/N-NO3(-) ratio to 0.29. As a result, the total nitrogen removal increased to 95%. The proposed process was further tested with typical strong nitrogenous effluent such as reject water (total N, 530-566 mg N/l; total COD, 1530-1780 mg/l) after thermophilic sludge anaerobic digestion. For this, the raw wastewater was split and partially ( approximately 50%) fed to a nitrifying reactor (to generate nitrate) and the remaining part ( approximately 50%) was directed to the DEAMOX reactor where this stream was mixed with the nitrified effluent. Stable process performance up to NLR of 1,243 mg N/l/d in the DEAMOX reactor was achieved resulting in 40, 100, and 66% removal of ammonia, NOx(-), and total nitrogen, respectively. PMID:18309208

  7. Fermentation products and plant cell wall-degrading enzymes produced by monocentric and polycentric anaerobic ruminal fungi.

    OpenAIRE

    Borneman, W. S.; Akin, D. E.; Ljungdahl, L G

    1989-01-01

    Five anaerobic fungal isolates from the bovine rumen were grown on Coastal Bermuda grass (CBG) leaf blades and monitored over a 9-day period for substrate utilization, fermentation products, cellulase, and xylanase activities. Two of the fungal isolates showed monocentric growth patterns; one (isolate MC-1) had monoflagellated zoospores and morphologically resembled members of the genus Piromyces; the other (isolate MC-2) had multiflagellated zoospores and resembled members of the genus Neoca...

  8. Hydrogen and methane production from condensed molasses fermentation soluble by a two-stage anaerobic process

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chiu-Yue; Liang, You-Chyuan; Lay, Chyi-How [Feng Chia Univ., Taichung, Taiwan (China). Dept. of Environmental Engineering and Science; Chen, Chin-Chao [Chungchou Institute of Technology, Taiwan (China). Environmental Resources Lab.; Chang, Feng-Yuan [Feng Chia Univ., Taichung, Taiwan (China). Research Center for Energy and Resources

    2010-07-01

    The treatment of condensed molasses fermentation soluble (CMS) is a troublesome problem for glutamate manufacturing factory. However, CMS contains high carbohydrate and nutrient contents and is an attractive and commercially potential feedstock for bioenergy production. The aim of this paper is to produce hydrogen and methane by two-stage anaerobic fermentation process. The fermentative hydrogen production from CMS was conducted in a continuously-stirred tank bioreactor (working volume 4 L) which was operated at a hydraulic retention time (HRT) of 8 h, organic loading rate (OLR) of 120 kg COD/m{sup 3}-d, temperature of 35 C, pH 5.5 and sewage sludge as seed. The anaerobic methane production was conducted in an up-flow bioreactor (working volume 11 L) which was operated at a HRT of 24 -60 hrs, OLR of 4.0-10 kg COD/m{sup 3}-d, temperature of 35 C, pH 7.0 with using anaerobic granule sludge from fructose manufacturing factory as the seed and the effluent from hydrogen production process as the substrate. These two reactors have been operated successfully for more than 400 days. The steady-state hydrogen content, hydrogen production rate and hydrogen production yield in the hydrogen fermentation system were 37%, 169 mmol-H{sub 2}/L-d and 93 mmol-H{sub 2}/g carbohydrate{sub removed}, respectively. In the methane fermentation system, the peak methane content and methane production rate were 66.5 and 86.8 mmol-CH{sub 4}/L-d with methane production yield of 189.3 mmol-CH{sub 4}/g COD{sub removed} at an OLR 10 kg/m{sup 3}-d. The energy production rate was used to elucidate the energy efficiency for this two-stage process. The total energy production rate of 133.3 kJ/L/d was obtained with 5.5 kJ/L/d from hydrogen fermentation and 127.8 kJ/L/d from methane fermentation. (orig.)

  9. Metabolic analysis of the soil microbe Dechloromonas aromatica str. RCB: indications of a surprisingly complex life-style and cryptic anaerobic pathways for aromatic degradation

    Directory of Open Access Journals (Sweden)

    Feil Helene

    2009-08-01

    Full Text Available Abstract Background Initial interest in Dechloromonas aromatica strain RCB arose from its ability to anaerobically degrade benzene. It is also able to reduce perchlorate and oxidize chlorobenzoate, toluene, and xylene, creating interest in using this organism for bioremediation. Little physiological data has been published for this microbe. It is considered to be a free-living organism. Results The a priori prediction that the D. aromatica genome would contain previously characterized "central" enzymes to support anaerobic aromatic degradation of benzene proved to be false, suggesting the presence of novel anaerobic aromatic degradation pathways in this species. These missing pathways include the benzylsuccinate synthase (bssABC genes (responsible for fumarate addition to toluene and the central benzoyl-CoA pathway for monoaromatics. In depth analyses using existing TIGRfam, COG, and InterPro models, and the creation of de novo HMM models, indicate a highly complex lifestyle with a large number of environmental sensors and signaling pathways, including a relatively large number of GGDEF domain signal receptors and multiple quorum sensors. A number of proteins indicate interactions with an as yet unknown host, as indicated by the presence of predicted cell host remodeling enzymes, effector enzymes, hemolysin-like proteins, adhesins, NO reductase, and both type III and type VI secretory complexes. Evidence of biofilm formation including a proposed exopolysaccharide complex and exosortase (epsH are also present. Annotation described in this paper also reveals evidence for several metabolic pathways that have yet to be observed experimentally, including a sulphur oxidation (soxFCDYZAXB gene cluster, Calvin cycle enzymes, and proteins involved in nitrogen fixation in other species (including RubisCo, ribulose-phosphate 3-epimerase, and nif gene families, respectively. Conclusion Analysis of the D. aromatica genome indicates there is much to be

  10. Metabolic analysis of the soil microbe Dechloromonas aromatica str. RCB: indications of a surprisingly complex life-style and cryptic anaerobic pathways for aromatic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Salinero, Kennan Kellaris; Keller, Keith; Feil, William S.; Feil, Helene; Trong, Stephan; Di Bartolo, Genevieve; Lapidus, Alla

    2008-11-17

    Initial interest in Dechloromonas aromatica strain RCB arose from its ability to anaerobically degrade benzene. It is also able to reduce perchlorate and oxidize chlorobenzoate, toluene, and xylene, creating interest in using this organism for bioremediation. Little physiological data has been published for this microbe. It is considered to be a free-living organism. The a priori prediction that the D. aromatica genome would contain previously characterized 'central' enzymes involved in anaerobic aromatic degradation proved to be false, suggesting the presence of novel anaerobic aromatic degradation pathways in this species. These missing pathways include the benzyl succinyl synthase (bssABC) genes (responsible for formate addition to toluene) and the central benzoylCoA pathway for monoaromatics. In depth analyses using existing TIGRfam, COG, and InterPro models, and the creation of de novo HMM models, indicate a highly complex lifestyle with a large number of environmental sensors and signaling pathways, including a relatively large number of GGDEF domain signal receptors and multiple quorum sensors. A number of proteins indicate interactions with an as yet unknown host, as indicated by the presence of predicted cell host remodeling enzymes, effector enzymes, hemolysin-like proteins, adhesins, NO reductase, and both type III and type VI secretory complexes. Evidence of biofilm formation including a proposed exopolysaccharide complex with the somewhat rare exosortase (epsH), is also present. Annotation described in this paper also reveals evidence for several metabolic pathways that have yet to be observed experimentally, including a sulphur oxidation (soxFCDYZAXB) gene cluster, Calvin cycle enzymes, and nitrogen fixation (including RubisCo, ribulose-phosphate 3-epimerase, and nif gene families, respectively). Analysis of the D. aromatica genome indicates there is much to be learned regarding the metabolic capabilities, and life-style, for this microbial

  11. Allophagy: A macroautophagic process degrading spermatozoid-inherited organelles

    OpenAIRE

    Al Rawi, Sara; Louvet-Vallée, Sophie; Djeddi, Abderazak; Sachse, Martin; Culetto, Emmanuel; Hajjar, Connie; Boyd, Lynn; Legouis, Renaud; Galy, Vincent

    2012-01-01

    In most animals, during oocyte fertilization the spermatozoon provides DNA and centrioles together with some cytoplasm and organelles, but paternal mitochondria are generally eliminated in the embryo. Using the model animal C. elegans we have shown that paternal organelle degradation is dependent on the formation of autophagosomes a few minutes after fertilization. This macroautophagic process is preceded by an active ubiquitination of some spermatozoon-inherited organelles. Analysis of ferti...

  12. Allophagy: a macroautophagic process degrading spermatozoid-inherited organelles.

    Science.gov (United States)

    Al Rawi, Sara; Louvet-Vallée, Sophie; Djeddi, Abderazak; Sachse, Martin; Culetto, Emmanuel; Hajjar, Connie; Boyd, Lynn; Legouis, Renaud; Galy, Vincent

    2012-03-01

    In most animals, during oocyte fertilization the spermatozoon provides DNA and centrioles together with some cytoplasm and organelles, but paternal mitochondria are generally eliminated in the embryo. Using the model animal C. elegans we have shown that paternal organelle degradation is dependent on the formation of autophagosomes a few minutes after fertilization. This macroautophagic process is preceded by an active ubiquitination of some spermatozoon-inherited organelles. Analysis of fertilized mouse embryos suggests that this autophagy event is evolutionarily conserved. PMID:22361582

  13. Using Geo-informational System for determining land degradation processes

    Science.gov (United States)

    Mangul, I.; Mangul, S.

    The largest part of agricultural lands of the Republic of Moldova is concentrated in the arid zone Frequent droughts once in 2-4 years inflict vital causalities to agriculture of the Republic of Moldova However droughts influence doesn t only limit itself to forming production Drought after-effect is highly ruinous for water reserves industrial enterprises functioning rhythm and human health Droughts make for the drying up and crumbling of soil which is subject to excessive human influence and result in land degradation desertification Term desertification means land degradation in the droughty zones It is necessary to mention that the droughty ecosystems are extremely fragile and sensitive overexploitation Nowadays in the Republic of Moldova 33-37 of agricultural lands is eroded Republic of Moldova joined the United Nations Convention to Combat Desertification on December 24 1998 The Government of the Republic of Moldova ratified the National Action Plan to Combat Desertification in 2000 Within the framework of executing the National Action Plan by National Committee to Combat Desertification Geo-informational System on arid questions was organized In addition a lot of indexes corresponding to international standards were used for the evaluation of drought of the territory and land degradation processes Mostly this information is presented in maps erosion landslides aridity water resources A rich experience of using satellite information for determining land degradation demonstrates high effectiveness of this method Satellite

  14. Anaerobic workout

    OpenAIRE

    McAdam, Ewan J.

    2010-01-01

    Anaerobic technology cannot directly replace current wastewater treatment processes exclusively. The UASB reactor configuration removes slightly less organic carbon by comparison as the process relies on lamella separation for passive clarification rather than using fine pores like anMBR. By contrast, whilst anMBR can operate as a single unit process for organic carbon removal, the membrane surface has to be cleaned using gas sparging to limit surface deposition, which requires extra energy. ...

  15. Sustainable Agro-Food Industrial Wastewater Treatment Using High Rate Anaerobic Process

    Directory of Open Access Journals (Sweden)

    Yung-Tse Hung

    2013-03-01

    Full Text Available This review article compiles the various advances made since 2008 in sustainable high-rate anaerobic technologies with emphasis on their performance enhancement when treating agro-food industrial wastewater. The review explores the generation and characteristics of different agro-food industrial wastewaters; the need for and the performance of high rate anaerobic reactors, such as an upflow anaerobic fixed bed reactor, an upflow anaerobic sludge blanket (UASB reactor, hybrid systems etc.; operational challenges, mass transfer considerations, energy production estimation, toxicity, modeling, technology assessment and recommendations for successful operation

  16. Nutrient removal and phosphorus recovery performances of a novel anaerobic-anoxic/nitrifying/induced crystallization process.

    Science.gov (United States)

    Shi, Jing; Lu, Xiwu; Yu, Ran; Zhu, Wentao

    2012-10-01

    An anaerobic-anoxic/nitrifying (A(2)N) two sludge process coupled with induced crystallization (IC) called A(2)N-IC process was developed for wastewater nutrient removal and phosphorus recovery. The performances of A(2)N-IC process in comparison with A(2)N process at different COD to phosphorus (COD/P) feeding ratios were investigated. The results indicated that A(2)N-IC achieved not only high and stable nutrient removal but also phosphorus recovery. Calcium phosphorus crystals were formed in the crystallization reactor in A(2)N-IC. Moreover, the incorporation of chemical induced crystallization improved biological phosphorus removal. In A(2)N-IC process, phosphorus removal efficiency was consistently maintained at 99.2%, whereas in A(2)N it decreased from 93.0% to 65.7% with the decrease of feeding COD/P ratio. The COD and ammonia removal efficiencies were regardless of feeding COD/P ratio in the two processes. PMID:22858484

  17. Reconstitution of dewatered food processing residuals with manure to increase energy production from anaerobic digestion

    International Nuclear Information System (INIS)

    Solid residuals generated from dewatering food processing wastewater contain organic carbon that can potentially be reclaimed for energy through anaerobic digestion. This results in the diversion of waste from a landfill and uses it for a beneficial purpose. Dewatering the waste concentrates the carbon, reducing transportation costs to a farm digester where it can be blended with manure to increase biogas yield. Polymers are often used in the dewatering of the food waste but little is known regarding their impact on biogas production. Four 2 dm3 working volume, semi-continuous reactors, were used at a mesophilic temperature and a solids retention time (SRT) of 15 days. Reactors were fed daily with a blended feedstock containing a food processing sludge waste (FPSW)/manure ratio of 2.2:1 (by weight) as this produced the optimized carbon to nitrogen ratio. Results demonstrated that reconstitution of dewatered FPSW with dairy manure produced approximately 2 times more methane than animal manure alone for the same volume. However, only approximately 30% of volatile solids (VS) were consumed indicating energy potential still remained. Further, the efficiency of the conversion of VS to methane for the blended FPSW/manure was substantially less than for manure only. However, the overall result is an increase in energy production for a given tank volume, which can decrease life cycle costs. Because all FPSW is unique and the determination of dewatering additives is customized based on laboratory testing and field adjustment, generalizations are difficult and specific testing is required. -- Highlights: ► Energy production in anaerobic digestion can increase by co-blending food waste. ► Energy for transporting food waste to blend with manure is less when dewatered. ► Dewatered food waste in manure produced twice as much methane than manure. ► Efficiency of carbon to methane was low because of ammonium bicarbonate production. ► Carbon destruction was 30%, more

  18. The role of paraffin oil on the interaction between denitrifying anaerobic methane oxidation and Anammox processes.

    Science.gov (United States)

    Fu, Liang; Ding, Zhao-Wei; Ding, Jing; Zhang, Fang; Zeng, Raymond J

    2015-10-01

    Methane is sparingly soluble in water, resulting in a slow reaction rate in the denitrifying anaerobic methane oxidation (DAMO) process. The slow rate limits the feasibility of research to examine the interaction between the DAMO and the anaerobic ammonium oxidation (Anammox) process. In this study, optimized 5 % (v/v) paraffin oil was added as a second liquid phase to improve methane solubility in a reactor containing DAMO and Anammox microbes. After just addition, methane solubility was found to increase by 25 % and DAMO activity was enhanced. After a 100-day cultivation, the paraffin reactor showed almost two times higher consumption rates of NO3 (-) (0.2268 mmol/day) and NH4 (+) (0.1403 mmol/day), compared to the control reactor without paraffin oil. The microbes tended to distribute in the oil-water interface. The quantitative (q) PCR result showed the abundance of gene copies of DAMO archaea, DAMO bacteria, and Anammox bacteria in the paraffin reactor were higher than those in the control reactor after 1 month. Fluorescence in situ hybridization revealed that the percentages of the three microbes were 55.5 and 77.6 % in the control and paraffin reactors after 100 days, respectively. A simple model of mass balance was developed to describe the interactions between DAMO and Anammox microbes and validate the activity results. A mechanism was proposed to describe the possible way that paraffin oil enhanced DAMO activity. It is quite clear that paraffin oil enhances not only DAMO activity but also Anammox activity via the interaction between them; both NO3 (-) and NH4 (+) consumption rates were about two times those of the control. PMID:26036704

  19. Liquefaction and methanization of solid and liquid coffee wastes by two phase anaerobic digestion process.

    Science.gov (United States)

    Houbron, E; Larrinaga, A; Rustrian, E

    2003-01-01

    This study attempted to investigate the feasibility of volatile fatty acid (VFA) production from coffee pulp hydrolyse, and further to determine the potential of methanization of both the pre-acidified effluent and the coffee wastewater. The experiments were carried out in 2 completely mixed reactors, each one with a working volume of 4 litres. Coffee pulp was used as substrate in the acidogenic reactor and different mixtures of pulper and wash-water and pre-acidified effluent in the methanogenic one. The acidogenic and methanogenic reactors were operated at an organic loading rate of 5 COD g x l(-1) x d(-1) and 0.5 COD g x l(-1) x d(-1). The total, soluble and VFA's effluent COD concentrations of the acidogenic reactor present average values of 57.75, 17.00 and 13.92 g x l(-1) respectively. Under these experimental conditions, 23% (COD based) of coffee pulp was hydrolysed with a rate of 1.32 gCOD x l(-1) x d(-1) and the soluble fraction was transformed to VFA's with an acidification efficiency of 82%. Total VFA's concentration reached a value of 13.9 gCOD x l(-1), and acetate, propionate, butyrate and valerate represented 52%, 28%, 9% and 11% respectively of the liquid phase COD. In the methanogenic reactor, COD removal and methanization of fresh coffee wastewater, pre-acidified effluent and both combined occur with an efficiency of 85% to 95% respectively, with a characteristic biogas composition of 80% CH4 and 20% CO2. These results show that a humid coffee "Beneficio" processing daily 23 tons of cherry coffee (fresh fruit), equipped with a two stage anaerobic digestion process could generate at least 1,886 CH4 m3 x d(-1). This represents an increase in methane production by a factor 3 to 5 compared to a "Beneficio" using anaerobic digestion only for the treatment of its wastewater. PMID:14640226

  20. Optimum Accelerated Degradation Tests for the Gamma Degradation Process Case under the Constraint of Total Cost

    Directory of Open Access Journals (Sweden)

    Heonsang Lim

    2015-04-01

    Full Text Available An accelerated degradation test (ADT is regarded as an effective alternative to an accelerated life test in the sense that an ADT can provide more accurate information on product reliability, even when few or no failures may be expected before the end of a practical test period. In this paper, statistical methods for optimal designing ADT plans are developed assuming that the degradation characteristic follows a gamma process (GP. The GP-based approach has an advantage that it can deal with more frequently encountered situations in which the degradation should always be nonnegative and strictly increasing over time. The optimal ADT plan is developed under the total experimental cost constraint by determining the optimal settings of variables such as the number of measurements, the measurement times, the test stress levels and the number of units allocated to each stress level such that the asymptotic variance of the maximum likelihood estimator of the q-th quantile of the lifetime distribution at the use condition is minimized. In addition, compromise plans are developed to provide means to check the adequacy of the assumed acceleration model. Finally, sensitivity analysis procedures for assessing the effects of the uncertainties in the pre-estimates of unknown parameters are illustrated with an example.

  1. Controlling of degradation effects in radiation processing of polymers

    International Nuclear Information System (INIS)

    The interest of Member States of the IAEA in introducing radiation technology into the polymer and plastics industry is growing. This publication summarizes a number of studies conducted in the framework of a coordinated research project (CRP) on controlling of degradation effects on polymers by radiation processing technologies. It reviews a variety of applications and details the most important results and achievements of the participating centres and laboratories during the course of the CRP. The publication is intended to be of use to scientists implementing the technology and managers of radiation processing facilities

  2. Study on biological phosphorus removal process by Acinetobacter lwoffi: possibility to by-pass the anaerobic phase

    Energy Technology Data Exchange (ETDEWEB)

    Ghigliazza, R.; Lodi, A.; Rovatti, M. [Institute of Chemical and Process Engineering ``G.B. Bonino``, University of Genoa (Italy)

    1998-03-01

    An Acinetobacter lwoffi culture has been submitted to anaerobic/aerobic conditions in a Sequencing Batch Reactor (SBR) in order to study the ability of this strain in biological phosphorus removal process. Even by feeding a pure sodium acetate substrate, no phosphorus release has been detected during anaerobiosis, while phosphorus uptake beyond metabolic needs has been recorded during the aerobic phase; the anaerobic phase seems to have no influence on the enhanced biological phosphorus removal mechanisms. Hence aerobic batch tests have been carried out in order to verify the ability of Acinetobacter lwoffi to remove phosphorus by ``luxury uptake`` and ``overplus accumulation`` without anaerobic stress. Obtained results revealed a phosphorus removal efficiency of 75-80%. (orig.) With 5 figs., 3 tabs., 18 refs.

  3. Restoration of degraded agricultural terraces: rebuilding landscape structure and process.

    Science.gov (United States)

    LaFevor, M C

    2014-06-01

    The restoration of severely degraded cropland to productive agricultural capacity increases food supply, improves soil and water conservation, and enhances environmental and ecological services. This article examines the key roles that long-term maintenance plays in the processes of repairing degraded agricultural land. Field measurements from Tlaxcala, Mexico stress that restoring agricultural structures (the arrangements of landforms and vegetation) is alone insufficient. Instead, an effective monitoring and maintenance regime of agricultural structures is also crucial if the efforts are to be successful. Consequently, methods of wildland restoration and agricultural restoration may differ in the degree to which the latter must plan for and facilitate a sustained human involvement. An improved understanding of these distinctions is critical for environmental management as restoration programs that employ the technologies of intensive agriculture continue to grow in number and scope. PMID:24355068

  4. Single-Genotype Syntrophy by Rhodopseudomonas palustris Is Not a Strategy to Aid Redox Balance during Anaerobic Degradation of Lignin Monomers

    Science.gov (United States)

    Doud, Devin F. R.; Angenent, Largus T.

    2016-01-01

    Rhodopseudomonas palustris has emerged as a model microbe for the anaerobic metabolism of p-coumarate, which is an aromatic compound and a primary component of lignin. However, under anaerobic conditions, R. palustris must actively eliminate excess reducing equivalents through a number of known strategies (e.g., CO2 fixation, H2 evolution) to avoid lethal redox imbalance. Others had hypothesized that to ease the burden of this redox imbalance, a clonal population of R. palustris could functionally differentiate into a pseudo-consortium. Within this pseudo-consortium, one sub-population would perform the aromatic moiety degradation into acetate, while the other sub-population would oxidize acetate, resulting in a single-genotype syntrophy through acetate sharing. Here, the objective was to test this hypothesis by utilizing microbial electrochemistry as a research tool with the extracellular-electron-transferring bacterium Geobacter sulfurreducens as a reporter strain replacing the hypothesized acetate-oxidizing sub-population. We used a 2 × 4 experimental design with pure cultures of R. palustris in serum bottles and co-cultures of R. palustris and G. sulfurreducens in bioelectrochemical systems. This experimental design included growth medium with and without bicarbonate to induce non-lethal and lethal redox imbalance conditions, respectively, in R. palustris. Finally, the design also included a mutant strain (NifA*) of R. palustris, which constitutively produces H2, to serve both as a positive control for metabolite secretion (H2) to G. sulfurreducens, and as a non-lethal redox control for without bicarbonate conditions. Our results demonstrate that acetate sharing between different sub-populations of R. palustris does not occur while degrading p-coumarate under either non-lethal or lethal redox imbalance conditions. This work highlights the strength of microbial electrochemistry as a tool for studying microbial syntrophy. PMID:27471497

  5. Seasonal and spatial variation in soil chemistry and anaerobic processes in an Arctic ecosystem

    Science.gov (United States)

    Lipson, D.; Mauritz, M.; Bozzolo, F.; Raab, T. K.; Santos, M. J.; Friedman, E. F.; Rosenbaum, M.; Angenent, L.

    2009-12-01

    Drained thaw lake basins (DTLB) are the dominant landform in the Arctic coastal plain near Barrow, Alaska. Our previous work in a DTLB showed that Fe(III) and humic substances are important electron acceptors in anaerobic respiration, and play a significant role in the C cycle of these organic-rich soils. In the current study, we investigated seasonal and spatial patterns of availability of electron acceptors and labile substrate, redox conditions and microbial activity. Landscapes within DTLB contain complex, fine-scale topography arising from ice wedge polygons, which produce raised and lowered areas. One goal of our study was to determine the effects of microtopographic variation on the potential for Fe(III) reduction and other anaerobic processes. Additionally, the soil in the study site has a complex vertical structure, with an organic peat layer overlying a mineral layer, overlying permafrost. We described variations in soil chemistry across depth profiles into the permafrost. Finally, we installed an integrated electrode/potentiostat system to electrochemically monitor microbial activity in the soil. Topographically low areas differed from high areas in most of the measured variables: low areas had lower oxidation-reduction potential, higher pH and electrical conductivity. Soil pore water from low areas had higher concentrations of Fe(III), Fe(II), dissolved organic C (DOC), and aromaticity (UV absorbance at 260nm, “A260”). Low areas also had higher concentrations of dissolve CO2 and CH4 in soil pore water. Laboratory incubations of soil showed a trend toward higher potentials for Fe(III) reduction in topographically low areas. Clearly, ice wedge-induced microtopography exerts a strong control on microbial processes in this DTLB landscape, with increased anaerobic activity occurring in the wetter, depressed areas. Soil water extracted from 5-15 cm depth had higher concentrations of Fe(III), Fe(II), A260, and DOC compared to soil water sampled from 0-5cm

  6. Anaerobic digestion of olive oil mill effluents together with swine manure in UASB reactors

    DEFF Research Database (Denmark)

    Angelidaki, Irini; Ahring, Birgitte Kiær; Deng, H.;

    2002-01-01

    . Using upflow anaerobic sludge blanket (UASB) reactors, it was shown that codigestion of OME with swine manure (up to 50% OME) was successful with a COD reduction up to 75%. The process was adapted for degradation of OME with stepwise increase of the OME load to the UASB reactor. The results showed...... that the high content of ammonia in swine manure, together with content of other nutrients, make it possible to degrade OME without addition of external alkalinity and without addition of external nitrogen source. Anaerobic treatment of OME in UASB reactors resulted in reduction of simple phenolic compounds......Combined anaerobic digestion of olive oil mill effluent (OME) with swine manure, was investigated. In batch experiments was shown that for anaerobic degradation of OME alone nitrogen addition was needed. A COD:N ratio in the range of 65:1 to 126:1 was necessary for the optimal degradation process...

  7. Aqueous oxytetracycline degradation and the toxicity change of degradation compounds in photoirradiation process

    Institute of Scientific and Technical Information of China (English)

    JIAO Shaojun; ZHENG Shourong; YIN Daqiang; WANG Lianhong; CHEN Liangyan

    2008-01-01

    The extensive use of antibiotics has been a worldwide environmental issue. In this study the fate of oxytetracycline (OTC), under photoirradiation, is investigated. The results show that OTC photolysis follows first order model kinetics. Direct photolysis rate is found to be dependent on the initial OTC concentration, with a k value ranging from 0.0075 to 0.0141 min-1, in the OTC concentration from 40 to 10 mg/L. OTC photolysis is highly pH-dependent and strongly enhanced at a high pH value, with a k value of 0.0629 min-1 at pH 9. Enhanced OTC photolysis has also been observed in the presence of nitrate and low concentration of dissolved organic matter. Upon irradiation for 240 min, only 13.5% reduction of TOC occurs in spite of a rapid consumption of 90% of OTC. The byproducts from OTC photolysis have been analyzed using high-performance liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS), and the degradation pathway of OTC in the photo process is proposed. By employing luminescent bacterium to assess the adversity of the degradation compounds, an increased effect of toxicity occurs in spite of the great consumption of OTC in the photoirradiation process. After irradiation for 240 min, the inhibition rate is 47%, significantly higher than the initial rate of 21% (p < 0.05), revealing a potentially higher adversity risk on the microorganism upon OTC photolysis.

  8. A condition-based maintenance of a dependent degradation-threshold-shock model in a system with multiple degradation processes

    International Nuclear Information System (INIS)

    This paper proposes a condition-based maintenance strategy for a system subject to two dependent causes of failure: degradation and sudden shocks. The internal degradation is reflected by the presence of multiple degradation processes in the system. Degradation processes start at random times following a Non-homogeneous Poisson process and their growths are modelled by using a gamma process. When the deterioration level of a degradation process exceeds a predetermined value, we assume that a degradation failure occurs. Furthermore, the system is subject to sudden shocks that arrive at the system following a Doubly Stochastic Poisson Process. A sudden shock provokes the total breakdown of the system. Thus, the state of the system is evaluated at inspection times and different maintenance tasks can be carried out. If the system is still working at an inspection time, a preventive maintenance task is performed if the deterioration level of a degradation process exceeds a certain threshold. A corrective maintenance task is performed if the system is down at an inspection time. A preventive (corrective) maintenance task implies the replacement of the system by a new one. Under this maintenance strategy, the expected cost rate function is obtained. A numerical example illustrates the analytical results. - Highlights: • A condition-based maintenance model is proposed. • Two dependent causes of failure are considered: deterioration and external shocks. • Deterioration is given by multiple degradation processes growing by a gamma process. • The initiation of degradation processes follows a Non-homogeneous Poisson process. • External shocks arrive at the system by using a Doubly Stochastic Poisson Process

  9. Pentachlorophenol Degradation in an Anaerobic System with Bioelectrochemical Catalysis%五氯酚的生物电化学催化厌氧转化过程与机制

    Institute of Scientific and Technical Information of China (English)

    曹占平; 张景丽; 张宏伟

    2013-01-01

    研究了电催化体系、厌氧微生物体系和厌氧微生物电化学催化体系(电生物体系)对五氯酚(PCP)的降解,研究发现电生物体系的降解效率较电催化体系提高85.2%,较微生物体系提高18.5%.电生物体系中PCP脱氯的途径为:PCP先间位脱氯主要生成2,3,4,6-TeCP和2,4,6-TCP,而后2,4,6-TCP脱氯主要生成2,4-DCP,再经对位脱氯生成邻氯酚和苯酚;苯酚在阳极附近多菌种协同作用下进一步氧化,从而减少苯酚的积累加快了PCP的还原转化.电生物体系通过微生物对电子的“长”距离传递和生物还原转化,形成了电化学与生物的交互反应过程,提高了PCP的降解效果.%The pentachlorophenol ( PCP) degradation using an electrocatalytic system, an anaerobic system, and an anaerobic system with bioelectrochemical catalysis (a bioelectrical system) was studied, respectively. The results showed that the degradation efficiency of the bioelectrical system increased by 85.2% than that of the electrocatalytic system and by 18.5% than that of the microbial system. In the bioelectrical system the main process of the PCP dechlorination was as follow:PCP was dechlorinated at the meta-position and converted to 2,3,4,6-TeCP and 2,4, 6-TCP in turn,the further dechlorination of 2,4,6-TCP mainly produced 2,4-DCP,and then 2, 4-DCP was dechlorinated at the para-position and generated ortho-chlorophenol and phenol. Phenol oxidation under the multi-strain synergy near the anode reduced the phenol concentration and accelerated the reductive degradation of PCP. Because the bacteria reduced PCP and transferred electrons for a long distance,the electrochemical and biological interactive response proceeded and the efficiency of the PCP degradation improved in the bioelectrical system.

  10. Meadow degradation, hydrological processes and rangeland management in Tibet

    Science.gov (United States)

    He, Siyuan; Richards, Keith

    2013-04-01

    Alpine meadow dominated by species of Kobresia is widely distributed in the Tibetan Plateau. Kobresia pygmaea is often a main species and the meadow has evolved as a result of long-term trampling, being a main rangeland resource for livestock grazing. This alpine meadow also plays an important role in regulating the water and energy balance through land-atmosphere interaction, leaving an impact on local hydrological processes and beyond. Therefore, alpine meadow degradation is detrimental to both the health of the ecosystems, and to pastoralism. This research therefore studies the hydrological process with regard to degradation of Kobresia pygmaea meadow, tracing the possible causes, detecting the impacts on soil and biological properties, and further considering the herders' role in future rangeland management. The study area is around the Kema village of the Nagqu Prefecture in Northern Tibet, where human population depends on livestock grazing for livelihood. Main driving factors of alpine meadow degradation are climatic variations and human disturbance. The periodical change in local climate may be related to quasi-oscillatory atmospheric circulations in this monsoon dominated area and the climatic trends with extreme weather conditions can make the whole system hard to recover. Along with climatic variations, overgrazing is predominant with an exceeding of the carrying capacity by almost every household in this village. This is related to the change of rangeland management by the policies of privatisation of pasture and sedentarisation. The acceleration of degradation since the 1980s results in a series of distinct soil-vegetation combination classified in this research as the normal meadow, compact crust and bare soil. The species composition, soil physical and chemical properties and the vertical water movement along the soil-plant-atmosphere continuum are significantly different at the sites representing stages of degradation, revealed by multiple methods

  11. Anaerobic degradation of cellulosic substrates - Bionic implementation of the forestomach sysem of a ruminant; Anaerober Abbau cellulosehaltiger Substrate. Bionische Implementierung des Vormagensystems des Wiederkaeuers

    Energy Technology Data Exchange (ETDEWEB)

    Weichgrebe, Dirk [Hannover Univ. (Germany). Inst. fuer Siedlungswasserwirtschaft und Abfalltechnik; Stopp, Paul; Rosenwinkel, Karl-Heinz; Breves, Gerhard; Strecker, Michael

    2011-07-01

    The forestomach system of a ruminant technically can be realized by means of a two-stage arrangement of hydrolysis/acidification (first step) and methanation (second stage). Both stages are connected by a retention of solid substances and by a recirculation of process water. The first stage converts cellulose-rich substrates in short-chain volatile organic acids. The second stage converts these short-chain volatile organic acids into biogas. The technical realization of this two-stage arrangement is investigated by the co-operation project RUMEN-DAUMEN 2.0 of the Institute of Environmental Engineering at the Leibniz University of Hannover (Hannover, Federal Republic of Germany) and the Physiological Institute of the University of Veterinary Medicine Hannover (Hannover, Federal Republic of Germany). The aim of this study is to design a viable implementation of cellulosic waste materials by means of an efficient hydrolysis and to convert produced fatty acids efficiently in biogas.

  12. Engineered Barrier System Degradation, Flow, and Transport Process Model Report

    Energy Technology Data Exchange (ETDEWEB)

    E.L. Hardin

    2000-07-17

    The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II).

  13. Engineered Barrier System Degradation, Flow, and Transport Process Model Report

    International Nuclear Information System (INIS)

    The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II)

  14. Techno-economic evaluation of stillage treatment with anaerobic digestion in a softwood-to-ethanol process

    Directory of Open Access Journals (Sweden)

    Barta Zsolt

    2010-09-01

    Full Text Available Abstract Background Replacing the energy-intensive evaporation of stillage by anaerobic digestion is one way of decreasing the energy demand of the lignocellulosic biomass to the ethanol process. The biogas can be upgraded and sold as transportation fuel, injected directly into the gas grid or be incinerated on-site for combined heat and power generation. A techno-economic evaluation of the spruce-to-ethanol process, based on SO2-catalysed steam pretreatment followed by simultaneous saccharification and fermentation, has been performed using the commercial flow-sheeting program Aspen Plus™. Various process configurations of anaerobic digestion of the stillage, with different combinations of co-products, have been evaluated in terms of energy efficiency and ethanol production cost versus the reference case of evaporation. Results Anaerobic digestion of the stillage showed a significantly higher overall energy efficiency (87-92%, based on the lower heating values, than the reference case (81%. Although the amount of ethanol produced was the same in all scenarios, the production cost varied between 4.00 and 5.27 Swedish kronor per litre (0.38-0.50 euro/L, including the reference case. Conclusions Higher energy efficiency options did not necessarily result in lower ethanol production costs. Anaerobic digestion of the stillage with biogas upgrading was demonstrated to be a favourable option for both energy efficiency and ethanol production cost. The difference in the production cost of ethanol between using the whole stillage or only the liquid fraction in anaerobic digestion was negligible for the combination of co-products including upgraded biogas, electricity and district heat.

  15. Influence of the dose rate in the PVDF degradation processes

    International Nuclear Information System (INIS)

    Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from gamma radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation by products such as peroxide degradation. Radiation cross-linking technologies include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, polymer recycling, hydrogels etc. The degradation of PVDF polymer exposed to gamma irradiation in oxygen atmosphere in high dose rate has been studied and compared to obtained under smaller dose rates. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h and 2,592 kGy/h), with doses ranging from 100 kGy to 3,000 kGy. Different dose rate determine the prevalence of the processes being evaluated in this work by thermal measurements and infrared spectroscopy. It is shown that the degradation processes involve chain scissions and crosslink formation. The formation of oxidation products was shown at the surface of the irradiated film. The FTIR data revealed absorption bands at 1730 and 1853 cm-1 which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm-1 which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm-1 which were associated with NH stretch of NH2 and OH. Thermogravimetric studies reveal that the irradiation induced the increasing residues and decrease of the temperature of the decomposition start. (author)

  16. Influence of the dose rate in the PVDF degradation processes

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Adriana S.M.; Pereira, Claubia, E-mail: adriananuclear@yahoo.com.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Gual, Maritza R., E-mail: maritzargual@gmail.com [Instituto Superior de Tecnologias y Ciencias Aplicadas (InsTEC), Departamento de Ingenieria Nuclear, La Habana (Cuba); Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from gamma radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation by products such as peroxide degradation. Radiation cross-linking technologies include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, polymer recycling, hydrogels etc. The degradation of PVDF polymer exposed to gamma irradiation in oxygen atmosphere in high dose rate has been studied and compared to obtained under smaller dose rates. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h and 2,592 kGy/h), with doses ranging from 100 kGy to 3,000 kGy. Different dose rate determine the prevalence of the processes being evaluated in this work by thermal measurements and infrared spectroscopy. It is shown that the degradation processes involve chain scissions and crosslink formation. The formation of oxidation products was shown at the surface of the irradiated film. The FTIR data revealed absorption bands at 1730 and 1853 cm{sup -1} which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm{sup -1} which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm{sup -1} which were associated with NH stretch of NH{sub 2} and OH. Thermogravimetric studies reveal that the irradiation induced the increasing residues and decrease of the temperature of the decomposition start. (author)

  17. Critical assessment of anaerobic processes for continuous biohydrogen production from organic wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Show, Kuan-Yeow [Faculty of Engineering and Green Technology, University Tunku Abdul Rahman, Jalan University, Bandar Barat, 31900 Kampar, Perak (Malaysia); Zhang, Zhen-Peng [Beijing Enterprises Water Group Limited, BLK 25, No. 3 Minzhuang Road, Beijing 100195 (China); Tay, Joo-Hwa [School of Civil and Environmental Engineering, Nanyang Technological University, Nanyang Avenue (Singapore); Liang, David Tee [Institute of Environmental Science and Engineering, Nanyang Technological University (Singapore); Lee, Duu-Jong [Department of Chemical Engineering, National Taiwan University, Taipei (China); Ren, Nanqi; Wang, Aijie [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China)

    2010-12-15

    Production of biohydrogen using dark fermentation has received much attention owing to the fact that hydrogen can be generated from renewable organics including waste materials. The key to successful application of anaerobic fermentation is to uncouple the liquid retention time and the biomass retention time in the reactor system. Various reactor designs based on biomass retention within the reactor system have been developed. This paper presents our research work on bioreactor designs and operation for biohydrogen production. Comparisons between immobilized-cell systems and suspended-cell systems based on biomass growth in the forms of granule, biofilm and flocs were made. Reactor configurations including column- and tank-based reactors were also assessed. Experimental results indicated that formation of granules or biofilms substantially enhanced biomass retention which was found to be proportional to the hydrogen production rate. Rapid hydrogen-producing culture growth and high organic loading rate might limit the application of biofilm biohydrogen production, since excessive growth of fermentative biomass would result in washout of support carrier. It follows that column-based granular sludge process is a preferred choice of process for continuous biohydrogen production from organic wastewater, indicating maximum hydrogen yield of 1.7 mol-H{sub 2}/mol-glucose and hydrogen production rate of 6.8 L-H{sub 2}/L-reactor h. (author)

  18. Energy efficiency in waste water treatments plants: Optimization of activated sludge process coupled with anaerobic digestion

    International Nuclear Information System (INIS)

    This paper presents a study concerning the optimization of a Waste Water Treatment process. The process deals with carbon and nitrogen removal and includes activated sludge reactors coupled with an anaerobic digestion reactor. Nitrification and de-nitrification biochemical reactions are due to the biological activity of heterotrophic and autotrophic micro-organisms occurring inside the reactors. Rigorous Plant-Wide models that represent the main biochemical transformations have been constructed as per the CEIT approach . The energy consumption for each Physical Unit Operation (P.U.O.) involved in the flow-sheet is evaluated and a full link is made between the biological activity and the electrical demand or production. Steady-state mathematical optimizations are then computed and the influence of primary settling efficiency on electrical autonomy is quantified and demonstrated. The ammonium recycling from digestion to activated sludge reactors is also demonstrated to be a limiting factor for the overall energy efficiency, as well as the C-substrate availability for denitrifying. Some conclusions are then drawn to improve the global electrical efficiency of the system.

  19. Anoxic phosphorus removal in a pilot scale anaerobic-anoxic oxidation ditch process

    Institute of Scientific and Technical Information of China (English)

    Hongxun HOU; Shuying WANG; Yongzhen PENG; Zhiguo YUAN; Fangfang YIN; Wang GAN

    2009-01-01

    The anaerobic-anoxic oxidation ditch (A2/O OD) process is popularly used to eliminate nutrients from domestic wastewater. In order to identify the existence of denitrifying phosphorus removing bacteria (DPB), evalu-ate the contribution of DPB to biological nutrient removal,and enhance the denitrifying phosphorus removal in the A2/O OD process, a pilot-scale A2/O OD plant (375 L)was conducted. At the same time batch tests using sequence batch reactors (12 L and 4 L) were operated to reveal the significance of anoxic phosphorus removal. The results indicated that: The average removal efficiency of COD, NH4+, pO3-4, and TN were 88.2%, 92.6%, 87.8%,and 73.1%, respectively, when the steady state of the pilotscale A2/O OD plant was reached during 31-73d,demonstrating a good denitrifying phosphorus removal performance. Phosphorus uptake took place in the anoxic zone by poly-phosphorus accumulating organisms NO2- could be used as electron receptors in denitrifying phosphorus removal, and the phosphorus uptake rate with NO2- as the electron receptor was higher than that with NO3- when the initial concentration of either NO2- or NO3 was 40 mg/L.

  20. Evaluation of granular anaerobic ammonium oxidation process for the disposal of pre-treated swine manure

    Directory of Open Access Journals (Sweden)

    Shou-Qing Ni

    2014-04-01

    Full Text Available With rising environmental concerns on potable water safety and eutrophication, increased media attention and tighter environmental regulations, managing animal waste in an environmentally responsible and economically feasible way can be a challenge. In this study, the possibility of using granular anammox process for ammonia removal from swine waste treatment water was investigated. A rapid decrease of NO2−–N and NH4+–N was observed during incubation with wastewater from an activated sludge deodorization reactor and anaerobic digestion-partial oxidation treatment process treating swine manure and its corresponding control artificial wastewaters. Ammonium removal dropped from 98.0 ± 0.6% to 66.9 ± 2.7% and nearly absent when the organic load in the feeding increased from 232 mg COD/L to 1160 mg COD/L and 2320 mg COD/L. The presence of organic carbon had limited effect on nitrite and total nitrogen removal. At a COD to N ratio of 0.9, COD inhibitory organic load threshold concentration was 727 mg COD/L. Mass balance indicated that denitrifiers played an important role in nitrite, nitrate and organic carbon removal. These results demonstrated that anammox system had the potential to effectively treat swine manure that can achieve high nitrogen standards at reduced costs.

  1. Experimental anaerobic digestion generator coupled at a plan plates solar collector; Biodigestor experimental acoplado a coletor solar de placas planas

    Energy Technology Data Exchange (ETDEWEB)

    Kaneshiro, Tsuneharu [Brasilia Univ., DF (Brazil); Venanzi, D. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Escola de Engenharia; Medeiros, J.T.N. de [Rio Grande do Norte Univ., Natal, RN (Brazil)

    1987-12-31

    Analysis of results of research in course in solar energy used as heat source to anaerobic degradation in organic matter are presented; water is circulated around the generator to rise and maintain a constant process. (author). 16 refs., 2 figs

  2. Natural and enhanced anaerobic degradation of 1,1,1-trichloroethane and its degradation products in the subsurface – A critical review

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Durant, Neal D.; Hansen, Maria Heisterberg; Bjerg, Poul Løgstrup

    2011-01-01

    demonstrating the utility of bioaugmentation with Dhb cultures for remediation of TCA in the field. In this paper we review the state-of-the-science of TCA degradation in aquifers, examining results from both laboratory experiments and twenty-two field case studies, focusing on the capabilities and limits of......1,1,1-Trichloroethane (TCA) in groundwater is susceptible to a variety of natural degradation mechanisms. Evidence of intrinsic decay of TCA in aquifers is commonly observed; however, TCA remains a persistent pollutant at many sites and some of the daughter products that accumulate from intrinsic...... daughter products. Laboratory studies have demonstrated that pure or mixed cultures containing certain Dehalobacter (Dhb) bacteria can catalyze respiratory dechlorination of TCA and 1,1-dichloroethane (1,1-DCA) to monochloroethane (CA) in groundwater systems. 16S rRNA Dhb gene probes have been used as...

  3. Liquefaction and methanization of solid and liquid coffee wastes by two phase anaerobic digestion process

    Energy Technology Data Exchange (ETDEWEB)

    Houbron, E.; Rustrian, E. [Universidad Veracruzana, Orizaba, Ver. (Mexico). Facultad de Ciencias Quimicas; Larrinaga, A. [Instituto tecnologico de Orizaba, Ver. (Mexico)

    2003-07-01

    This study attempted to investigate the feasibility of volatile fatty acid (VFA) production from coffee pulp hydrolyse, and further to determine the potential of methanization of both the pre-acidified effluent and the coffee wastewater. The experiments were carried out in 2 completely mixed reactors, each one with working volume of 4 litres. Coffee pulp was used as substrate in the acidogenic reactor and different mixtures of pulper and wash-water and pre-acidified effluent in the methanogenic one. The acidogenic and methanogenic reactors were operated at an organic loading rate of 5 COD g.l{sup -1}.d{sup -1} and 0.5 COD g.l{sup -1}.d{sup -1}. The total, soluble and VFA's effluent COD concentrations of the acidogenic reactor present average values of 57.75, 17.00 and 13.92 g.l{sup -1} respectively. Under these experimental conditions, 23% (COD based) of coffee pulp was hydrolysed with a rate of 1.32 gCOD.l{sup -1}.d{sup -1} and the soluble fraction was transformed to VFA's with an acidification efficiency of 82%. Total VFA's concentration reached a value of 13.9 gCOD.l{sup -1}, and acetate, propionate, butyrate and valerate represented 52%, 28%, 9% and 11% respectively of the liquid phase COD. In the methanogenic reactor, COD removal and methanization of fresh coffee wastewater, pre-acidified effluent and both combined occur with an efficiency of 85% to 95% respectively, with a characteristic biogas composition of 80% CH{sub 4} and 20% CO{sub 2}. These results show that a humid coffee 'Beneficio' processing daily 23 tons of cherry coffee (fresh fruit), equipped with a two stage anaerobic digestion process could generate at least 1,886 CH{sub 4} m{sup 3}.d{sup -1}. This represents an increase in methane production by a factor 3 to 5 compared to a 'Beneficio' using anaerobic digestion only for the treatment of its wastewater. (author)

  4. Acid resistance of methanogenic bacteria in a two-stage anaerobic process treating high concentration methanol Wastewater

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xuefei; REN Nanqi

    2007-01-01

    In this study,the two-stage upflow anaerobic sludge blanket(UASB)system and batch experiments were employed to evaluate the performance of anaerobic digestion for the treatment of high concentration methanol wastewater.The acid resistance of granular sludge and methanogenic bacteria and their metabolizing activity were investigated.The results show that the pH of the first UASB changed from 4.9 to 5.8 and 5.5 to 6.2 for the second reactor.Apparently,these were not the advisable pH levels that common metha nogenic bacteria could accept.The methanogenic bacteria of the system,viz.Methanosarcina barkeri,had some acid resistance and could still degrade methanol at pH 5.0.If the methanogenic bacteria were trained further,their acid resistance would be improved somewhat.Granular sludge of the system could protect the methanogenic bacteria within its body against the impact of the acidic environment and make them degrade methanol at pH 4.5.The performance of granular sludge was attributed to its structure,bacteria species,and the distribution of bacterium inside the granule.

  5. Subsurface aeration of anaerobic groundwater : iron colloid formation and the nitrification process

    OpenAIRE

    Wolthoorn, A.

    2003-01-01

    Keywords: Iron, anaerobic groundwater, groundwater purification, heterogeneous oxidation, iron colloid formation, electron microscopy, nitrification In anaerobic groundwater iron and ammonium can be found in relatively high concentrations. These substances need to be removed when groundwater is used for the production of drinking water. Subsurface aeration can be applied to remove iron before the groundwater reaches the purification plant. The primary goal of subsurface aeration is to oxidise...

  6. Developing a nutrient recovery process for recovering nutrients in anaerobic digestate in low income countries

    OpenAIRE

    Rose, Christopher

    2015-01-01

    It is estimated that 2.7 billion people worldwide are served by on-site sanitation facilities that require faecal sludge management. Anaerobic digestion is a treatment mechanism that can provide faecal sludge management, methane production and an effluent digestate rich in nutrients. However, there is a paucity of information regarding the composition of the input faecal sludge which hinders the advancement of anaerobic digestion treatment and downstream nutrient recovery to...

  7. Effect of Acetylene Concentration on Denitrification and Related Microbial Processes in Anaerobically Incubasted Soil Slurries

    Institute of Scientific and Technical Information of China (English)

    巩晓佘

    1996-01-01

    In order to study the influence of difference in C2H2 concentration on the production of CO2,N2O,NH4-N and volatile fatty acids(VFA).soil slurries with a gradient in C2H2 concentration were anaerobically incubated at 25℃ for 2 weeks.Acetate,butyrate and CO2 production and NH4-N accumulation were inhibited in the slurres in the presence of C2H2;and the inhibition effect increased with increasing C2H2 from 0 to 20 kPa in the headspace gas of the incubation bottle.However,N2O,isobutyrate and propionate production was not obviously different among the slurres amended with C2H2 from 2.5 to 20 kPa.Therefore,the results implied that the C2H2 did not promote the inhibition but only increased the side effect on other microbial processes.The C2H2 of 2.5 kPa was suggested to be the optimum choice for the present denitrification study.

  8. Pretreatment on Anaerobic Sludge for Enhancement of Biohydrogen Production from Cassava Processing Wastewater

    Directory of Open Access Journals (Sweden)

    Franciele do Carmo Lamaison

    2014-02-01

    Full Text Available Methods for the enrichment of an anaerobic sludge with H2-producing bacteria have been compared by using cassava processing wastewater as substrate.The sludge was submitted to three different pretreatments: 1 heat pretreatment by boiling at 98 °C for 15 min., 2 heat pretreatment followed by sludge washout in a Continuous Stirring Tank Reactor (CSTR operated at a dilution rate (D of 0.021 h-1, and 3 sludge washout as the sole enrichment method. The pretreated sludge and the sludge without pretreatment (control were employed in the seeding of 4 batch bioreactors, in order to verify the volume and composition of the generated biogas. Maximum H2 production rates (Rm from the pretreated sludges, were estimated by the modified Gompertz model. Compared to the control, H2 production was ca. 4 times higher for the sludge submitted to the heat pretreatment only and for the sludge subjected to heat pretreatment combined with washout, and 10 times higher for washout. These findings demonstrated that the use of sludge washout as the sole sludge pretreatment method was the most effective in terms of H2 production, as compared to the heat and to the combined heat and washout pretreatments.

  9. Effects of multiple inhibitory components on anaerobic treatment processes in municipal solid waste incineration leachate.

    Science.gov (United States)

    Lei, Yuqing; Dang, Yan; Lan, Zhangheng; Sun, Dezhi

    2016-06-01

    This study served to investigate the comparative and combined effects of calcium, ammonia nitrogen, and aquatic humic substances (AHS) on specific methanogenic activity (SMA) in municipal solid waste leachate at mesophilic conditions. Using orthogonal experiments, anaerobic granular sludge was cultured with different concentrations combinations of the three added components for 13 days. The combination of 6000 mg/L calcium, 400 mg/L ammonia nitrogen, and 4000 mg/L AHS was the most inhibitory combination on the SMA of granular sludge, with a calculated 4.49 mL (standard temperature and atmospheric pressure) (STP) CH4/(gVSS·d) of SMA. The SMA with the addition of the inhibitory components was much lower than the control group's (1000 mg/L calcium, 200 mg/L ammonia nitrogen and 2000 mg/L AHS) with a calculated 12.97 mL (STP) CH4/(gVSS·d) of SMA. Calcium was the major inhibitor among the three components followed by AHS. High concentrations of calcium significantly inhibited the utilization of propionate and butyrate in the substrate and further affected the methanogenic process. PMID:26830102

  10. Degradation of organic pollutants and characteristics of activated sludge in an anaerobic/anoxic/oxic reactor treating chemical industrial wastewater

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2014-09-01

    Full Text Available A laboratory-scale anaerobic/anoxic/oxic system operated at the hydraulic retention times (HRT of 20, 40, and 60 h with mixed liquor suspended solids (MLSS concentrations of 3 g/L and 6 g/L was considered for treating chemical industrial wastewater rich in complex organic compounds and total dissolved solids. Extending the HRT and increasing the MLSS concentration resulted in higher removal efficiency for chemical oxygen demand at 72%. Organic compounds in wastewater could be classified into easily-removed and refractory compounds during treatment. The easily-removed compounds consisted primarily of ethers, alcohols, and aldehydes, whereas the refractory compounds included mainly oxygen-containing heterocyclic and benzene-containing compounds. Results from energy-dispersive X-ray spectroscopy showed that several metal ions accumulated in activated sludge, particularly Fe(III. Fe accumulated mainly on the surface of sludge floc pellets and resulted in the compactness of activated sludge, which caused the values of mixed liquor volatile suspended solids /MLSS and sludge volume index to decrease.

  11. Influence of step increases in hydraulic retention time on (RS)-MCPP degradation using an anaerobic membrane bioreactor.

    Science.gov (United States)

    Yuzir, Ali; Chelliapan, Shreeshivadasan; Sallis, Paul J

    2011-10-01

    The effects of different hydraulic retention time (HRT) on (RS)-MCPP utilisation was investigated by decreasing the feed flow rate in an anaerobic membrane bioreactor (AnMBR). Results showed an average COD removal efficiency of 91.4%, 96.9% and 94.4% when the reactor was operated at HRT 3, 7 and 17 d, respectively. However, when the HRT was reduced to 1d, the COD removal efficiency declined to just only 60%, confirming the AnMBR is stable to a large transient hydraulic shock loads. The (RS)-MCPP removal efficiency fluctuated from 6% to 39% at HRT 3 d, however when it was increased to 7 and 17 d, the removal efficiency increased to an average of 60% and 74.5%. In addition, (RS)-MCPP specific utilisation rates (SUR) were dependent on the HRT and gradually improved from 18 to 43 μg mg VSS(-1) d(-1) as flow rate increased. PMID:21862323

  12. Enhancement of bioenergy production from organic wastes by two-stage anaerobic hydrogen and methane production process

    OpenAIRE

    Luo, Gang; Xie, Li; Zhou, Qi; Angelidaki, Irini

    2011-01-01

    The present study investigated a two-stage anaerobic hydrogen and methane process for increasing bioenergy production from organic wastes. A two-stage process with hydraulic retention time (HRT) 3d for hydrogen reactor and 12d for methane reactor, obtained 11% higher energy compared to a single-stage methanogenic process (HRT 15d) under organic loading rate (OLR) 3gVS/(Ld). The two-stage process was still stable when the OLR was increased to 4.5gVS/(Ld), while the single-stage process failed....

  13. The importance of copper in pig-farming, the anaerobic process and the environment; Cobre: su importancia en porcicultura, proceso anaerobio y medio ambiente

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez Borges, E.; Poggi Varaldo, H. M.

    2006-07-01

    A review of the literature forms the basis for assessing the incidence of copper forms pig-farming waste, the use of the anaerobic process and the presence of this element in bodies of water. Since the optimum amounts of minerals for promoting growth in pigs is not known, there is a tendency to employ large amounts of food supplements containing trace metals, including copper, which then pass into pig waste. Copper is present in the anaerobic process in hydrogenase, an enzyme involved in the biotransformation of hydrogen into biogas. The toxic and inhibitory levels of copper during the anaerobic processing of organic matter are given. (Author) 22 refs.

  14. Anaerobic degradation of methanethiol in a process for Liquefied Petroleum Gas (LPG) biodesulfurization

    NARCIS (Netherlands)

    Leerdam, van R.C.

    2007-01-01

    Due to increasingly stringent environmental legislation car fuels have to be desulfurized to levels below 10 ppm in order to minimize negative effects on the environment as sulfur-containing emissions contribute to acid deposition (‘acid rain’) and to reduce the amount of particulates formed during

  15. Anaerobic degradation of methanethiol in a process for Liquefied Petroleum Gas (LPG) biodesulfurization

    OpenAIRE

    Leerdam, van, M.E.

    2007-01-01

    Due to increasingly stringent environmental legislation car fuels have to be desulfurized to levels below 10 ppm in order to minimize negative effects on the environment as sulfur-containing emissions contribute to acid deposition (‘acid rain’) and to reduce the amount of particulates formed during the burning of the fuel. Moreover, low sulfur specifications are also needed to lengthen the lifetime of car exhaust catalysts. The research presented in this thesis focuses on the biological desul...

  16. Probabilistic risk assessment for zinc in some commercial dishwashing detergents: the anaerobic digestion processes in US POTWs.

    Science.gov (United States)

    Ren, S

    2008-03-01

    A US patent was issued to a commercial dishwashing detergent composition in which soluble zinc serves as an anti-corrosion agent. Since the detergents are used in a down-the-drain fashion, some of the detergents are discharged as wastewater and treated in publicly owned treatment works (POTWs). A risk assessment was previously conducted which focused on the nitrification processes in US POTWs. As a conservative pollutant, zinc removed from wastewater during treatment is transferred to sludges and at sufficiently high concentrations may inhibit the sludge treatment processes. In the present assessment, a probabilistic risk assessment was conducted to quantitatively determine the risk of zinc in the detergents to the anaerobic digestion processes in US POTWs. The procedure for POTW local limit development designed by the US Environmental Protection Agency (EPA) was used as a reference when conducting the risk assessment. The assessment took into account the background zinc concentrations in POTW influents and was conducted at different market penetration rates (MPRs) for the US market of detergents based on the patented formula. Several factors were present that contributed to the conservativeness of the assessment. Results indicate that zinc in detergents does not present a significant risk to the anaerobic digestion processes in POTWs at a MPR up to 10%, with a probability of anaerobic digestion inhibition of below 1%. PMID:17959223

  17. Improvement in the degradation resistance of LDPE for radiochemical processing

    Science.gov (United States)

    Zaharescu, Traian; Pleşa, Ilona; Jipa, Silviu

    2014-01-01

    The effect of rosemary extract on radiochemical stability of low density polyethylene was studied by chemiluminescence, FT-IR spectroscopy and differential scanning calorimetry after γ(137Cs)-irradiation at processing low doses (10 and 20 kGy) in respect of pristine material. The additive concentrations (1, 2 and 5 wt%) induced a significant improvement in radiation stability, especially at high temperatures, for example 200 °C, which is proved chiefly by lower values of chemiluminescence intensities. The comparison of neat and rosemary-modified LDPE samples has revealed the protection action of this natural extract, which delays efficiently the propagation of oxidative degradation in γ-exposed polyethylene. The most evident proof for antioxidative protection efficiency promoted by rosemary is the smooth changes in hydroxyl and carbonyl indexes calculated on LDPE/5 wt% rosemary samples at all exposure doses.

  18. Degradation of atrazine in soil through induced photocatalytic processes

    Energy Technology Data Exchange (ETDEWEB)

    Pelizzetti, E. (Univ. di Parma (Italy)); Carlin, V.; Maurino, V.; Minero, C.; Dolci, M. (Univ. di Torino (Italy)); Marchesini, A. (Istituto Sperimentale per la Nutrizione delle Piante, Torino (Italy))

    1990-08-01

    The authors observed photocatalytic degradation of atrazine in the presence of semiconductor metal oxide particulates (TiO{sub 2}, ZnO) suspended in aqueous solution under simulated sunlight irradiation. The half-life for the process is ca. 5 and 80 min for TiO{sub 2} and ZnO, respectively (at an initial atrazine concentration of 25 mg/liter with 0.5 g of semiconductor per liter and with a photon flux of 3 {times} 10{sup {minus}5} einstein/min, and over a cell cross section of 4 cm{sup 2}). The authors investigated the catalytic activity of different soils. The weak photocatalytic activity of the soils (2 g/liter) is dramatically increased by the addition of 0.5 g of the semiconductor per liter. Half-lives are 10 to 40 minutes, depending on the nature of the soil.

  19. Microbial community dynamics in the two-stage anaerobic digestion process of two-phase olive mill residue

    OpenAIRE

    Rincón, Bárbara; Portillo Guisado, María del Carmen; González Grau, Juan Miguel; Borja Padilla, Rafael

    2013-01-01

    The microbial communities in a two-stage anaerobic digestion process treating olive mill >solid> residues were studied by molecular identification techniques. The microbial species identification in the hydrolytic-acidogenic step and in the methanogenic step was carried out by polymerase chain reaction amplification of 16S ribosomal RNA genes, denaturing gradient gel electrophoresis, cloning, and sequencing. This study revealed that Firmicutes (from 31.1 to 61.1 %, average 42.1 %) mainly repr...

  20. Study of the diversity of microbial communities in a sequencing batch reactor oxic-settling-anaerobic process and its modified process.

    Science.gov (United States)

    Sun, Lianpeng; Chen, Jianfan; Wei, Xiange; Guo, Wuzhen; Lin, Meishan; Yu, Xiaoyu

    2016-05-01

    To further reveal the mechanism of sludge reduction in the oxic-settling-anaerobic (OSA) process, the polymerase chain reaction - denaturing gradient gel electrophoresis protocol was used to study the possible difference in the microbial communities between a sequencing batch reactor (SBR)-OSA process and its modified process, by analyzing the change in the diversity of the microbial communities in each reactor of both systems. The results indicated that the structure of the microbial communities in aerobic reactors of the 2 processes was very different, but the predominant microbial populations in anaerobic reactors were similar. The predominant microbial population in the aerobic reactor of the SBR-OSA belonged to Burkholderia cepacia, class Betaproteobacteria, while those of the modified process belonged to the classes Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria. These 3 types of microbes had a cryptic growth characteristic, which was the main cause of a greater sludge reduction efficiency achieved by the modified process. PMID:27021584

  1. State of the art review of degradation processes in LMFBR materials. Volume II. Corrosion behavior

    International Nuclear Information System (INIS)

    Degradation of materials exposed to Na in LMFBR service is reviewed. The degradation processes are discussed in sections on corrosion and mass transfer, erosion, wear and self welding, sodium--water reactions, and external corrosion. (JRD)

  2. Anaerobic degradation of Polychlorinated Biphenyls (PCBs) and Polychlorinated Biphenyls Ethers (PBDEs), and microbial community dynamics of electronic waste-contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Song, Mengke [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Luo, Chunling, E-mail: clluo@gig.ac.cn [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Li, Fangbai [Guangdong Institute of Eco-environmental and Soil Sciences, Guangzhou 510650 (China); Jiang, Longfei [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); College of Life Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Wang, Yan [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Zhang, Dayi [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Zhang, Gan [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)

    2015-01-01

    Environmental contamination caused by electronic waste (e-waste) recycling is attracting increasing attention worldwide because of the threats posed to ecosystems and human safety. In the present study, we investigated the feasibility of in situ bioremediation of e-waste-contaminated soils. We found that, in the presence of lactate as an electron donor, higher halogenated congeners were converted to lower congeners via anaerobic halorespiration using ferrous ions in contaminated soil. The 16S rRNA gene sequences of terminal restriction fragments indicated that the three dominant strains were closely related to known dissimilatory iron-reducing bacteria (DIRB) and those able to perform dehalogenation upon respiration. The functional species performed the activities of ferrous oxidation to ferric ions and further ferrous reduction for dehalogenation. The present study links iron cycling to degradation of halogenated materials in natural e-waste-contaminated soil, and highlights the synergistic roles of soil bacteria and ferrous/ferric ion cycling in the dehalogenation of polychlorinated biphenyls (PCBs) and polybrominated biphenyl ethers (PBDEs). - Highlights: • The biodegradation PCBs and PBDEs in e-waste contaminated soils was studied. • DIRB and arylhalorespiring bacteria were responsive to dehalogenation respiration. • Soil bacteria and Fe ion cycling play synergistic roles in dehalogenation.

  3. Anaerobic degradation of Polychlorinated Biphenyls (PCBs) and Polychlorinated Biphenyls Ethers (PBDEs), and microbial community dynamics of electronic waste-contaminated soil

    International Nuclear Information System (INIS)

    Environmental contamination caused by electronic waste (e-waste) recycling is attracting increasing attention worldwide because of the threats posed to ecosystems and human safety. In the present study, we investigated the feasibility of in situ bioremediation of e-waste-contaminated soils. We found that, in the presence of lactate as an electron donor, higher halogenated congeners were converted to lower congeners via anaerobic halorespiration using ferrous ions in contaminated soil. The 16S rRNA gene sequences of terminal restriction fragments indicated that the three dominant strains were closely related to known dissimilatory iron-reducing bacteria (DIRB) and those able to perform dehalogenation upon respiration. The functional species performed the activities of ferrous oxidation to ferric ions and further ferrous reduction for dehalogenation. The present study links iron cycling to degradation of halogenated materials in natural e-waste-contaminated soil, and highlights the synergistic roles of soil bacteria and ferrous/ferric ion cycling in the dehalogenation of polychlorinated biphenyls (PCBs) and polybrominated biphenyl ethers (PBDEs). - Highlights: • The biodegradation PCBs and PBDEs in e-waste contaminated soils was studied. • DIRB and arylhalorespiring bacteria were responsive to dehalogenation respiration. • Soil bacteria and Fe ion cycling play synergistic roles in dehalogenation

  4. Sewage treatment by anaerobic biological process associated with dissolved air flotation.

    Science.gov (United States)

    Reali, M A; Campos, J R; Penetra, R G

    2001-01-01

    This paper presents the results of a study performed with a lab-scale batch DAF unit fed with previously coagulated (with FeCl3 or cationic polymer) effluent from a pilot scale up-flow anaerobic sludge blanket (UASB) reactor treating domestic sewage. The adequate coagulation/flocculation conditions--chemical dosage, time (Tf) and mean velocity gradient (Gf) in the flocculation step--and air requirements for flotation process were investigated. Best results were achieved for 65 mg.l-1 of FeCl3 at Tf around 15 min and Gf of 80 s-1. In the assays where only polymer was applied, 7 mg.l-1 of cationic polymer dosage gave optimum removals with Tf around 15 min and Gf of 30 s-1. Air requirements ranged from 9.5 to 19.0 g of air.m-3 wastewater. Best TSS (95% and residual of 2 mg.l-1), COD (85% and residual of 20 mg.l-1) and total phosphate (95% and residual of 0.6 mg.l-1) removals were obtained when applying FeCl3, although the use of cationic polymer also produced good level of TSS (74% and residual of 14 mg.l-1) and COD (75% and residual of 45 mg.l-1) removals. For the UASB-DAF (batch) system and FeCl3, global efficiencies would be 97.2% for COD, 97.9% for phosphate and 98.9% for TSS. PMID:11394285

  5. Start-up of simultaneous removal of ammonium and sulfate from an anaerobic ammonium oxidation (anammox) process in an anaerobic up-flow bioreactor

    International Nuclear Information System (INIS)

    A laboratory testing of simultaneous removal of ammonium and sulfate (SRAS) was studied from an anammox process in an anaerobic bioreactor filled with granular activated carbon. Two different phases of experiment were investigated to start up the SRAS process, and final batch tests were performed to analyze the SRAS process. The experiment included an anammox process and an SRAS process. During the anammox process, the highest removal efficiency of ammonium and nitrite was up to 97 and 98%, respectively. After 160 days in the stationary phase of anammox process, the ratio of ammonium to nitrite consumption was approximately 1:1.15, which is much higher than 1:1.32 in the traditional anammox process. The extra electron acceptor, such as sulfate, was thought to react with ammonium by bacteria. Synthetic wastewater containing ammonium chlorine and sodium sulfate was used as the feed for the bioreactor in the second phase of experiment. During the SRAS process, the influent concentrations of ammonium and sulfate were controlled to be 50-60 and 210-240 mg L-1 respectively. After start-up and acclimatization of this process for 60 days, the average effluent concentrations of ammonium and sulfate were 30 and 160 mg L-1, respectively. The simultaneous ammonium and sulfate removal was detected in the reactor. In order to further validate the biochemical interaction between ammonium and sulfate, batch tests was carried out. Abiotic tests were carried out to demonstrate that the pure chemical action between ammonium and sulfate without microorganism was not possible. Biotic assays with different ammonium and sulfate concentrations were further investigated that high concentrations of ammonium and sulfate could promote simultaneous removal of ammonium and sulfate. And elemental sulfur and nitrogen gas as the products measured in the SRAS process helped to demonstrate the occurrence of new interaction between nitrogen and sulfur. The new process of SRAS in the inorganic

  6. Prediction of Vacuum Pump Degradation in Semiconductor Processing

    OpenAIRE

    Butler, Shane W.; Ringwood, John; MacGearailt, Niall

    2009-01-01

    This paper addresses the issue of vacuum pump degradation in semiconductor manufacturing. The ability to identify the current level of vacuum pump degradation and predict the Remaining-Useful-Life (RUL) of a dry vacuum pump would allow manufacturers to schedule pump swaps at convenient times, and reduce the instances of unexpected pump failures, which can incur significant costs. In this paper, artificial neural networks are used to model the current level of pump degradation u...

  7. Sulfate-reducing bacteria in anaerobic bioreactors.

    OpenAIRE

    Oude Elferink, S.J.W.H.

    1998-01-01

    The treatment of industrial wastewaters containing high amounts of easily degradable organic compounds in anaerobic bioreactors is a well-established process. Similarly, wastewaters which in addition to organic compounds also contain sulfate can be treated in this way. For a long time, the occurrence of sulfate reduction was considered to be undesired. However, there are some recent developments in which sulfate reduction is optimized for the removal of sulfur compounds from waste streams. In...

  8. Anaerobic Digestion of Paper Mill Wastewater

    Directory of Open Access Journals (Sweden)

    Shreeshivadasan Chelliapan

    2012-01-01

    Full Text Available In general, paper mill wastewater contains complex organic substances which could not be treated completely using conventional treatment processes, e.g. aerobic processes. As a result, anaerobic technology is a promising alternative for paper mill wastewater treatment due to its ability to degrade hard organic compounds. In the present study, treatment of paper mill wastewater using a stage anaerobic reactor was investigated. The more specific objectives of this study were to confirm whether paper mill wastewater can be tolerated by methanogenic sludge and to assess the stability of reactor for measured parameters (e.g. COD removal, and methane composition. Results showed up to 98% COD removal efficiency in the anaerobic reactor when the reactor was operated at an OLR of 1.560 kg COD/m3.d. Anaerobic digestion can provide high treatment efficiency for recalcitrant substrates, which generates robust microorganism (acidogenesis and methanogenesis, for the degradation of recalcitrant compounds such as in the paper mill wastewater.

  9. Effect of continuous oleate addition on microbial communities involved in anaerobic digestion process

    DEFF Research Database (Denmark)

    Baserba, Manel Garrido; Angelidaki, Irini; Karakashev, Dimitar Borisov

    2012-01-01

    In the present study, the microbial diversity in anaerobic reactors, continuously exposed to oleate, added to a manure reactor influent, was investigated. Relative changes in archaeal community were less remarkable in comparison to changes in bacterial community indicating that dominant archaeal...

  10. Biogas production from food-processing industrial wastes by anaerobic digestion

    DEFF Research Database (Denmark)

    Fang, Cheng

    Konfronteret med energikrise og klimaforandringer, har verden brug for grønne, effektive og kulstofneutrale energikilder, som kan erstatte fossile brændstoffer. Biogas, som dannes ved anaerob nedbrydning af organisk materiale, er en bæredygtig, pålidelig og vedvarende energikilde. Der er stor...

  11. Perspectives for anaerobic digestion

    DEFF Research Database (Denmark)

    Ahring, Birgitte Kiær

    2003-01-01

    to the soil. Anaerobic digestion (AD) is one way of achieving this goal and it will furthermore, reduce energy consumption or may even be net energy producing. This chapter aims at provide a basic understanding of the world in which anaerobic digestion is operating today. The newest process developments...

  12. Degradation Processes in Corona-Charged Electret Filter-Media

    OpenAIRE

    Warren J. Jasper, Ph.D; Roger Barker, Ph.D.; Anushree Mohan; Juan Hinestroza, Ph.D.

    2007-01-01

    The degradation of filtration performance for coronachargedelectret filter media exposed to ethyl benzenewas assessed. Nonwoven corona-charged polypropylenefiber mats were exposed to ethyl-benzene using acustom made apparatus. Evaluated scenarios includedethyl-benzene vapor and liquid exposures. The filtrationperformance was evaluated using DOP as a testaerosol to measure filtration performance. It was observedthat significant filtration degradation occurredonly when liquid ethyl benzene came...

  13. Quantitating protein synthesis, degradation, and endogenous antigen processing.

    Science.gov (United States)

    Princiotta, Michael F; Finzi, Diana; Qian, Shu-Bing; Gibbs, James; Schuchmann, Sebastian; Buttgereit, Frank; Bennink, Jack R; Yewdell, Jonathan W

    2003-03-01

    Using L929 cells, we quantitated the macroeconomics of protein synthesis and degradation and the microeconomics of producing MHC class I associated peptides from viral translation products. To maintain a content of 2.6 x 10(9) proteins, each cell's 6 x 10(6) ribosomes produce 4 x 10(6) proteins min(-1). Each of the cell's 8 x 10(5) proteasomes degrades 2.5 substrates min(-1), creating one MHC class I-peptide complex for each 500-3000 viral translation products degraded. The efficiency of complex formation is similar in dendritic cells and macrophages, which play a critical role in activating T cells in vivo. Proteasomes create antigenic peptides at different efficiencies from two distinct substrate pools: rapidly degraded newly synthesized proteins that clearly represent defective ribosomal products (DRiPs) and a less rapidly degraded pool in which DRiPs may also predominate. PMID:12648452

  14. Evaluation of hydrogen and methane production from sugarcane bagasse hemicellulose hydrolysates by two-stage anaerobic digestion process.

    Science.gov (United States)

    Baêta, Bruno Eduardo Lobo; Lima, Diego Roberto Sousa; Filho, José Gabriel Balena; Adarme, Oscar Fernando Herrera; Gurgel, Leandro Vinícius Alves; Aquino, Sérgio Francisco de

    2016-10-01

    This study aimed at optimizing the net energy recovery from hydrogen and methane production through anaerobic digestion of the hemicellulose hydrolysate (HH) obtained by desirable conditions (DC) of autohydrolysis pretreatment (AH) of sugarcane bagasse (SB). Anaerobic digestion was carried out in a two-stage (acidogenic-methanogenic) batch system where the acidogenic phase worked as a hydrolysis and biodetoxification step. This allowed the utilization of more severe AH pretreatment conditions, i.e. T=178.6°C and t=55min (DC3) and T=182.9°C and t=40.71min (DC4). Such severe conditions resulted in higher extraction of hemicelluloses from SB (DC1=68.07%, DC2=48.99%, DC3=77.40% and DC4=73.90%), which consequently improved the net energy balance of the proposed process. The estimated energy from the combustion of both biogases (H2 and CH4) accumulated during the two-stage anaerobic digestion of HH generated by DC4 condition was capable of producing a net energy of 3.15MJ·kgSB(-1)dry weight. PMID:27393834

  15. The rheology, degradation, processing, and characterization of renewable resource polymers

    Science.gov (United States)

    Conrad, Jason David

    Renewable resource polymers have become an increasingly popular alternative to conventional fossil fuel based polymers over the past couple decades. The push by the government as well as both industrial and consumer markets to go "green" has provided the drive for companies to research and develop new materials that are more environmentally friendly and which are derived from renewable materials. Two polymers that are currently being produced commercially are poly-lactic acid (PLA) and polyhydroxyalkanoate (PHA) copolymers, both of which can be derived from renewable feedstocks and have shown to exhibit similar properties to conventional materials such as polypropylene, polyethylene, polystyrene, and PET. PLA and PHA are being used in many applications including food packaging, disposable cups, grocery bags, and biomedical applications. In this work, we report on the rheological properties of blends of PLA and PHA copolymers. The specific materials used in the study include Natureworks RTM 7000D grade PLA and PHA copolymers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Blends ranging from 10 to 50 percent PHA by weight are also examined. Shear and extensional experiments are performed to characterize the flow behavior of the materials in different flow fields. Transient experiments are performed to study the shear rheology over time in order to determine how the viscoelastic properties change under typical processing conditions and understand the thermal degradation behavior of the materials. For the blends, it is determined that increasing the PHA concentration in the blend results in a decrease in viscosity and increase in degradation. Models are fit to the viscosity of the blends using the pure material viscosities in order to be able to predict the behavior at a given blend composition. We also investigate the processability of these materials into films and examine the resultant properties of the cast films. The mechanical and thermal properties of the

  16. Degradation of phenolic compounds by using advanced oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, M. [Univ. de los Andes, Escuela Basica de Ingenieria, La Hechicera, Merida (Venezuela); Hincapie, M. [Dept. de Ingenieria Sanitaria y Ambiental, Univ. de Antioquia, Medellin (Colombia); Curco, D.; Contreras, S.; Gimenez, J.; Esplugas, S. [Dept. de Ingenieria Quimica, Facultad de Quimica, Univ. de Barcelona, Barcelona (Spain)

    2003-07-01

    A new empirical kinetic equation [r = k{sub 1}c - k{sub 2} (c{sub 0} - c)] is proposed for the photocatalytic degradation of phenolic compounds. This equation considers the influence of the intermediates in the degradation of the pollutant. The correct formulation of the contaminant mass balance in the experimental device that operates in recycle mode was done. The proposed empirical kinetic equation fitted quite well with the experimental results obtained in the TiO{sub 2}-photocatalytic degradation of phenol. (orig.)

  17. A two-stage process for the anaerobic digestion of sludge generated during the production of bioethanol from sweet sorghum

    Energy Technology Data Exchange (ETDEWEB)

    Stamatelatou, K.; Dravillas, K.; Lyberatos, G.

    2003-07-01

    Sweet sorghum is an energy crop, often cultivated to recover energy in the form of ethanol, hydrogen etc by applying biological processes. These processes, however, produce a significant amount of sludge (bagasse) which contains the recalcitrant unconverted portion of sorghum, the non-hydrolyzed portion of the plant biomass as well as microbial biomass. In this work, the sludge from the alcoholic fermentation of sweet sorghum following a distillation step (to remove the generated bioethanol) was subjected to anaerobic digestion for further biodegradation and energy production (methane). A two-stage configuration for the anaerobic digestion of this type of industrial sludge was conceived and compared with a single stage anaerobic digestion of bagasse. For the two-stage process, the sludge was separated into one solid and one liquid stream. The solid portion of the sludge (9%) contributed mainly to the total organic load, although there was a significant organic load dissolved in the liquid portion too (28.73{+-}11.01 g/l). In the two stage system the solid and liquid phases of the sludge were separately treated under different operating conditions in two separate reactors: the solid phase in a thermophilic hydrolyzing reactor and the liquid phase in a mesophilic high-rate digester. The overall yield of the continuous two-stage process was 16 l methane/l wastewater at a hydraulic retention time of almost 20 days, while the maximum methane yield that could be achieved in batch experiments (duration 40d) was 30 l/l wastewater. (author)

  18. Reuse of recalcitrant-rich anaerobic effluent as dilution water after enhancement of biodegradability by Fenton processes.

    Science.gov (United States)

    Arimi, Milton M; Zhang, Yongjun; Namango, Saul S; Geißen, Sven-Uwe

    2016-03-01

    Anaerobic digestion is used to treat effluents with a lot of organics, such as molasses distillery wastewater (MDW) which is the effluent of bioethanol production from molasses. The raw MDW requires a lot of dilution water before biodigestion, while the digested MDW has high level of recalcitrants which are problematic for its discharge. This study investigated ferric coagulation, Fenton, Fenton-like (with ferric ions as catalyst) processes and their combinations on the biodegradability of digested MDW. The Fenton and Fenton-like processes after coagulation increased the MDW biodegradability defined by (BOD5/COD) from 0.07 to (0.4-0.6) and saved 50% of H2O2 consumed in the classic Fenton process. The effluent from coagulation coupled to a Fenton-like process was used as dilution water for the raw MDW before the anaerobic digestion. The process was stable with volumetric loading of approx. 2.7 g COD/L/d. It resulted in increased overall biogas recovery and significantly decreased the demand for the dilution water. PMID:26692412

  19. Enhancement of bioenergy production from organic wastes by two-stage anaerobic hydrogen and methane production process

    DEFF Research Database (Denmark)

    Luo, Gang; Xie, Li; Zhou, Qi;

    2011-01-01

    The present study investigated a two-stage anaerobic hydrogen and methane process for increasing bioenergy production from organic wastes. A two-stage process with hydraulic retention time (HRT) 3d for hydrogen reactor and 12d for methane reactor, obtained 11% higher energy compared to a single......-stage methanogenic process (HRT 15d) under organic loading rate (OLR) 3gVS/(Ld). The two-stage process was still stable when the OLR was increased to 4.5gVS/(Ld), while the single-stage process failed. The study further revealed that by changing the HRThydrogen:HRTmethane ratio of the two-stage process from 3...

  20. Catalytic Effect of Tungsten on Anaerobic Digestion Process for Biogas Production from Fruit and Vegetable Wastes

    OpenAIRE

    Das A; Mondal.C

    2013-01-01

    In the recent years global energy crisis increased at a fast pace. Demand for the use of fossil fuels for cooking and other commercial activities increased along with the increasing population of India. Use of renewable sources of energy viz. biogas for cooking etc can somewhat be an alternative for the excessive demand of fossil fuels like LPG. In this study, the catalytic effect of tungsten for maximizing biogas have been presented. Essentially, anaerobic digesti...

  1. Evaluation of anaerobic digestion process for derived-MBT organic solid wastes

    OpenAIRE

    Arsand, Marcel

    2008-01-01

    Semi-continuous and batch system bench-scale reactors, at mesophilic temperature, were set-up to investigate the performance of anaerobic digestion treating mixed waste from municipal solid collection, derived from two large-scale mechanical biological treatment (MBT) plant, in the UK. The biogas yield using the semi-continuous reactor was determined to be between 300 and 410 mL/gVS with average methane content of 51% and average volatile solid destruction of 70%. During the...

  2. Anaerober Abbau von Kresolen und Monohydroxybenzoaten

    OpenAIRE

    Müller, Jochen A.

    2000-01-01

    All aromatic compounds are potential substrates for microorganisms. Hence, microorganisms play an eminent role in the global carbon cycle. The present work describes the anaerobic degradation of cresols and toluene, both bulk chemicals of the petroleum industry, and the anaerobic degradation of 3-hydroxybenzoate, a model compound for degradation of lignin-monomers. Degradation pathways for these aromatic substrates are postulated on the basis of in vitro measurements of key enzymes in various...

  3. Oxygen transport and degradation processes in mixed conducting perovskites

    International Nuclear Information System (INIS)

    The application of oxide ion conducting ceramics in solid oxide electrochemical devices, such as solid oxide fuel cells, air separation membranes and oxygen sensors, is an area currently of great commercial interest. Much recent research has focused on the optimisation of the structural and electrical properties of these ceramics. However little is known about the long term stability of these materials under the realistic operating conditions of the systems, and it is this concern which has provided the motivation for this project. The study has been divided into two sections. Part 1 deals with the measurement of the oxygen transport properties of the mixed ionic-electronic conducting (MIEC) perovskite, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) using the oxygen isotope exchange-depth profiling technique, combined with Secondary Ion Mass Spectrometry (SIMS). The oxygen surface exchange data obtained from these measurements have enabled inferences to be made regarding the mechanism of the surface exchange process. Part 2 is concerned with the chemical stability of LSCF under the operating conditions of an oxygen separation membrane. The membrane may be operating at temperatures of 750-800 deg C, under an aggressive atmosphere of steam, carbon dioxide and oxygen. A study of the degradation of the material when exposed to these atmospheres for varying periods of time has been undertaken. The oxygen surface exchange between the ceramic and oxygen ions in the carbon dioxide and water has been investigated using 18O isotopically labelled species combined with SIMS. Also presented in Part 2 is an overview of the principles involved in the application of MIEC ceramics in oxygen separation membranes, with respect to the optimisation of oxygen fluxes and membrane performance. (author)

  4. Influence of co-substrate on textile wastewater treatment and microbial community changes in the anaerobic biological sulfate reduction process.

    Science.gov (United States)

    Rasool, Kashif; Mahmoud, Khaled A; Lee, Dae Sung

    2015-12-15

    This study investigated the anaerobic treatment of sulfate-rich synthetic textile wastewater in three sulfidogenic sequential batch reactors (SBRs). The experimental protocol was designed to examine the effect of three different co-substrates (lactate, glucose, and ethanol) and their concentrations on wastewater treatment performance. Sulfate reduction and dye degradation were improved when lactate and ethanol were used as electron donors, as compared with glucose. Moreover, under co-substrate limited concentrations, color, sulfate, and chemical oxygen demand (COD) removal efficiencies were declined. By reducing co-substrate COD gradually from 3000 to 500 mg/L, color removal efficiencies were decreased from 98.23% to 78.46%, 63.37%, and 69.10%, whereas, sulfate removal efficiencies were decreased from 98.42%, 82.35%, and 87.0%, to 30.27%, 21.50%, and 10.13%, for lactate, glucose, and ethanol fed reactors, respectively. Fourier transform infrared spectroscopy (FTIR) and total aromatic amine analysis revealed lactate to be a potential co-substrate for further biodegradation of intermediate metabolites formed after dye degradation. Pyrosequencing analysis showed that microbial community structure was significantly affected by the co-substrate. The reactor with lactate as co-substrate showed the highest relative abundance of sulfate reducing bacteria (SRBs), followed by ethanol, whereas the glucose-fed reactor showed the lowest relative abundance of SRB. PMID:26241771

  5. Degradation of Synthetic Dyeing Wastewater by Underwater Electrical Discharge Processes

    International Nuclear Information System (INIS)

    Electrical discharge treatments of synthetic dyeing wastewater were carried out with two different systems: underwater pulsed electrical discharge (UPED) and underwater dielectric barrier discharge (UDBD). Reactive Blue 4 (RB4) and Acid Red 4 (AR4) were used as model contaminants for the synthetic wastewater. The performance of the aforementioned systems was compared with respect to the chromaticity removal and the energy requirement. The results showed that the present electrical discharge systems were very effective for degradation of the dyes. The dependences of the dye degradation rate on treatment time, initial dye concentration, electrical energy, and the type of working gas including air, O2, and N2 were examined. The change in the initial dye concentration did not largely affect the degradation of either RB4 or AR4. The energy delivered to the UPED system was only partially utilized for generating reactive species capable of degrading the dyes, leading to higher energy requirement than the UDBD system. Among the working gases, the best performance was observed with O2. As the degradation proceeded, the concentration of total dissolved solids and the solution conductivity kept increasing while pH showed a decreasing trend, revealing that the dyes were effectively mineralized

  6. Degradation of Synthetic Dyeing Wastewater by Underwater Electrical Discharge Processes

    Science.gov (United States)

    D. Kim, S.; I. Jang, D.; J. Lim, B.; B. Lee, S.; S. Mok, Y.

    2013-07-01

    Electrical discharge treatments of synthetic dyeing wastewater were carried out with two different systems: underwater pulsed electrical discharge (UPED) and underwater dielectric barrier discharge (UDBD). Reactive Blue 4 (RB4) and Acid Red 4 (AR4) were used as model contaminants for the synthetic wastewater. The performance of the aforementioned systems was compared with respect to the chromaticity removal and the energy requirement. The results showed that the present electrical discharge systems were very effective for degradation of the dyes. The dependences of the dye degradation rate on treatment time, initial dye concentration, electrical energy, and the type of working gas including air, O2, and N2 were examined. The change in the initial dye concentration did not largely affect the degradation of either RB4 or AR4. The energy delivered to the UPED system was only partially utilized for generating reactive species capable of degrading the dyes, leading to higher energy requirement than the UDBD system. Among the working gases, the best performance was observed with O2. As the degradation proceeded, the concentration of total dissolved solids and the solution conductivity kept increasing while pH showed a decreasing trend, revealing that the dyes were effectively mineralized.

  7. Perfluorooctanoic Acid Degradation Using UV-Persulfate Process: Modeling of the Degradation and Chlorate Formation.

    Science.gov (United States)

    Qian, Yajie; Guo, Xin; Zhang, Yalei; Peng, Yue; Sun, Peizhe; Huang, Ching-Hua; Niu, Junfeng; Zhou, Xuefei; Crittenden, John C

    2016-01-19

    In this study, we investigated the destruction and by-product formation of perfluorooctanoic acid (PFOA) using ultraviolet light and persulfate (UV-PS). Additionally, we developed a first-principles kinetic model to simulate both PFOA destruction and by-product and chlorate (ClO3(-)) formation in ultrapure water (UW), surface water (SW), and wastewater (WW). PFOA degradation was significantly suppressed in the presence of chloride and carbonate species and did not occur until all the chloride was converted to ClO3(-) in UW and for low DOC concentrations in SW. The model was able to simulate the PS decay, pH changes, radical concentrations, and ClO3(-) formation for UW and SW. However, our model was unable to simulate PFOA degradation well in WW, possibly from PS activation by NOM, which in turn produced sulfate radicals. PMID:26686982

  8. Bioaugmentation of anaerobic sludge digestion with iron-reducing bacteria: process and microbial responses to variations in hydraulic retention time.

    Science.gov (United States)

    Baek, Gahyun; Kim, Jaai; Shin, Seung Gu; Lee, Changsoo

    2016-01-01

    Although anaerobic digestion (AD) is a widely used option to manage waste activated sludge (WAS), there are some drawbacks related to its slow reaction rate and low energy productivity. This study examined an anaerobic WAS digester, augmented with an iron-reducing microbial consortium, relative to changes in microbial community structure and process performance at decreasing hydraulic retention times (HRTs) of 20 to 10 days. The enhanced methanation performance (approximately 40 % increase in methane yield) by the bioaugmentation was sustained until the HRT was decreased to 12.5 days, under Fe(3+)-rich conditions (ferric oxyhydroxide, 20 mM Fe). Enhanced iron-reducing activity was evidenced by the increased Fe(2+) to total Fe ratio maintained above 50 % during the stable operational phases. A further decrease in HRT to 10 days resulted in a significant performance deterioration, along with a drop in the Fe(2+) to total Fe ratio to <35 %, after four turnovers of operation. Prevailing existence of putative iron-reducing bacteria (IRBs) was identified by denaturing gradient gel electrophoresis (DGGE), with Spirochaetaceae- and Thauera-related organisms being dominant members, and clear dominance shifts among them with respect to decrease in HRT were observed. Lowering HRT led to evident shifts in bacterial community structure likely associated with washout of IRBs, leading to decreases in iron respiration activity and AD performance at a lower HRT. The bacterial community structure shifted dynamically over phases, and the community transitions correlated well with the changes in process performance. Overall, the combined biostimulation and bioaugmentation investigated in this study proved effective for enhanced methane recovery from anaerobic WAS digestion, which suggests an interesting potential for high-rate AD. PMID:26428233

  9. A laboratory investigation of interactions between denitrifying anaerobic methane oxidation (DAMO) and anammox processes in anoxic environments

    Science.gov (United States)

    Hu, Shihu; Zeng, Raymond J.; Haroon, Mohamed F.; Keller, Jurg; Lant, Paul A.; Tyson, Gene W.; Yuan, Zhiguo

    2015-03-01

    This study investigates interactions between recently identified denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (anammox) processes in controlled anoxic laboratory reactors. Two reactors were seeded with the same inocula containing DAMO organisms Candidatus Methanoperedens nitroreducens and Candidatus Methylomirabilis oxyfera, and anammox organism Candidatus Kuenenia stuttgartiensis. Both were fed with ammonium and methane, but one was also fed with nitrate and the other with nitrite, providing anoxic environments with different electron acceptors. After steady state reached in several months, the DAMO process became solely/primarily responsible for nitrate reduction while the anammox process became solely responsible for nitrite reduction in both reactors. 16S rRNA gene amplicon sequencing showed that the nitrate-driven DAMO organism M. nitroreducens dominated both the nitrate-fed (~70%) and the nitrite-fed (~26%) reactors, while the nitrite-driven DAMO organism M. oxyfera disappeared in both communities. The elimination of M. oxyfera from both reactors was likely the results of this organism being outcompeted by anammox bacteria for nitrite. K. stuttgartiensis was detected at relatively low levels (1-3%) in both reactors.

  10. Increasing biogas production from sewage sludge anaerobic co-digestion process by adding crude glycerol from biodiesel industry.

    Science.gov (United States)

    Nartker, Steven; Ammerman, Michelle; Aurandt, Jennifer; Stogsdil, Michael; Hayden, Olivia; Antle, Chad

    2014-12-01

    In an effort to convert waste streams to energy in a green process, glycerol from biodiesel manufacturing has been used to increase the gas production and methane content of biogas within a mesophilic anaerobic co-digestion process using primary sewage sludge. Glycerol was systematically added to the primary digester from 0% to 60% of the organic loading rate (OLR). The optimum glycerol loading range was from 25% to 60% OLR. This resulted in an 82-280% improvement in specific gas production. Following the feeding schedule described, the digesters remained balanced and healthy until inhibition was achieved at 70% glycerol OLR. This suggests that high glycerol loadings are possible if slow additions are upheld in order to allow the bacterial community to adjust properly. Waste water treatment plant operators with anaerobic digesters can use the data to increase loadings and boost biogas production to enhance energy conversion. This process provides a safe, environmentally friendly method to convert a typical waste stream to an energy stream of biogas. PMID:25249492

  11. A hybrid cascade control scheme for the VFA and COD regulation in two-stage anaerobic digestion processes.

    Science.gov (United States)

    Méndez-Acosta, H O; Campos-Rodríguez, A; González-Álvarez, V; García-Sandoval, J P; Snell-Castro, R; Latrille, E

    2016-10-01

    A hybrid (continuous-discrete) cascade control is proposed to regulate both, volatile fatty acids (VFA) and chemical oxygen demand (COD) concentrations in two-stage (acidogenic-methanogenic) anaerobic digestion (TSAD) processes. The outer loop is a discrete controller that regulates the COD concentration of the methanogenic bioreactor by using a daily off-line measurement and that modifies the set-point tracked by inner loop, which manipulates the dilution rate to regulate the VFA concentration of the acidogenic bioreactor, estimated by continuous on-line conductivity measurements, avoiding acidification. The experimental validation was conducted in a TSAD process for the treatment of tequila vinasses during 110days. Results showed that the proposed cascade control scheme was able to achieve the VFA and COD regulation by using conventional measurements under different set-point values in spite of adverse common scenarios in full-scale anaerobic digestion processes. Microbial composition analysis showed that the controller also favors the abundance and diversity toward methane production. PMID:27474953

  12. Anaerobic digestion technology in livestock manure treatment for biogas production: a review

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, Ismail M. [Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, Selangor (Malaysia); Mohd Ghazi, Tinia I.; Omar, Rozita

    2012-06-15

    This article reviews the potential of anaerobic digestion (AD) for biogas production from livestock manure wastes and compares the operating and performance data for various anaerobic process configurations. It examines different kinds of manure waste treatment techniques and the influence of several parameters on biogas and methane yield. The comparison indicates that a variety of different operational conditions, various reactor configurations such as batch reactors, continuously stirred tank reactor (CSTR), plug flow reactor (PFR), up-flow anaerobic sludge blanket (UASB), anaerobic sequencing batch reactor (ASBR), temperature phased anaerobic digestion (TPAD), and continuous one- and two-stage systems, present a suitable technology for the AD of livestock manure waste. Main performance indicators are biogas and methane yield, degradation of volatile solids (VS), higher loading, and process stability with a short retention time. (copyright 2012 WILEY-VCH Verlag GmbH 8 Co. KGaA, Weinheim)

  13. The Influence of the industrial processing on the degradation of poly(hidroxybutyrate - PHB

    Directory of Open Access Journals (Sweden)

    Wagner Maurício Pachekoski

    2012-01-01

    Full Text Available PHB was characterized after different industrial processes by Differential Scanning Calorimetry (DSC, Fourier Transform Infrared Spectroscopy (FTIR, Melt Flow Index (MFI, Complex Dielectric Relaxation (CDR and Size Exclusion Chromatography (SEC. Some properties of PHB were investigated before and after processing, in order to understand how temperature and other extrusion or injection conditions affect the polymer degradation. All the processed samples showed an increasing in the melt flow index, a decreasing of the dynamic crystallization temperature, and a reduction in the molar mass, suggesting some degradation. The molar mass reduction after processing, predicted when only thermal degradation is considered, was calculated in function of the kinetic parameters, such as constant thermal degradation and residence time during the industrial processing. It was found that the real molar mass reduction was higher than the theoretical value, indicating an important contribution of the shearing of polymeric chains during processing in the PHB degradation.

  14. The influence of the industrial processing on the degradation of poly(hidroxybutyrate - PHB

    Directory of Open Access Journals (Sweden)

    Wagner Maurício Pachekoski

    2013-04-01

    Full Text Available PHB was characterized after different industrial processes by Differential Scanning Calorimetry (DSC, Fourier Transform Infrared Spectroscopy (FTIR, Melt Flow Index (MFI, Complex Dielectric Relaxation (CDR and Size Exclusion Chromatography (SEC. Some properties of PHB were investigated before and after processing, in order to understand how temperature and other extrusion or injection conditions affect the polymer degradation. All the processed samples showed an increasing in the melt flow index, a decreasing of the dynamic crystallization temperature, and a reduction in the molar mass, suggesting some degradation. The molar mass reduction after processing, predicted when only thermal degradation is considered, was calculated in function of the kinetic parameters, such as constant thermal degradation and residence time during the industrial processing. It was found that the real molar mass reduction was higher than the theoretical value, indicating an important contribution of the shearing of polymeric chains during processing in the PHB degradation.

  15. Degradation of triketone herbicides, mesotrione and sulcotrione, using advanced oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Jović, Milica, E-mail: milica_jovic@chem.bg.ac.rs [Innovation Center of the Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Manojlović, Dragan [Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Stanković, Dalibor [Innovation Center of the Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Dojčinović, Biljana [Center of Chemistry, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia); Obradović, Bratislav [Faculty of Physics, University of Belgrade, Cara Dušana 13, 11000 Belgrade (Serbia); Gašić, Uroš; Roglić, Goran [Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, 11000 Belgrade (Serbia)

    2013-09-15

    Highlights: • Thirteen products are identified during all degradations for both pesticides. • In all degradations same products and mechanism was observed for both pesticides. • Dominant mechanism for all degradations starts with attack on the carbonyl group. • Only in ozone and DBD degradation one product is formed in radical reaction. • Only in Fenton degradation opening of benzene ring occurs. -- Abstract: Degradation of two triketone herbicides, mesotrione and sulcotrione, was studied using four different advanced oxidation processes (AOPs): ozonization, dielectric barrier discharge (DBD reactor), photocatalysis and Fenton reagent, in order to find differences in mechanism of degradation. Degradation products were identified by high performance liquid chromatography (HPLC–DAD) and UHPLC–Orbitrap–MS analyses. A simple mechanism of degradation for different AOP was proposed. Thirteen products were identified during all degradations for both pesticides. It was assumed that the oxidation mechanisms in the all four technologies were not based only on the production and use of the hydroxyl radical, but they also included other kinds of oxidation mechanisms specific for each technology. Similarity was observed between degradation mechanism of ozonation and DBD. The greatest difference in the products was found in Fenton degradation which included the opening of benzene ring. When degraded with same AOP pesticides gave at the end of treatment the same products. Global toxicity and COD value of samples was determined after all degradations. Real water sample was used to study influence of organic matter on pesticide degradation. These results could lead to accurate estimates of the overall effects of triketone herbicides on environmental ecosystems and also contributed to the development of improved removal processes.

  16. Degradation of triketone herbicides, mesotrione and sulcotrione, using advanced oxidation processes

    International Nuclear Information System (INIS)

    Highlights: • Thirteen products are identified during all degradations for both pesticides. • In all degradations same products and mechanism was observed for both pesticides. • Dominant mechanism for all degradations starts with attack on the carbonyl group. • Only in ozone and DBD degradation one product is formed in radical reaction. • Only in Fenton degradation opening of benzene ring occurs. -- Abstract: Degradation of two triketone herbicides, mesotrione and sulcotrione, was studied using four different advanced oxidation processes (AOPs): ozonization, dielectric barrier discharge (DBD reactor), photocatalysis and Fenton reagent, in order to find differences in mechanism of degradation. Degradation products were identified by high performance liquid chromatography (HPLC–DAD) and UHPLC–Orbitrap–MS analyses. A simple mechanism of degradation for different AOP was proposed. Thirteen products were identified during all degradations for both pesticides. It was assumed that the oxidation mechanisms in the all four technologies were not based only on the production and use of the hydroxyl radical, but they also included other kinds of oxidation mechanisms specific for each technology. Similarity was observed between degradation mechanism of ozonation and DBD. The greatest difference in the products was found in Fenton degradation which included the opening of benzene ring. When degraded with same AOP pesticides gave at the end of treatment the same products. Global toxicity and COD value of samples was determined after all degradations. Real water sample was used to study influence of organic matter on pesticide degradation. These results could lead to accurate estimates of the overall effects of triketone herbicides on environmental ecosystems and also contributed to the development of improved removal processes

  17. Increase of the efficiency of anaerobic digestion by various pre-treatment processes of sewage sludge

    OpenAIRE

    Łukasz Krawczyk; Małgorzata Budych; Łukasz Chrzanowski; Agnieszka Drożdżyńska; Roman Marecik; Agnieszka Piotrowska-Cyplik; Artur Szwengiel; Katarzyna Czaczyk; Paweł Cyplik

    2011-01-01

    The aim of this paper is to demonstrate the effects of pre-treatment increase of the efficiency of anaerobic digestion on waste activated sludge. There were four methods for pre-treatment of the waste activated sludge: A – thermally treated at 121°C for 30 min, homogenized and hydrolysed by Bacillus subtilis bacteria, B – thermally treated at 121°C for 30 min and homogenized, C – thermally treated at 121°C for 30 min and hydrolysed by B. subtilis bacteria, D &nda...

  18. Modelling phosphorus (P), sulfur (S) and iron (Fe) interactions for dynamic simulations of anaerobic digestion processes

    DEFF Research Database (Denmark)

    Flores Alsina, Xavier; Solon, Kimberly; Kazadi Mbamba, Christian;

    2016-01-01

    This paper proposes a series of extensions to functionally upgrade the IWA Anaerobic Digestion Model No. 1 (ADM1) to allow for plant-wide phosphorus (P) simulation. The close interplay between the P, sulfur (S) and iron (Fe) cycles requires a substantial (and unavoidable) increase in model...... reduces the quantities of struvite (XMgNH4PO4) and calcium phosphate (XCa3(PO4)2) that are formed due to its higher affinity for phosphate anions. This study provides a detailed analysis of the different model assumptions, the effect that operational/design conditions have on the model predictions...

  19. Influence of wastewater composition on nutrient removal behaviors in the new anaerobic-anoxic/nitrifying/induced crystallization process.

    Science.gov (United States)

    Shi, Jing; Lu, Xiwu; Yu, Ran; Gu, Qian; Zhou, Yi

    2014-01-01

    In this study, the new anaerobic-anoxic/nitrifying/induced crystallization (A2N-IC) system was compared with anaerobic-anoxic/nitrifying (A2N) process to investigate nutrient removal performance under different influent COD and ammonia concentrations. Ammonia and COD removal rates were very stable in both processes, which were maintained at 84.9% and 86.6% when the influent ammonia varied from 30 mg L(-1) to 45 mg L(-1) and COD ranged from 250 mg L(-1) to 300 mg L(-1). The effluent phosphorus always maintained below 0.2 mg L(-1) in A2N-IC, whereas in A2N the effluent phosphorus concentration was 0.4-1.7 mg L(-1), demonstrating that A2N-IC is suitable to apply in a broader influent COD and ammonia concentration range. Under higher influent COD (300 mg L(-1)) or lower ammonia conditions (30 mg L(-1)), the main function of chemical induced crystallization was to coordinate better nutrient ratio for anoxic phosphorus uptake, whereas under high phosphorus concentration, it was to reduce phosphorus loading for biological system. Under the similar influent wastewater compositions, phosphorus release amounts were always lower in A2N-IC. To clarify the decrease procedure of phosphorus release in the A2N-IC, the equilibrium between chemical phosphorus removal and biological phosphorus removal in A2N-IC was analyzed by mass balance equations. During the long-term experiment, some undesirable phenomena were observed: the declining nitrification in post-aerobic tank and calcium phosphorus precipitation in the anaerobic tank. The reasons were analyzed; furthermore, the corresponding improvements were proposed. Nitrification effect could be enhanced in the post-aerobic tank, therefore ammonia removal rate could be increased; and biologically induced phosphorus precipitation could be inhibited by controlling pH at the anaerobic stage, so the phosphorus release and recovery could be improved. PMID:24596502

  20. Anaerobic membrane bio-reactors for severe industrial effluents and urban spill waters: The AMBROSIUS project

    OpenAIRE

    van Lier, J B; Ozgun, H.; Ersahin, M.E.; Dereli, R.K.

    2013-01-01

    With growing application experiences from aerobic membrane bioreactors, combination of membrane and anaerobic processes become more and more attractive and feasible. In anaerobic membrane bioreactors (AnMBRs), biomass and particulate organic matter are physically retained inside the reactor, providing optimal conditions for organic matter degradation. AnMBRs offer high quality effluents free of solids and complete retention of biomass, regardless its settling and/or granulation properties. Th...

  1. Combined electrical-alkali pretreatment to increase the anaerobic hydrolysis rate of waste activated sludge during anaerobic digestion

    International Nuclear Information System (INIS)

    Highlights: • Combined electrical-alkali pretreatment for improving sludge anaerobic digestion was proposed. • Combined process enhanced the cell lysis, biopolymers releases, and thus sludge disintegration. • Increased solubilization of sludge increased the anaerobic hydrolysis rate. • Increased solubilization does not always induce an improved anaerobic digestion efficiency. - Abstract: Pretreatment can be used prior to anaerobic digestion to improve the efficiency of waste activated sludge (WAS) digestion. In this study, electrolysis and a commonly used pretreatment method of alkaline (NaOH) solubilization were integrated as a pretreatment method for promoting WAS anaerobic digestion. Pretreatment effectiveness of combined process were investigated in terms of disintegration degree (DDSCOD), suspended solids (TSS and VSS) removals, the releases of protein (PN) and polysaccharide (PS), and subsequent anaerobic digestion as well as dewaterability after digestion. Electrolysis was able to crack the microbial cells trapped in sludge gels and release the biopolymers (PN and PS) due to the cooperation of alkaline solubilization, enhancing the sludge floc disintegration/solubilization, which was confirmed by scanning electron microscopy (SEM) analysis. Biochemical methane potential (BMP) assays showed the highest methane yield was achieved with 5 V plus pH 9.2 pretreatment with up to 20.3% improvement over the non-pretreated sludge after 42 days of mesophilic operation. In contrast, no discernible improvements on anaerobic degradability were observed for the rest of pretreated sludges, probably due to the overmuch leakage of refractory soluble organics, partial chemical mineralization of solubilized compounds and sodium inhibition. The statistical analysis further indicated that increased solubilization induced by electrical-alkali pretreatment increased the first-order anaerobic hydrolysis rate (khyd), but had no, or very slight enhancement on WAS ultimate

  2. 三氯乙烯厌氧降解颗粒污泥影响因素分析%Research on influencing factors of trichloroethylene (TCE) anaerobic degradation granular sludge

    Institute of Scientific and Technical Information of China (English)

    张颖; 刘洋; 李娟; 胡淼; 王薪

    2014-01-01

    Acclimation of trichloroethylene (TCE)-degrading anaerobic granular sludge was successful by using upflow anaerobic sludge blanket (UASB) reactor. The influences of temperature, pH and initial concentration of TCE on the degradation characteristics of TCE-degrading anaerobic granular sludge were investigated in serum bottles. The results showed that 35℃was the optimum temperature of the granular sludge, the degradation rate constant was 0.1879, the half-life was 3.69 d, and the TCE degradation rate was 90.15%; 7.2 was the optimum pH of granular sludge, the degradation rate constant was 0.1672, the half-life was 4.15 d, and the TCE degradation rate was 88.74%; Under the conditions of temperature of 35℃, pH of 7.2, and the TCE test concentration range from 14.6 to 73.0 mg·L-1, the smal er the initial TCE concentration was, the faster the degradation rate was; When TCE concentration was 73 mg·L-1, TCE-degrading anaerobic granular sludge stil had higher ability to degrade TCE. After 14 d, TCE could be effectively removed and the final TCE degradation rate was over 80%.%通过在上流式厌氧污泥床(UASB)反应器成功驯化TCE厌氧降解颗粒污泥,于小瓶中进行温度、pH和TCE浓度等对TCE厌氧降解颗粒污泥降解特性影响的试验研究。结果表明,35℃是颗粒污泥最适温度,降解速率常数为0.1879,半衰期为3.69 d,TCE降解率为90.15%;颗粒污泥最适pH为7.2,降解速率常数为0.1672,半衰期为4.15 d,TCE降解率为88.74%;在温度为35℃,pH 7.2条件下,试验浓度范围内(14.6~73.0 mg·L-1),TCE初始浓度越小,降解速率越快,降解率越大;当TCE浓度达到73 mg·L-1时,TCE厌氧降解颗粒污泥仍能以较高速率降解TCE,14 d后TCE均可被有效去除,最终降解率在80%以上。

  3. Aerobic degradation of BDE-209 by Enterococcus casseliflavus: Isolation, identification and cell changes during degradation process.

    Science.gov (United States)

    Tang, Shaoyu; Yin, Hua; Chen, Shuona; Peng, Hui; Chang, Jingjing; Liu, Zehua; Dang, Zhi

    2016-05-01

    Decabromodiphenyl ether (BDE-209) is one of the most commonly used brominated flame retardants that have contaminated the environment worldwide. Microbial bioremediation has been considered as an effective technique to remove these sorts of persistent organic pollutants. Enterococcus casseliflavus, a gram-positive bacterium capable of aerobically transforming BDE-209, was isolated by our team from sediments in Guiyu, an e-waste dismantling area in Guangdong Province, China. To promote microbial bioremediation of BDE-209 and elucidate the mechanism behind its aerobic degradation, the effects of BDE-209 on the cell changes of E. casseliflavus were examined in this study. The experimental results demonstrated that the high cell surface hydrophobicity (CSH) of E. casseliflavus made the bacteria absorb hydrophobic BDE-209 more easily. E. casseliflavus responded to BDE-209 stress, resulting in an increase in cell membrane permeability and accumulation of BDE-209 inside the cell. The differential expression of intracellular protein was analyzed through two-dimensional gel electrophoresis (2-DE). More than 50 differentially expressed protein spots were reproducibly detected, including 25 up, and 25 down regulated after a 4 days exposure. Moreover, the apoptotic-like cell changes were observed during E. casseliflavus mediated degradation of BDE-209 by means of flow cytometry. PMID:26852209

  4. Anaerobic degradation of aromatic hydrocarbons

    International Nuclear Information System (INIS)

    This paper reports that toluene and m-xylene were rapidly mineralized in a denitrifying laboratory aquifer column operated under continuous flow conditions in the complete absence of molecular oxygen. A bacterium, tentatively identified as a Pseudomonas sp., was isolated from this column. This organism mineralized toluene and m-xylene under pure culture conditions with nitrate or nitrous oxide as the sole electron acceptors. Carbon balance studies using 0.3mM [ring-UL-14C]toluene revealed that more than 50 percent of the radioactivity was evolved as 14CO2

  5. Antibody degradation in tobacco plants: a predominantly apoplastic process

    Directory of Open Access Journals (Sweden)

    Hehle Verena K

    2011-12-01

    Full Text Available Abstract Background Interest in using plants for production of recombinant proteins such as monoclonal antibodies is growing, but proteolytic degradation, leading to a loss of functionality and complications in downstream purification, is still a serious problem. Results In this study, we investigated the dynamics of the assembly and breakdown of a human IgG1κ antibody expressed in plants. Initial studies in a human IgG transgenic plant line suggested that IgG fragments were present prior to extraction. Indeed, when the proteolytic activity of non-transgenic Nicotiana tabacum leaf extracts was tested against a human IgG1 substrate, little activity was detectable in extraction buffers with pH > 5. Significant degradation was only observed when the plant extract was buffered below pH 5, but this proteolysis could be abrogated by addition of protease inhibitors. Pulse-chase analysis of IgG MAb transgenic plants also demonstrated that IgG assembly intermediates are present intracellularly and are not secreted, and indicates that the majority of proteolytic degradation occurs following secretion into the apoplastic space. Conclusions The results provide evidence that proteolytic fragments derived from antibodies of the IgG subtype expressed in tobacco plants do not accumulate within the cell, and are instead likely to occur in the apoplastic space. Furthermore, any proteolytic activity due to the release of proteases from subcellular compartments during tissue disruption and extraction is not a major consideration under most commonly used extraction conditions.

  6. Screening of Natural Rubber-Degrading Microorganisms from Rubber Processing Factory Waste in Vietnam

    OpenAIRE

    Nguyen Lan Huong; To Kim Anh; Phan Trung Nghia; Dao Viet Linh; Bui Thi Trang; Masao Fukuda

    2013-01-01

    Natural rubber-degrading microorganisms were isolated from waste of rubber processing factory in Cam Thuy of Vietnam. Four of them belong to Streptomyces sp. that showed the higher abilities for natural rubber degradation than the others. They are able to use both deproteinised natural rubber (DPNR) and synthetic rubber cis-1,4-polyisoprene (SR) as a sole source of carbon. Gel permeation chromatography (GPC) analysis revealed that these strains degraded DPNR and SR to low-molecular-weight pro...

  7. ANAEROBIC AND AEROBIC TREATMENT OF CHLORINATED ALIPHATIC COMPOUNDS

    Science.gov (United States)

    Biological degradation of 12 chlorinated aliphatic compounds (CACs) was assessed in bench-top reactors and in serum bottle tests. Three continuously mixed daily batch-fed reactor systems were evaluated: anaerobic, aerobic, and sequential-anaerobic-aerobic (sequential). Glucose,...

  8. The Effect of Nitrogen Gas Flushing on Intermediate Products Formation in Acidogenic Stage of Anaerobic Process of Cocoa Sweatings

    Directory of Open Access Journals (Sweden)

    Mindriany Syafila

    2010-11-01

    Full Text Available Cocoa is one of Indonesian-main plantation commodities. During the cocoa seed drying process, there are two types of waste that are cocoa pod and cocoa sweating. Since the organic compounds contained in cocoa sweating is high enough, it is possible to anaerobically treat this wastewater in order to recover either intermediate or end products. Preliminary study showed that the existence of H2 in the reactor would block acetic acid formation. Therefore, the aim of this current experiment was to decrease hydrogen partial pressure by flushing various nitrogen gas flow rate to shift the intermediate products during the cocoa sweating anaerobic treatment. The experiments were carried on a Circulating Bed Reactor (CBR which contained organic compounds around 100,000 mg/l COD. Then, the reactor was flushed continuously with nitrogen gas as without flushing, 125 ml/min, 500 ml/min and 750 ml/min. The results show there was a possibility that the introduction of nitrogen gas into the reactor could shift the profile of the intermediate product formation. At lower nitrogen gas flow rate more ethanol was formed than acetate formation, although at higher nitrogen gas flow rate the formation of acetate was still low enough.

  9. Production of methane from sugar beet silage without manure addition by a single-stage anaerobic digestion process

    International Nuclear Information System (INIS)

    Single-stage continuous anaerobic conversion of sugar beet silage without manure to methane was investigated in this experimental work, using a laboratory-scale mesophilic anaerobic biogas digester. The sugar beet silage had an extreme low pH of 3.3. The reactor was operated in a hydraulic retention time (HRT) range of between 95 and 15 days, and an organic loading rate (OLR) range of between 0.937 and 6.33 g-1 VS l-1 d-1. The highest specific gas production rate (spec. GPR) of 0.72 l g VS-1 d-1 could be obtained at 25 days of HRT, with an average methane content of about 63%, at a pH of around 6.8. Since sugar beet silage without the leaves is a poor substrate, in terms of the availability of the nutrients and the buffering capacity, external supplementation of nitrogen and buffering agents has to be regularly performed, in order to achieve a stable and an efficient process. Sodium or potassium hydrogen carbonate addition seemed to function best in our case, among the other agents used, to provide adequate buffering capacity and to keep the digester pH stable during the operation. Use of a new harvest (a new charge of substrate) also affected the spec. GPR values significantly

  10. Color, organic matter and sulfate removal from textile effluents by anaerobic and aerobic processes.

    Science.gov (United States)

    Amaral, F M; Kato, M T; Florêncio, L; Gavazza, S

    2014-07-01

    An upflow anaerobic sludge blanket (UASB)-submerged aerated biofilter (SAB) system was evaluated to remove color and chemical oxygen demand (COD) from real textile effluent. The system was operated for 335 days in three phases (P-1, P-2, P-3) with total hydraulic retention time varying from 21 h to 14 h. The results showed that high sulfate levels (>300 mg SO4(2-)/L) impaired the dye reduction. The best color removal efficiencies of 30% and 96% for the UASB and the reactor system, respectively, were obtained in P-1; the SAB higher efficiency was associated with adsorption. The best COD removal efficiency of 71% for the reactor system was obtained in P-2. Precipitation of some material composed mostly of sulfur (98%) and some metals occurred in the UASB. However, the precipitated sulfur was again oxidized in the SAB. The system also showed an effective toxicity reduction in tests (Daphnia magna) with the treated effluent. PMID:24813565

  11. Anaerobic Digestion and Biogas Potential: Simulation of Lab and Industrial-Scale Processes

    Directory of Open Access Journals (Sweden)

    Ihsan Hamawand

    2015-01-01

    Full Text Available In this study, a simulation was carried out using BioWin 3.1 to test the capability of the software to predict the biogas potential for two different anaerobic systems. The two scenarios included: (1 a laboratory-scale batch reactor; and (2 an industrial-scale anaerobic continuous lagoon digester. The measured data related to the operating conditions, the reactor design parameters and the chemical properties of influent wastewater were entered into BioWin. A sensitivity analysis was carried out to identify the sensitivity of the most important default parameters in the software’s models. BioWin was then calibrated by matching the predicted data with measured data and used to simulate other parameters that were unmeasured or deemed uncertain. In addition, statistical analyses were carried out using evaluation indices, such as the coefficient of determination (R-squared, the correlation coefficient (r and its significance (p-value, the general standard deviation (SD and the Willmott index of agreement, to evaluate the agreement between the software prediction and the measured data. The results have shown that after calibration, BioWin can be used reliably to simulate both small-scale batch reactors and industrial-scale digesters with a mean absolute percentage error (MAPE of less than 10% and very good values of the indexes. Furthermore, by changing the default parameters in BioWin, which is a way of calibrating the models in the software, as well, this may provide information about the performance of the digester. Furthermore, the results of this study showed there may be an over estimation for biogas generated from industrial-scale digesters. More sophisticated analytical devices may be required for reliable measurements of biogas quality and quantity.

  12. An innovative bioelectrochemical-anaerobic digestion-coupled system for in-situ ammonia recovery and biogas enhancement: process performance and microbial ecology

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    Ammonia (NH4+/NH3) inhibition during anaerobic digestion process is one of the most frequent problems existing in biogas plants, resulting in unstable process and reduced biogas production. In this study, we developed a novel hybrid system, consisted of a submersed microbial resource recovery cell...

  13. Anaerobic digestion of peel waste and wastewater for on site energy generation in a citrus processing facility

    International Nuclear Information System (INIS)

    A citrus processing facility produces significant quantities of both peel waste and wastewater. A leach – bed batch anaerobic digester was operated successfully at thermophilic (55 °C) temperature for biogasification of citrus peel waste. The retention time in the digester was 25 days. The citrus processing wastewater was digested in a thermophilic DSFF (down flow stationary fixed film) anaerobic reactor fed continuously and operated for 76 days. At an average organic loading rate of 0.51 kg sCOD m−3 d−1 the hydraulic retention time was 16 days. No long term toxicity issues due to limonene were observed during digestion of both citrus waste feedstocks. Biogasification yielded, 0.116 m3 methane at STP kg−1 peel waste received and 2.1 m3 at STP m−3 wastewater received. An energy analysis showed that in a citrus processing plant handling 600 tons per day of fruits, the biogas produced from the waste streams is more than sufficient to meet all the electricity and fuel demands. Excess electricity generated from biogas may be sold generating estimated revenues of more than a $1 million annually (at electricity sale price of $0.04/kWhe). - Highlights: • Citrus peel waste digestion yields 0.116 m3 of methane at STP per kg as received. • Citrus processing wastewater digestion yields 2.1 m3 of methane at STP per m3. • 600 ton/day citrus factory can produce 3.2 MWe on site, using biogas from wastes. • Biogas can supply all the energy (electricity and fuel) needs of the plant

  14. Anaerobic thermophiles.

    Science.gov (United States)

    Canganella, Francesco; Wiegel, Juergen

    2014-01-01

    The term "extremophile" was introduced to describe any organism capable of living and growing under extreme conditions. With the further development of studies on microbial ecology and taxonomy, a variety of "extreme" environments have been found and an increasing number of extremophiles are being described. Extremophiles have also been investigated as far as regarding the search for life on other planets and even evaluating the hypothesis that life on Earth originally came from space. The first extreme environments to be largely investigated were those characterized by elevated temperatures. The naturally "hot environments" on Earth range from solar heated surface soils and water with temperatures up to 65 °C, subterranean sites such as oil reserves and terrestrial geothermal with temperatures ranging from slightly above ambient to above 100 °C, to submarine hydrothermal systems with temperatures exceeding 300 °C. There are also human-made environments with elevated temperatures such as compost piles, slag heaps, industrial processes and water heaters. Thermophilic anaerobic microorganisms have been known for a long time, but scientists have often resisted the belief that some organisms do not only survive at high temperatures, but actually thrive under those hot conditions. They are perhaps one of the most interesting varieties of extremophilic organisms. These microorganisms can thrive at temperatures over 50 °C and, based on their optimal temperature, anaerobic thermophiles can be subdivided into three main groups: thermophiles with an optimal temperature between 50 °C and 64 °C and a maximum at 70 °C, extreme thermophiles with an optimal temperature between 65 °C and 80 °C, and finally hyperthermophiles with an optimal temperature above 80 °C and a maximum above 90 °C. The finding of novel extremely thermophilic and hyperthermophilic anaerobic bacteria in recent years, and the fact that a large fraction of them belong to the Archaea has definitely

  15. Anaerobic Thermophiles

    Directory of Open Access Journals (Sweden)

    Francesco Canganella

    2014-02-01

    Full Text Available The term “extremophile” was introduced to describe any organism capable of living and growing under extreme conditions. With the further development of studies on microbial ecology and taxonomy, a variety of “extreme” environments have been found and an increasing number of extremophiles are being described. Extremophiles have also been investigated as far as regarding the search for life on other planets and even evaluating the hypothesis that life on Earth originally came from space. The first extreme environments to be largely investigated were those characterized by elevated temperatures. The naturally “hot environments” on Earth range from solar heated surface soils and water with temperatures up to 65 °C, subterranean sites such as oil reserves and terrestrial geothermal with temperatures ranging from slightly above ambient to above 100 °C, to submarine hydrothermal systems with temperatures exceeding 300 °C. There are also human-made environments with elevated temperatures such as compost piles, slag heaps, industrial processes and water heaters. Thermophilic anaerobic microorganisms have been known for a long time, but scientists have often resisted the belief that some organisms do not only survive at high temperatures, but actually thrive under those hot conditions. They are perhaps one of the most interesting varieties of extremophilic organisms. These microorganisms can thrive at temperatures over 50 °C and, based on their optimal temperature, anaerobic thermophiles can be subdivided into three main groups: thermophiles with an optimal temperature between 50 °C and 64 °C and a maximum at 70 °C, extreme thermophiles with an optimal temperature between 65 °C and 80 °C, and finally hyperthermophiles with an optimal temperature above 80 °C and a maximum above 90 °C. The finding of novel extremely thermophilic and hyperthermophilic anaerobic bacteria in recent years, and the fact that a large fraction of them belong

  16. Evaluation of Novel Inoculation Strategies for Solid State Anaerobic Digestion of Yam Peelings in Low-Tech Digesters

    OpenAIRE

    Stefan Heiske; Linas Jurgutis; Zsófia Kádár

    2015-01-01

    The operation of household scale anaerobic digesters is typically based on diluted animal dung, requiring stabled livestock and adequate water availability. This excludes many rural households in low-income countries from the benefits of a domestic biogas digester. Solid state anaerobic digestion (SSAD) can be operated with low process water demands, but the technology involves operational challenges, as e.g., risk of process acidification or low degradation rates. This study aimed at develop...

  17. Soil quality degradation processes along a deforestation chronosequence in the Ziwuling Area, China

    Science.gov (United States)

    Accelerated erosion caused by deforestation and soil degradation has become the primary factor limiting sustainable utilization of soil resources on the Loess Plateau of Northwestern China. We studied the physical, chemical, and microbiological processes of soil degradation along a chronosequence o...

  18. Anaerobic biotransformation of estrogens

    Energy Technology Data Exchange (ETDEWEB)

    Czajka, Cynthia P. [Department of Microbiology, University of Manitoba, Winnipeg, MB, R3T 2N2 (Canada); Londry, Kathleen L. [Department of Microbiology, University of Manitoba, Winnipeg, MB, R3T 2N2 (Canada)]. E-mail: londryk@cc.umanitoba.ca

    2006-08-31

    Estrogens are important environmental contaminants that disrupt endocrine systems and feminize male fish. We investigated the potential for anaerobic biodegradation of the estrogens 17-{alpha}-ethynylestradiol (EE2) and 17-{beta}-estradiol (E2) in order to understand their fate in aquatic and terrestrial environments. Cultures were established using lake water and sediment under methanogenic, sulfate-, iron-, and nitrate-reducing conditions. Anaerobic degradation of EE2 (added at 5 mg/L) was not observed in multiple trials over long incubation periods (over three years). E2 (added at 5 mg/L) was transformed to estrone (E1) under all four anaerobic conditions (99-176 {mu}g L{sup -1} day{sup -1}), but the extent of conversion was different for each electron acceptor. The oxidation of E2 to E1 was not inhibited by E1. Under some conditions, reversible inter-conversion of E2 and E1 was observed, and the final steady state concentration of E2 depended on the electron-accepting condition but was independent of the total amount of estrogens added. In addition, racemization occurred and E1 was also transformed to 17-{alpha}-estradiol under all but nitrate-reducing conditions. Although E2 could be readily transformed to E1 and in many cases 17-{alpha}-estradiol under anaerobic conditions, the complete degradation of estrogens under these conditions was minimal, suggesting that they would accumulate in anoxic environments.

  19. Environmental persistence of pesticides and their ecotoxicity: A review of natural degradation processes

    International Nuclear Information System (INIS)

    Pesticides are allochthonous pollutants discharged in natural environments. Once in the environment, natural factors such as biodegradation, photodegradation and chemical hydrolysis trigger partial or total pesticide transformation and reduce their environmental persistence. However, some degraded compounds have a greater ecotoxicological effect on the biota that the parent compounds and the change in the physicochemical properties increase the bioaccumulation, toxicity and transference processes. Therefore, knowledge about degradation processes in the environment is crucial in studies related to the dynamics and behavior of these substances in the environment and the impact on aquatic and terrestrial ecosystems. This review aims to show the influence of natural degradation processes on the persistence of pesticides, their ecotoxicity and dynamics. Also discuss the application of the degradation processes in water treatment and pesticides removal. While biodegradation processes have been improved by using genetically engineered microorganisms, in the photodegradation has been applied advanced oxidation technologies (TAOS) in the treatment of water contaminated with pesticides.

  20. Degradation of bisphenol A using electrochemical assistant Fe(Ⅱ-activated peroxydisulfate process

    Directory of Open Access Journals (Sweden)

    Chun-wei YANG

    2015-04-01

    Full Text Available Degradation of bisphenol A (BPA in aqueous solution using sulfate radicals was investigated using the Fe(Ⅱ-activated peroxydisulfate (PDS process, electrochemical process, electrochemical process with 2.5 mmol/L Na2S2O8 without Fe(Ⅱ, and electrochemical assistant Fe(Ⅱ-activated PDS process. It was found that the electrochemical assistant Fe(Ⅱ-activated PDS process performed best in the degradation of BPA. The variables considered to influence the degradation efficiency of BPA were the initial concentration of Fe2+, the initial concentration of Na2S2O8, and the current density. More than 97% of the BPA removals were achieved within 120 min under the optimum operational condition. The degradation of BPA was accompanied by the formation of phenol, hydroquinone, and small-molecule compounds such as succinic acid. The electron transfer was the principal step in the oxidation of BPA.

  1. The anaerobic treatment approach towards a more sustainable and robust environemnetal protection

    NARCIS (Netherlands)

    Lettinga, G.

    2005-01-01

    Anaerobic biological degradation processes (AnDe), when properly integrated with complementary biological and physical methods, constitute the ideal route to a sustainable protection of the life environment. However unfortunately for a smooth implementation of AnDe-processes drastic conceptual innov

  2. Biodegradability of leathers through anaerobic pathway.

    Science.gov (United States)

    Dhayalan, K; Fathima, N Nishad; Gnanamani, A; Rao, J Raghava; Nair, B Unni; Ramasami, T

    2007-01-01

    Leather processing generates huge amounts of both solid and liquid wastes. The management of solid wastes, especially tanned leather waste, is a challenging problem faced by tanners. Hence, studies on biodegradability of leather become imperative. In this present work, biodegradability of untanned, chrome tanned and vegetable tanned leather under anaerobic conditions has been addressed. Two different sources of anaerobes have been used for this purpose. The effect of detanning as a pretreatment method before subjecting the leather to biodegradation has also been studied. It has been found that vegetable tanned leather leads to more gas production than chrome tanned leather. Mixed anaerobic isolates when employed as an inoculum are able to degrade the soluble organics of vegetable tanned material and thus exhibit an increased level of gas production during the initial days, compared to the results of the treatments that received the anaerobic sludge. With chrome tanned materials, there was not much change in the volume of the gas produced from the two different sources. It has been found that detanning tends to improve the biodegradability of both types of leathers. PMID:16740383

  3. Mesophilic anaerobic co-digestion of poultry dropping and Carica papaya peels: Modelling and process parameter optimization study.

    Science.gov (United States)

    Dahunsi, S O; Oranusi, S; Owolabi, J B; Efeovbokhan, V E

    2016-09-01

    The study evaluated anaerobic co-digestion of poultry dropping and pawpaw peels and the optimization of important process parameters. The physic-chemical analyses of the substrates were done using standard methods after application of mechanical, thermal and chemical pre-treatments methods. Gas chromatography analysis revealed the gas composition to be within the range of 66-68% methane and 18-23% carbon dioxide. The study equally revealed that combination of the different pre-treatment methods enhanced enormous biogas yield from the digestion. Optimization of the generated biogas data were carried out using the Response Surface Methodology and the Artificial Neural Networks. The coefficient of determination (R(2)) for RSM (0.9181) was lower compare to that of ANN (0.9828). This shows that ANN model gives higher accuracy than RSM model for the current. Further usage of Carica papaya peels for biogas generation is advocated. PMID:27285574

  4. Methane production improvement by modulation of solid phase immersion in dry batch anaerobic digestion process: Dynamic of methanogen populations.

    Science.gov (United States)

    André, L; Ndiaye, M; Pernier, M; Lespinard, O; Pauss, A; Lamy, E; Ribeiro, T

    2016-05-01

    Several 60L dry batch anaerobic digestion (AD) reactors were implemented with or without liquid reserve on cattle manure. The immersed part modulation of cattle manure increased the methane flow of about 13%. The quantitative real time PCR and the optimized DNA extraction were implemented and validated to characterize and quantify the methanogen dynamic in dry batch AD process. Final quantities of methanogens converged toward the same level in several inocula at the end of AD. Methanogen dynamic was shown by dominance of Methanosarcinaceae for acetotrophic methanogens and Methanobacteriales for the hydrogenotrophic methanogens. Overall, methanogens populations were stabilized in liquid phase, except Methanosaetaceae. Solid phase was colonized by Methanomicrobiales and Methanosarcinaceae populations giving a support to biofilm development. The methane increase could be explained by a raise of Methanosarcinaceae population in presence of a total contact between solid and liquid phases. Methanosarcinaceae was a bio-indicator of the methane production. PMID:26897414

  5. Performance of biological phosphorus removal and characteristics of microbial community in the oxic-settling-anaerobic process by FISH analysis

    Institute of Scientific and Technical Information of China (English)

    Jian-fang WANG; Qing-liang ZHAO; Wen-biao JIN; Shi-jie YOU; Jin-na ZHANG

    2008-01-01

    Performance of biological phosphorus removal in the oxic-settling-anaerobic (OSA) process was investigated. Cell staining and fluorescent in situ hybridization (FISH) were used to analyze characteristics and microbial community of sludge.Experimental results showed that phosphorus removal efficiency was near 60% and the amount of biological phosphorus accumulation in aerobic sludge of the OSA system was up to 26.9 mg/g. Biological phosphorus removal efficiency was partially inhibited by carbon sources in the continuous OSA system. Contrasted to the OSA system, biological phosphorus removal efficiency was enhanced by 14% and the average total phosphorus (TP) contents of aerobic sludge were increased by 0.36 mg/g when sufficient carbon sources were supplied in batch experiments. Staining methods indicated that about 35% of microorganisms had typical characteristics of phosphorus accumulating organisms (PAOs). FISH analysis demonstrated that PAOMIX-binding bacteria were predominant microbial communities in the OSA system, which accounted for around 28% of total bacteria.

  6. Co-occurrence of nitrite-dependent anaerobic ammonium and methane oxidation processes in subtropical acidic forest soils.

    Science.gov (United States)

    Meng, Han; Wang, Yong-Feng; Chan, Ho-Wang; Wu, Ruo-Nan; Gu, Ji-Dong

    2016-09-01

    Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two new processes of recent discoveries linking the microbial nitrogen and carbon cycles. In this study, 16S ribosomal RNA (rRNA) gene of anammox bacteria and pmoA gene of n-damo bacteria were used to investigate their distribution and diversity in natural acidic and re-vegetated forest soils. The 16S rRNA gene sequences retrieved featured at least three species in two genera known anammox bacteria, namely Candidatus Brocadia anammoxidans, Candidatus Brocadia fulgida, and Candidatus Kuenenia stuttgartiensis while the pmoA gene amplified was affiliated with two species of known n-damo bacteria Candidatus Methylomirabilis oxyfera and a newly established Candidatus Methylomirabilis sp. According to the results, the diversity of anammox bacteria in natural forests was lower than in re-vegetated forests, but no significant difference was observed in n-damo community between them. Quantitative real-time PCR showed that both anammox and n-damo bacteria were more abundant in the lower layer (10-20 cm) than the surface layer (0-5 cm). The abundance of anammox bacteria varied from 2.21 × 10(5) to 3.90 × 10(6) gene copies per gram dry soil, and n-damo bacteria quantities were between 1.69 × 10(5) and 5.07 × 10(6) gene copies per gram dry soil in the two different layers. Both anammox and n-damo bacteria are reported for the first time to co-occur in acidic forest soil in this study, providing a more comprehensive information on more defined microbial processes contributing to C and N cycles in the ecosystems. PMID:27178181

  7. Kinetic modelling of anaerobic hydrolysis of solid wastes, including disintegration processes

    Energy Technology Data Exchange (ETDEWEB)

    García-Gen, Santiago [Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Sousbie, Philippe; Rangaraj, Ganesh [INRA, UR50, Laboratoire de Biotechnologie de l’Environnement, Avenue des Etangs, Narbonne F-11100 (France); Lema, Juan M. [Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Rodríguez, Jorge, E-mail: jrodriguez@masdar.ac.ae [Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Institute Centre for Water and Environment (iWater), Masdar Institute of Science and Technology, PO Box 54224 Abu Dhabi (United Arab Emirates); Steyer, Jean-Philippe; Torrijos, Michel [INRA, UR50, Laboratoire de Biotechnologie de l’Environnement, Avenue des Etangs, Narbonne F-11100 (France)

    2015-01-15

    Highlights: • Fractionation of solid wastes into readily and slowly biodegradable fractions. • Kinetic coefficients estimation from mono-digestion batch assays. • Validation of kinetic coefficients with a co-digestion continuous experiment. • Simulation of batch and continuous experiments with an ADM1-based model. - Abstract: A methodology to estimate disintegration and hydrolysis kinetic parameters of solid wastes and validate an ADM1-based anaerobic co-digestion model is presented. Kinetic parameters of the model were calibrated from batch reactor experiments treating individually fruit and vegetable wastes (among other residues) following a new protocol for batch tests. In addition, decoupled disintegration kinetics for readily and slowly biodegradable fractions of solid wastes was considered. Calibrated parameters from batch assays of individual substrates were used to validate the model for a semi-continuous co-digestion operation treating simultaneously 5 fruit and vegetable wastes. The semi-continuous experiment was carried out in a lab-scale CSTR reactor for 15 weeks at organic loading rate ranging between 2.0 and 4.7 g VS/L d. The model (built in Matlab/Simulink) fit to a large extent the experimental results in both batch and semi-continuous mode and served as a powerful tool to simulate the digestion or co-digestion of solid wastes.

  8. Kinetic modelling of anaerobic hydrolysis of solid wastes, including disintegration processes

    International Nuclear Information System (INIS)

    Highlights: • Fractionation of solid wastes into readily and slowly biodegradable fractions. • Kinetic coefficients estimation from mono-digestion batch assays. • Validation of kinetic coefficients with a co-digestion continuous experiment. • Simulation of batch and continuous experiments with an ADM1-based model. - Abstract: A methodology to estimate disintegration and hydrolysis kinetic parameters of solid wastes and validate an ADM1-based anaerobic co-digestion model is presented. Kinetic parameters of the model were calibrated from batch reactor experiments treating individually fruit and vegetable wastes (among other residues) following a new protocol for batch tests. In addition, decoupled disintegration kinetics for readily and slowly biodegradable fractions of solid wastes was considered. Calibrated parameters from batch assays of individual substrates were used to validate the model for a semi-continuous co-digestion operation treating simultaneously 5 fruit and vegetable wastes. The semi-continuous experiment was carried out in a lab-scale CSTR reactor for 15 weeks at organic loading rate ranging between 2.0 and 4.7 g VS/L d. The model (built in Matlab/Simulink) fit to a large extent the experimental results in both batch and semi-continuous mode and served as a powerful tool to simulate the digestion or co-digestion of solid wastes

  9. Jarosite-related chemical processes and water ecotoxicity in simplified anaerobic microcosm wetlands

    Science.gov (United States)

    Zhu, L.; Lin, C.; Wu, Y.; Lu, W.; Liu, Y.; Ma, Y.; Chen, A.

    2008-02-01

    Simulation experiments were conducted to examine whether jarosite is decomposed and toxic products are produced under anaerobic microcosm wetland conditions. The results show that jarosite was stable under water inundation in the microcosm wetland for a period of at least 56 days when no organic substance was added. However, jarosite became increasingly unstable with increasing amount of added organic matter. This resulted in entry of ferrous Fe into the soil solutions. Concentration of other heavy metals in the leachates was extremely low except for Mn. This is attributed to the maintenance of a high pH in the microcosm wetlands, which might cause re-precipitation of originally jarosite-borne heavy metals, if any. No acute toxicity was observed for leachate from the control (non organic matter-added treatment). However, leachates from various organic matter-added treatments show varying degrees of toxicity to the test organism and soluble Fe was likely to be the dominant metal of potential toxicity. Atmospheric exposure of leachate led to oxidation of ferrous Fe and precipitation of iron hydroxide, which caused a drop in leachate pH. This, in turn, inhibited further oxidation of ferrous Fe.

  10. Anammox for nitrogen removal from anaerobically pre-treated municipal wastewater: Effect of COD/N ratios on process performance and bacterial community structure.

    Science.gov (United States)

    Leal, Cíntia Dutra; Pereira, Alyne Duarte; Nunes, Fernando Terra; Ferreira, Luísa Ornelas; Coelho, Aline Carolina Cirilo; Bicalho, Sarah Kinaip; Mac Conell, Erika F Abreu; Ribeiro, Thiago Bressani; de Lemos Chernicharo, Carlos Augusto; de Araújo, Juliana Calábria

    2016-07-01

    Long-term effects of COD/N ratios on the nitrogen removal performance and bacterial community of an anammox reactor were evaluated by adding a synthetic medium (with glucose) and real anaerobic effluent to a SBR. At a COD/N ratio of 2.8 (COD, 390mg·L(-1)) ammonium removal efficiency was 66%, while nitrite removal remained high (99%). However, at a COD/N ratio of 5.0 (COD, 300mg·L(-1)), ammonium and nitrite removal efficiencies were high (84% and 99%, respectively). High COD, nitrite, and ammonium removal efficiencies (80%, 90% and 95%, respectively) were obtained on adding anaerobically pre-treated municipal wastewater (with nitrite) to the reactor. DGGE revealed that the addition of anaerobic effluent changed the bacterial community structure and selected for DNA sequences related to Brocadia sinica and Chloroflexi. Adding glucose and anaerobic effluent increased denitrifiers concentration threefold. Thus, the possibility of using the anammox process to remove nitrogen from anaerobically pre-treated municipal wastewater was demonstrated. PMID:27023380

  11. Degradation of 2,4-dichlorophenoxyacetic acid in water by ozone-hydrogen peroxide process

    Institute of Scientific and Technical Information of China (English)

    YU Ying-hui; MA Jun; HOU Yan-jun

    2006-01-01

    This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O3/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation of 2,4-dichlorophenoxyacetic acid was studied under different H2O2/O3 molar ratio and pH value. Meanwhile, TOC removal was investigated both in distilled water and tap water. The influences of ozone transfer and consumed hydrogen peroxide were also discussed. The degradation products and oxidation intermediates were identified by GC-MS and LC-MS. A possible reaction mechanism was thus proposed.

  12. ANAEROBIC BIOREMEDIATION OF PAH-CONTAMINATED SOIL: ASSESSMENT OF THE DEGRADATION OF CONTAMINANTS AND BIOGAS PRODUCTION UNDER THERMOPHILIC AND MESOPHILIC CONDITIONS

    Czech Academy of Sciences Publication Activity Database

    Sayara, T.; Čvančarová, Monika; Cajthaml, Tomáš; Sarra, M.; Sánchez, A.

    2015-01-01

    Roč. 14, č. 1 (2015), s. 153-165. ISSN 1582-9596 R&D Projects: GA ČR GA525/09/1058 Institutional support: RVO:61388971 Keywords : anaerobic digestion * central composite design * PAH-contaminated soil Subject RIV: EE - Microbiology, Virology Impact factor: 1.065, year: 2014

  13. Bio-hythane production from food waste by dark fermentation coupled with anaerobic digestion process: A long-term pilot scale experience

    OpenAIRE

    Cavinato, Cristina; Giuliano, Antonio; Bolzonella, David; Pavan, Paolo; Cecchi, Franco

    2012-01-01

    In this paper are presented the results of the investigation on optimal process operational conditions of thermophilic dark fermentation and anaerobic digestion of food waste, testing a long term run, applying an organic loading rate of 16.3 kgTVS/m3d in the first phase and 4.8 kgTVS/m3d in the second phase. The hydraulic retention times were maintained at 3.3 days and 12.6 days, respectively, for the first and second phase. Recirculation of anaerobic digested sludge, after a mild solid separ...

  14. The Technology and Economy of Farm-Scale, High-Solids Anaerobic Digestion of Plant Biomass

    OpenAIRE

    Svensson, Mattias

    2005-01-01

    Anaerobic digestion is a microbially mediated process occurring in nature in the absence of oxygen and other non-carbonaceous electron acceptors. The majority of the carbon of the organic matter degraded in the process is transformed into carbon dioxide and methane. Most of the energy potential of the degraded material is conserved in the methane, thus providing a renewable energy carrier, which can be converted into heat and/or electricity, or upgraded for use as a vehicle fuel. The remainin...

  15. Lignocellulose Biomass: Constitutive Polymers. Biological Processes of Lignin Degradation

    International Nuclear Information System (INIS)

    The structure of the lignocellulosic materials and the chemical composition of their main constitutive polymers, cellulose, hemicelluloses and lignin are described. The most promising transformation processes according to the type of biomass considered: hardwood, softwood an herbaceous and the perspectives of biotechnological processes for bio pulping, bio bleaching and effluents decolorisation in the paper pulp industry are also discussed. (Author) 7 refs

  16. Using the properties of soil to speed up the start-up process, enhance process stability, and improve the methane content and yield of solid-state anaerobic digestion of alkaline-pretreated poplar processing residues

    OpenAIRE

    Yao, Yiqing; Luo, Yang; Li, Tian; Yang, Yingxue; Sheng, Hongmei; Virgo, Nolan; Xiang, Yun; Song, Yuan; Zhang, Hua; An, Lizhe

    2015-01-01

    Background Solid-state anaerobic digestion (SS-AD) was initially adopted for the treatment of municipal solid waste. Recently, SS-AD has been increasingly applied to treat lignocellulosic biomass, such as agricultural and forestry residues. However, studies on the SS-AD process are few. In this study, the process performance and methane yield from SS-AD of alkaline-pretreated poplar processing residues (PPRs) were investigated using the properties of soil, such as buffering capacity and nutri...

  17. Biotransformation of nonylphenol ethoxylates during sewage treatment under anaerobic and aerobic conditions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Biotransformation of nonylphenol ethoxylates (NPEOs) during continuous anaerobic sewage treatment was compared with the aerobic treatment of sewage spiked with 23 μmol/L technical NPEOs over a period of 90 d. Immediate degradation of NPEOs was observed under both anaerobic and aerobic conditions, indicating that the enzymes and bacteria required for NPEO degradation existed abundantly in both aerobic and anaerobic sludge. Both treatments achieved high removal (>92%) of the spiked NPEO9 mixture.Liquid chromatography-mass spectrometry (LC-MS) analysis showed that short-chain NPEOs (NPEO1-NPEO3) accumulated in anaerobic (2.01-2.56 μmol/L) and aerobic (1.62-2.03 μmol/L) effluents, with nonylphenol (NP) (0.24-0.31 μmol/L) as another group of metabolites in the anaerobic effluent, and nonylphenoxy carboxylates (NPECs) (2.79-3.30 μmol/L) in the aerobic effluent. Significant accumulation of NP in the anaerobic sludge and NPEO1-3 in the sludge of two reactors was observed. These results indicated that it was difficult to control these harmful metabolites in the conventional treatment processes. Denaturing gradient gel electrophoresis profiles of sludge samples support the speculation that the NPEO degradation bacteria might be the dominant indigenous species.

  18. A Novel Process Configuration for Anaerobic Digestion of Source-Sorted Household Waste Using Hyper-Thermophilic Post-Treatment

    DEFF Research Database (Denmark)

    Hartmann, H.; Ahring, Birgitte Kiær

    2005-01-01

    A novel reactor configuration was investigated for anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW). An anaerobic hyper-thermophilic (68°C) reactor R68 was implemented as a post–treatment step for the effluent of a thermophilic reactor R1 (55°C) in order to enhanc...

  19. Enhanced biological nutrient removal in modified carbon source division anaerobic anoxic oxic process with return activated sludge pre-concentration☆

    Institute of Scientific and Technical Information of China (English)

    Qin Lu; Haiyan Wu; Haoyan Li; Dianhai Yang

    2015-01-01

    A pilot-scale modified carbon source division anaerobic anoxic oxic (AAO) process with pre-concentration of returned activated sludge (RAS) was proposed in this study for the enhanced biological nutrient removal (BNR) of municipal wastewater with limited carbon source. The influent carbon source was fed in step while a novel RAS pre-concentration tank was adopted to improve BNR efficiency, and the effects of an influent carbon source distribution ratio and a RAS pre-concentration ratio were investigated. The results show that the removal efficiency of TN is mainly influenced by the carbon source distribution ratio while the TP removal relies on the RAS pre-concentration ratio. The optimum carbon source distribution ratio and RAS pre-concentration ratio are 60%and 50%, respectively, with an inner recycling ratio of 100%under the optimum steady operation of pilot test, reaching an average effluent TN concentration of 9.8 mg·L−1 with a removal efficiency of 63%and an average TP removal efficiency of 94%. The mechanism of nutrient removal is discussed and the kinetics is analyzed. The results reveal that the optimal carbon source distribution ratio provides sufficient denitrifying carbon source to each anoxic phase, reducing nitrate accumulation while the RAS pre-concentration ratio improves the condition of anaerobic zone to ensure the phosphorus release due to less nitrate in the returned sludge. Therefore, nitrifying bacteria, denitrifying bacteria and phosphorus accumulation organisms play an important role under the optimum condition, enhancing the performance of nutrient removal in this test.

  20. Treatment process and toxicities assessment of wastewater issued from anaerobic digestion of household wastes.

    Science.gov (United States)

    Djelal, Hayet; Tahrani, Leyla; Fathallah, Salem; Cabrol, Audrey; Mansour, Hedi Ben

    2014-02-01

    Modern society grapples with large amounts of household waste. The anaerobic digestion of this waste offers a promising source for energy-rich biogas production but generates high toxic effluents that require treatment before reuse or disposal into the environment. This study aimed to investigate three techniques, namely coagulation/flocculation, electro-coagulation, and activated sludge, in terms of efficiency in the treatment of these effluents. It also aimed to assess their toxicity effects on the germination and growth of durum wheat Triticum aestivum L. seeds before and after 6 days of treatment. Activated sludge was most efficient in reducing chemical oxygen demand, turbidity, and conductivity (95.7 %, 15.8 %, and 37.5 %, respectively). The effluent treated with this technique induced a marked delay in germination (low mean time of germination) and a significant reduction in the percentages of seed germination and root and leaf growths. It was also noted to strongly induce lipid peroxidation in roots and leaves, which presumably explained the germination/growth inhibition of the wheat seeds. The effluent also induced marked lipid peroxidation effects and strongly inhibited the activities of butyrylcholinesterase in mice bone marrows. The effluent shows a high ability to inhibit the growth of three microalgae; these endpoints are useful tools to biomonitor the physico-chemical quality of this wastewater. Overall, while no significant alterations were observed in terms of animal and vegetable toxicities when the effluent was treated by coagulation/flocculation, activated sludge treatment proved efficient in reducing the toxicities induced by the untreated effluents. The results indicate that the application of this technique is promising with regards to attaining efficient, eco-friendly, and cost-effective strategies for the management and treatment of household waste. PMID:24072641

  1. Reliability modeling of degradation of products with multiple performance characteristics based on gamma processes

    International Nuclear Information System (INIS)

    Many highly reliable products usually have complex structure, with their reliability being evaluated by two or more performance characteristics. In certain physical situations, the degradation of these performance characteristics would be always positive and strictly increasing. In such a case, the gamma process is usually considered as a degradation process due to its independent and non-negative increments properties. In this paper, we suppose that a product has two dependent performance characteristics and that their degradation can be modeled by gamma processes. For such a bivariate degradation involving two performance characteristics, we propose to use a bivariate Birnbaum-Saunders distribution and its marginal distributions to approximate the reliability function. Inferential method for the corresponding model parameters is then developed. Finally, for an illustration of the proposed model and method, a numerical example about fatigue cracks is discussed and some computational results are presented.

  2. Controlling of degradation effects in radiation processing of polymers. Second RCM report

    International Nuclear Information System (INIS)

    The research and development works carried out by the participants of the CRP (Coordinated Research Project) dealt with natural polymers, synthetic polymers and new techniques for better understanding of radiation degradation of polymers. It includes progress in radiation degradation of polysaccharides from agricultural products (including sodium alginate, carrageenans, chitosan and gum acacia); use of radiation-degradation for doping of conductive polymers; controlling degradation processes in artificial joint implants, surface treatment of materials and food packaging; stabilizer additives for radiation environments; surface treatment of materials; and application of specialized analytical techniques (positron annihilation spectroscopy, ESR, RBS, ERDA, NMR/isotopic-labeling) to gain improved understanding of radiation degradation effects and mechanisms. Projects within the RCM group span the spectrum from fundamental studies through specific technological applications. Participants from Czech Republic, Spain and Turkey benefited from scientific collaboration with Bulgaria on PAS

  3. Modelling and estimating degradation processes with application in structural reliability; Modelisation et estimation des processus de degradation avec application en fiabilite des structures

    Energy Technology Data Exchange (ETDEWEB)

    Chiquet, J

    2007-06-15

    The characteristic level of degradation of a given structure is modeled through a stochastic process called the degradation process. The random evolution of the degradation process is governed by a differential system with Markovian environment. We put the associated reliability framework by considering the failure of the structure once the degradation process reaches a critical threshold. A closed form solution of the reliability function is obtained thanks to Markov renewal theory. Then, we build an estimation methodology for the parameters of the stochastic processes involved. The estimation methods and the theoretical results, as well as the associated numerical algorithms, are validated on simulated data sets. Our method is applied to the modelling of a real degradation mechanism, known as crack growth, for which an experimental data set is considered. (authors)

  4. Preliminary degradation process study of infectious biological waste in a 5 k W thermal plasma equipment

    International Nuclear Information System (INIS)

    This work is a preliminary study of infectious biological waste degradation process by thermal plasma and was made in Thermal Plasma Applications Laboratory of Environmental Studies Department of the National Institute of Nuclear Research (ININ). Infectious biological waste degradation process is realized by using samples such polyethylene, cotton, glass, etc., but the present study scope is to analyze polyethylene degradation process with mass and energy balances involved. Degradation method is realized as follow: a polyethylene sample is put in an appropriated crucible localized inside a pyrolysis reactor chamber, the plasma jet is projected to the sample, by the pyrolysis phenomena the sample is degraded into its constitutive particles: carbon and hydrogen. Air was utilized as a recombination gas in order to obtain the higher percent of CO2 if amount of O2 is greater in the recombination gas, the CO generation is reduced. The effluent gases of exhaust pyrolysis reactor through are passed through a heat exchanger to get cooled gases, the temperature water used is 15 Centigrade degrees. Finally the gases was tried into absorption tower with water as an absorbent fluid. Thermal plasma degradation process is a very promising technology, but is necessary to develop engineering process area to avail all advantages of thermal plasma. (Author)

  5. Degradation of the commercial surfactant nonylphenol ethoxylate by advanced oxidation processes

    International Nuclear Information System (INIS)

    Highlights: • NP4EO in industrial effluents can be treated before reaching water reservoirs. • Advanced oxidation processes are proposed for the degradation of NP4EO. • The degradation rate depends mainly on the light intensity. • The mineralization rate depends mainly on the current density. • Photo-assisted electrochemical oxidation showed the best degradation results. - Abstract: Four different oxidation process, namely direct photolysis (DP) and three advanced oxidation processes (heterogeneous photocatalysis – HP, eletrochemical oxidation – EO and photo-assisted electrochemical oxidation – PEO) were applied in the treatment of wastewater containing nonylphenol ethoxylate (NPnEO). The objective of this work was to determine which treatment would be the best option in terms of degradation of NPnEO without the subsequent generation of toxic compounds. In order to investigate the degradation of the surfactant, the processes were compared in terms of UV/Vis spectrum, mineralization (total organic carbon), reaction kinetics, energy efficiency and phytotoxicity. A solution containing NPnEO was prepared as a surrogate of the degreasing wastewater, was used in the processes. The results showed that the photo-assisted processes degrade the surfactant, producing biodegradable intermediates in the reaction. On the other hand, the electrochemical process influences the mineralization of the surfactant. The process of PEO carried out with a 250 W lamp and a current density of 10 mA/cm2 showed the best results in terms of degradation, mineralization, reaction kinetics and energy consumption, in addition to not presenting phytotoxicity. Based on this information, this process can be a viable alternative for treating wastewater containing NPnEO, avoiding the contamination of water resources

  6. Anaerobic Co-Digestion of the Microalgae Scenedesmus Sp.

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Suarez, J. L.; Carreras, N.

    2011-06-07

    Microalgae biomass has been widely studied for biogas production over the last years and results show that anaerobic digestion is often limited by the low C/N ratio of this type of biomass. Therefore, codigestion with substrates of high C/N ratio is necessary. The objectives of this study are to set up an experimental method that ease reproducibility and control of anaerobic digestion processes in laboratory conditions and to determine the biodegradability and biogas production potential of the co-digestion process of microalgae Scenedesmus sp. and energy crop Opuntia ficus indica (L.) Miller. Results obtained showed that higher C/N ratios are preferred in order to maximize methane production. Highest methane yield obtained was 0.252m3CH4/Kg VS and degradability expressed as percentage COD reduced is around 30% for the ideal mixture found, made up of 75% O. ficus-indica and 25% Scenedesmus sp. in VS basis. A laboratory setup using MicroOxymax respirometer, after its adaptation to work under anaerobic conditions, can be used for the monitoring of anaerobic digestion processes. Scenedesmus sp. as sole substrate for anaerobic digestion does not give good results due to low C/N ratio. However, when codigesting it with O. ficus-indica methane production is satisfactory. Best mixture was made up of 75% O. ficus-indica and 25% Scenedesmus sp. in VS basis. (Author)

  7. Anaerobic bacteria

    Science.gov (United States)

    Brook I, Goldstein EJ. Diseases caused by non-spore forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 297. Stedman's Online ...

  8. Degradation of household biowaste in reactors.

    Science.gov (United States)

    Krzystek, L; Ledakowicz, S; Kahle, H J; Kaczorek, K

    2001-12-28

    Household derived biowaste was degraded by biological methods. The system involves the combined method of low-solids (up to 10% w/v of total solids (TS)) anaerobic digestion and aerobic degradation for the recovery of energy (biogas) and the production of fine humus-like material which can be used as a soil amender or a substrate for further thermal treatment (pyrolysis, gasification). The performance of batch and continuous processes carried out in bioreactors (stirred tank reactor, air-lift) of working volume 6 and 18 dm(3), at different temperatures (25-42 degrees C) was monitored by reduction of TS, volatile solids, chemical oxygen demand, total organic carbon, C/N in time. The application of continuous process with recirculation (33%) caused that for residence time of 8-16 h the obtained degree of organic load reduction was similar to that obtained after 72-96 h of the batch process. The experimental data of batch aerobic degradation was also subjected to kinetic analysis. The sequence of the two processes: aerobic and anaerobic or anaerobic and aerobic showed that the degree of organic load reduction was similar in both cases, while the amount of produced biogas was four times higher when the first stage was anaerobic. The final product after dewatering was subjected to pyrolysis and gasification. The gases obtained were characterised by a high heat of combustion of about 11-15 MJ Nm(-3). PMID:11640982

  9. Dioxygen reactivity of meso-hydroxylated hemes: intermediates in heme degradation process catalyzed by heme oxygenase

    Indian Academy of Sciences (India)

    Sankar Prasad Rath

    2006-11-01

    Heme oxygenase (HO) is the only enzyme in mammals known to catalyse the physiological degradation of unwanted heme into biliverdin, Fe ion and CO. The process involves introduction of the hydroxyl group at one of its meso-positions as the first fundamental step of the heme cleavage process. It was also found that meso-amino heme undergoes similar ring-cleavage process while reacting with dioxygen in presence of pyridine as an axial ligand. The present paper briefly reviews the reactions of model meso-hydroxylated heme and its analogues with dioxygen, and their relevance in the heme degradation process.

  10. Reliability demonstration methodology for products with Gamma Process by optimal accelerated degradation testing

    International Nuclear Information System (INIS)

    For products with high reliability and long lifetime, accelerated degradation testing (ADT) may be adopted during product development phase to verify whether its reliability satisfies the predetermined level within feasible test duration. The actual degradation from engineering is usually a strictly monotonic process, such as fatigue crack growth, wear, and erosion. However, the method for reliability demonstration by ADT with monotonic degradation process has not been investigated so far. This paper proposes a reliability demonstration methodology by ADT for this kind of product. We first apply Gamma process to describe the monotonic degradation. Next, we present a reliability demonstration method by converting the required reliability level into allowable cumulative degradation in ADT and comparing the actual accumulative degradation with the allowable level. Further, we suggest an analytical optimal ADT design method for more efficient reliability demonstration by minimizing the asymptotic variance of decision variable in reliability demonstration under the constraints of sample size, test duration, test cost, and predetermined decision risks. The method is validated and illustrated with example on reliability demonstration of alloy product, and is applied to demonstrate the wear reliability within long service duration of spherical plain bearing in the end. - Highlights: • We present a reliability demonstration method by ADT for products with monotonic degradation process, which may be applied to verify reliability with long service life for products with monotonic degradation process within feasible test duration. • We suggest an analytical optimal ADT design method for more efficient reliability demonstration, which differs from the existed optimal ADT design for more accurate reliability estimation by different objective function and different constraints. • The methods are applied to demonstrate the wear reliability within long service duration of

  11. The limits of feedforward vision: recurrent processing promotes robust object recognition when objects are degraded.

    Science.gov (United States)

    Wyatte, Dean; Curran, Tim; O'Reilly, Randall

    2012-11-01

    Everyday vision requires robustness to a myriad of environmental factors that degrade stimuli. Foreground clutter can occlude objects of interest, and complex lighting and shadows can decrease the contrast of items. How does the brain recognize visual objects despite these low-quality inputs? On the basis of predictions from a model of object recognition that contains excitatory feedback, we hypothesized that recurrent processing would promote robust recognition when objects were degraded by strengthening bottom-up signals that were weakened because of occlusion and contrast reduction. To test this hypothesis, we used backward masking to interrupt the processing of partially occluded and contrast reduced images during a categorization experiment. As predicted by the model, we found significant interactions between the mask and occlusion and the mask and contrast, such that the recognition of heavily degraded stimuli was differentially impaired by masking. The model provided a close fit of these results in an isomorphic version of the experiment with identical stimuli. The model also provided an intuitive explanation of the interactions between the mask and degradations, indicating that masking interfered specifically with the extensive recurrent processing necessary to amplify and resolve highly degraded inputs, whereas less degraded inputs did not require much amplification and could be rapidly resolved, making them less susceptible to masking. Together, the results of the experiment and the accompanying model simulations illustrate the limits of feedforward vision and suggest that object recognition is better characterized as a highly interactive, dynamic process that depends on the coordination of multiple brain areas. PMID:22905822

  12. Degradation of florfenicol in water by UV/Na2S 2O 8 process.

    Science.gov (United States)

    Gao, Yu-Qiong; Gao, Nai-Yun; Deng, Yang; Yin, Da-Qiang; Zhang, Yan-Sen

    2015-06-01

    UV irradiation-activated sodium persulfate (UV/PS) was studied to degrade florfenicol (FLO), a phenicol antibiotic commonly used in aquaculture, in water. Compared with UV/H2O2 process, UV/PS process achieves a higher FLO degradation efficiency, greater mineralization, and less cost. The quantum yield for direct photolysis of FLO and the second-order rate constant of FLO with sulfate radicals were determined. The effects of various factors, namely PS concentration, anions (NO3 (-), Cl(-), and HCO3 (-)), ferrous ion, and humic acid (HA), on FLO degradation were investigated. The results showed that the pseudo-first-order rate constant increased linearly with increased PS concentration. The tested anions all adversely affected FLO degradation performance with the order of HCO3 (-) > Cl(-) > NO3 (-). Coexisting ferrous ions enhanced FLO degradation at a Fe(2+)/PS molar ratio under 1:1. HA significantly inhibited FLO degradation due to radical scavenging and light-screening effect. Toxicity assessment showed that it is capable of controlling the toxicity for FLO degradation. These findings indicated that UV/PS is a promising technology for water polluted by antibiotics, and the treatment is optimized only after the impacts of water characteristics are carefully considered. PMID:25567063

  13. A study on the enhancement of sonochemical degradation of eosin B using other advanced oxidation processes

    OpenAIRE

    Goel, Mukesh; Das, Ashutosh; Ravikumar, K.; ASTHANA, ABHISHEK

    2014-01-01

    Eosin B is a xanthenes dye and is a derivate of fluorescein. The efficacy of sonochemical degradation coupled with other advanced oxidation process (AOP’s) has been studied for eosin B degradation in aqueous solution. The study compares the effects of H2O2 concentration, saturating gas (argon, N2, and O2), temperature and pH (3–11). Furthermore, kinetic comparison and a figure of merit for the electrical energy consumption were carried out for the degradation under combination of different AO...

  14. Degradation of l-polylactide during melt processing with layered double hydroxides

    DEFF Research Database (Denmark)

    Gerds, Nathalie; Katiyar, Vimal; Koch, Christian Bender; Hansen, Hans Christian Bruun; Plackett, David; Larsen, Erik Huusfeldt; Risbo, Jens

    2012-01-01

    PLA was melt compounded in small-scale batches with two forms of laurate-modified magnesium–aluminum layered double hydroxide (Mg-Al-LDH-C12), the corresponding carbonate form (Mg-Al-LDH-CO3) and a series of other additives. Various methods were then adopted to characterize the resulting compounds...... in an effort to gain greater insights into PLA degradation during melt processing. PLA molecular weight reduction was found to vary according to the type of LDH additive. It is considered that the degree of particle dispersion and LDH exfoliation, and hence the accessibility of the hydroxide layer...... surfaces and catalytically active Mg site centers are causative factors for PLA degradation. Interestingly, the release of water under the processing conditions was found to have a rather small effect on the PLA degradation. Low loadings of sodium laurate also caused PLA degradation indicating that...

  15. Photocatalytic Processes for Degradation of Endocrine Disruptors from Wastewater

    Czech Academy of Sciences Publication Activity Database

    Spáčilová, Lucie; Maléterová, Ywetta; Krejčíková, Simona; Cajthaml, Tomáš; Šolcová, Olga

    Praha : Orgit, 2012, P3.121. ISBN 978-80-905035-1-9. [International Congress of Chemical and Process Engineering CHISA 2012 and 15th Conference PRES 2012 /20./. Prague (CZ), 25.08.2012-29.08.2012] R&D Projects: GA TA ČR TA01020804 Institutional support: RVO:67985858 ; RVO:61388971 Keywords : wastewater * industrial chemicals * pollutants Subject RIV: CI - Industrial Chemistry, Chemical Engineering www.chisa.cz/2012

  16. Degradation of chlorophenols by fenton and photo-fenton processes

    OpenAIRE

    BENBACHIR, H.; GUETTAIA, D.; Mokhtari, M

    2012-01-01

    The domestic use and industrial activity, of especially impact among the developed counties, generate high amounts of residual wastewater, whose direct disposal to natural channels causes a considerable effect in the environment. This fact, together with the need to restore this water for new uses, makes practically essential the purification of wastewater to achieve the desired degree of quality. Advanced oxidation processes (AOPs) constituted a promising technology for the treatment of w...

  17. Degradability of ionic liquids : Systematic investigations on aerobic and anaerobic biodegradability of ionic liquid cations and anions as well as on the hydrolytical stability of ionic liquid anions - contributions to a sound hazard assessment

    OpenAIRE

    Neumann, Jennifer

    2014-01-01

    The presented studies deal with the degradability of ionic liquids under conditions that occur in biological waste water treatment and within the environment. Degradation studies are relevant for the assessment of the technological applicability of chemicals and of their hazard potential, including their environmental fate. In former studies some ionic liquids have shown to remain stable against abiotic and biotic degradation processes. The systematic investigation of chemical structures whic...

  18. Anaerobic Biodegradation of Ethylene Glycol within Hydraulic Fracturing Fluid

    Science.gov (United States)

    Heyob, K. M.; Mouser, P. J.

    2014-12-01

    Ethylene glycol (EG) is a commonly used organic additive in hydraulic fracturing fluids used for shale gas recovery. Under aerobic conditions, this compound readily biodegrades to acetate and CO2 or is oxidized through the glycerate pathway. In the absence of oxygen, organisms within genera Desulfovibrio, Acetobacterium, and others can transform EG to acetaldehyde, a flammable and suspected carcinogenic compound. Acetaldehyde can then be enzymatically degraded to ethanol or acetate and CO2. However, little is known on how EG degrades in the presence of other organic additives, particularly under anaerobic conditions representative of deep groundwater aquifers. To better understand the fate and attenuation of glycols within hydraulic fracturing fluids we are assessing their biodegradation potential and pathways in batch anaerobic microcosm treatments. Crushed Berea sandstone was inoculated with groundwater and incubated with either EG or a synthetic fracturing fluid (SFF) containing EG formulations. We tracked changes in dissolved organic carbon (DOC), EG, and its transformation products over several months. Approximately 41% of bulk DOC in SFF is degraded within 21 days, with 58% DOC still remaining after 63 days. By comparison, this same SFF degrades by 70% within 25 days when inoculated with sediment-groundwater microbial communities, suggesting that bulk DOC degradation occurs at a slower rate and to a lesser extent with bedrock. Aerobic biodegradation of EG occurs rapidly (3-7 days); however anaerobic degradation of EG is much slower, requiring several weeks for substantial DOC loss to be observed. Ongoing experiments are tracking the degradation pathways of EG alone and in the presence of SFF, with preliminary data showing incomplete glycol transformation within the complex hydraulic fracturing fluid mixture. This research will help to elucidate rates, processes, and pathways for EG biodegradation and identify key microbial taxa involved in its degradation.

  19. Modelling phosphorus (P), sulfur (S) and iron (Fe) interactions for dynamic simulations of anaerobic digestion processes.

    Science.gov (United States)

    Flores-Alsina, Xavier; Solon, Kimberly; Kazadi Mbamba, Christian; Tait, Stephan; Gernaey, Krist V; Jeppsson, Ulf; Batstone, Damien J

    2016-05-15

    This paper proposes a series of extensions to functionally upgrade the IWA Anaerobic Digestion Model No. 1 (ADM1) to allow for plant-wide phosphorus (P) simulation. The close interplay between the P, sulfur (S) and iron (Fe) cycles requires a substantial (and unavoidable) increase in model complexity due to the involved three-phase physico-chemical and biological transformations. The ADM1 version, implemented in the plant-wide context provided by the Benchmark Simulation Model No. 2 (BSM2), is used as the basic platform (A0). Three different model extensions (A1, A2, A3) are implemented, simulated and evaluated. The first extension (A1) considers P transformations by accounting for the kinetic decay of polyphosphates (XPP) and potential uptake of volatile fatty acids (VFA) to produce polyhydroxyalkanoates (XPHA) by phosphorus accumulating organisms (XPAO). Two variant extensions (A2,1/A2,2) describe biological production of sulfides (SIS) by means of sulfate reducing bacteria (XSRB) utilising hydrogen only (autolithotrophically) or hydrogen plus organic acids (heterorganotrophically) as electron sources, respectively. These two approaches also consider a potential hydrogen sulfide ( [Formula: see text] inhibition effect and stripping to the gas phase ( [Formula: see text] ). The third extension (A3) accounts for chemical iron (III) ( [Formula: see text] ) reduction to iron (II) ( [Formula: see text] ) using hydrogen ( [Formula: see text] ) and sulfides (SIS) as electron donors. A set of pre/post interfaces between the Activated Sludge Model No. 2d (ASM2d) and ADM1 are furthermore proposed in order to allow for plant-wide (model-based) analysis and study of the interactions between the water and sludge lines. Simulation (A1 - A3) results show that the ratio between soluble/particulate P compounds strongly depends on the pH and cationic load, which determines the capacity to form (or not) precipitation products. Implementations A1 and A2,1/A2,2 lead to a reduction in

  20. Inhibitory Effects of Silver Nanoparticles on Removal of Organic Pollutants and Sulfate in an Anaerobic Biological Wastewater Treatment Process.

    Science.gov (United States)

    Rasool, Kashif; Lee, Dae Sung

    2016-05-01

    The increasing use of silver nanoparticles (AgNPs) in commercial products and industrial processes raises issues regarding the toxicity of sludge biomass in biological wastewater treatment plants, due to potential antimicrobial properties. This study investigated the effects of AgNPs on removal of organic pollutants and sulfate in an anaerobic biological sulfate reduction process. At AgNPs concentrations of up to 10 mg/L, no significant inhibition of sulfate and COD removal was observed. However, at higher concentrations (50-200 mg/L) sulfate and COD removal efficiencies were significantly decreased to 51.8% and 33.6%, respectively. Sulfate and COD reduction followed first-order kinetics at AgNPs concentrations of up to 10 mg/L and second-order kinetics at AgNPs concentrations of 50-200 mg/L. Lactate dehydrogenase release profiles showed increases in cytotoxicity at AgNPs concentrations greater than 50 mg/L suggesting cell membrane disruption. Analysis of extracellular polymeric substances (EPS) from sulfidogenic sludge biomass and of Fourier transform infrared (FT-IR) spectra showed a decrease in concentrations of carbohydrates, proteins, humic substances, and lipids in the presence of AgNPs. Moreover, the interaction of AgNPs with sludge biomass and the damage caused to cell walls were confirmed through scanning electron microscopy with energy dispersive X-ray spectroscopy. PMID:27483773

  1. Performance of nitrate-dependent anaerobic ferrous oxidizing (NAFO) process: a novel prospective technology for autotrophic denitrification.

    Science.gov (United States)

    Zhang, Meng; Zheng, Ping; Li, Wei; Wang, Ru; Ding, Shuang; Abbas, Ghulam

    2015-03-01

    Nitrate-dependent anaerobic ferrous oxidizing (NAFO) is a valuable biological process, which utilizes ferrous iron to convert nitrate into nitrogen gas, removing nitrogen from wastewater. In this work, the performance of NAFO process was investigated as a nitrate removal technology. The results showed that NAFO system was feasible for autotrophic denitrification. The volumetric loading rate (VLR) and volumetric removal rate (VRR) under steady state were 0.159±0.01 kg-N/(m(3) d) and 0.073±0.01 kg-N/(m(3) d), respectively. In NAFO system, the effluent pH was suggested as an indicator which demonstrated a good correlation with nitrogen removal. The nitrate concentration was preferred to be less than 130 mg-N/L. Organic matters had little influence on NAFO performance. Abundant iron compounds were revealed to accumulate in NAFO sludge with peak value of 51.73% (wt), and they could be recycled for phosphorus removal, with capacity of 16.57 mg-P/g VS and removal rate of 94.77±2.97%, respectively. PMID:25576990

  2. Anaerobic Digestion of Piggery Waste

    NARCIS (Netherlands)

    Velsen, van A.F.M.

    1981-01-01

    Anaerobic digestion is a biological process by which organic matter is converted to methane and carbon dioxide by microbes in the absence of air (oxygen). In nature, anaerobic conversions occur at all places where organic material accumulates and the supply of oxygen is deficient, e.g. in marshes an

  3. Ionic process in radiation-induced degradation of polymers

    International Nuclear Information System (INIS)

    Poly (α-methylstyrene) powder was irradiated in vacuum at high temperature up to 200 deg C. The volatile products were collected in a cooled finger, and analyzed by gas chromatography. The results obtained were compared with those by pyrolysis at the same temperature and radiolysis at room temperature. One poly (α-methylstyrene) used was prepared by the radiation-induced cationic polymerization, and had the number-average molecular weight of 2.5 x 104, and the other was the anionic polymer having the average molecular weight of 1.5 x 106. The molecular weight of the polymers was reduced to about 1/2 of its initial values in the radiolysis at 200 deg C. On the other hand, when they were heated at 200 deg C without irradiation, the only product detected was a small amount of monomer, and the molecular weight of the polymers did not vary. In the radiolysis at room temperature, the product yields and the decrease in the molecular weight of the polymers were much smaller than those in the radiolysis at 200 deg C. In the pyrolysis of poly (α-methylstyrene), the polymer decomposed almost completely into monomer below about 400 deg C by the radical chain reaction involving unzipping process. In the radiolysis of hydrocarbons, the effect of the addition of cation scavengers such as amines, alcohols and ethers, which have larger proton affinity than hydrocarbons, was investigated in order to obtain evidence for the cationic processes of product formation. It appears that the product formation and the decrease in the molecular weight are suppressed by the addition of 5 wt.% of the additives. (Yamashita, S.)

  4. Anaerobic Mercury Methylation and Demethylation by Geobacter bemidjiensis Bem.

    Science.gov (United States)

    Lu, Xia; Liu, Yurong; Johs, Alexander; Zhao, Linduo; Wang, Tieshan; Yang, Ziming; Lin, Hui; Elias, Dwayne A; Pierce, Eric M; Liang, Liyuan; Barkay, Tamar; Gu, Baohua

    2016-04-19

    Microbial methylation and demethylation are two competing processes controlling the net production and bioaccumulation of neurotoxic methylmercury (MeHg) in natural ecosystems. Although mercury (Hg) methylation by anaerobic microorganisms and demethylation by aerobic Hg-resistant bacteria have both been extensively studied, little attention has been given to MeHg degradation by anaerobic bacteria, particularly the iron-reducing bacterium Geobacter bemidjiensis Bem. Here we report, for the first time, that the strain G. bemidjiensis Bem can mediate a suite of Hg transformations, including Hg(II) reduction, Hg(0) oxidation, MeHg production and degradation under anoxic conditions. Results suggest that G. bemidjiensis utilizes a reductive demethylation pathway to degrade MeHg, with elemental Hg(0) as the major reaction product, possibly due to the presence of genes encoding homologues of an organomercurial lyase (MerB) and a mercuric reductase (MerA). In addition, the cells can strongly sorb Hg(II) and MeHg, reduce or oxidize Hg, resulting in both time and concentration-dependent Hg species transformations. Moderate concentrations (10-500 μM) of Hg-binding ligands such as cysteine enhance Hg(II) methylation but inhibit MeHg degradation. These findings indicate a cycle of Hg methylation and demethylation among anaerobic bacteria, thereby influencing net MeHg production in anoxic water and sediments. PMID:27019098

  5. Metabolic and microbial community dynamics during the anaerobic digestion of maize silage in a two-phase process.

    Science.gov (United States)

    Sträuber, Heike; Lucas, Rico; Kleinsteuber, Sabine

    2016-01-01

    Two-phasic anaerobic digestion processes (hydrolysis/acidogenesis separated from acetogenesis/methanogenesis) can be used for biogas production on demand or a combined chemicals/bioenergy production. For an effective process control, detailed knowledge about the microbial catalysts and their correlation to process conditions is crucial. In this study, maize silage was digested in a two-phase process and interrelationships between process parameters and microbial communities were revealed. In the first-phase reactor, alternating metabolic periods were observed which emerged independently from the feeding frequency. During the L-period, up to 11.8 g L(-1) lactic acid was produced which significantly correlated to lactic acid bacteria of the genus Lactobacillus as the most abundant community members. During the alternating G-period, the production of volatile fatty acids (up to 5.3, 4.0 and 3.1 g L(-1) for propionic, n-butyric and n-caproic acid, respectively) dominated accompanied by a high gas production containing up to 28 % hydrogen. The relative abundance of various Clostridiales increased during this metabolic period. In the second-phase reactor, the metabolic fluctuations of the first phase were smoothed out resulting in a stable biogas production as well as stable bacterial and methanogenic communities. However, the biogas composition followed the metabolic dynamics of the first phase: the hydrogen content increased during the L-period whereas highest CH4/CO2 ratios (up to 2.8) were reached during the G-period. Aceticlastic Methanosaeta as well as hydrogenotrophic Methanoculleus and Methanobacteriaceae were identified as dominant methanogens. Consequently, a directed control of the first-phase stabilizing desired metabolic states can lead to an enhanced productivity regarding chemicals and bioenergy. PMID:26411455

  6. Hydrogen Production By Anaerobic Fermentation Using Agricultural and Food Processing Wastes Utilizing a Two-Stage Digestion System

    OpenAIRE

    Thompson, Reese S

    2008-01-01

    Hydrogen production by means of anaerobic fermentation was researched utilizing three different substrates. Synthetic wastewater, dairy manure, and cheese whey were combined together at different concentrations under batch anaerobic conditions to determine the optimal hydrogen producing potential and waste treatment of each. Cheese whey at a concentration of 55% was combined with dairy manure at a concentration of 45% to produce 1.53 liters of hydrogen per liter of substrate. These results...

  7. Formaldehyde degradation by UV/TiO2/O3 process using continuous flow mode

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode.The effects of humidity,initial formaldehyde concentration,residence time and ozone adding amount on degradation of formaldehyde gas were investigated.The experimental results indicated that the combination of ozonation with photocatalytic oxidation on the degradation of formaldehyde showed a synergetic action,e.g.,it could considerably increase decomposing of formaldehyde.The degradation efficiency of formaldehyde was between 73.6% and 79.4% while the initial concentration in the range of 1.84-24 mg/m3 by O3/TiO2/UV process.The optimal humidity was about 50% in UV/TiO2/O3 processs and degradation of formaldehyde increases from 39.0% to 94.1% when the ozone content increased from 0 to 141 mg/m3.Furthermore.the kinetics of formaldehyde degradation coefficient K of 0.0268 m3/mg were obtained.

  8. Degradation of hydroxycinnamic acid mixtures in aqueous sucrose solutions by the Fenton process.

    Science.gov (United States)

    Nguyen, Danny M T; Zhang, Zhanying; Doherty, William O S

    2015-02-11

    The degradation efficiencies and behaviors of caffeic acid (CaA), p-coumaric acid (pCoA), and ferulic acid (FeA) in aqueous sucrose solutions containing the mixture of these hydroxycinnamic acids (HCAs) were studied by the Fenton oxidation process. Central composite design and multiresponse surface methodology were used to evaluate and optimize the interactive effects of process parameters. Four quadratic polynomial models were developed for the degradation of each individual acid in the mixture and the total HCAs degraded. Sucrose was the most influential parameter that significantly affected the total amount of HCA degraded. Under the conditions studied there was a analysis showed goodness of fit between the experimental results and the predicted values. The degradation behavior of CaA differed from those of pCoA and FeA, where further CaA degradation is observed at increasing sucrose and decreasing solution pH. The differences (established using UV/vis and ATR-FTIR spectroscopy) were because, unlike the other acids, CaA formed a complex with Fe(III) or with Fe(III) hydrogen-bonded to sucrose and coprecipitated with lepidocrocite, an iron oxyhydroxide. PMID:25585639

  9. Uncoupled hydrogen and volatile fatty acids generation in a two-step biotechnological anaerobic process fed with actual site wastewater.

    Science.gov (United States)

    Monti, Matilde; Scoma, Alberto; Martinez, Gonzalo; Bertin, Lorenzo; Fava, Fabio

    2015-05-25

    Among agro-wastes, olive mill wastewater (OMW) truly qualifies as a high impact organic residue due to its biochemical-rich composition and high annual production. In the present investigation, dephenolized OMW (OMWdeph) was employed as the feedstock for a biotechnological two-stage anaerobic process dedicated to the production of biohydrogen and volatile fatty acids (VFAs), respectively. To this end, two identically configured packed-bed biofilm reactors were operated sequentially. In the first, the hydraulic retention time was set to 1 day, whereas in the second it was equal to 5 days. The rationale was to decouple the hydrolysis of the organic macronutrients held by the OMWdeph, so as to quantitatively generate a biogas enriched in H2 (first stage aim), for the acidogenesis of the residual components left after hydrolysis, to then produce a highly concentrated mixture of VFAs (second stage aim). Results showed that the generation of H2 and VFAs was effectively split, with carbohydrates and lipids, respectively, being the main substrates of the two processes. About 250 ml H2 L(-1) day(-1) was produced, corresponding to a yield of 0.36 mol mol(-1) of consumed carbohydrates (expressed as glucose equivalents). The overall concentration of VFAs in the acidogenic process was 13.80 g COD L(-1), so that 2.76 g COD L(-1) day(-1) was obtained. Second generation biorefineries use a selected fraction of an organic waste to conduct a microbiologically-driven pathway towards the generation of one target molecule. With the proposed approach, a greater value of the waste was attained, since the multi-purpose two-stage process did not entail competition for substrates between the first and the second steps. PMID:25174889

  10. Bearing Degradation Process Prediction Based on the Support Vector Machine and Markov Model

    Directory of Open Access Journals (Sweden)

    Shaojiang Dong

    2014-01-01

    Full Text Available Predicting the degradation process of bearings before they reach the failure threshold is extremely important in industry. This paper proposed a novel method based on the support vector machine (SVM and the Markov model to achieve this goal. Firstly, the features are extracted by time and time-frequency domain methods. However, the extracted original features are still with high dimensional and include superfluous information, and the nonlinear multifeatures fusion technique LTSA is used to merge the features and reduces the dimension. Then, based on the extracted features, the SVM model is used to predict the bearings degradation process, and the CAO method is used to determine the embedding dimension of the SVM model. After the bearing degradation process is predicted by SVM model, the Markov model is used to improve the prediction accuracy. The proposed method was validated by two bearing run-to-failure experiments, and the results proved the effectiveness of the methodology.

  11. PA-1, a Versatile Anaerobe Obtained in Pure Culture, Catabolizes Benzenoids and Other Compounds in Syntrophy with Hydrogenotrophs, and P-2 plus Wolinella sp. Degrades Benzenoids

    OpenAIRE

    Barik, Sudhakar; Brulla, W. J.; Bryant, M. P.

    1985-01-01

    Methanogenic enrichments catabolizing 13 mM phenylacetate or 4 mM phenol were established at 37°C, using a 10% inoculum from a municipal anaerobic digester. By using agar roll tubes of the basal medium plus 0.1% yeast extract-25 mM fumarate, a hydrogenotrophic lawn of Wolinella succinogenes and phenol or phenylacetate, strains P-2 and PA-1, respectively, were isolated in coculture with W. succinogenes. With the lawn deleted, PA-1 was isolated in pure culture. Strain P-2 is apparently a new sp...

  12. Bio-hydrolysis and bio-hydrogen production from food waste by thermophilic and hyperthermophilic anaerobic process.

    Science.gov (United States)

    Algapani, Dalal E; Qiao, Wei; Su, Min; di Pumpo, Francesca; Wandera, Simon M; Adani, Fabrizio; Dong, Renjie

    2016-09-01

    High-temperature pretreatment plays a key role in the anaerobic digestion of food waste (FW). However, the suitable temperature is not yet determined. In this work, a long-term experiment was conducted to compare hydrolysis, acidogenesis, acetogenesis, and hydrogen production at 55°C and 70°C, using real FW in CSTR reactors. The results obtained indicated that acidification was the rate-limiting step at both temperatures with similar process kinetics characterizations. However, the thermophilic pretreatment was more advantageous than the hyperthermophilic with suspended solids solubilization of 47.7% and 29.5% and total VFA vs. soluble COD ratio of 15.2% and 4.9%, for thermophilic and hyperthermophilic treatment, respectively, with a hydrolytic reaction time (HRT) of 10days and an OLR of 14kgCOD/m(3)d. Moreover, stable hydrogen yield (70.7ml-H2/gVSin) and content in off gas (58.6%) was achieved at HRT 5days, pH 5.5, and temperature of 55°C, as opposed to 70°C. PMID:27295255

  13. Anaerobic treatment of sulfate-containing wastewater from distilleries

    International Nuclear Information System (INIS)

    Bioprocess evaluation of a staged arrangement of a Pulse Driven Loop Reaktor (PDLR) and a Pulsed Anaerobic Filter (PAF) using highly polluted cherry slops as industrial wastewater shows a COD removal efficiency of 80-90% at loading rates of 8-4 kg COD/(M3.d). Contamination of cherry slops by sulfate (2 g/l) and copper (150-200 mg/l) reduces COD degradation to 40-50 percent. A pulsed anaerobic baffled reactor was envisaged as a corrective tool to improve mineralisation in the presence of sulfate-rich substrates by confining sulfate reducing bacteria to the first 4 chambers of the reactor. Phasing slightly improves COD degradation yield, but is not sufficient for stable process performance. Consequently, the use of lactic acid in stead of sulfuric acid in cherry-fermentation was suggested as a preventive method to avoid sulphide-induced digester failure. (orig.)

  14. Modelling of Two-Stage Anaerobic Treating Wastewater from a Molasses-Based Ethanol Distillery with the IWA Anaerobic Digestion Model No.1

    Directory of Open Access Journals (Sweden)

    Kittikhun Taruyanon

    2010-03-01

    Full Text Available This paper presents the application of ADM1 model to simulate the dynamic behaviour of a two-stage anaerobic treatment process treating the wastewater generated from the ethanol distillery process. The laboratory-scale process comprised an anaerobic continuous stirred tank reactor (CSTR and an upflow anaerobic sludge blanket (UASB connecting in series, was used to treat wastewater from the ethanol distillery process. The CSTR and UASB hydraulic retention times (HRT were 12 and 70 hours, respectively. The model was developed based on ADM1 basic structure and implemented with the simulation software AQUASIM. The simulated results were compared with measured data obtained from using the laboratory-scale two-stage anaerobic treatment process to treat wastewater. The sensitivity analysis identified maximum specific uptake rate (km and half-saturation constant (Ks of acetate degrader and sulfate reducing bacteria as the kinetic parameters which highly affected the process behaviour, which were further estimated. The study concluded that the model could predict the dynamic behaviour of a two-stage anaerobic treatment process treating the ethanol distillery process wastewater with varying strength of influents with reasonable accuracy.

  15. Lab-scale demonstration of recuperative thickening technology for enhanced biogas production and dewaterability in anaerobic digestion processes.

    Science.gov (United States)

    Cobbledick, Jeffrey; Aubry, Nicholas; Zhang, Victor; Rollings-Scattergood, Sasha; Latulippe, David R

    2016-05-15

    There is growing interest in the use of high performance anaerobic digestion (AD) processes for the production of biogas at wastewater treatment facilities to offset the energy demands associated with wastewater treatment. Recuperative thickening (RT) is a promising technique which involves recycling a portion of the digested solids back to the incoming feed. In general there exists a significant number of knowledge gaps in the field of RT because the studies that have been conducted to date have almost exclusively occurred in pilot plant or full scale trials; this approach greatly limits the amount of process optimization that can be done in a given trial. In this work, a detailed and comprehensive study of RT was conducted at the lab scale; two custom designed digesters (capacity = 1.5 L) were operated in parallel with one acting as a 'control' digester and the other operating under a semi-batch RT mode. There was no significant change in biogas methane composition for the two digesters, however the RT digester had an average biogas productivity over two times higher than the control one. It was found that the recycling of the polymer flocculant back into the RT digester resulted in a significant improvement in dewatering performance. At the highest polymer concentration tested, the capillary suction time (CST) values for flocculated samples for the RT digester were over 6 times lower than the corresponding values for the control digester. Thus, there exists an opportunity to decrease the overall consumption of polymer flocculants through judicious selection of the dose of polymer flocculant that is used both for the thickening and end-stage dewatering steps in RT processes. PMID:26986495

  16. Comparative study of the degradation of carbamazepine in water by advanced oxidation processes.

    Science.gov (United States)

    Dai, Chao-Meng; Zhou, Xue-Fei; Zhang, Ya-Lei; Duan, Yan-Ping; Qiang, Zhi-Min; Zhang, Tian C

    2012-06-01

    Degradation of carbamazepine (CBZ) using ultraviolet (UV), UV/H2O2, Fenton, UV/Fenton and photocatalytic oxidation with TiO2 (UV/TiO2) was studied in deionized water. The five different oxidation processes were compared for the removal kinetics of CBZ. The results showed that all the processes followed pseudo-first-order kinetics. The direct photolysis (UV alone) was found to be less effective than UV/H2O2 oxidation for the degradation of CBZ. An approximate 20% increase in the CBZ removal efficiency occurred with the UV/Fenton reaction as compared with the Fenton oxidation. In the UV/TiO2 system, the kinetics of CBZ degradation in the presence of different concentrations of TiO2 followed the pseudo-first order degradation, which was consistent with the Langmuir-Hinshelwood (L-H) model. On a time basis, the degradation efficiencies ofCBZ were in the following order: UV/Fenton (86.9% +/- 1.7%) > UV/TiO2 (70.4% +/- 4.2%) > Fenton (67.8% +/- 2.6%) > UV/H2O2 (40.65 +/- 5.1%) > UV (12.2% +/- 1.4%). However, the lowest cost was obtained with the Fenton process. PMID:22856279

  17. Integrated extraction and anaerobic digestion process for recovery of nutraceuticals and biogas from pomegranate marcs

    Science.gov (United States)

    Pomegranate marc (PM), a by-product from pomegranate juice processing, has not been effectively utilized. The objectives of this study were to (1) determine the yields and properties of antioxidants (henceforth referring to total phenolics in terms of tannic acid equivalent) and oil extracted from v...

  18. Process model for ammonia volatilization from anaerobic swine lagoons incorporating varying wind speeds and biogas bubbling

    Science.gov (United States)

    Ammonia volatilization from treatment lagoons varies widely with the total ammonia concentration, pH, temperature, suspended solids, atmospheric ammonia concentration above the water surface, and wind speed. Ammonia emissions were estimated with a process-based mechanistic model integrating ammonia ...

  19. The effect of anaerobic fermentation processing of cattle waste for biogas as a renewable energy resources on the number of contaminant microorganism

    Science.gov (United States)

    Kurnani, Tb. Benito A.; Hidayati, Yuli Astuti; Marlina, Eulis Tanti; Harlia, Ellin

    2016-02-01

    Beef cattle waste has a positive potential that can be exploited, as well as a negative potential that must be controlled so as not to pollute the environment. Beef cattle waste can be processed into an alternative energy, namely biogas. Anaerobic treatment of livestock waste to produce gas can be a solution in providing optional energy, while the resulted sludge as the fermentation residue can be used as organic fertilizer for crops. However, this sludge may containt patogenic microorganism that will damage human and environmet healt. Therefor, this study was aimed to know the potency of beef cattle waste to produce biogas and the decrease of the microorganism's number by using fixed dome digester. Beef cattle waste was processed into biogas using fixed dome digester with a capacity of 12 m3. Biogas composition was measured using Gas Cromatografi, will microorganism species was identified using Total plate Count Methode. The result of this study shows that the produced biogas contains of 75.77% Mol (CH4), 13.28% Mol (N), and 6.96% Mol (CO2). Furthermor, this study show that the anaerobic fermrntation process is capable of reducing microorganisms that could potentially pollute the environment. The number of Escherichia coli and Samonella sp. were protozoa can be reduced in order of 94.73%. Protozoa that can be identified in cattle waste before, and after anaerobic fermentation was merely Eimeria sp.. The process also reduced the yeast of 86.11%. The remaining yeast after fermentation was Candida sp. Finally, about 93.7% of endoparasites was reduced by this process. In this case, every trematode and cestoda were 100% reduced, while the nematode only 75%. Reducing some microorganisms that have the potential to pollute the environment signifies sludge anaerobic fermentation residue is safe to be applied as organic fertilizer for crops.

  20. The effect of anaerobic fermentation processing of cattle waste for biogas as a renewable energy resources on the number of contaminant microorganism

    Science.gov (United States)

    Kurnani, Tb. Benito A.; Hidayati, Yuli Astuti; Marlina, Eulis Tanti; Harlia, Ellin

    2016-02-01

    Beef cattle waste has a positive potential that can be exploited, as well as a negative potential that must be controlled so as not to pollute the environment. Beef cattle waste can be processed into an alternative energy, namely biogas. Anaerobic treatment of livestock waste to produce gas can be a solution in providing optional energy, while the resulted sludge as the fermentation residue can be used as organic fertilizer for crops. However, this sludge may containt patogenic microorganism that will damage human and environmet healt. Therefor, this study was aimed to know the potency of beef cattle waste to produce biogas and the decrease of the microorganism's number by using fixed dome digester. Beef cattle waste was processed into biogas using fixed dome digester with a capacity of 12 m3. Biogas composition was measured using Gas Cromatografi, will microorganism species was identified using Total plate Count Methode. The result of this study shows that the produced biogas contains of 75.77% Mol (CH4), 13.28% Mol (N), and 6.96% Mol (CO2). Furthermor, this study show that the anaerobic fermrntation process is capable of reducing microorganisms that could potentially pollute the environment. The number of Escherichia coli and Samonella sp. were waste before, and after anaerobic fermentation was merely Eimeria sp.. The process also reduced the yeast of 86.11%. The remaining yeast after fermentation was Candida sp. Finally, about 93.7% of endoparasites was reduced by this process. In this case, every trematode and cestoda were 100% reduced, while the nematode only 75%. Reducing some microorganisms that have the potential to pollute the environment signifies sludge anaerobic fermentation residue is safe to be applied as organic fertilizer for crops.

  1. Diversity of Anaerobic Microorganisms Involved in Long-Chain Fatty Acid Degradation in Methanogenic Sludges as Revealed by RNA-Based Stable Isotope Probing▿

    OpenAIRE

    Hatamoto, Masashi; IMACHI, HIROYUKI; Yashiro, Yuto; Ohashi, Akiyoshi; Harada, Hideki

    2007-01-01

    Long-chain fatty acid (LCFA) degradation is a key step in methanogenic treatment of wastes/wastewaters containing high concentrations of lipids. However, despite the importance of LCFA-degrading bacteria, their natural diversity is little explored due to the limited availability of isolate information and the lack of appropriate molecular markers. We therefore investigated these microbes by using RNA-based stable isotope probing. We incubated four methanogenic sludges (mesophilic sludges MP a...

  2. DEAMOX--new biological nitrogen removal process based on anaerobic ammonia oxidation coupled to sulphide-driven conversion of nitrate into nitrite.

    Science.gov (United States)

    Kalyuzhnyi, Sergey; Gladchenko, Marina; Mulder, Arnold; Versprille, Bram

    2006-11-01

    This paper reports about the successful laboratory testing of a new nitrogen removal process called DEAMOX (DEnitrifying AMmonium OXidation) for treatment of typical strong nitrogenous wastewater such as baker's yeast effluent. The concept of this process combines the recently discovered anammox (anaerobic ammonium oxidation) reaction with autotrophic denitrifying conditions using sulphide as an electron donor for the production of nitrite from nitrate within an anaerobic biofilm. To generate sulphide and ammonia, a Upflow Anaerobic Sludge Bed (UASB) reactor was used as a pre-treatment step. The UASB effluent was split and partially fed to a nitrifying reactor (to generate nitrate) and the remaining part was directly fed to the DEAMOX reactor where this stream was mixed with the nitrified effluent. Stable process performance and volumetric nitrogen loading rates of the DEAMOX reactor well above 1000 mgN/l/d with total nitrogen removal efficiencies of around 90% were obtained after long-term (410 days) optimisation of the process. Important prerequisites for this performance are appropriate influent ratios of the key species fed to the DEAMOX reactor, namely influent N-NO(x)/N-NH(4) ratios >1.2 (stoichiometry of the anammox reaction) and influent S-H(2)S/N-NO(3) ratios >0.57 mgS/mgN (stoichiometry of the sulphide-driven denitrification of nitrate to nitrite). The paper further describes some characteristics of the DEAMOX sludge as well as the preliminary results of its microbiological characterisation. PMID:16893559

  3. Effects of ultrasonic processing on degradation of salvianolic acid B in aqueous solution.

    Science.gov (United States)

    Guo, Y X; Zhang, L; Lu, L; Liu, E H; Shi, C Z

    2016-09-10

    To evaluate the stability of salvianolic acid B (Sal B) under ultrasound-assisted extraction in the pharmaceutical industry, degradation of Sal B under ultrasonic irradiation was investigated as the function of buffer concentration, pH, and temperature. With regard to Sal-B concentration, a first-order degradation process was determined, with 10% change in assay from its initial concentration as t90=4.81h, under maximum stability acidic conditions (pH 2.0) and at 25°C. The logkpH-pH profile described by specific acid-base catalysis and water molecules supported the experimental results. Liquid chromatography-mass spectrometry (LC-MS) analyses revealed 7 major degradation products whose structures were characterized by electrospray ionization/mass spectrometry. A primary degradation pathway involved cleavage of the ester bond and ring-opening of benzofuran in Sal B was proposed. The complete degradation pathway of Sal B was also proposed. Results showed that ultrasonic irradiation leads to degradation of Sal B in aqueous solution. PMID:27442887

  4. Lessons learned from the Febex in situ test: geochemical processes associated to the microbial degradation and gas generation

    International Nuclear Information System (INIS)

    existence of gaps between the bentonite blocks, which favour the development and growth of inactive and dormant cells or spores belonging to the original bentonite. In this work, the observed geochemical and corrosion processes influenced both by organic matter degradation and micro-organisms in the 1:1 scale FEBEX in situ test (Grimsel, Switzerland) are described. This test consists of two heaters, simulating radioactive waste containers, emplaced in a horizontal gallery and surrounded by a highly compacted bentonite barrier. Samples from pore water, gases and bentonite (SHSDI-01: clay in contact with AISI 316L metal; S29 and BSBI-26: clay in contact with carbon steel) have been analysed. The samples were obtained during the test and the dismantling of the heater 1 after six years of experiment. The solid samples were analysed by XRD, SEM, XPS, FTIR, ATD-TG and chemical analysis; the water samples by IC and ICP-OES, and the gases by gas chromatography. Different geochemical processes have been detected as a function of the temperature and water content of the samples. When the water content is high, there are aerobic respiration and fermentation processes, anaerobic respiration with SO42- as electron acceptor, and anaerobic production of methane with CO2 as electron acceptor. In a first phase, both oxygen consumption and an increase of CH4 and CO2 is observed. Afterwards, there is a reduction of sulfates by SRB bacteria, which provokes corrosion processes. As a consequence, a precipitation of sulphurs, iron oxy-hydroxides and carbonates occurs, as well as H2 generation. There is an increase of the iron content in the smectite and the neo-formation of zeolites. However this alteration is punctual and localized. The redox potential of the bentonite pore water was of -284 mV. When the temperature is high and water content is low, other processes take place

  5. Environmental assessment of waste to energy processes specifically incineration and anaerobic digestion using life cycle assessment

    OpenAIRE

    Tawatsin, Anuda

    2014-01-01

    Municipal solid waste is an issue every community in the world has to be concerned with. Without any management, municipal solid waste poses environmental and health risks to the community such as from water and air pollution. In selecting methods to deal with the waste, environmental impacts considerations are important to reduce these risks. Environmentally sustainable waste management processes should also decrease greenhouse gases contributing to global warming and climate change. Waste t...

  6. Degrading organic micropollutants: The next challenge in the evolution of biological wastewater treatment processes

    Directory of Open Access Journals (Sweden)

    Naresh eSinghal

    2016-05-01

    Full Text Available Global water scarcity is driving the need for identifying new water source. Wastewater could be a potential water resource if appropriate treatment technologies could be developed. One of the barriers to obtaining high quality water from wastewater arises from the presence of organic micropollutants, which are biologically active at trace levels. Removal of these compounds from wastewater by current physico-chemical technologies is prohibitively expensive. While biological treatment processes are comparatively cheap, current systems are not capable of degrading the wide range of organic micropollutants present in wastewater. As current wastewater treatment processes were developed for treating conventional pollutants present at mg/L levels, degrading the ng/L levels of micropollutants will require a different approach to system design and operation. In this paper we discuss strategies that could be employed to develop biological wastewater treatment systems capable of degrading organic micropollutants.

  7. Biodegradation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine and Its Mononitroso Derivative Hexahydro-1-Nitroso-3,5-Dinitro-1,3,5-Triazine by Klebsiella pneumoniae Strain SCZ-1 Isolated from an Anaerobic Sludge

    OpenAIRE

    Zhao, Jian-Shen; Halasz, Annamaria; Paquet, Louise; Beaulieu, Chantale; Hawari, Jalal

    2002-01-01

    In previous work, we found that an anaerobic sludge efficiently degraded hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), but the role of isolates in the degradation process was unknown. Recently, we isolated a facultatively anaerobic bacterium, identified as Klebsiella pneumoniae strain SCZ-1, using MIDI and the 16S rRNA method from this sludge and employed it to degrade RDX. Strain SCZ-1 degraded RDX to formaldehyde (HCHO), methanol (CH3OH) (12% of total C), carbon dioxide (CO2) (72% of total...

  8. [Degradation of phenol with a Fe/cu-catalytic heterogeneous-Fenton process].

    Science.gov (United States)

    Yang, Yue-Zhu; Li, Yu-Ping; Yang, Dao-Wu; Duan, Feng; Cao, Hong-Bin

    2013-07-01

    The catalysts of Fe/AC, Cu/AC and Fe-Cu/AC with active carbon as support were prepared by a wet impregnation method, and were characterized using X-ray diffraction (XRD), nitrogen adsorption and X-ray photoelectron spectroscopy (XPS) measurements; the catalytic heterogeneous-Fenton processes of phenol degradation with these catalysts were also investigated, and the degradation mechanism was discussed with analysis of intermediate products and electron spin resonance (ESR) measurement. The results showed that the active component states varied in different catalysts; CuO was the main state of Cu in Cu/AC and Fe exhibited various valence states in Fe/AC. The degradation rate of phenol with Fe/AC, Cu/AC and Fe-Cu/AC as catalyst in the initial 60 min reached 96.7%, 77.5% and 99%, respectively; the dissolution of a little active-component metal was found in Cu/AC and Fe-Cu/AC, but little Fe in Fe/AC was dissolved; the degradation of phenol was performed by heterogeneous Fe/AC instead of dissolved Fe, and the degradation rate was above 93% after Fe/AC was used for three cycle runs, showing a stable catalytic activity. Under the optimum conditions of pH = 3, T = 303 K, and 4.38 mmol x L(-1) H2O2, the removal of phenol and TOC in the Fe/AC-catalytic Fenton process could reach 97% and 53%, respectively, while little phenol was degraded without catalyst. The ESR results indicated that hydroxyl radical was produced in the catalytic decomposition of H2O2 with Fe/AC as catalyst, demonstrating that the degradation of phenol mainly followed an oxidation pathway of hydroxyl radical; intermediates such as hydroquinone, p-benzenequinone and catechol were obtained, and the results showed thatortho- and para-substitution reaction by hydroxyl might be the main mechanism of phenol oxidation. PMID:24027996

  9. Studying the degradation of polyhydroxybutyrate-co-valerate during processing with clay-based nanofillers

    DEFF Research Database (Denmark)

    Cabedo, Luis; Plackett, David; Gimenez, Enrique;

    2009-01-01

    nanofillers could influence polymer properties. PHBV was processed with three-layered clay types using different mixing methods, and we examined the effect of processing time, clay type, and clay content on polymer molecular weight and composite morphology. PHBV molecular weight (Mw) decreased by 38% after...... extrusion processing and was further reduced in the presence of montmorillonite (MMT). However, when PHBV was processed with kaolinite as the additive, no further reduction in polymer molecular weight was observed. Molecular weight also decreased as the MMT clay content increased from 1 to 5 wt %. The...... results suggest that release of tightly bound water from clay surfaces at elevated temperature may be responsible for PHBV degradation during processing. Evidence also points to the possibility that the surface modifier present in organically modified MMT may catalyze PHBV degradation in some way. X...

  10. The conversion of anaerobic digestion waste into biofuels via a novel Thermo-Catalytic Reforming process.

    Science.gov (United States)

    Neumann, Johannes; Meyer, Johannes; Ouadi, Miloud; Apfelbacher, Andreas; Binder, Samir; Hornung, Andreas

    2016-01-01

    Producing energy from biomass and other organic waste residues is essential for sustainable development. Fraunhofer UMSICHT has developed a novel reactor which introduces the Thermo-Catalytic Reforming (TCR®) process. The TCR® is a process which can convert any type of biomass and organic feedstocks into a variety of energy products (char, bio-oil and permanent gases). The aim of this work was to demonstrate this technology using digestate as the feedstock and to quantify the results from the post reforming step. The temperature of a post reformer was varied to achieve optimised fuel products. The hydrogen rich permanent gases produced were maximised at a post reforming temperature of 1023 K. The highly de-oxygenated liquid bio-oil produced contained a calorific value of 35.2 MJ/kg, with significantly improved fuel physical properties, low viscosity and acid number. Overall digestate showed a high potential as feedstock in the Thermo-Catalytic Reforming to produce pyrolysis fuel products of superior quality. PMID:26190827

  11. Oxidative degradation of N-Nitrosopyrrolidine by the ozone/UV process: Kinetics and pathways.

    Science.gov (United States)

    Chen, Zhi; Fang, Jingyun; Fan, Chihhao; Shang, Chii

    2016-05-01

    N-Nitrosopyrrolidine (NPYR) is an emerging contaminant in drinking water and wastewater. The degradation kinetics and mechanisms of NPYR degradation by the O3/UV process were investigated and compared with those of UV direct photolysis and ozonation. A synergistic effect of ozone and UV was observed in the degradation of NPYR due to the accelerated production of OH• by ozone photolysis. This effect was more pronounced at higher ozone dosages. The second-order rate constants of NPYR reacting with OH• and ozone was determined to be 1.38 (± 0.05) × 10(9) M(-1) s(-1) and 0.31 (± 0.02) M(-1) s(-1), respectively. The quantum yield by direct UV photolysis was 0.3 (± 0.01). An empirical model using Rct (the ratio of the exposure of OH• to that of ozone) was established for NPYR degradation in treated drinking water and showed that the contributions of direct UV photolysis and OH• oxidation on NPYR degradation were both significant. As the reaction proceeded, the contribution by OH• became less important due to the exhausting of ozone. Nitrate was the major product in the O3/UV process by two possible pathways. One is through the cleavage of nitroso group to form NO• followed by hydrolysis, and the other is the oxidation of the intermediates of amines by ozonation. PMID:26733013

  12. Effect of temperature and pH on the kinetics of methane production, organic nitrogen and phosphorus removal in the batch anaerobic digestion process of cattle manure

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, E. [Consultores Ambientales (CONAM), Havanna (Cuba); Borja, R. [Instituto de la Grasa (C.S.I.C.)., Sevilla (Spain); Weiland, P. [Institute of Technology, Federal Research Center of Agriculture (FAL), Braunschweig (Germany); Travieso, L. [Departamento de Estudios sobre Contaminacion Ambiental (DECA-CNIC), Centro Nacional de Investigaciones Cientificas (CNIC), La Habana (Cuba); Martin, A. [Departamento de Ingenieria Quimica, Facultad de Ciencias, Cordoba (Spain)

    2000-03-01

    A study of the effect of temperature and pH on the kinetics of methane production and organic nitrogen and phosphorus degradation in the anaerobic digestion process of cattle manure was carried out. Two laboratory-scale batch completely mixed reactors, operating at 35 C (mesophilic temperature), and other two, operating at 60 C (thermophilic temperature) were used. For each temperature selected, the influent pH values were 7.6 (initial pH of the waste used) and 7.0. The apparent kinetic constants of the biomethanization process increased 2.3 times when the initial pH of the influent was increased from 7.0 to 7.6 at mesophilic temperature. The values found at thermophilic temperature were similar. The kinetic constants of methane production decreased 2.6 and 7.2 times when the operating temperature increased from 35 C to 60 C for the experiments carried out at initial pH of 7.0 and 7.6, respectively. The methane yield coefficient (l CH{sub 4} STP/g VS removed) also decreased when the temperature increased from 35 C to 60 C for the two initial pH values studied. This behaviour agreed with the major inhibition level observed at thermophilic temperature as a result of the higher organic nitrogen removal and ammonia nitrogen production observed at 60 C. Specifically, the specific rate constants for organic nitrogen removal and ammonia nitrogen production increased 3.6 and 12 times when the temperature was increased from 35 C to 60 C for the experiments carried out at initial pH values of 7.0 and 7.6, respectively. In the same way, the values of the kinetic constant for phosphorus removal were 44% and 80% higher than those obtained at 35 C for the two initial pH values above-mentioned, respectively. Finally, the experimental values of organic nitrogen and phosphorus concentrations were reproduced with deviations equal to or less than 10% and 15% in every case, respectively. (orig.)

  13. Anaerobic phosphate release from activated sludge with enhanced biological phosphorus removal. A possible mechanism of intracellular pH control

    Energy Technology Data Exchange (ETDEWEB)

    Bond, P.L.; Keller, J.; Blackall, L.L. [Univ. of Queensland, Brisbane (Australia)

    1999-06-05

    The biochemical mechanisms of the wastewater treatment process known as enhanced biological phosphorus removal (EBPR) are presently described in a metabolic model. The authors investigated details of the EBPR model to determine the nature of the anaerobic phosphate release and how this may be metabolically associated with polyhydroxyalkanoate (PHA) formation. Iodoacetate, an inhibitor of glycolysis, was found to inhibit the anaerobic formation of PHA and phosphate release, supporting the pathways proposed in the EBPR metabolic model. In the metabolic model, it is proposed that polyphosphate degradation provides energy for the microorganisms in anaerobic regions of these treatment systems. Other investigations have shown that anaerobic phosphate release depends on the extracellular pH. The authors observed that when the intracellular pH of EBPR sludge was raised, substantial anaerobic phosphate release was caused without volatile fatty acid (VFA) uptake. Acidification of the sludge inhibited anaerobic phosphate release even in the presence of VFA. from these observations, the authors postulate that an additional possible role of anaerobic polyphosphate degradation in EBPR is for intracellular pH control. Intracellular pH control may be a metabolic feature of EBPR, not previously considered, that could have some use in the control and optimization of EBPR.

  14. Degradation of flumequine by the Fenton and photo-Fenton processes: Evaluation of residual antimicrobial activity

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues-Silva, Caio; Maniero, Milena Guedes [School of Civil Engineering, Architecture and Urbanism, University of Campinas — UNICAMP, P.O. Box 6021, CEP 13083-852, Campinas, SP (Brazil); Rath, Susanne [Chemistry Institute, University of Campinas — UNICAMP, P.O. Box 6154, CEP 13084-971, Campinas, SP (Brazil); Guimarães, José Roberto, E-mail: jorober@fec.unicamp.br [School of Civil Engineering, Architecture and Urbanism, University of Campinas — UNICAMP, P.O. Box 6021, CEP 13083-852, Campinas, SP (Brazil)

    2013-02-15

    Flumequine is a broad-spectrum antimicrobial agent of the quinolone class, and it is widely used as a veterinary drug in food-producing animals. The presence of flumequine in the environment may contribute to the development of drug resistant bacterial strains. In this study, water samples fortified with flumequine (500 μg L{sup −1}) were degraded using the Fenton and photo-Fenton processes. The maximum degradation efficiency for flumequine by the Fenton process was approximately 40% (0.5 mmol L{sup −1} Fe(II), 2.0 mmol L{sup −1} H{sub 2}O{sub 2} and 15 min). By applying UV radiation (photo-Fenton process), the efficiency reached more than 94% in 60 min when 0.25 mmol L{sup −1} Fe(II) and 10.0 mmol L{sup −1} H{sub 2}O{sub 2} were used. Under these conditions, the Fenton process was able to reduce the biological activity, whereas the photo-Fenton process eliminated almost all of the antimicrobial activity because it was not detected. Four byproducts with an m/z of 244, 238, 220 and 202 were identified by mass spectrometry, and a degradation pathway for flumequine was proposed. The byproducts were derived from decarboxylation and defluorination reactions and from modifications in the alkylamino chain of the fluoroquinolone. - Highlights: ► Photo-Fenton process achieved the maximum performance, degrading 94% of flumequine. ► As the flumequine concentration decreased, antimicrobial activity also decreased. ► Four byproducts with m/z of 244, 238, 220 and 202 were identified. ► A degradation pathway for flumequine was proposed.

  15. Comparing mesophilic and thermophilic anaerobic digestion of chicken manure: Microbial community dynamics and process resilience

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Qigui; Takemura, Yasuyuki; Kubota, Kengo [Department of Civil and Environmental Engineering, Graduate School of Engineering Tohoku University, 6-6-06 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Li, Yu-You, E-mail: yyli@epl1.civil.tohoku.ac.jp [Department of Civil and Environmental Engineering, Graduate School of Engineering Tohoku University, 6-6-06 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Key Lab of Northwest Water Resource, Environment and Ecology, MOE, Xi’an University of Architecture and Technology, Xi’an (China)

    2015-09-15

    Highlights: • Microbial community dynamics and process functional resilience were investigated. • The threshold of TAN in mesophilic reactor was higher than the thermophilic reactor. • The recoverable archaeal community dynamic sustained the process resilience. • Methanosarcina was more sensitive than Methanoculleus on ammonia inhibition. • TAN and FA effects the dynamic of hydrolytic and acidogenic bacteria obviously. - Abstract: While methane fermentation is considered as the most successful bioenergy treatment for chicken manure, the relationship between operational performance and the dynamic transition of archaeal and bacterial communities remains poorly understood. Two continuous stirred-tank reactors were investigated under thermophilic and mesophilic conditions feeding with 10%TS. The tolerance of thermophilic reactor on total ammonia nitrogen (TAN) was found to be 8000 mg/L with free ammonia (FA) 2000 mg/L compared to 16,000 mg/L (FA1500 mg/L) of mesophilic reactor. Biomethane production was 0.29 L/gV S{sub in} in the steady stage and decreased following TAN increase. After serious inhibition, the mesophilic reactor was recovered successfully by dilution and washing stratagem compared to the unrecoverable of thermophilic reactor. The relationship between the microbial community structure, the bioreactor performance and inhibitors such as TAN, FA, and volatile fatty acid was evaluated by canonical correspondence analysis. The performance of methanogenic activity and substrate removal efficiency were changed significantly correlating with the community evenness and phylogenetic structure. The resilient archaeal community was found even after serious inhibition in both reactors. Obvious dynamics of bacterial communities were observed in acidogenic and hydrolytic functional bacteria following TAN variation in the different stages.

  16. Comparing mesophilic and thermophilic anaerobic digestion of chicken manure: Microbial community dynamics and process resilience

    International Nuclear Information System (INIS)

    Highlights: • Microbial community dynamics and process functional resilience were investigated. • The threshold of TAN in mesophilic reactor was higher than the thermophilic reactor. • The recoverable archaeal community dynamic sustained the process resilience. • Methanosarcina was more sensitive than Methanoculleus on ammonia inhibition. • TAN and FA effects the dynamic of hydrolytic and acidogenic bacteria obviously. - Abstract: While methane fermentation is considered as the most successful bioenergy treatment for chicken manure, the relationship between operational performance and the dynamic transition of archaeal and bacterial communities remains poorly understood. Two continuous stirred-tank reactors were investigated under thermophilic and mesophilic conditions feeding with 10%TS. The tolerance of thermophilic reactor on total ammonia nitrogen (TAN) was found to be 8000 mg/L with free ammonia (FA) 2000 mg/L compared to 16,000 mg/L (FA1500 mg/L) of mesophilic reactor. Biomethane production was 0.29 L/gV Sin in the steady stage and decreased following TAN increase. After serious inhibition, the mesophilic reactor was recovered successfully by dilution and washing stratagem compared to the unrecoverable of thermophilic reactor. The relationship between the microbial community structure, the bioreactor performance and inhibitors such as TAN, FA, and volatile fatty acid was evaluated by canonical correspondence analysis. The performance of methanogenic activity and substrate removal efficiency were changed significantly correlating with the community evenness and phylogenetic structure. The resilient archaeal community was found even after serious inhibition in both reactors. Obvious dynamics of bacterial communities were observed in acidogenic and hydrolytic functional bacteria following TAN variation in the different stages

  17. Linking trajectories of land change, land degradation processes and ecosystem services

    NARCIS (Netherlands)

    Smiraglia, D.; Ceccarelli, T.; Bajocco, S.; Salvati, L.; Perini, L.

    2016-01-01

    Land Degradation (LD) is a complex phenomenon resulting in a progressive reduction in the capacity of providing ecosystem services (ES). Landscape transformations promoting an unsustainable use of land often reveal latent processes of LD. An evaluation carried out in respect to the different ecos

  18. Ammonia stripping, activated carbon adsorption and anaerobic biological oxidation as process combination for the treatment of oil shale wastewater.

    Science.gov (United States)

    Alexandre, Verônica M F; do Nascimento, Felipe V; Cammarota, Magali C

    2016-10-01

    Anaerobic biodegradability of oil shale wastewater was investigated after the following pretreatment sequence: ammonia stripping and activated carbon adsorption. Anaerobic biological treatment of oil shale wastewater is technically feasible after stripping at pH 11 for reducing the N-NH3 concentration, adsorption with 5 g/L of activated carbon in order to reduce recalcitrance and pH adjustment with CO2 so that the sulphate concentration in the medium remains low. After this pretreatment sequence, it was possible to submit the wastewater without dilution to an anaerobic treatment with 62.7% soluble chemical oxygen demand removal and specific methane production of 233.2 mL CH4STP/g CODremoved. PMID:27003628

  19. Economic viability of anaerobic digestion

    Energy Technology Data Exchange (ETDEWEB)

    Wellinger, A. [INFOENERGIE, Ettenhausen (Switzerland)

    1996-01-01

    The industrial application of anaerobic digestion is a relatively new, yet proven waste treatment technology. Anaerobic digestion reduces and upgrades organic waste, and is a good way to control air pollution as it reduces methane and nitrous gas emissions. For environmental and energy considerations, anaerobic digestion is a nearly perfect waste treatment process. However, its economic viability is still in question. A number of parameters - type of waste (solid or liquid), digester system, facility size, product quality and end use, environmental requirements, cost of alternative treatments (including labor), and interest rates - define the investment and operating costs of an anaerobic digestion facility. Therefore, identical facilities that treat the same amount and type of waste may, depending on location, legislation, and end product characteristics, reveal radically different costs. A good approach for evaluating the economics of anaerobic digestion is to compare it to treatment techniques such as aeration or conventional sewage treatment (for industrial wastewater), or composting and incineration (for solid organic waste). For example, the cost (per ton of waste) of in-vessel composting with biofilters is somewhat higher than that of anaerobic digestion, but the investment costs 1 1/2 to 2 times more than either composting or anaerobic digestion. Two distinct advantages of anaerobic digestion are: (1) it requires less land than either composting or incinerating, which translates into lower costs and milder environmental and community impacts (especially in densely populated areas); and (2) it produces net energy, which can be used to operate the facility or sold to nearby industries.

  20. Characteristics of Membrane Fouling in an Anaerobic-(Anoxic/Oxic)n-MBR Process

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chuan-yi; DING Yi; YUAN Li-mei; ZHANG Yan-qiu; XI Dan-li

    2007-01-01

    The characteristics of membrane fouling and cleaning, in a hybrid MBR process, was investigated. Under the condition of sub-critical flux operation, a characteristic three-stage trans-membrane pressure (TMP) profile is observed as time passes. The initially extended period of slow pressure rise, followed by a somewhat faster rise, is then supplanted by a sudden transition to rapid pressure rise. Membrane cleaning experiments and SEM examination make it apparent that the rapid TMP rise is mainly caused by the accumulation of a surface cake layer, which is a reversible fouling that can be removed by tap water washing. Fouling caused by a gel layer, which is an irreversible fouling, can be removed efficiently by chemical cleaning. NaClO can oxidize the gel layer, which is formed mainly of macro-molecular organic substances. The HCl can remove inorganic particles formed by Ca2+, Mg2+ ions etc. The sequence of chemicals used in membrane cleaning has an influence on the cleaning result. The effect of the NaClO+HCl cleaning procedure is superior to that of the HCl+NaClO one. Particle size distribution measurements (PSD) reveal that fine particles are inclined to deposit or attach on the membrane surface, or in the membrane pores, and caused rapid fouling.

  1. Recent advances in remote sensing and geoinformation processing for land degradation assessment

    CERN Document Server

    Roeder, Achim

    2009-01-01

    Acknowledgements Contributors Achim Röder & Joachim Hill, Remote sensing and geoinformation processing in land degradation assessment-an introduction Part 1 Setting the scene: principles in remote sensing and spatial scene modelling for land degradation assessmentEric F. Lambin, Helmut Geist, James F. Reynolds & D. Mark Stafford-Smith, Coupled human-environment system approaches to desertification: Linking people to pixels Susan L. Ustin, Alacia Palacios-Orueta, Michael L. Whiting, Stéphane Jacquemoud & Lin Li, Remote sensing based assessm

  2. COMPARISON OF DIFFERENT ADVANCED OXIDATION PROCESSES DEGRADING P-CHLOROPHENOL IN AQUEOUS SOLUTION

    OpenAIRE

    H. Movahedyan ، A. M. Seid Mohammadi ، A. Assadi

    2009-01-01

    In present study, degradation of p-chlorophenol using several oxidation systems involving advanced oxidation processes such as ultraviolet/H2O2, microwave/H2O2 and both in the absence of hydrogen peroxide in batch mode by photolytic pilot plant and modified domestic microwave oven was evaluated. The oxidation rate was influenced by many factors, such as the pH value, the amount of hydrogen peroxide, irradiation time and microwave power. The optimum conditions obtained for the best degradation...

  3. Polymer degradation in reactive ion etching and its possible application to all dry processes

    International Nuclear Information System (INIS)

    Dry etching processes involving CF4-plasma and reactive ion etching become increasingly important for microcircuit fabrication techniques. In these techniques polymer degradation and etch resistance against reactive species like F atoms and CF3+ ions are the key factors in the processes. It is well-known that classical electron beam resists like poly(methyl methacrylate) and poly(1-butene sulfone) are not suitable for dry etching processes because they degrade rapidly under these etching conditions. In order to find a correlation of etching rate and polymer structures the thickness loss of polymer films have been measured for a variety of polymer films in reactive ion etching conditions, where CF3+ ions are the major reactive species with an accelerating potential of 500 volts. Because of its high CF4-plasma and reactive ion etch resistance, and because of its high electron beam sensitivity, poly(methacrylonitrile) provides a positive working electron beam resist uniquely suited for all dry processes. (author)

  4. Sulfate addition as an effective method to improve methane fermentation performance and propionate degradation in thermophilic anaerobic co-digestion of coffee grounds, milk and waste activated sludge with AnMBR.

    Science.gov (United States)

    Li, Qian; Li, Yu-You; Qiao, Wei; Wang, Xiaochang; Takayanagi, Kazuyuki

    2015-06-01

    This study was conducted to investigate the effects of sulfate on propionate degradation and higher organic loading rate (OLR) achievement in a thermophilic AnMBR for 373days using coffee grounds, milk and waste activated sludge (WAS) as the co-substrate. Without the addition of sulfate, the anaerobic system failed at an OLR of 14.6g-COD/L/d, with propionate accumulating to above 2.23g-COD/L, and recovery by an alkalinity supplement was not successful. After sulfate was added into substrates at a COD/SO4(2-) ratio of 200:1 to 350:1, biogas production increased proportionally with OLR increasing from 4.06 to 15.2g-COD/L/d. Propionic acid was maintained at less than 100mg-COD/L due to the effective conversion of propionic acid to methane after the sulfate supplement was added. The long-term stable performance of the AnMBR indicated that adding sulfate was beneficial for the degradation of propionate and achieving a higher OLR under the thermophilic condition. PMID:25791749

  5. Cleaner production of citric acid by recycling its extraction wastewater treated with anaerobic digestion and electrodialysis in an integrated citric acid-methane production process.

    Science.gov (United States)

    Xu, Jian; Su, Xian-Feng; Bao, Jia-Wei; Chen, Yang-Qiu; Zhang, Hong-Jian; Tang, Lei; Wang, Ke; Zhang, Jian-Hua; Chen, Xu-Sheng; Mao, Zhong-Gui

    2015-01-01

    To solve the pollution problem of extraction wastewater in citric acid production, an integrated citric acid-methane production process was proposed. Extraction wastewater was treated through anaerobic digestion and the anaerobic digestion effluent (ADE) was recycled for the next batch of citric acid fermentation, thus eliminating wastewater discharge and reducing water consumption. Excessive Na(+) contained in ADE could significantly inhibit citric acid fermentation in recycling and was removed by electrodialysis in this paper. Electrodialysis performance was improved after pretreatment of ADE with air stripping and activated carbon adsorption to remove precipitable metal ions and pigments. Moreover, the concentrate water was recycled and mixed with feed to improve the water recovery rate above 95% in electrodialysis treatment, while the dilute water was collected for citric acid fermentation. The removal rate of Na(+) in ADE was above 95% and the citric acid production was even higher than that with tap water. PMID:25898079

  6. Biodegradation of phenol with chromium(VI) reduction in an anaerobic fixed-biofilm process-Kinetic model and reactor performance

    International Nuclear Information System (INIS)

    A mathematical model system was derived to describe the simultaneous removal of phenol biodegradation with chromium(VI) reduction in an anaerobic fixed-biofilm reactor. The model system incorporates diffusive mass transport and double Monod kinetics. The model was solved using a combination of the orthogonal collocation method and Gear's method. A laboratory-scale column reactor was employed to validate the kinetic model system. Batch kinetic tests were conducted independently to evaluate the biokinetic parameters used in the model simulation. The removal efficiencies of phenol and chromium(VI) in an anaerobic fixed-biofilm process were approximately 980 mg/g and 910 mg/g, respectively, under a steady-state condition. In the steady state, model-predicted biofilm thickness reached up to 350 μm and suspended cells in the effluent were 85 mg cell/l. The experimental results agree closely with the results of the model simulations.

  7. Degradation of the anti-inflammatory drug ibuprofen by electro-peroxone process.

    Science.gov (United States)

    Li, Xiang; Wang, Yujue; Yuan, Shi; Li, Zhaoxin; Wang, Bin; Huang, Jun; Deng, Shubo; Yu, Gang

    2014-10-15

    Electro-peroxone (E-peroxone) treatment of the anti-inflammatory drug ibuprofen aqueous solution was investigated in this study. The E-peroxone process combined conventional ozonation with electrolysis processes, and used a carbon-polytetrafluorethylene cathode to electrochemically generate H2O2 from O2 in the sparged ozone generator effluent (O2 and O3 mixture). The in-situ generated H2O2 then reacted with the sparged O3 to produce aqueous •OH, which can in turn oxidize pollutants effectively in the bulk solution. The E-peroxone process overcomes several intrinsic limitations of conventional ozonation and electrolysis processes for pollutant degradation such as the selective oxidation with O3 and mass transfer limitations of pollutants to the electrodes, and thus significantly enhanced both ibuprofen degradation and total organic carbon (TOC) mineralization. Results show that ibuprofen could be completely degraded much more rapidly in the E-peroxone process (e.g., 5-15 min under all tested reaction conditions) than in ozonation (≥30 min) and electrolysis (several hours) processes. In addition, thanks to the powerful and non-selective oxidation capacity of •OH, toxic intermediates formed during ibuprofen degradation could be completely mineralized in the E-peroxone process. The E-peroxone effluent (2 h) thus exhibited much lower toxicity (5% inhibition of bioluminescence of Vibrio fisheri) than the ozonation and electrolysis effluents (22% and 88% inhibition, respectively). The results of this study indicate that the E-peroxone process may provide a promising technology for pharmaceutical wastewater treatment. PMID:24981746

  8. Stochastic model for the geometrical rail track degradation process in the Portuguese railway Northern Line

    International Nuclear Information System (INIS)

    The geometrical track degradation is characterized by the evolution over time (or tonnage) of several parameters such as the longitudinal level, the alignment, the gauge, the twist and the cross level. Dynamic track inspections allow monitoring the track geometrical quality which is essential to ensure track availability and reliability, passenger safety and comfort and also energy efficiency. The track geometrical quality is guaranteed by performing condition-based maintenance and renewal actions during the life of the track and for that it is crucial to understand the geometrical track degradation process. In this paper, a stochastic model for characterizing the geometrical track degradation process over time is presented. The Portuguese railway Northern Line is adopted as a case-study and a statistic analysis is performed for different vehicle speed groups, in accordance with CEN [1]. The new contribution of this research is that the Dagum distribution, usually adopted for representing the income distribution, may represent the geometrical track degradation process in terms of the longitudinal level

  9. Impact of process variations and long term degradation on 6T-SRAM cells

    Directory of Open Access Journals (Sweden)

    Th. Fischer

    2007-06-01

    Full Text Available In modern deep-submicron CMOS technologies voltage scaling can not keep up with the scaling of the dimensions of transistors. Therefore the electrical fields inside the transistors are not constant anymore, while scaling down the device area. The rising electrical fields bring up reliability problems, such as hot carrier injection. Also other long term degradation mechanisms like Negative Bias Temperature Instability (NBTI come into the focus of circuit design.

    Along with process device parameter variations (threshold voltage, mobility, variations due to the degradation of devices form a big challenge for designers to build circuits that both yield high under the influence of process variations and remain functional with respect to long term device drift.

    In this work we present the influence of long term degradation and process variations on the performance of SRAM core-cells and parametric yield of SRAM arrays. For different use cases we show the performance degradation depending on temperature and supply voltage.

  10. Enhanced degradation of 4-nitrophenol by microwave assisted Fe/EDTA process

    International Nuclear Information System (INIS)

    A microwave assisted zero-valent iron oxidation process was studied in order to investigate the synergetic effects of MW irradiation on Fe/EDTA system (Fe/EDTA/MW) treated 4-nitrophenol (4-NP) from aqueous solution. The results indicated that the thermal effect of microwave improved the removal effect of 4-NP and TOC through raising the temperature of the system, as well as the non-thermal effect generated by the interaction between the microwave and the Fe resulting in an increase in the hydrophobic character of Fe surface. During the degradation of 4-NP in Fe/EDTA/MW system, the optimum value for MW power, Fe, EDTA dosage was 400 W, 2 g and 0.4 mM, respectively. The possible pathway for degrading the 4-NP was proposed based on GC/MS and HPLC analysis of the degradation intermediates. The concentration change course of the main bio-refractory by-products, the aminophenol formed in the degradation of 4-NP suggested a more efficient degradation and mineralization in Fe/EDTA/MW system. Finally, BOD5/CODCr of the solution increased from 0.237 to 0.635 after reaction for 18 min, indicating that the biodegradability of wastewater was greatly improved by Fe/EDTA/MW system and would benefit to further treatment by biochemical methods.

  11. Degradation reliability modeling based on an independent increment process with quadratic variance

    Science.gov (United States)

    Wang, Zhihua; Zhang, Yongbo; Wu, Qiong; Fu, Huimin; Liu, Chengrui; Krishnaswamy, Sridhar

    2016-03-01

    Degradation testing is an important technique for assessing life time information of complex systems and highly reliable products. Motivated by fatigue crack growth (FCG) data and our previous study, this paper develops a novel degradation modeling approach, in which degradation is represented by an independent increment process with linear mean and general quadratic variance functions of test time or transformed test time if necessary. Based on the constructed degradation model, closed-form expressions of failure time distribution (FTD) and its percentiles can be straightforwardly derived and calculated. A one-stage method is developed to estimate model parameters and FTD. Simulation studies are conducted to validate the proposed approach, and the results illustrate that the approach can provide reasonable estimates even for small sample size situations. Finally, the method is verified by the FCG data set given as the motivating example, and the results show that it can be considered as an effective degradation modeling approach compared with the multivariate normal model and graphic approach.

  12. Fermentative Hydrogen Production from Combination of Tofu processing and anaerobic digester sludge wastes using a microbial consortium

    Energy Technology Data Exchange (ETDEWEB)

    You-Kwan, O.; Mi-Sun, K.

    2009-07-01

    The combination of Tofu manufacturing waste and anaerobic digester sludge was studied for fermentative H{sub 2} production in batch and continuous modes using a mixed culture originated from sewage. In order to increase the solubilization of organic substrates from Tofu waste, various pretreatments including heat-treatment, acid/alkali treatment, and sonication were examined alone or in combination with others. (Author)

  13. Computer-aided optimation and process control of continuous biotechnical processes - anaerobic waste water purification. Rechnergestuetzte Optimierung und Prozessfuehrung kontinuierlicher biotechnischer Prozesse - untersucht am Beispiel der anaeroben Abwasserreinigung

    Energy Technology Data Exchange (ETDEWEB)

    Schuerbuescher, D.

    1989-11-01

    On the basis of test results a mathematical model for the methanisation phase of anaerobic waste water purification was set up and used for further simulations. A continuously working adaptive pH-controller was used. It guarantees auxostatic process control and a very precise maintenance of a defined pH-value with continuously running substrate pump. A automatised method of optimising the temperature of continuous biotechnical processes was developed. The pH-value was kept constant by adapting the flow rate by means of the parameter-adaptive controller. This produced a cause-effect-relation between temperature and reactor output. The relation was observed and evaluated online via a pattern-recognition program and used for the further control decisions in such a way as to increase the output during the period of the test while avoiding any short-term damaging of the cultures. Performance increases of up to 30% were achieved that way. Balancing of the biogas flow allowed online calculation and precise control of the substrate concentration. Manual input of off-line measured values biogas amount and substrate concentration at irregular times were also integrated in the control concept. (orig./EF).

  14. Recent development of VUV-based processes for air pollutants degradation

    Directory of Open Access Journals (Sweden)

    Haibao eHuang

    2016-03-01

    Full Text Available As air pollution become more and more serious nowadays, it is essential to find out a way to efficiently degrade the air pollutants. Vacuum ultraviolet (VUV-based processes are an emerging and promising technologies for environmental remediation such as air cleaning, wastewater treatment and air/water disinfection. With VUV irradiation, photolysis, photocatalyst is and ozone-assisted oxidation are involved at the same time, resulting in the fast degradation of air pollutants because of their strong oxidizing capacity. The mechanisms of how the oxidants are produced and reacted are discussed in this review. This paper mainly focuses on the three VUV-based oxidation processes including VUV photolysis, VUV combined with ozone-assisted oxidation and VUV-PCO with emphasis on their mechanisms and applications. Also, the outlooks of these processes are outlined in this paper.

  15. SIMULTANEOUS DEGRADATION OF SOME PHTHALATE ESTERS UNDER FENTON AND PHOTO-FENTON OXIDATION PROCESSES

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    BELDEAN-GALEA M.S.

    2015-03-01

    Full Text Available In this study the assessment of the degradation efficiency of five phthalates, DEP, BBP, DEHP, DINP and DIDP, found in a mixture in a liquid phase, using the Fenton and Photo Fenton oxidation processes, was conducted. It was observed that the main parameters that influence the Fenton oxidative processes of phthalates were the concentration of the oxidizing agent, H2O2, the concentration of the catalyst used, Fe2+, the pH value, UV irradiation and the reaction time. For the Fenton oxidative process, the highest degradation efficiencies were 19% for DEP, 50% for BBP, 84% for DEHP, 90% for DINP and 48% for DIDP, when the experiments were carried out using concentrations of 20 mg L-1 phthalate mixture, 100 mg L-1 H2O2, 10 mg L-1 Fe2+ at a pH value of 3, with a total reaction time of 30 minutes. For the Photo-Fenton oxidative process carried out in the same conditions as Fenton oxidative process, it was observed that after an irradiation time of 90 minutes under UV radiation the degradation efficiencies of phthalates were improved, being 22% for DEP, 71% for BBP, 97% for DEHP, 97% for DINP and 81% for DIDP.

  16. ProBNP1-108 Processing and Degradation in Human Heart Failure

    Science.gov (United States)

    Huntley, Brenda K.; Sandberg, Sharon M.; Heublein, Denise M.; Sangaralingham, S. Jeson; Burnett, John C.; Ichiki, Tomoko

    2014-01-01

    Background We have reported that proBNP1-108 circulates and is processed to mature BNP1-32 in human blood. Building on these findings, we sought to determine whether proBNP1-108 processed forms in normal circulation are biologically active and stimulate cGMP, and whether proBNP1-108 processing and activity are altered in human heart failure (HF) compared to normal. Since BNP1-32 is deficient while proBNP1-108 is abundant in HF, we hypothesize that proBNP1-108 processing and degradation are impaired in HF patients ex vivo. Methods and Results We measured circulating molecular forms including BNP1-32, proBNP1-108, and NT-proBNP and all were significantly higher in HF patients compared to normals. Fresh serum samples from normals or HF patients were incubated with or without exogenous non-glycosylated proBNP1-108 tagged with 6 C-terminal Histidines to facilitate peptide isolation. His-tag ProBNP1-108 was efficiently processed into BNP1-32/3-32 at 5 min in normal serum, persisted for 15 min, then disappeared. Delayed processing of proBNP1-108 was observed in HF samples and the degradation pattern differed depending on LV function. The 5 min processed forms from both normal and HF serums were active and generated cGMP via GC-A receptors, however the 180 min samples were not active. The proBNP1-108 processing enzyme corin and BNP degrading enzyme DPPIV were reduced in HF versus normal, perhaps contributing to differential BNP metabolism in HF. Conclusions Exogenous proBNP1-108 is processed into active BNP1-32 and ultimately degraded in normal circulation. The processing and degradation of BNP molecular forms was altered but complete in HF which may contribute the pathophysiology of HF. PMID:25339504

  17. Relationship between fiber degradation and residence time distribution in the processing of long fiber reinforced thermoplastics

    Directory of Open Access Journals (Sweden)

    2008-08-01

    Full Text Available Long fiber reinforced thermoplastics (LFT were processed by in-line compounding equipment with a modified single screw extruder. A pulse stimulus response technique using PET spheres as the tracer was adopted to obtain residence time distribution (RTD of extrusion compounding. RTD curves were fitted by the model based on the supposition that extrusion compounding was the combination of plug flow and mixed flow. Characteristic parameters of RTD model including P the fraction of plug flow reactor (PFR and d the fraction of dead volume of continuous stirred tank reactor (CSTR were used to associate with fiber degradation presented by fiber length and dispersion. The effects of screw speed, mixing length and channel depth on RTD curves, and characteristic parameters of RTD models as well as their effects on the fiber degradation were investigated. The influence of shear force with different screw speeds and variable channel depth on fiber degradation was studied and the main impetus of fiber degradation was also presented. The optimal process for obtaining the balance of fiber length and dispersion was presented.

  18. Colloids-associated concentrations model and experimental studies for a waste form degradation process model

    International Nuclear Information System (INIS)

    A Waste Form Degradation Process Model has been developed as part of the total system performance assessment (TSPA) that will be used to evaluate the postclosure performance of a potential monitoring geologic repository at Yucca Mountain. For the Colloidal Radioisotope Concentration Component of this degradation model, the conceptualization directly used Yucca Mountain Project (YMP)-relevant experimental results from YMP-specific work and from the published literature. The conceptualization identified the availability and the stability of three categories of colloids: (1) existing colloids in the groundwater, (2) colloids generated during degradation of the waste, and (3) colloids generated during degradation of the disposal container. The faction of the colloidal radioisotope concentration component is to calculate the concentration of colloid-associated radionuclides that may be transported from the waste package. Attachment of radionuclides can range from instantaneously reversible to completely irreversibly bound attachment. This process was modeled using these two bounding end members. For waste form colloids, radionuclides can be incorporated into the substrate material before it is suspended as colloids. All colloid types may sorb radionuclides to form pseudocolloids, depending on the affinity of the colloid mineral substrate for a dissolved radionuclide. The contributions of each colloid type are summed to produce the mobile colloid source term for each important radionuclide. The models are based on laboratory results from waste form corrosion testing and testing of adsorption and desorption properties of Pu and Am on clay and iron-(hydr)oxide colloids. To the extent that the laboratory tests and test conditions represent anticipated repository conditions, the model is valid for calculating the colloid-associated radionuclide concentrations and colloid mass concentrations. This paper will describe and summarize the models and experimental studies used in

  19. Degradation processes in high power multi-mode InGaAs strained quantum well lasers

    Science.gov (United States)

    Sin, Yongkun; Presser, Nathan; Foran, Brendan; Moss, Steven C.

    2009-02-01

    Recently, broad-area InGaAs-AlGaAs strained quantum well (QW) lasers have attracted much attention because of their unparalleled high optical output power characteristics that narrow stripe lasers or tapered lasers can not achieve. However, broad-area lasers suffer from poor beam quality and their high reliability operation has not been proven for communications applications. This paper concerns reliability and degradation aspects of broad-area lasers. Good facet passivation techniques along with optimized structural designs have led to successful demonstration of reliable 980nm single-mode lasers, and the dominant failure mode of both single-mode and broadarea lasers is catastrophic optical mirror damage (COMD), which limits maximum output powers and also determines operating output powers. Although broad-area lasers have shown characteristics unseen from singlemode lasers including filamentation, their effects on long-term reliability and degradation processes have not been fully investigated. Filamentation can lead to instantaneous increase in optical power density and thus temperature rise at localized areas through spatial-hole burning and thermal lensing which significantly reduces filament sizes under high power operation, enhancing the COMD process. We investigated degradation processes in commercial MOCVD-grown broad-area InGaAs-AlGaAs strained QW lasers at ~975nm with and without passivation layers by performing accelerated lifetests of these devices followed by failure mode analyses with various micro-analytical techniques. Since instantaneous fluctuations of filaments can lead to faster wear-out of passivation layer thus leading to facet degradation, both passivated and unpassivated broad-area lasers were studied that yielded catastrophic failures at the front facet and also in the bulk. Electron beam induced current technique was employed to study dark line defects (DLDs) generated in degraded lasers stressed under different test conditions and focused

  20. COMPARISON OF DIFFERENT ADVANCED OXIDATION PROCESSES DEGRADING P-CHLOROPHENOL IN AQUEOUS SOLUTION

    Directory of Open Access Journals (Sweden)

    H. Movahedyan ، A. M. Seid Mohammadi ، A. Assadi

    2009-07-01

    Full Text Available In present study, degradation of p-chlorophenol using several oxidation systems involving advanced oxidation processes such as ultraviolet/H2O2, microwave/H2O2 and both in the absence of hydrogen peroxide in batch mode by photolytic pilot plant and modified domestic microwave oven was evaluated. The oxidation rate was influenced by many factors, such as the pH value, the amount of hydrogen peroxide, irradiation time and microwave power. The optimum conditions obtained for the best degradation rate were pH=7 and H2O2 concentration of 0.05 mol/L for ultraviolet/H2O2 system and pH=10.5, H2O2 concentration of about 0.1 mol/L and microwave irradiation power of about 600W for microwave/H2O2 system at constant p-chlorophenol concentration. The degradation of p-chlorophenol by different types of oxidation processes followed first order rate decay kinetics. The rate constants were 0.137, 0.012, 0.02 and 0.004/min1 for ultraviolet/H2O2, microwave/H2O2, ultraviolet and microwave irradiation alone. Finally a comparison of the specific energy consumption showed that ultraviolet/H2O2 process reduced the energy consumption by at least 67% compared with the microwave/H2O2 process.