Anaerobic digestion of municipal solid waste: Technical developments

Energy Technology Data Exchange (ETDEWEB)

Rivard, C.J. [National Renewable Energy Lab., Golden, CO (United States)

1996-01-01

The anaerobic biogasification of organic wastes generates two useful products: a medium-Btu fuel gas and a compost-quality organic residue. Although commercial-scale digestion systems are used to treat municipal sewage wastes, the disposal of solid organic wastes, including municipal solid wastes (MSW), requires a more cost-efficient process. Modern biogasification systems employ high-rate, high-solids fermentation methods to improve process efficiency and reduce capital costs. The design criteria and development stages are discussed. These systems are also compared with conventional low-solids fermentation technology.

Anaerobic digestion of solid slaughterhouse waste chemically pretreated

Energy Technology Data Exchange (ETDEWEB)

Flores, C.; Montoya, L.; Rodirguez, A.

2009-07-01

One of the mayor problems facing the industrialized world today is to solve environmental contamination and identify efficient treatment to give solution to the current problems like the generation of enormous quantities of liquid and solid wastes. The solid slaughterhouse waste, due to its elevated concentration of biodegradable organics, can be efficiently treated by anaerobic digestion although the high content of lignocellulose materials, makes it a slowly process. (Author)

Anaerobic digestion of solid slaughterhouse waste chemically pretreated

International Nuclear Information System (INIS)

Flores, C.; Montoya, L.; Rodirguez, A.

2009-01-01

One of the mayor problems facing the industrialized world today is to solve environmental contamination and identify efficient treatment to give solution to the current problems like the generation of enormous quantities of liquid and solid wastes. The solid slaughterhouse waste, due to its elevated concentration of biodegradable organics, can be efficiently treated by anaerobic digestion although the high content of lignocellulose materials, makes it a slowly process. (Author)

[Anaerobic digestion of lignocellulosic biomass with animal digestion mechanisms].

Science.gov (United States)

Wu, Hao; Zhang, Pan-Yue; Guo, Jian-Bin; Wu, Yong-Jie

2013-02-01

Lignocellulosic material is the most abundant renewable resource in the earth. Herbivores and wood-eating insects are highly effective in the digestion of plant cellulose, while anaerobic digestion process simulating animal alimentary tract still remains inefficient. The digestion mechanisms of herbivores and wood-eating insects and the development of anaerobic digestion processes of lignocellulose were reviewed for better understanding of animal digestion mechanisms and their application in design and operation of the anaerobic digestion reactor. Highly effective digestion of lignocellulosic materials in animal digestive system results from the synergistic effect of various digestive enzymes and a series of physical and biochemical reactions. Microbial fermentation system is strongly supported by powerful pretreatment, such as rumination of ruminants, cellulase catalysis and alkali treatment in digestive tract of wood-eating insects. Oxygen concentration gradient along the digestive tract may stimulate the hydrolytic activity of some microorganisms. In addition, the excellent arrangement of solid retention time, digesta flow and end product discharge enhance the animal digestion of wood cellulose. Although anaerobic digestion processes inoculated with rumen microorganisms based rumen digestion mechanisms were developed to treat lignocellulose, the fermentation was more greatly limited by the environmental conditions in the anaerobic digestion reactors than that in rumen or hindgut. Therefore, the anaerobic digestion processes simulating animal digestion mechanisms can effectively enhance the degradation of wood cellulose and other organic solid wastes.

Effect of Increasing Total Solids Contents on Anaerobic Digestion of Food Waste under Mesophilic Conditions: Performance and Microbial Characteristics Analysis

OpenAIRE

Yi, Jing; Dong, Bin; Jin, Jingwei; Dai, Xiaohu

2014-01-01

The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste...

Solid anaerobic digestion batch with liquid digestate recirculation and wet anaerobic digestion of organic waste: Comparison of system performances and identification of microbial guilds.

Science.gov (United States)

Di Maria, Francesco; Barratta, Martino; Bianconi, Francesco; Placidi, Pisana; Passeri, Daniele

2017-01-01

Solid anaerobic digestion batch (SADB) with liquid digestate recirculation and wet anaerobic digestion of organic waste were experimentally investigated. SADB was operated at an organic loading rate (OLR) of 4.55kgVS/m 3 day, generating about 252NL CH 4 /kgVS, whereas the wet digester was operated at an OLR of 0.9kgVS/m 3 day, generating about 320NL CH 4 /kgVS. The initial total volatile fatty acids concentrations for SADB and wet digestion were about 12,500mg/L and 4500mg/L, respectively. There were higher concentrations of ammonium and COD for the SADB compared to the wet one. The genomic analysis performed by high throughput sequencing returned a number of sequences for each sample ranging from 110,619 to 373,307. More than 93% were assigned to the Bacteria domain. Seven and nine major phyla were sequenced for the SADB and wet digestion, respectively, with Bacteroidetes, Firmicutes and Proteobacteria being the dominant phyla in both digesters. Taxonomic profiles suggested a methanogenic pathway characterized by a relevant syntrophic acetate-oxidizing metabolism mainly in the liquid digestate of the SADB. This result also confirms the benefits of liquid digestate recirculation for improving the efficiency of AD performed with high solids (>30%w/w) content. Copyright © 2016 Elsevier Ltd. All rights reserved.

Research advances in dry anaerobic digestion process of solid ...

African Journals Online (AJOL)

The dry anaerobic digestion process is an innovative waste-recycling method to treat high-solidcontent bio-wastes. This can be done without dilution with water by microbial consortia in an oxygenfree environment to recover potential renewable energy and nutrient-rich fertilizer for sustainable solid waste management.

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.

Laboratory scale anaerobic digestion of fruit and vegetable solid waste

Energy Technology Data Exchange (ETDEWEB)

Lane, A.G.

1984-01-01

Anaerobic digestions that were fed waste apple, corn cobs, apple press cake, extracted sugarbeet pulp, pineapple pressings or asparagus waste were stable in trials lasting up to 226 days. Loading rates of 3.5-4.25 kg/m/sup 3/ day and conversions of 88-96% of the organic solids fed were obtained by ensuring adequate levels of alkalinity, nitrogen and other nutrients during digestion. Gas yields ranged from 0.429 to 0.568 litre (50-60% methane) per gram organic solids fed. For reasons not understood, gas yields from digestion of apricot waste declined after 63 days from 0.477 to 0.137 litre/g of feedstock. 22 references.

Effect of increasing total solids contents on anaerobic digestion of food waste under mesophilic conditions: performance and microbial characteristics analysis.

Directory of Open Access Journals (Sweden)

Jing Yi

Full Text Available The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies.

Effect of Increasing Total Solids Contents on Anaerobic Digestion of Food Waste under Mesophilic Conditions: Performance and Microbial Characteristics Analysis

Science.gov (United States)

Jin, Jingwei; Dai, Xiaohu

2014-01-01

The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies. PMID:25051352

Effect of increasing total solids contents on anaerobic digestion of food waste under mesophilic conditions: performance and microbial characteristics analysis.

Science.gov (United States)

Yi, Jing; Dong, Bin; Jin, Jingwei; Dai, Xiaohu

2014-01-01

The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies.

Microbial and nutritional regulation of high-solids anaerobic mono-digestion of fruit and vegetable wastes.

Science.gov (United States)

Mu, Hui; Li, Yan; Zhao, Yuxiao; Zhang, Xiaodong; Hua, Dongliang; Xu, Haipeng; Jin, Fuqiang

2018-02-01

The anaerobic digestion of single fruit and vegetable wastes (FVW) can be easily interrupted by rapid acidogenesis and inhibition of methanogen, and the digestion system tends to be particularly unstable at high solid content. In this study, the anaerobic digestion of FVW in batch experiments under mesophilic condition at a high solid concentration of 10% was successfully conducted to overcome the acidogenesis problem through several modifications. Firstly, compared with the conventional anaerobic sludge (CAS), the acclimated anaerobic granular sludge (AGS) was found to be a better inoculum due to its higher Archaea abundance. Secondly, waste activated sludge (WAS) was chosen to co-digest with FVW, because WAS had abundant proteins that could generate intermediate ammonium. The ammonium could neutralize the accumulated volatile fatty acids (VFAs) and prevent the pH value of the digestion system from rapidly decreasing. Co-digestion of FVW and WAS with TS ratio of 60:40 gave the highest biogas yield of 562 mL/g-VS and the highest methane yield of 362 mL/g-VS. Key parameters in the digestion process, including VFAs concentration, pH, enzyme activity, and microbial activity, were also examined.

High-solid Anaerobic Co-digestion of Sewage Sludge and Cattle Manure: The Effects of Volatile Solid Ratio and pH

Science.gov (United States)

Dai, Xiaohu; Chen, Yang; Zhang, Dong; Yi, Jing

2016-01-01

High-solid anaerobic digestion is an attractive solution to the problem of sewage sludge disposal. One method that can be used to enhance the production of volatile fatty acids (VFAs) and the generation of methane from anaerobic digestion involves combining an alkaline pretreatment step with the synergistic effects of sewage sludge and cattle manure co-digestion, which improves the activity of key enzymes and microorganisms in the anaerobic co-digestion system to promote the digestion of organic waste. In this study, we describe an efficient strategy that involves adjusting the volatile solid (VS) ratio (sewage sludge/cattle manure: 3/7) and initial pH (9.0) to improve VFA production and methane generation from the co-digestion of sludge and manure. The experimental results indicate that the maximum VFA production was 98.33 g/kg-TS (total solid) at the optimal conditions. Furthermore, methane generation in a long-term semi-continuously operated reactor (at a VS ratio of 3/7 and pH of 9.0) was greater than 120.0 L/kg-TS. PMID:27725704

Performance and kinetic study of semi-dry thermophilic anaerobic digestion of organic fraction of municipal solid waste

International Nuclear Information System (INIS)

Sajeena Beevi, B.; Madhu, G.; Sahoo, Deepak Kumar

2015-01-01

Highlights: • Performance of the reactor was evaluated by the degradation of volatile solids. • Biogas yield at the end of the digestion was 52.9 L/kg VS. • Value of reaction rate constant, k, obtained was 0.0249 day −1 . • During the digestion 66.7% of the volatile solid degradation was obtained. - Abstract: Anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) is promoted as an energy source and waste disposal. In this study semi dry anaerobic digestion of organic solid wastes was conducted for 45 days in a lab-scale batch experiment for total solid concentration of 100 g/L for investigating the start-up performances under thermophilic condition (50 °C). The performance of the reactor was evaluated by measuring the daily biogas production and calculating the degradation of total solids and the total volatile solids. The biogas yield at the end of the digestion was 52.9 L/kg VS (volatile solid) for the total solid (TS) concentration of 100 g/L. About 66.7% of the volatile solid degradation was obtained during the digestion. A first order model based on the availability of substrate as the limiting factor was used to perform the kinetic studies of batch anaerobic digestion system. The value of reaction rate constant, k, obtained was 0.0249 day −1

Performance and kinetic study of semi-dry thermophilic anaerobic digestion of organic fraction of municipal solid waste

Energy Technology Data Exchange (ETDEWEB)

Sajeena Beevi, B., E-mail: sajeenanazer@gmail.com [Department of Chemical Engineering, Govt. Engineering College, Thrissur, Kerala 680 009 (India); Madhu, G., E-mail: profmadhugopal@gmail.com [Division of Safety & Fire Engineering, School of Engineering, Cochin University of Science and Technology, Cochin, Kerala 682 022 (India); Sahoo, Deepak Kumar, E-mail: dksahoo@gmail.com [Division of Safety & Fire Engineering, School of Engineering, Cochin University of Science and Technology, Cochin, Kerala 682 022 (India)

2015-02-15

Highlights: • Performance of the reactor was evaluated by the degradation of volatile solids. • Biogas yield at the end of the digestion was 52.9 L/kg VS. • Value of reaction rate constant, k, obtained was 0.0249 day{sup −1}. • During the digestion 66.7% of the volatile solid degradation was obtained. - Abstract: Anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) is promoted as an energy source and waste disposal. In this study semi dry anaerobic digestion of organic solid wastes was conducted for 45 days in a lab-scale batch experiment for total solid concentration of 100 g/L for investigating the start-up performances under thermophilic condition (50 °C). The performance of the reactor was evaluated by measuring the daily biogas production and calculating the degradation of total solids and the total volatile solids. The biogas yield at the end of the digestion was 52.9 L/kg VS (volatile solid) for the total solid (TS) concentration of 100 g/L. About 66.7% of the volatile solid degradation was obtained during the digestion. A first order model based on the availability of substrate as the limiting factor was used to perform the kinetic studies of batch anaerobic digestion system. The value of reaction rate constant, k, obtained was 0.0249 day{sup −1}.

Modified anaerobic digestion elutriated phased treatment for the anaerobic co-digestion of sewage sludge and food wastewater.

Science.gov (United States)

Mo, Kyung; Lee, Wonbae; Kim, Moonil

2017-02-01

A modified anaerobic digestion elutriated phased treatment (MADEPT) process was developed for investigating anaerobic co-digestion of sewage sludge and food wastewater. The anaerobic digestion elutriated phased treatment (ADEPT) process is similar to a two-phase system, however, in which the effluent from a methanogenic reactor recycles into an acidogenic reactor to elutriate mainly dissolved organics. Although ADEPT could reduce reactor volume significantly, the unsolubilized solids should be wasted from the system. The MADEPT process combines thermo-alkali solubilization with ADEPT to improve anaerobic performance and to minimize the sludge disposal. It was determined that the optimal volume mixing ratio of sewage sludge and food wastewater was 4 : 1 for the anaerobic co-digestion. The removal efficiencies of total chemical oxygen demand, volatile solids, and volatile suspended solids in the MADEPT process were 73%, 70%, and 64%, respectively. However, those in the ADEPT process were only 48%, 37%, and 40%, respectively, at the same hydraulic retention time (HRT) of 7 days. The gas production of MADEPT was two times higher than that of ADEPT. The thermo-alkali solubilization increased the concentration of dissolved organics so that they could be effectively degraded in a short HRT, implying that MADEPT could improve the performance of ADEPT in anaerobic co-digestion.

Anaerobic Digestion Assessment for Contingency Base Waste

Science.gov (United States)

2014-05-01

heating. The use of anaerobic digestion for high solids organic waste (15 to 50 percent solids; i.e., mixed organic solids, such as food waste, manure ...but the team was not able to identify any for anaerobic digestion . One potentially widespread source is manure from ruminant organisms, such as...plug-flow digesters treating swine manure and used cooking grease. Bioresource Technology 101:4362-4370. ERDC TR-14-3 63 Lansing, S., and A.R

Study of the operational conditions for anaerobic digestion of urban solid wastes

International Nuclear Information System (INIS)

Castillo M, Edgar Fernando; Cristancho, Diego Edison; Victor Arellano, A.

2006-01-01

This paper describes an experimental evaluation of anaerobic digestion technology as an option for the management of organic solid waste in developing countries. As raw material, a real and heterogeneous organic waste from urban solid wastes was used. In the first experimental phase, seed selection was achieved through an evaluation of three different anaerobic sludges coming from wastewater treatment plants. The methanization potential of these sludges was assessed in three different batch digesters of 500 mL, at two temperature levels. The results showed that by increasing the temperature to 15 deg. C above room temperature, the methane production increases to three times. So, the best results were obtained in the digester fed with a mixed sludge, working at mesophilic conditions (38-40 deg. C). Then, this selected seed was used at the next experimental phase, testing at different digestion times (DT) of 25, 20 and 18 days in a bigger batch digester of 20 L with a reaction volume of 13 L. The conversion rates were registered at the lowest DT (18 days), reaching 44.9 L/kg -1 of wet waste day -1 . Moreover, DT also has a strong influence over COD removal, because there is a direct relationship between solids removal inside the reactor and DT

Chemically pretreating slaughterhouse solid waste to increase the efficiency of anaerobic digestion.

Science.gov (United States)

Flores-Juarez, Cyntia R; Rodríguez-García, Adrián; Cárdenas-Mijangos, Jesús; Montoya-Herrera, Leticia; Godinez Mora-Tovar, Luis A; Bustos-Bustos, Erika; Rodríguez-Valadez, Francisco; Manríquez-Rocha, Juan

2014-10-01

The combined effect of temperature and pretreatment of the substrate on the anaerobic treatment of the organic fraction of slaughterhouse solid waste was studied. The goal of the study was to evaluate the effect of pretreating the waste on the efficiency of anaerobic digestion. The effect was analyzed at two temperature ranges (the psychrophilic and the mesophilic ranges), in order to evaluate the effect of temperature on the performance of the anaerobic digestion process for this residue. The experiments were performed in 6 L batch reactors for 30 days. Two temperature ranges were studied: the psychrophilic range (at room temperature, 18°C average) and the mesophilic range (at 37°C). The waste was pretreated with NaOH before the anaerobic treatment. The result of pretreating with NaOH was a 194% increase in the soluble chemical oxygen demand (COD) with a dose of 0.6 g NaOH per g of volatile suspended solids (VSS). In addition, the soluble chemical oxygen demand/total chemical oxygen demand ratio (sCOD/tCOD) increased from 0.31 to 0.7. For the anaerobic treatment, better results were observed in the mesophilic range, achieving 70.7%, 47% and 47.2% removal efficiencies for tCOD, total solids (TS), and volatile solids (VS), respectively. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Fast characterization of solid organic waste content with near infrared spectroscopy in anaerobic digestion.

Science.gov (United States)

Charnier, Cyrille; Latrille, Eric; Jimenez, Julie; Lemoine, Margaux; Boulet, Jean-Claude; Miroux, Jérémie; Steyer, Jean-Philippe

2017-01-01

The development of anaerobic digestion involves both co-digestion of solid wastes and optimization of the feeding recipe. Within this context, substrate characterisation is an essential issue. Although it is widely used, the biochemical methane potential is not sufficient to optimize the operation of anaerobic digestion plants. Indeed the biochemical composition in carbohydrates, lipids, proteins and the chemical oxygen demand of the inputs are key parameters for the optimisation of process performances. Here we used near infrared spectroscopy as a robust and less-time consuming tool to predict the solid waste content in carbohydrates, lipids and nitrogen, and the chemical oxygen demand. We built a Partial Least Square regression model with 295 samples and validated it with an independent set of 46 samples across a wide range of solid wastes found in anaerobic digestion units. The standard errors of cross-validation were 90mgO 2 ⋅gTS -1 carbohydrates, 2.5∗10 -2 g⋅gTS -1 lipids, 7.2∗10 -3 g⋅gTS -1 nitrogen and 99mgO 2 ⋅gTS -1 chemical oxygen demand. The standard errors of prediction were 53mgO 2 ⋅gTS -1 carbohydrates, 3.2∗10 -2 g⋅gTS -1 lipids, 8.6∗10 -3 g⋅gTS -1 nitrogen and 83mgO 2 ⋅gTS -1 chemical oxygen demand. These results show that near infrared spectroscopy is a new fast and cost-efficient way to characterize solid wastes content and improve their anaerobic digestion monitoring. Copyright © 2016 Elsevier Ltd. All rights reserved.

Indigenous microbial capability in solid manure residues to start-up solid-phase anaerobic digesters.

Science.gov (United States)

Yap, S D; Astals, S; Jensen, P D; Batstone, D J; Tait, S

2017-06-01

Batch solid-phase anaerobic digestion is a technology for sustainable on-farm treatment of solid residues, but is an emerging technology that is yet to be optimised with respect to start-up and inoculation. In the present study, spent bedding from two piggeries (site A and B) were batch digested at total solids (TS) concentration of 5, 10 and 20% at mesophilic (37°C) and thermophilic (55°C) temperatures, without adding an external inoculum. The results showed that the indigenous microbial community present in spent bedding was able to recover the full methane potential of the bedding (140±5 and 227±6L CH 4 kgVS fed -1 for site A and B, respectively), but longer treatment times were required than for digestion with an added external inoculum. Nonetheless, at high solid loadings (i.e. TS level>10%), the digestion performance was affected by chemical inhibition due to ammonia and/or humic acid. Thermophilic temperatures did not influence digestion performance but did increase start-up failure risk. Further, inoculation of residues from the batch digestion to subsequent batch enhanced start-up and achieved full methane potential recovery of the bedding. Inoculation with liquid residue (leachate) was preferred over a solid residue, to preserve treatment capacity for fresh substrate. Overall, the study highlighted that indigenous microbial community in the solid manure residue was capable of recovering full methane potential and that solid-phase digestion was ultimately limited by chemical inhibition rather than lack of suitable microbial community. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhancing anaerobic digestion of waste activated sludge by pretreatment: effect of volatile to total solids.

Science.gov (United States)

Wang, Xiao; Duan, Xu; Chen, Jianguang; Fang, Kuo; Feng, Leiyu; Yan, Yuanyuan; Zhou, Qi

2016-01-01

In this study the effect of volatile to total solids (VS/TS) on anaerobic digestion of waste activated sludge (WAS) pretreated by alkaline, thermal and thermal-alkaline strategies was studied. Experimental results showed that the production of methane from sludge was increased with VS/TS. When anaerobic digesters were fed with sludge pretreated by the thermal-alkaline method, the average methane yield was improved from 2.8 L/d at VS/TS 0.35 to 4.7 L/d at VS/TS 0.56. Also, the efficiency of VS reduction during sludge anaerobic digestion varied between 18.9% and 45.6%, and increased gradually with VS/TS. Mechanism investigation of VS/TS on WAS anaerobic digestion suggested that the general activities of anaerobic microorganisms, activities of key enzymes related to sludge hydrolysis, acidification and methanogenesis, and the ratio of Archaea to Bacteria were all increased with VS/TS, showing good agreement with methane production.

Hydrothermal carbonization of autoclaved municipal solid waste pulp and anaerobically treated pulp digestate

Science.gov (United States)

In this study, the autoclaved organic fraction of municipal solid waste pulp (OFMSW) and the digestate from OFMSW pulp after anaerobic digestion (AD) were processed by hydrothermal carbonization (HTC) at 200, 250, and 300 °C for 30 min and 2 h. The focus of this work was to evaluate the potential fo...

Anaerobic digestion apparatus and process. Procede et installation de digestion anaerobie

Energy Technology Data Exchange (ETDEWEB)

De Baere, L.

1989-05-09

This invention concerns a process for the anaerobic digestion of apparently solid organic matter. The matter is mixed and kneaded with an inoculant to form an apparently solid mass having a water content which varies from around 55 wt % to around 75 wt %. This mass is then introduced into a digestor, where it is digested for a period of around less than 50 days. The biogas produced during the anaerobic digestion stage is recovered, said biogas being a byproduct of the digestion process. The digested mass is extracted, and at least a third, by weight, of that mass is recycled to act as the inoculant. The non-recycled digested mass is removed.

Microbial Insight into a Pilot-Scale Enhanced Two-Stage High-Solid Anaerobic Digestion System Treating Waste Activated Sludge.

Science.gov (United States)

Wu, Jing; Cao, Zhiping; Hu, Yuying; Wang, Xiaolu; Wang, Guangqi; Zuo, Jiane; Wang, Kaijun; Qian, Yi

2017-11-30

High solid anaerobic digestion (HSAD) is a rapidly developed anaerobic digestion technique for treating municipal sludge, and has been widely used in Europe and Asia. Recently, the enhanced HSAD process with thermal treatment showed its advantages in both methane production and VS reduction. However, the understanding of the microbial community is still poor. This study investigated microbial communities in a pilot enhanced two-stage HSAD system that degraded waste activated sludge at 9% solid content. The system employed process "thermal pre-treatment (TPT) at 70 °C, thermophilic anaerobic digestion (TAD), and mesophilic anaerobic digestion (MAD)". Hydrogenotrophic methanogens Methanothermobacter spp. dominated the system with relative abundance up to about 100% in both TAD and MAD. Syntrophic acetate oxidation (SAO) bacteria were discovered in TAD, and they converted acetate into H₂ and CO₂ to support hydrogenotrophic methanogenesis. The microbial composition and conversion route of this system are derived from the high solid content and protein content in raw sludge, as well as the operational conditions. This study could facilitate the understanding of the enhanced HSAD process, and is of academic and industrial importance.

Wet and Dry Anaerobic Digestion of Biowaste and of Co-substrates

OpenAIRE

Li, Chaoran

2015-01-01

Treatment of municipal solid waste by anaerobic digestion can solve the environmental problems caused by this organic solid waste and also supply biogas as renewable energy for a sustainable development. In this study the improvement of wet anaerobic digestion by addition of co-substrates and the effect of moisture on dry anaerobic digestion were investigated.

Impact of Organic Loading Rate on Psychrophilic Anaerobic Digestion of Solid Dairy Manure

Directory of Open Access Journals (Sweden)

Noori M. Cata Saady

2015-03-01

Full Text Available Increasing the feed total solids to anaerobic digester improves the process economics and decreases the volume of liquid effluent from current wet anaerobic digestion. The objective of this study was to develop a novel psychrophilic (20 °C anaerobic digestion technology of undiluted cow feces (total solids of 11%–16%. Two sets of duplicate laboratory-scale sequence batch bioreactors have been operated at organic loading rates (OLR of 6.0 to 8.0 g total chemical oxygen demand (TCOD kg−1 inoculum day−1 (d−1 during 210 days. The results demonstrated that the process is feasible at treatment cycle length (TCL of 21 days; however, the quality of cow feces rather than the OLR had a direct influence on the specific methane yield (SMY. The SMY ranged between 124.5 ± 1.4 and 227.9 ± 4.8 normalized liter (NL CH4 kg−1 volatile solids (VS fed d−1. Substrate-to-inoculum mass ratio (SIR was 0.63 ± 0.05, 0.90 ± 0.09, and 1.06 ± 0.07 at OLR of 6.0, 7.0, and 8.0 g TCOD kg−1 inoculum d−1, respectively. No volatile fatty acids (VFAs accumulation has been observed which indicated that hydrolysis was the rate limiting step and VFAs have been consumed immediately. Bioreactors performance consistency in terms of the level of SMYs, VFAs concentrations at end of the TCL, pH stability and volatile solids reduction indicates a stable and reproducible process during the entire operation.

Kinetic modeling of the effect of solids retention time on methanethiol dynamics in anaerobic digestion.

Science.gov (United States)

Zhang, Dian; Strawn, Mary; Novak, John T; Wang, Zhi-Wu

2018-07-01

The highly volatile methanethiol (MT) with an extremely low odor threshold and distinctive putrid smell is often identified as a major odorous compound generated under anaerobic conditions. As an intermediate compound in the course of anaerobic digestion, the extent of MT emission is closely related to the time of anaerobic reaction. In this study, lab-scale anaerobic digesters were operated at solids retention time (SRTs) of 15, 20, 25, 30, 40 and 50 days to investigate the effect of SRT on MT emission. The experimental results demonstrated a bell-shaped curve of MT emission versus SRT with a peak around 20 days SRT. In order to understand this SRT effect, a kinetic model was developed to describe MT production and utilization dynamics in the course of anaerobic digestion and calibrated with the experimental results collected from this study. The model outcome revealed that the high protein content in the feed sludge together with the large maintenance coefficient of MT fermenters are responsible for the peak MT emission emergence in the range of typical SRT used for anaerobic digestion. A further analysis of the kinetic model shows that it can be extensively simplified with reasonable approximation to a form that anaerobic digestion practitioners could easily use to predict the MT and SRT relationship. Copyright © 2018 Elsevier Ltd. All rights reserved.

Solid-State Anaerobic Digestion of Dairy Manure from a Sawdust-Bedded Pack Barn: Moisture Responses

Directory of Open Access Journals (Sweden)

Eunjong Kim

2018-02-01

Full Text Available Bedded pack manure has long been considered an unsuitable feedstock for conventional anaerobic digestion systems due to its high solids content. However, solid-state anaerobic digestion (SS-AD provides an opportunity to generate methane from such high-solids feedstocks. This study was conducted to determine the influence of moisture content on the digestion of bedded pack dairy manure using SS-AD. Mixtures of sawdust bedding and dairy manure were prepared with moisture contents (MCs of 70, 76, and 83% and digested at 37 °C for 85 days. The performance of digesters containing manure at 83% MC was 1.3 to 1.4-fold higher than that of digesters containing 70% MC manure in terms of volatile solids (VS reduction and biogas production. VS reduction rates were 55 to 75% and cumulative methane yield ranged from 64 to 90 NmL (gVS−1. These values are lower than those from SS-AD of fresh manure and this is likely due to the partial decomposition of biodegradable materials during the two to three-month period before the manure was removed from the barn. However, in terms of efficient management of farm odors and providing a renewable energy source for heating, SS-AD of bedded pack manure offers a potential alternative to the conventional composting systems currently in use.

Prospects of Anaerobic Digestion Technology in China

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

As the world's largest developing country, China must face the problem of managing municipal solid waste, and the challenge of organic waste disposal is even more serious. Considering the characteristics of traditional waste disposal technologies and the subsequent secondary pollution, anaerobic digestion has various advantages such as reduction in the land needed for disposal and preservation of environmental quality. In light of the energy crisis, this paper focuses on the potential production of biogas from biowaste through anaerobic digestion processes, the problems incurred by the waste collection system, and the efficiency of the anaerobic digestion process. Use of biogas in a combined heat and power cogeneration system is also discussed. Finally, the advantages of anaerobic digestion technology for the Chinese market are summarized. The anaerobic digestion is suggested to be a promising treating technology for the organic wastes in China.

Modeling the fate of antibiotic resistance genes and class 1 integrons during thermophilic anaerobic digestion of municipal wastewater solids.

Science.gov (United States)

Burch, Tucker R; Sadowsky, Michael J; LaPara, Timothy M

2015-10-19

This study investigated the use of thermophilic anaerobic digestion for removing antibiotic resistance genes (ARGs) from residual municipal wastewater solids. Four laboratory-scale anaerobic digesters were operated in 8-day batch cycles at temperatures of 40, 56, 60, and 63 °C. Two tetracycline resistance genes (tet(W) and tet(X)), a fluoroquinolone resistance gene (qnrA), the integrase gene of class 1 integrons (intI1), 16S rRNA genes of all Bacteria, and 16S rRNA genes of methanogens were quantified using real-time quantitative PCR. ARG and intI1 quantities decreased at all temperatures and were described well by a modified form of the Collins-Selleck disinfection kinetic model. The magnitudes of Collins-Selleck kinetic parameters were significantly greater at thermophilic temperatures compared to 40 °C, but few statistically significant differences were observed among these parameters for the thermophilic anaerobic digesters. This model allows for the direct comparison of different operating conditions (e.g., temperature) on anaerobic digestion performance in mitigating the quantity of ARGs in wastewater solids and could be used to design full-scale anaerobic digesters to specifically treat for ARGs as a "pollutant" of concern.

Comparison of high-solids to liquid anaerobic co-digestion of food waste and green waste.

Science.gov (United States)

Chen, Xiang; Yan, Wei; Sheng, Kuichuan; Sanati, Mehri

2014-02-01

Co-digestion of food waste and green waste was conducted with six feedstock mixing ratios to evaluate biogas production. Increasing the food waste percentage in the feedstock resulted in an increased methane yield, while shorter retention time was achieved by increasing the green waste percentage. Food waste/green waste ratio of 40:60 was determined as preferred ratio for optimal biogas production. About 90% of methane yield was obtained after 24.5 days of digestion, with total methane yield of 272.1 mL/g VS. Based the preferred ratio, effect of total solids (TS) content on co-digestion of food waste and green waste was evaluated over a TS range of 5-25%. Results showed that methane yields from high-solids anaerobic digestion (15-20% TS) were higher than the output of liquid anaerobic digestion (5-10% TS), while methanogenesis was inhibited by further increasing the TS content to 25%. The inhibition may be caused by organic overloading and excess ammonia. Copyright © 2013 Elsevier Ltd. All rights reserved.

Performance of dry anaerobic technology in the co-digestion of rural organic solid wastes in China

International Nuclear Information System (INIS)

Yang, Tianxue; Li, Yingjun; Gao, Jixi; Huang, Caihong; Chen, Bin; Zhang, Lieyu; Wang, Xiaowei; Zhao, Ying; Xi, Beidou; Li, Xiang

2015-01-01

The dry anaerobic co-digestion of LW (livestock waste), OFHW (organic fraction of household waste), and AR (agricultural residue) was evaluated in terms of pH stability, organic removal rate, and methane yield. The total quantity of the solids involved in the digestion was adjusted to 25%. All the reactors were inoculated by 20% (in dry weight) of the municipal sludge. The dynamic changes in the pH values of the LW-AR-OFHW mixture co-digestions underwent four stages and differed from those of wet anaerobic digestion. The decrease in VS (volatile solids), volume, and weight of the LW-AR-OFHW mixtures was higher than those in AR and OFHW. The VS, volume, and weight reductions in LW-AR-OFHW co-digestion were 54.7%, 82.2%, and 72.7%, respectively. However, the VS, volume, and weight reductions in AR were only 11.1%, 20.5%, and 19.8%, respectively, and those in OFHW were only 27.4%, 45.0%, and 40.9%, respectively. The LW-AR-OFHW mixture co-digestions enhanced the methane production of the co-digester (256 m 3 /ton VS), whereas AR and OFHW produced only 12 and 93 m 3 methane/ton VS, respectively. - Highlights: • The pH values dynamic of LW-AR-OFHW differed from wet anaerobic digestion. • The degradation effect of LW-AR-OFHW was better than those of AR and OFHW. • The LW-AR-OFHW mixture co-digestions enhanced the methane production.

Effect of solids retention time on the bioavailability of organic carbon in anaerobically digested swine waste.

Science.gov (United States)

Kinyua, Maureen N; Cunningham, Jeffrey; Ergas, Sarina J

2014-06-01

Anaerobic digestion (AD) can be used to stabilize and produce energy from livestock waste; however, digester effluents may require further treatment to remove nitrogen. This paper quantifies the effects of varying solids retention time (SRT) methane yield, volatile solids (VS) reduction and organic carbon bioavailability for denitrification during swine waste AD. Four bench-scale anaerobic digesters, with SRTs of 14, 21, 28 and 42 days, operated with swine waste feed. Effluent organic carbon bioavailability was measured using anoxic microcosms and respirometry. Excellent performance was observed for all four digesters, with >60% VS removal and CH4 yields between 0.1 and 0.3(m(3)CH4)/(kg VS added). Organic carbon in the centrate as an internal organic carbon source for denitrification supported maximum specific denitrification rates between 47 and 56(mg NO3(-)-N)/(g VSS h). The digester with the 21-day SRT had the highest CH4 yield and maximum specific denitrification rates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of initial bulk density on high-solids anaerobic digestion of MSW: General mechanism.

Science.gov (United States)

Caicedo, Luis M; Wang, Hongtao; Lu, Wenjing; De Clercq, Djavan; Liu, Yanjun; Xu, Sai; Ni, Zhe

2017-06-01

Initial bulk density (IBD) is an important variable in anaerobic digestion since it defines and optimizes the treatment capacity of a system. This study reveals the mechanism on how IBD might affect anaerobic digestion of waste. Four different IBD values: D 1 (500-700kgm -3 ), D 2 (900-1000kgm -3 ), D 3 (1100-1200kgm -3 ) and D 4 (1200-1400kgm -3 ) were set and tested over a period of 90days in simulated landfill reactors. The main variables affected by the IBD are the methane generation, saturation degree, extraction of organic matter, and the total population of methanogens. The study identified that IBD >1000kgm -3 may have significant effect on methane generation, either prolonging the lag time or completely inhibiting the process. This study provides a new understanding of the anaerobic digestion process in saturated high-solids systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-solid anaerobic digestion of corn straw for methane production and pretreatment of bio-briquette.

Science.gov (United States)

Li, Yeqing; Yan, Fang; Li, Tao; Zhou, Ying; Jiang, Hao; Qian, Mingyu; Xu, Quan

2018-02-01

In this study, an integrated process was developed to produce methane and high-quality bio-briquette (BB) using corn straw (CS) through high-solid anaerobic digestion (HS-AD). CS was anaerobic digested by using a leach bed reactor at four leachate recirculation strategies. After digesting for 28 days, highest methane yield of 179.6 mL/g-VS, which was corresponded to energy production of 5.55 MJ/kg-CS, was obtained at a higher initial recirculation rate of 32 L-leachate per day. Compared with bio-briquette manufactured from raw CS and lignite, the compressive, immersion and falling strength properties of bio-briquette made from AD-treated CS (solid digestate) and lignite were significantly improved. A preferred BB can be obtained with side compressive strength of 863.8 ± 10.8 N and calorific value of 20.21 MJ/kg-BB. The finding of this study indicated that the integrated process could be an alternative way to produce methane and high-quality BB with CS. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimisation Study on the Production of Anaerobic Digestate ...

African Journals Online (AJOL)

Organic fraction of municipal solid waste (OFMSW) is a rich substrate for biogas and compost production. Anaerobic Digestate compost (ADC) is an organic fertilizer produced from stabilized residuals of anaerobic digestion of OFMSW. This paper reports the result of studies carried out to optimise the production of ADC from ...

High-solids anaerobic co-digestion of sewage sludge and food waste in comparison with mono digestions: stability and performance.

Science.gov (United States)

Dai, Xiaohu; Duan, Nina; Dong, Bin; Dai, Lingling

2013-02-01

System stability and performance of high-solids anaerobic co-digestion of dewatered sludge (DS) and food waste (FW) in comparison with mono digestions were investigated. System stability was improved in co-digestion systems with co-substrate acting as a diluting agent to toxic chemicals like ammonia or Na(+). For high-solids digestion of DS, the addition of FW not only improved system stability but also greatly enhanced volumetric biogas production. For high-solids digestion of FW, the addition of DS could reduce Na(+) concentration and help maintain satisfactory stability during the conversion of FW into biogas. System performances of co-digestion systems were mainly determined by the mixing ratios of DS and FW. Biogas production and volatile solids (VSs) reduction in digestion of the co-mixture of DS and FW increased linearly with higher ratios of FW. A kinetic model, which aimed to forecast the performance of co-digestion and to assist reactor design, was developed from long-term semi-continuous experiments. Maximum VS reduction for DS and FW was estimated to be 44.3% and 90.3%, respectively, and first order constant k was found to be 0.17d(-1) and 0.50 d(-1), respectively. Experimental data of co-digestion were in good conformity to the predictions of the model. Copyright © 2012 Elsevier Ltd. All rights reserved.

Multiphase modeling of settling and suspension in anaerobic digester

International Nuclear Information System (INIS)

Yu, Liang; Ma, Jingwei; Frear, Craig; Zhao, Quanbao; Dillon, Robert; Li, Xiujin; Chen, Shulin

2013-01-01

Highlights: • Develop biowaste fluid dynamics for collision, aggregation and breakup of clusters. • Explore the mechanisms of settling and suspension in anaerobic digester. • Biowaste particles tended to have fluid properties. • Aided with CFD simulation, the scale-up effect was reduced. - Abstract: Effective suspension and settling are critical for controlling biomass retention in a bioreactor. In this paper, a multi-fluid model with kinetic theory of granular flow (KTGF) was established to describe these phenomena in the biowaste particles flow in anaerobic digesters. Solid retention time (SRT) was added as a parameter into anaerobic digestion No.1 (ADM1) model to evaluate its effect on the biogas productivity. The model was experimentally validated in a liquid–gas–solid column reactor with gas and solid volume fraction and granular temperature as the major variables. The wastewater residence time distribution was also determined through modeling and measurement to evaluate the mixing pattern in the pilot column reactor. The effect of restitution coefficient on flow behavior of biowaste particles, particles settling and suspension were predicted. Settling and suspension processes of anaerobic digesters were simulated for lab and pilot-scale reactors with comparisons made for reactor configuration and geometry model, respectively. This study demonstrated that the multi-fluid model with KTGF could provide better understanding of impact of suspension and settling upon retaining biomass particles in the anaerobic digesters

Some effects of aeration on anaerobic digestion

Energy Technology Data Exchange (ETDEWEB)

Bhywapathanapun, S

1972-01-01

The anaerobic digestion of meat works waste water is made possible by separating the sludge solids, after which necessary amounts of the concentrated sludge are returned to the digester. Sludge recirculation prolongs solid retention time in the digester. However, sludge separation by gravitational sedimentation is almost impossible because the sludge tends to rise with the continuous gassing. Therefore treatment of the sludge suspension prior to sedimentation is necessary for effective solid separation. The present study examined aeration degasification as a method for sludge suspension pretreatment and found that the rates of aeration of 0.75 to 1.0 VVM (0.12 to 0.16 cubic foot of air per gallon of mixed liquor per minute) were optimal for aeration degasification. The toxic effects on the anaerobic bacteria were small, daily gas production being reduced by only 5%.

Fungal pretreatment of albizia chips for enhanced biogas production by solid-state anaerobic digestion

Science.gov (United States)

Albizia biomass is a forestry waste, and holds a great potential in biogas production by solid-state anaerobic digestion (SS-AD). However, low methane yields from albizia chips were observed due to their recalcitrant structure. In this study, albizia chips were pretreated by Ceriporiopsis subvermisp...

The prospects for methane recovery from the anaerobic digestion of municipal solid waste in the UK

Energy Technology Data Exchange (ETDEWEB)

Coombs, J. (CPL Scientific Ltd., Newbury (GB))

1990-01-01

The availability, composition and energy output of municipal solid wastes (MSW) in the United Kingdom are considered. The sorting of MSW, the production of organic fractions and the technical aspects of their biological consolidation are examined. A description of anaerobic digestion activities and pilot and commercial scale plants in the United Kingdom, the European Communities and the USA is given. Finally,the potential for electricity generation from, and the co-products, by-products and cost of, the anaerobic digestion of MWS are summarized. It is concluded that, on the basis of the evidence available, there appears to be a good case for government support aimed at boosting the waste treatment industry's confidence in the anaerobic digestion of the organic fraction of MSW in fabricated systems. A programme of field trials and related research is recommended. (UK).

A study of operational conditions for anaerobic digestion of solid urban waste

Directory of Open Access Journals (Sweden)

Édgar Femando Castillo M.

2003-07-01

Full Text Available This paper describes an experimental evaluation of anaerobic digestion as a technological option for organic solid-waste treatment in the city of Bucaramanga (Santander, Colombia. The inoculum was selected by evaluating three different anaerobic sludges. Sludge from UASB No. 2 digestor at the Waste Water Treatment Plant in Rio Frío (Girón, Santander was named [PTAR]. Sludge from the anaerobic biodigestor for pig manure treatment (Mesa de Los Santos, Santander was named [PIG] a 1:1 sludge mixture of [PTAR] and [PIG] sludges was named [MIX]. These sludges' methanisation behaviour was evaluated in three different 500 ml capacity CSTR digesters at mesophyllic and thermophyllic temperatures. 25,20 and 18 day retention times were studied in a 20 1 CSTR digester having a 131 reaction volume. The results showed that raising the temperature from 10 °C to 15 °C above normal reactor temperature increased methane production by 3 times. It was also seen that retention time had a strong influence on specific methane production since the best conversions were registered at the longest time recorded (25 days and it had a strong influence on DQO removal too. Another important condition for biodigestor optimal operation was agitation speed;this operation must be semi-continuous for maintaining methanisation process biological activity.

The effects of different mixing intensities during anaerobic digestion of the organic fraction of municipal solid waste

International Nuclear Information System (INIS)

Lindmark, Johan; Eriksson, Per; Thorin, Eva

2014-01-01

Highlights: • Effects of mixing on the anaerobic digestion of municipal solid waste. • Digestion of fresh substrate and post-digestion at three mixing intensities were evaluated. • Mixing performed at 150 RPM, 25 RPM and minimally intermittently. • Increased biogas production rates and yields at lower mixing intensities. - Abstract: Mixing inside an anaerobic digester is often continuous and is not actively controlled. The selected mixing regime can however affect both gas production and the energy efficiency of the biogas plant. This study aims to evaluate these effects and compare three different mixing regimes, 150 RPM and 25 RPM continuous mixing and minimally intermittent mixing for both digestion of fresh substrate and post-digestion of the organic fraction of municipal solid waste. The results show that a lower mixing intensity leads to a higher biogas production rate and higher total biogas production in both cases. 25 RPM continuous mixing and minimally intermittent mixing resulted in similar biogas production after process stabilization, while 150 RPM continuous mixing resulted in lower production throughout the experiment. The lower gas production at 150 RPM could not be explained by the inhibition of volatile fatty acids. Cumulative biogas production until day 31 was 295 ± 2.9, 317 ± 1.9 and 304 ± 2.8 N ml/g VS added during digestion of fresh feed and 113 ± 1.3, 134 ± 1.1 and 130 ± 2.3 N ml/g VS added during post digestion for the 150 RPM, 25 RPM and minimally mixed intensities respectively. As well as increasing gas production, optimal mixing can improve the energy efficiency of the anaerobic digestion process

The effects of different mixing intensities during anaerobic digestion of the organic fraction of municipal solid waste

Energy Technology Data Exchange (ETDEWEB)

Lindmark, Johan, E-mail: Johan.lindmark@mdh.se; Eriksson, Per; Thorin, Eva, E-mail: Eva.Thorin@mdh.se

2014-08-15

Highlights: • Effects of mixing on the anaerobic digestion of municipal solid waste. • Digestion of fresh substrate and post-digestion at three mixing intensities were evaluated. • Mixing performed at 150 RPM, 25 RPM and minimally intermittently. • Increased biogas production rates and yields at lower mixing intensities. - Abstract: Mixing inside an anaerobic digester is often continuous and is not actively controlled. The selected mixing regime can however affect both gas production and the energy efficiency of the biogas plant. This study aims to evaluate these effects and compare three different mixing regimes, 150 RPM and 25 RPM continuous mixing and minimally intermittent mixing for both digestion of fresh substrate and post-digestion of the organic fraction of municipal solid waste. The results show that a lower mixing intensity leads to a higher biogas production rate and higher total biogas production in both cases. 25 RPM continuous mixing and minimally intermittent mixing resulted in similar biogas production after process stabilization, while 150 RPM continuous mixing resulted in lower production throughout the experiment. The lower gas production at 150 RPM could not be explained by the inhibition of volatile fatty acids. Cumulative biogas production until day 31 was 295 ± 2.9, 317 ± 1.9 and 304 ± 2.8 N ml/g VS added during digestion of fresh feed and 113 ± 1.3, 134 ± 1.1 and 130 ± 2.3 N ml/g VS added during post digestion for the 150 RPM, 25 RPM and minimally mixed intensities respectively. As well as increasing gas production, optimal mixing can improve the energy efficiency of the anaerobic digestion process.

The effect of moisture content on solid-state anaerobic digestion of dairy manure from a sawdust-bedded pack barn

Science.gov (United States)

The effect of moisture content on solid-state anaerobic digestion of dairy manure from a Korean sawdust-bedded pack barn was determined using laboratory-scale digesters operated at three moisture levels (70, 76, and 83% on a wet basis) at 37 C for 85 days. Results showed that digesters containing m...

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...

Reactor performance and energy analysis of solid state anaerobic co-digestion of dairy manure with corn stover and tomato residues.

Science.gov (United States)

Li, Yangyang; Xu, Fuqing; Li, Yu; Lu, Jiaxin; Li, Shuyan; Shah, Ajay; Zhang, Xuehua; Zhang, Hongyu; Gong, Xiaoyan; Li, Guoxue

2018-03-01

Anaerobic co-digestion is commonly believed to be benefical for biogas production. However, additional of co-substrates may require additional energy inputs and thus affect the overall energy efficiency of the system. In this study, reactor performance and energy analysis of solid state anaerobic digestion (SS-AD) of tomato residues with dairy manure and corn stover were investigated. Different fractions of tomato residues (0, 20, 40, 60, 80 and 100%, based on volatile solid weight (VS)) were co-digested with dairy manure and corn stover at 15% total solids. Energy analysis based on experimental data was conducted for three scenarios: SS-AD of 100% dairy manure, SS-AD of binary mixture (60% dairy manure and 40% corn stover, VS based), and SS-AD of ternary mixture (36% dairy manure, 24% corn stover, and 40% tomato residues, VS based). For each scenario, the energy requirements for individual process components, including feedstock collection and transportation, feedstock pretreatment, biogas plant operation, digestate processing and handling, and the energy production were examined. Results showed that the addition of 20 and 40% tomato residues increased methane yield compared to that of the dairy manure and corn stover mixture, indicating that the co-digestion could balance nutrients and improve the performance of solid-state anaerobic digestion. The energy required for heating substrates had the dominant effect on the total energy consumption. The highest volatile solids (VS) reduction (57.0%), methane yield (379.1 L/kg VS feed ), and net energy production were achieved with the mixture of 24% corn stover, 36% dairy manure, and 40% tomato residues. Thus, the extra energy input for adding tomato residues for co-digestion could be compensated by the increase of methane yield. Copyright © 2017 Elsevier Ltd. All rights reserved.

University of Wisconsin Oshkosh Anaerobic Dry Digestion Facility

Energy Technology Data Exchange (ETDEWEB)

Koker, John [Univ. of Wisconsin, Oshkosh, WI (United States); Lizotte, Michael [Univ. of Wisconsin, Oshkosh, WI (United States)

2017-02-08

The University of Wisconsin Oshkosh Anaerobic Dry Digestion Facility is a demonstration project that supported the first commercial-scale use in the United States of high solids, static pile technology for anaerobic digestion of organic waste to generate biogas for use in generating electricity and heat. The research adds to the understanding of startup, operation and supply chain issues for anaerobic digester technology. Issues and performance were documented for equipment installation and modifications, feedstock availability and quality, weekly loading and unloading of digestion chambers, chemical composition of biogas produced, and energy production. This facility also demonstrated an urban industrial ecology approach to siting such facilities near sewage treatment plants (to capture and use excess biogas generated by the plants) and organic yard waste collection sites (a source of feedstock).

Characterization of Spartina alterniflora as feedstock for anaerobic digestion

International Nuclear Information System (INIS)

Yang, Shiguan; Zheng, Zheng; Meng, Zhuo; Li, Jihong

2009-01-01

Smooth cordgrass (Spartina alterniflora), a saltmarsh plant with high production, was characterized for its potential for use as feedstock for anaerobic digestion processes. The anaerobic digestibility and biogas yield of S. alterniflora were evaluated by anaerobic batch digestion experiments performed at 35 ± 1 C at initial volatile solids (VS) of 6%. The nutrient content analysis indicated that S. alterniflora contained the required nutrition for anaerobic microorganisms, but its high C/N of 58.8, high K and Na contents of 8.1, 22.7 g kg -1 , respectively, may be disadvantageous to its anaerobic digestion. The cumulative biogas yield was determined to be 358 L kg -1 VS and the biodegradation efficiency was 45% after 60 days of digestion. The methane content of biogas increased from 53% on day 3 to around 62% after 13 days of digestion. The changes of volatile fatty acids (VFAs) indicated that the acidification of S. alterniflora was propionate-type fermentation with proportion of acetate and propionate ranging from 54.8% to 98.4%, and the hydrolysis of lignocellulose was the rate-limiting step for its anaerobic digestion. The analysis of cations suggested that K + and Mg 2+ , with the maximum concentration of 1.35 and 0.43 g L -1 in fermentation liquor, respectively, could be inhibitory to the anaerobic digestion of S. alterniflora. It is concluded that S. alterniflora can be transformed into clean energy by anaerobic digestion and the high contents of K, Na, Ca and Mg may be the inhibitory factors when S. alterniflora is digested by continuous or semi-continuous anaerobic process. (author)

Instrumentation and Control in Anaerobic Digestion

DEFF Research Database (Denmark)

Anaerobic digestion is a multistep process, and is most applied to solids destruction and wastewater treatment for energy production. Despite wide application, and long-term industrial proof of application, some industries are still reluctant to apply this technology. One of the classical reasons...... benchmark. There has therefore been, overall, a quantum advance in application and sophistication of instrumentation and control in anaerobic digestion, and it is an effective option for improved process loading rate and conversion efficiency....... are still a limitation, but this is being partly addressed by the increased complexity of digestion processes. Methods for control benchmarking have also been improved, as there is now an industry standard model (the IWA ADM1), and this is being applied in an improved whole wastewater treatment plant...

Recovery of methane-rich gas from solid-feed anaerobic digestion of ipomoea (Ipomoea carnea).

Science.gov (United States)

Sankar Ganesh, P; Sanjeevi, R; Gajalakshmi, S; Ramasamy, E V; Abbasi, S A

2008-03-01

Studies are presented on new types of anaerobic digesters in which chopped or dry crushed Ipomoea carnea was fed without any other pretreatment, in an attempt to develop commercially viable means of utilizing the otherwise very harmful plant. Two types of solid-feed anaerobic digesters (SFADs) were studied. The first type had a single vessel in which the bottom 35% portion was separated from the top portion by a perforated PVC disk. The weed was charged from the top and inoculated with anaerobically digested cowdung-water slurry. The fermentation of the weed in the reactor led to the formation of volatile fatty acids (VFAs) plus some biogas. The leachate, rich in the VFAs, was passed through the perforated PVC sheet and collected in the lower portion of the vessel. The other type of reactors had two vessels, the first one was fully charged with the weed and the second received the VFA leachate. With both types were attached upflow anaerobic filters (UAFs) which converted the leachate into combustible biogas consisting of approximately 70% methane. All SFADs developed very consistent performance in terms of biogas yield within 17 weeks of start. The two-compartment reactors yielded significantly more biogas than the single-compartment reactors of corresponding total volume, and the reactors with which anaerobic filters (AF) were attached yielded more biogas than the ones without AF. The best performing units generated 2.41m(3) of biogas per m(3) of digester volume, as compared to 0.1-0.2m(3) of biogas, m(-3)d(-1), obtainable with conventional digesters. This indicates the viability of this technology. The spent weed can be vermicomposted directly to obtain good soil-conditioner cum fertilizer; earthworm Eudrilus eugeniae produced 540mg vermicast per animal every day, achieving near total conversion of feed to vermicast in 20 days. The proposed systems, thus, makes it possible to accomplish total utilization of ipomoea.

Effects of thermal treatment on high solid anaerobic digestion of swine manure: Enhancement assessment and kinetic analysis.

Science.gov (United States)

Wu, Jing; Hu, Yu-Ying; Wang, Shi-Feng; Cao, Zhi-Ping; Li, Huai-Zhi; Fu, Xin-Mei; Wang, Kai-Jun; Zuo, Jian-E

2017-04-01

Anaerobic digestion (AD), which is a process for generating biogas, can be applied to the treatment of organic wastes. Owing to its smaller footprint, lower energy consumption, and less digestate, high solid anaerobic digestion (HSAD) has attracted increasing attention. However, its biogas production is poor. In order to improve biogas production and decrease energy consumption, an improved thermal treatment process was proposed. Raw swine manure (>20% solid content) without any dilution was thermally treated at 70±1°C for different retention times, and then its effect on HSAD was investigated via batch AD experiments at 8.9% solid content. Results showed that the main organic components of swine manure hydrolyzed significantly during the thermal treatment, and HSAD's methane production rate was improved by up to 39.5%. Analysis using two kinetic models confirmed that the treatment could increase biodegradable organics (especially the readily biodegradable organics) in swine manure rather than upgrading its hydrolysis rate. It is worth noting that the superimposed first-order kinetics model was firstly applied in AD, and was a good tool to reveal the AD kinetics mechanism of substrates with complex components. Copyright © 2017 Elsevier Ltd. All rights reserved.

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...

Proceedings of the 10. world congress on anaerobic digestion 2004 : anaerobic bioconversion, answer for sustainability

International Nuclear Information System (INIS)

2004-01-01

This conference reviewed the broad scope of anaerobic process-related activities taking place globally and confirmed the possibilities of using anaerobic processes to add value to industrial wastewaters, municipal solid wastes and organic wastes while minimizing pollution and greenhouse gases. It focused on biomolecular tools, instrumentation of anaerobic digestion processes, anaerobic bioremediation of chlorinated organics, and thermophilic and mesophilic digestion. Several papers focused on the feasibility of using waste products to produce hydrogen and methane for electricity generation. The sessions of the conference were entitled acidogenesis; microbial ecology; process control; sulfur content; technical development; domestic wastewater; agricultural waste; organic municipal solid wastes; instrumentation; molecular biology; sludges; agricultural feedstock; bioremediation; industrial wastewater; hydrogen production; pretreatments; sustainability; and integrated systems. The conference featured 387 posters and 192 oral presentations, of which 111 have been indexed separately for inclusion in this database. refs., tabs., figs

Anaerobic was co-digestion with OMW and glycerol

International Nuclear Information System (INIS)

Athanasoulia, E.; Melidis, P.; Aivasidis, A.

2009-01-01

The main by-product of any biological wastewater treatment is waste activated sludge (WAS). Anaerobic digestion is the most common treatment technique for sludge stabilization, resulting in a reduction in the amount of volatile solids (VS) with biogas production, at the same time. On the other hand, many agro-industrial organic wastes are readily biodegradable and as a result, anaerobic co-digestion of sludge with agro-industrial wastes is being developed potential advantages such as increased biogas production and improved nutrience balance. (Author)

Distribution of sulfonamides in liquid and solid anaerobic digestates: effects of hydraulic retention time and swine manure to rice straw ratio.

Science.gov (United States)

Jin, Hongmei; Xu, Caiyun; Du, Jing; Wu, Huashan; Huang, Hongying; Chang, Zhizhou; Xu, Yueding; Zhou, Lixiang

2017-02-01

The effects of hydraulic retention time (20 and 15 days) and swine manure to rice straw ratios on distribution of sulfonamides (SAs) in liquid and solid anaerobic digestates were studied using bench-scale completely stirred tank reactors at (37 ± 1) °C. Results showed that anaerobic digestion (AD) treatment exhibited a good removal effect on sulfadiazine (SDZ), sulfadimidine (SM2) and sulfachloropyridazine (SCP), especially at HRT = 20 days and co-digestion with swine manure and rice straw. The removal rates of SDZ and SM2 were more than 90%, but only 72.8% for SCP. The residual SAs were mainly remained in solid digestates, with residual rates ranging from 28.8% to 71.3%, 40.6% to 88.0, and 82.7% to 97.0% for SDZ, SM2 and SCP, respectively. Due to lower pKa and higher log K ow of SCP, its residue in solid digestates was far more than SDZ and SM2. Higher HRT and co-digestion could improve the degradation of SAs, which can also be put down to the occurrence of cometabolism of SAs and COD.

Evaluation the anaerobic digestion performance of solid residual kitchen waste by NaHCO3 buffering

International Nuclear Information System (INIS)

Gao, Shumei; Huang, Yue; Yang, Lili; Wang, Hao; Zhao, Mingxing; Xu, Zhiyang; Huang, Zhenxing; Ruan, Wenquan

2015-01-01

Highlights: • The maximum methane production of SRKW was 479 mL/gTS added . • Anaerobic digestion capacity increased by 33.3% through NaHCO 3 buffering. • Protease activity was mainly affected by high organic load. - Abstract: Anaerobic digestion has been considered as a promising energy-producing process for kitchen waste treatment. In this paper, the anaerobic digestion (AD) performances of solid residual kitchen waste (SRKW) with or without NaHCO 3 buffering were investigated. The results indicated that the methane production reached the maximum of 479 mL/gTS added at the inoculum to substrate ratio (ISR, based on VS) of 1:1.4 without buffering, accompanied by VS removal rate of 78.91%. Moreover, the anaerobic digestion capacity increased by 33.3% through NaHCO 3 buffering, and the methane yield at ISR 1:2.8 was improved by 48.5% with NaHCO 3 addition. However, the methanogenesis with or without NaHCO 3 buffer was suppressed at ISR 1:3.5, indicated from the lowest methane yield of 55.50 mL/gTS added and high volatile fatty acids concentration of more than 14,000 mg/L. Furthermore, proteins in SRKW were not degraded completely at excessive organic loading, since the concentrations of ammonia nitrogen in ISR 1:3.5 groups with (2738 mg/L) and without NaHCO 3 buffering (2654 mg/L) were lower than the theoretical value of 3500 mg/L and the protease activities in ISR 1:3.5 groups were also inhibited

Biogas Production from Rice Husk Waste by using Solid State Anaerobic Digestion (SSAD) Method

Science.gov (United States)

Matin, Hashfi Hawali Abdul; Hadiyanto

2018-02-01

An effort to obtain alternative energy is still interesting subject to be studied, especially production of biogas from agriculture waste. This paper was an overview of the latest development of biogas researches from rice husk waste by Solid State Anaerobic Digestion (SSAD). The main obstacle of biogas production from rice husk waste was the lignin content which is very difficult degraded by microbes. Various pretreatments have been conducted, either physically, chemically as well as biologically. The SSAD method was an attractive option because of the low water content of rice husk waste. The biogas yield by SSAD method gave more attractive result compared to Liquid Anaerobic Digestion (LAD) method. Various studies were still conducted in batch mode laboratory scale and also has not found optimum operating conditions. Research on a larger scale such as bench and pilot scale with continuous systems will be an increase trend in the future research.

Temperature-phased anaerobic digestion of food waste: A comparison with single-stage digestions based on performance and energy balance.

Science.gov (United States)

Xiao, Benyi; Qin, Yu; Zhang, Wenzhe; Wu, Jing; Qiang, Hong; Liu, Junxin; Li, Yu-You

2018-02-01

The temperature-phased anaerobic digestion (TPAD) of food waste was studied for the purpose of comparing with single-stage mesophilic and thermophilic anaerobic digestion. The biogas and methane yields in the TPAD during the steady period were 0.759 ± 0.115 L/g added VS and 0.454 ± 0.201 L/g added VS, which were lower than those in the two single-stage anaerobic digestion. The improper sludge retention time may be the reason for the lower biogas and methane production in TPAD. The removal of volatile solids in the TPAD was 78.55 ± 4.59% and the lowest among the three anaerobic digestion processes. The reaction ratios of the four anaerobic digestion steps in the TPAD were all lower than those in the two single-stage anaerobic digestion. The energy conversion efficiency of the degraded substrate in the TPAD was similar with those in single-stage mesophilic and thermophilic anaerobic digestion systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic co-digestion of coffee husks and microalgal biomass after thermal hydrolysis.

Science.gov (United States)

Passos, Fabiana; Cordeiro, Paulo Henrique Miranda; Baeta, Bruno Eduardo Lobo; de Aquino, Sergio Francisco; Perez-Elvira, Sara Isabel

2018-04-01

Residual coffee husks after seed processing may be better profited if bioconverted into energy through anaerobic digestion. This process may be improved by implementing a pretreatment step and by co-digesting the coffee husks with a more liquid biomass. In this context, this study aimed at evaluating the anaerobic co-digestion of coffee husks with microalgal biomass. For this, both substrates were pretreated separately and in a mixture for attaining 15% of total solids (TS), which was demonstrated to be the minimum solid content for pretreatment of coffee husks. The results showed that the anaerobic co-digestion presented a synergistic effect, leading to 17% higher methane yield compared to the theoretical value of both substrates biodegraded separately. Furthermore, thermal hydrolysis pretreatment increased coffee husks anaerobic biodegradability. For co-digestion trials, the highest values were reached for pretreatment at 120 °C for 60 min, which led to 196 mLCH 4 /gVS and maximum methane production rate of 0.38 d -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Digestion of frozen/thawed food waste in the hybrid anaerobic solid-liquid system

International Nuclear Information System (INIS)

Stabnikova, O.; Liu, X.Y.; Wang, J.Y.

2008-01-01

The hybrid anaerobic solid-liquid (HASL) system, which is a modified two-phase anaerobic digester, is to be used in an industrial scale operation to minimize disposal of food waste at incineration plants in Singapore. The aim of the present research was to evaluate freezing/thawing of food waste as a pre-treatment for its anaerobic digestion in the HASL system. The hydrolytic and fermentation processes in the acidogenic reactor were enhanced when food waste was frozen for 24 h at -20 deg. C and then thawed for 12 h at 25 deg. C (experiment) in comparison with fresh food waste (control). The highest dissolved COD concentrations in the leachate from the acidogenic reactors were 16.9 g/l on day 3 in the control and 18.9 g/l on day 1 in the experiment. The highest VFA concentrations in the leachate from the acidogenic reactors were 11.7 g/l on day 3 in the control and 17.0 g/l on day 1 in the experiment. The same volume of methane was produced during 12 days in the control and 7 days in the experiment. It gave the opportunity to diminish operational time of batch process by 42%. The effect of freezing/thawing of food waste as pre-treatment for its anaerobic digestion in the HASL system was comparable with that of thermal pre-treatment of food waste at 150 deg. C for 1 h. However, estimation of energy required either to heat the suspended food waste to 150 deg. C or to freeze the same quantity of food waste to -20 deg. C showed that freezing pre-treatment consumes about 3 times less energy than thermal pre-treatment

Anaerobic digestion in mesophilic and room temperature conditions: Digestion performance and soil-borne pathogen survival.

Science.gov (United States)

Chen, Le; Jian, Shanshan; Bi, Jinhua; Li, Yunlong; Chang, Zhizhou; He, Jian; Ye, Xiaomei

2016-05-01

Tomato plant waste (TPW) was used as the feedstock of a batch anaerobic reactor to evaluate the effect of anaerobic digestion on Ralstonia solanacearum and Phytophthora capsici survival. Batch experiments were carried out for TS (total solid) concentrations of 2%, 4% and 6% respectively, at mesophilic (37±1°C) and room (20-25°C) temperatures. Results showed that higher digestion performance was achieved under mesophilic digestion temperature and lower TS concentration conditions. The biogas production ranged from 71 to 416L/kg VS (volatile solids). The inactivation of anaerobic digestion tended to increase as digestion performance improved. The maximum log copies reduction of R. solanacearum and P. capsici detected by quantitative PCR (polymerase chain reaction) were 3.80 and 4.08 respectively in reactors with 4% TS concentration at mesophilic temperatures. However, both in mesophilic and room temperature conditions, the lowest reduction of R. solanacearum was found in the reactors with 6% TS concentration, which possessed the highest VFA (volatile fatty acid) concentration. These findings indicated that simple accumulation of VFAs failed to restrain R. solanacearum effectively, although the VFAs were considered poisonous. P. capsici was nearly completely dead under all conditions. Based on the digestion performance and the pathogen survival rate, a model was established to evaluate the digestate biosafety. Copyright © 2015. Published by Elsevier B.V.

Investigations into Improving Dewaterability at a Bio-P/Anaerobic Digestion Plant.

Science.gov (United States)

Alm, Rebecca; Sealock, Adam W; Nollet, Yabing; Sprouse, George

2016-11-01

  Metropolitan Council Environmental Services has observed poorer than expected dewatering performance at its Empire Plant. This plant has both anaerobic digestion and enhanced biological phosphorus removal in its treatment train. A research program using pilot-scale anaerobic digesters investigated potential solutions to the plant's poor dewaterability. The dewaterability goal was to increase the cake solids from 12% total solids (TS) to 16% TS or higher. This research investigated 20 different reactor conditions including chemical, feed sludge, and digested sludge treatments. At the pilot scale, unaerated storage of waste activated sludge prior to thickening and addition of ferric chloride to digestion was found to achieve dewatered cake solids of nearly 17% TS with the added benefit of reducing polymer demand. Issues including the amount of chemical required and the resulting volatile solids destruction influence the viability of the process change, so a full-scale pilot and financial analysis is recommended before making permanent process changes.

Biogas Production from Rice Husk Waste by using Solid State Anaerobic Digestion (SSAD Method

Directory of Open Access Journals (Sweden)

Hawali Abdul Matin Hashfi

2018-01-01

Full Text Available An effort to obtain alternative energy is still interesting subject to be studied, especially production of biogas from agriculture waste. This paper was an overview of the latest development of biogas researches from rice husk waste by Solid State Anaerobic Digestion (SSAD. The main obstacle of biogas production from rice husk waste was the lignin content which is very difficult degraded by microbes. Various pretreatments have been conducted, either physically, chemically as well as biologically. The SSAD method was an attractive option because of the low water content of rice husk waste. The biogas yield by SSAD method gave more attractive result compared to Liquid Anaerobic Digestion (LAD method. Various studies were still conducted in batch mode laboratory scale and also has not found optimum operating conditions. Research on a larger scale such as bench and pilot scale with continuous systems will be an increase trend in the future research.

Biological conversion of biogas to methanol using methanotrophs isolated from solid-state anaerobic digestate.

Science.gov (United States)

Sheets, Johnathon P; Ge, Xumeng; Li, Yueh-Fen; Yu, Zhongtang; Li, Yebo

2016-02-01

The aim of this work was to isolate methanotrophs (methane oxidizing bacteria) that can directly convert biogas produced at a commercial anaerobic digestion (AD) facility to methanol. A methanotrophic bacterium was isolated from solid-state anaerobic digestate. The isolate had characteristics comparable to obligate methanotrophs from the genus Methylocaldum. This newly isolated methanotroph grew on biogas or purified CH4 and successfully converted biogas from AD to methanol. Methanol production was achieved using several methanol dehydrogenase (MDH) inhibitors and formate as an electron donor. The isolate also produced methanol using phosphate with no electron donor or using formate with no MDH inhibitor. The maximum methanol concentration (0.43±0.00gL(-1)) and 48-h CH4 to methanol conversion (25.5±1.1%) were achieved using biogas as substrate and a growth medium containing 50mM phosphate and 80mM formate. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fertilizer potential of liquid and solid effluent from thermophilic anaerobic digestion of poultry waste.

Science.gov (United States)

Liedl, B E; Bombardiere, J; Chaffield, J M

2006-01-01

Thermophilic anaerobic treatment of poultry litter produces an effluent stream of digested materials that can be separated into solid and liquid fractions for use as a crop fertilizer. The majority of the phosphorus is partitioned into the solid fraction while the majority of the nitrogen is present in the liquid fraction in the form of ammonium. These materials were tested over six years as an alternative fertilizer for the production of vegetable, fruit, and grassland crops. Application of the solids as a field crop fertilizer for vegetables and blueberries resulted in lower yields than the other fertilizer treatments, but an increase in soil phosphorus over a four-year period. Application of the digested liquids on grass and vegetable plots resulted in similar or superior yields to plots treated with commercially available nitrogen fertilizers. Hydroponic production of lettuce using liquid effluent was comparable to a commercial hydroponic fertilizer regime; however, the effluent treatment for hydroponic tomato production required supplementation and conversion of ammonium to nitrate. While not a total fertilizer solution, our research shows the effectiveness of digested effluent as part of a nutrient management program which could turn a livestock residuals problem into a crop nutrient resource.

Biological nutrients removal from the supernatant originating from the anaerobic digestion of the organic fraction of municipal solid waste.

Science.gov (United States)

Malamis, S; Katsou, E; Di Fabio, S; Bolzonella, D; Fatone, F

2014-09-01

This study critically evaluates the biological processes and techniques applied to remove nitrogen and phosphorus from the anaerobic supernatant produced from the treatment of the organic fraction of municipal solid waste (OFMSW) and from its co-digestion with other biodegradable organic waste (BOW) streams. The wide application of anaerobic digestion for the treatment of several organic waste streams results in the production of high quantities of anaerobic effluents. Such effluents are characterized by high nutrient content, because organic and particulate nitrogen and phosphorus are hydrolyzed in the anaerobic digestion process. Consequently, adequate post-treatment is required in order to comply with the existing land application and discharge legislation in the European Union countries. This may include physicochemical and biological processes, with the latter being more advantageous due to their lower cost. Nitrogen removal is accomplished through the conventional nitrification/denitrification, nitritation/denitritation and the complete autotrophic nitrogen removal process; the latter is accomplished by nitritation coupled with the anoxic ammonium oxidation process. As anaerobic digestion effluents are characterized by low COD/TKN ratio, conventional denitrification/nitrification is not an attractive option; short-cut nitrogen removal processes are more promising. Both suspended and attached growth processes have been employed to treat the anaerobic supernatant. Specifically, the sequencing batch reactor, the membrane bioreactor, the conventional activated sludge and the moving bed biofilm reactor processes have been investigated. Physicochemical phosphorus removal via struvite precipitation has been extensively examined. Enhanced biological phosphorus removal from the anaerobic supernatant can take place through the sequencing anaerobic/aerobic process. More recently, denitrifying phosphorus removal via nitrite or nitrate has been explored. The removal of

Anaerobic Digestion in a Flooded Densified Leachbed

Science.gov (United States)

Chynoweth, David P.; Teixeira, Arthur A.; Owens, John M.; Haley, Patrick J.

2009-01-01

A document discusses the adaptation of a patented biomass-digesting process, denoted sequential batch anaerobic composting (SEBAC), to recycling of wastes aboard a spacecraft. In SEBAC, high-solids-content biomass wastes are converted into methane, carbon dioxide, and compost.

Dry anaerobic digestion of food waste and cardboard at different substrate loads, solid contents and co-digestion proportions.

Science.gov (United States)

Capson-Tojo, Gabriel; Trably, Eric; Rouez, Maxime; Crest, Marion; Steyer, Jean-Philippe; Delgenès, Jean-Philippe; Escudié, Renaud

2017-06-01

The increasing food waste production calls for developing efficient technologies for its treatment. Anaerobic processes provide an effective waste valorization. The influence of the initial substrate load on the performance of batch dry anaerobic co-digestion reactors treating food waste and cardboard was investigated. The load was varied by modifying the substrate to inoculum ratio (S/X), the total solids content and the co-digestion proportions. The results showed that the S/X was a crucial parameter. Within the tested values (0.25, 1 and 4gVS·gVS -1 ), only the reactors working at 0.25 produced methane. Methanosarcina was the main archaea, indicating its importance for efficient methanogenesis. Acidogenic fermentation was predominant at higher S/X, producing hydrogen and other metabolites. Higher substrate conversions (≤48%) and hydrogen yields (≤62mL·gVS -1 ) were achieved at low loads. This study suggests that different value-added compounds can be produced in dry conditions, with the initial substrate load as easy-to-control operational parameter. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced high-solids anaerobic digestion of waste activated sludge by the addition of scrap iron.

Science.gov (United States)

Zhang, Yaobin; Feng, Yinghong; Yu, Qilin; Xu, Zibin; Quan, Xie

2014-05-01

Anaerobic digestion of waste activated sludge usually requires pretreatment procedure to improve the bioavailability of sludge, which involves considerable energy and high expenditures. This study proposes a cost-effective method for enhanced anaerobic digestion of sludge without a pretreatment by directly adding iron into the digester. The results showed that addition of Fe(0) powder could enhance 14.46% methane yield, and Fe scrap (clean scrap) could further enhance methane yield (improving rate 21.28%) because the scrap has better mass transfer efficiency with sludge and liquid than Fe(0) powder. The scrap of Fe with rust (rusty scrap) could induce microbial Fe(III) reduction, which resulted in achieving the highest methane yield (improving rate 29.51%), and the reduction rate of volatile suspended solids (VSS) was also highest (48.27%) among Fe powder, clean scrap and rusty scrap. PCR-DGGE proved that the addition of rusty scrap could enhance diversity of acetobacteria and enrich iron-reducing bacteria to enhance degradation of complex substrates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biogas production from cattle manure by anaerobic digestion

International Nuclear Information System (INIS)

Chuen, S.C.; Tinia Idaty Mohd Ghazi; Rozita Omar; Azni Idris

2009-01-01

Full text: In order to deal with the energy shortage problem, we are searching for more alternative energy resources especially renewable or sustainable. Biogas is one of the solutions in dealing with the energy shortage problem. Biogas is a type of energy resources derives from organic matter during the process called anaerobic digestion. The biogas produced is mainly consisting of methane and carbon dioxide. In this research, diluted cattle manure (1:1 ration with water) was inoculated with palm oil mill (POME) activated sludge at the ratio of 1:5 and placed in a 10 liter bioreactor. The temperature and pH in the bioreactor was regulated at 6.95 and 53 degree Celsius, respectively to enhance the anaerobic digestion process. Parameters such as chemical oxygen demand, biochemical oxygen demand, total solid, volatile solid, ammonia nitrogen (NH 3 -N), methane (CH 4 ) and the volume of biogas generated was monitored for effectiveness of the treatment of cattle manure via anaerobic digestion. The total volume of biogas produced in this study is 80.25 liter in 29 days while being able to treat the COD content up to 52 %. (author)

Effect of temperature on the fate of genes encoding tetracycline resistance and the integrase of class 1 integrons within anaerobic and aerobic digesters treating municipal wastewater solids.

Science.gov (United States)

Diehl, David L; LaPara, Timothy M

2010-12-01

The objective of this research was to investigate the ability of anaerobic and aerobic digesters to reduce the quantity of antibiotic resistant bacteria in wastewater solids. Lab-scale digesters were operated at different temperatures (22 °C, 37 °C, 46 °C, and 55 °C) under both anaerobic and aerobic conditions and fed wastewater solids collected from a full-scale treatment facility. Quantitative PCR was used to track five genes encoding tetracycline resistance (tet(A), tet(L), tet(O), tet(W), and tet(X)) and the gene encoding the integrase (intI1) of class 1 integrons. Statistically significant reductions in the quantities of these genes occurred in the anaerobic reactors at 37 °C, 46 °C, and 55 °C, with the removal rates and removal efficiencies increasing as a function of temperature. The aerobic digesters, in contrast, were generally incapable of significantly decreasing gene quantities, although these digesters were operated at much shorter mean hydraulic residence times. This research suggests that high temperature anaerobic digestion of wastewater solids would be a suitable technology for eliminating various antibiotic resistance genes, an emerging pollutant of concern.

Effect of anaerobic digestion on sequential pyrolysis kinetics of organic solid wastes using thermogravimetric analysis and distributed activation energy model.

Science.gov (United States)

Li, Xiaowei; Mei, Qingqing; Dai, Xiaohu; Ding, Guoji

2017-03-01

Thermogravimetric analysis, Gaussian-fit-peak model (GFPM), and distributed activation energy model (DAEM) were firstly used to explore the effect of anaerobic digestion on sequential pyrolysis kinetic of four organic solid wastes (OSW). Results showed that the OSW weight loss mainly occurred in the second pyrolysis stage relating to organic matter decomposition. Compared with raw substrate, the weight loss of corresponding digestate was lower in the range of 180-550°C, but was higher in 550-900°C. GFPM analysis revealed that organic components volatized at peak temperatures of 188-263, 373-401 and 420-462°C had a faster degradation rate than those at 274-327°C during anaerobic digestion. DAEM analysis showed that anaerobic digestion had discrepant effects on activation energy for four OSW pyrolysis, possibly because of their different organic composition. It requires further investigation for the special organic matter, i.e., protein-like and carbohydrate-like groups, to confirm the assumption. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

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

Livestock Anaerobic Digester Database

Science.gov (United States)

The Anaerobic Digester Database provides basic information about anaerobic digesters on livestock farms in the United States, organized in Excel spreadsheets. It includes projects that are under construction, operating, or shut down.

Evaluation of biogas production by dry anaerobic digestion of switchgrass-animal manure mixtures

Science.gov (United States)

Anaerobic digestion is a biological method used to convert organic wastes into a stable product for land application without adverse environmental effects. The biogas produced can be used as an alternative renewable energy source. Dry anaerobic digestion (> 15% TS; total solid) has an advantage ov...

On the effect of aqueous ammonia soaking pretreatment on batch and continuous anaerobic digestion of digested swine manure fibers

DEFF Research Database (Denmark)

Mirtsou Xanthopoulou, Chrysoula; Jurado, Esperanza; Skiadas, Ioannis

2012-01-01

, their economical profitable operation relies on increasing the methane yield from manure, and especially of its solid fraction which is not so easily degradable. Aqueous Ammonia Soaking (AAS) has been successfully applied on digested fibers separated from the effluent of a manure-fed, full-scale anaerobic digester......-pretreated digested manure fibers on the kinetics of anaerobic digestion process. It was found that AAS treatment had a profound effect mainly on the hydrolysis rate of particulate carbohydrates....

Semi-continuous anaerobic digestion of solid poultry slaughterhouse waste: effect of hydraulic retention time and loading.

Science.gov (United States)

Salminen, Esa A; Rintala, Jukka A

2002-07-01

We studied the effect of hydraulic retention time (HRT) and loading on anaerobic digestion of poultry slaughterhouse wastes, using semi-continuously fed, laboratory-scale digesters at 31 degrees C. The effect on process performance was highly significant: Anaerobic digestion appeared feasible with a loading of up to 0.8 kg volatile solids (VS)/m3 d and an HRT of 50-100 days. The specific methane yield was high, from 0.52 to 0.55 m3/kg VS(added). On the other hand, at a higher loading, in the range from 1.0 to 2.1 kg VS/m3 d, and a shorter HRT, in the range from 25 to 13 days, the process appeared inhibited and/or overloaded, as indicated by the accumulation of volatile fatty acids and long-chain fatty acids and the decline in the methane yield. However, the inhibition was reversible. The nitrogen in the feed, ca. 7.8% of total solids (TS), was organic nitrogen with little ammonia present, whereas in the digested material ammonia accounted for 52-67% (up to 3.8 g/l) of total nitrogen. The TS and VS removals amounted to 76% and 64%, respectively. Our results show that on a continuous basis under the studied conditions and with a loading of up to 0.8 kg VS/m3 d metric ton (wet weight) of the studied waste mixture could yield up to 140 m3 of methane.

Parameters affecting the stability of the digestate from a two-stage anaerobic process treating the organic fraction of municipal solid waste

International Nuclear Information System (INIS)

Trzcinski, Antoine P.; Stuckey, David C.

2011-01-01

This paper focused on the factors affecting the respiration rate of the digestate taken from a continuous anaerobic two-stage process treating the organic fraction of municipal solid waste (OFMSW). The process involved a hydrolytic reactor (HR) that produced a leachate fed to a submerged anaerobic membrane bioreactor (SAMBR). It was found that a volatile solids (VS) removal in the range 40-75% and an operating temperature in the HR between 21 and 35 o C resulted in digestates with similar respiration rates, with all digestates requiring 17 days of aeration before satisfying the British Standard Institution stability threshold of 16 mg CO 2 g VS -1 day -1 . Sanitization of the digestate at 65 o C for 7 days allowed a mature digestate to be obtained. At 4 g VS L -1 d -1 and Solid Retention Times (SRT) greater than 70 days, all the digestates emitted CO 2 at a rate lower than 25 mg CO 2 g VS -1 d -1 after 3 days of aeration, while at SRT lower than 20 days all the digestates displayed a respiration rate greater than 25 mg CO 2 g VS -1 d -1 . The compliance criteria for Class I digestate set by the European Commission (EC) and British Standard Institution (BSI) could not be met because of nickel and chromium contamination, which was probably due to attrition of the stainless steel stirrer in the HR.

Thermophilic co-digestion feasibility of distillers grains and swine manure: effect of C/N ratio and organic loading rate during high solid anaerobic digestion (HSAD).

Science.gov (United States)

Sensai, P; Thangamani, A; Visvanathan, C

2014-01-01

Anaerobic co-digestion of high solids containing distillers grains and swine manure (total solids, 27 +/- 2% and 18 +/- 2%, respectively) was evaluated in this study to assess the effect of C/N ratio and organic loading rate (OLR). Feed mixture was balanced to achieve a C/N ratio of 30/1 by mixing distillers grains and swine manure. Pilot-scale co-digestion of distillers grains and swine manure was carried out under thermophilic conditions in the continuous mode for seven different OLRs from R1 to R7 (3.5, 5, 6, 8, 10, 12 and 14 kg VS/m3 day) under high solid anaerobic digestion. The methane yield and volatile solid (VS) removal were consistent; ranging from 0.33 to 0.34 m3CH4/kg VS day and 50-53%, respectively, until OLR 8 kg VS/m3 day. After which methane yield and VS removal significantly decreased to 0.26 m3 CH4/kg VS day and 42%, respectively, when OLR was increased to 14 kg VS/m3 day. However, during operation, at OLR of 10 kg VS/m3 day, the methane yield and VS removal increased after the 19th day to 0.33 m3 CH4/kg VS day and 46%, respectively, indicating that a longer acclimatization period is required by methanogens at a higher loading rate.

Evaluating inhibition conditions in high-solids anaerobic digestion of organic fraction of municipal solid waste.

Science.gov (United States)

Schievano, Andrea; D'Imporzano, Giuliana; Malagutti, Luca; Fragali, Emilio; Ruboni, Gabriella; Adani, Fabrizio

2010-07-01

High-solids anaerobic digestion (HSAD) processes, when applied to different types of organic fractions of municipal solid waste (OFMSW), may easily be subjected to inhibition due to organic overloading. In this study, a new approach for predicting these phenomena was proposed based on the estimation of the putrescibility (oxygen consumption in 20 h biodegradation, OD(20)) of the organic mixtures undergoing the HSAD process. Different wastes exhibiting different putrescibility were subjected to lab-scale batch-HSAD. Measuring the organic loading (OL) as volatile solids (VS) was found unsuitable for predicting overload inhibition, because similar VS contents corresponded to both inhibited and successful trials. Instead, the OL calculated as OD(20) was a very good indicator of the inhibiting conditions (inhibition started for OD(20)>17-18 g O(2)kg(-1)). This new method of predicting inhibition in the HSAD process of diverse OFMSW may be useful for developing a correct approach to the technology in very different contexts. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Anaerobic digestion of cellulosic wastes

International Nuclear Information System (INIS)

Lee, D.D.; Donaldson, T.L.

1985-01-01

Anaerobic digestion is a potentially attractive technology for volume reduction of low-level radioactive cellulosic wastes. A substantial fraction of the waste is converted to off-gas and a relatively small volume of biologically stabilized sludge is produced. Process development work has been completed using a 75-L digester to verify rates and conversions obtained at the bench scale. Start-up and operating procedures have been developed, and effluent was generated for characterization and disposal studies. Three runs using batch and fed-batch conditions were made lasting 36, 90, and 423 d. Solids solubilization rates and gas production rates averaged approximately 1.8 g cellulose per L of reactor per d and 1.2 L of off-gas per L reactor per d. Greater than 80% destruction of the volatile suspended solids was obtained. A simple dynamic process model was constructed to aid in process design and for use in process monitoring and control of a large-scale digester

Anaerobic digestion for sustainable development: a natural approach.

Science.gov (United States)

Gljzen, H J

2002-01-01

After the discovery of methane gas by Alessandro Volta in 1776, it took about 100 years before anaerobic processes for the treatment of wastewater and sludges were introduced. The development of high rate anaerobic digesters for the treatment of sewage and industrial wastewater took until the nineteen-seventies and for solid waste even till the nineteen-eighties. All digesters have in common that they apply natural anaerobic consortia of microorganisms for degradation and transformation processes. In view of this, it could be rewarding to evaluate the efficiency of natural ecosystems for their possible application. Examples of high rate anaerobic natural systems include the forestomach of ruminants and the hindgut of certain insects, such as termites and cockroaches. These 'natural reactors' exhibit volumetric methane production rates as high as 35 l/l.d. The development of anaerobic reactors based on such natural anaerobic systems could produce eco-technologies for the effective management of a wide variety of solid wastes and industrial wastewater. Important limitations of anaerobic treatment of domestic sewage relate to the absence of nutrient and pathogen removal. A combination of anaerobic pre-treatment followed by photosynthetic posttreatment is proposed for the effective recovery of energy and nutrients from sewage. This eco-technology approach is based on the recognition that the main nutrient assimilating capacity is housed in photosynthetic plants. The proposed anaerobic-photosynthetic process is energy efficient, cost effective and applicable under a wide variety of rural and urban conditions. a natural systems approach towards waste management could generate affordable eco-technologies for effective treatment and resource recovery.

Aged refuse enhances anaerobic digestion of waste activated sludge.

Science.gov (United States)

Zhao, Jianwei; Gui, Lin; Wang, Qilin; Liu, Yiwen; Wang, Dongbo; Ni, Bing-Jie; Li, Xiaoming; Xu, Rui; Zeng, Guangming; Yang, Qi

2017-10-15

In this work, a low-cost alternative approach (i.e., adding aged refuse (AR) into waste activated sludge) to significantly enhance anaerobic digestion of sludge was reported. Experimental results showed that with the addition dosage of AR increasing from 0 to 400 mg/g dry sludge soluble chemical oxygen demand (COD) increased from 1150 to 5240 mg/L at the digestion time of 5 d, while the maximal production of volatile fatty acids (VFA) increased from 82.6 to 183.9 mg COD/g volatile suspended solids. Although further increase of AR addition decreased the concentrations of both soluble COD and VFA, their contents in these systems with AR addition at any concentration investigated were still higher than those in the blank, which resulted in higher methane yields in these systems. Mechanism studies revealed that pertinent addition of AR promoted solubilization, hydrolysis, and acidogenesis processes and did not affect methanogenesis significantly. It was found that varieties of enzymes and anaerobes in AR were primary reason for the enhancement of anaerobic digestion. Humic substances in AR benefited hydrolysis and acidogenesis but inhibited methanogenesis. The effect of heavy metals in AR on sludge anaerobic digestion was dosage dependent. Sludge anaerobic digestion was enhanced by appropriate amounts of heavy metals but inhibited by excessive amounts of heavy metals. The relative abundances of microorganisms responsible for sludge hydrolysis and acidogenesis were also observed to be improved in the system with AR addition, which was consistent with the performance of anaerobic digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Combined electrical-alkali pretreatment to increase the anaerobic hydrolysis rate of waste activated sludge during anaerobic digestion

International Nuclear Information System (INIS)

Zhen, Guangyin; Lu, Xueqin; Li, Yu-You; Zhao, Youcai

2014-01-01

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 (DD SCOD ), 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 (k hyd ), but had no, or very slight enhancement on WAS ultimate

Effects of anaerobic digestion and aerobic treatment on gaseous emissions from dairy manure storages

Science.gov (United States)

Effects of anaerobic digestion and aerobic treatment on the reduction of gaseous emissions from dairy manure storages were evaluated in this study. Screened dairy manure containing 3.5% volatile solids (VS) was either anaerobically digested or aerobically treated prior to storage in air-tight vessel...

Anaerobic digestion of hog wastes

Energy Technology Data Exchange (ETDEWEB)

Taiganides, E P; Baumann, E R; Johnson, H P; Hazen, T E

1963-01-01

A short history, a list of advantages and limitations, and a short introduction to the principles of the process of anaerobic digestion are given. Six five gallon bottle digesters were daily fed hog manure, maintained at 35/sup 0/C, and constantly agitated. Satisfactory operation was assured at 3.2 g VS/l/day with a detention time of 10 days, yielding 490-643 ml gas/g VS/day with a CH/sub 4/ content of 59% (2.1 x 10/sup 7/ joules/m/sup 3/). A figure and discussion portray the interrelationships of loading rate, solids concentration and detention time. They estimate that a marginal profit might be obtained by the operation of a heated digester handling the wastes of 10,000 hogs.

Use of hydrodynamic disintegration to accelerate anaerobic digestion of surplus activated sludge.

Science.gov (United States)

Grübel, Klaudiusz; Machnicka, Alicja

2009-12-01

Hydrodynamic disintegration of activated sludge resulted in organic matter and polymers transfer from the solid phase into the liquid phase. Disintegration by hydrodynamic cavitation had a positive effect on the degree and rate of excess sludge anaerobic digestion. Also, addition of a part of anaerobic digested sludge containing adapted microorganisms resulted in acceleration of the process. The disruption of cells of foam microorganisms and addition to the digestion process led to an increase of biogas production.

[Impact of Thermal Treatment on Biogas Production by Anaerobic Digestion of High-solid-content Swine Manure].

Science.gov (United States)

Hu, Yu-ying; Wu, Jing; Wang, Shi-feng; Cao, Zhi-ping; Wang, Kai-jun; Zuo, Jian-e

2015-08-01

Livestock manure is a kind of waste with high organic content and sanitation risk. In order to investigate the impact of thermal treatment on the anaerobic digestion of high-solid-content swine manure, 70 degrees C thermal treatment was conducted to treat raw manure (solid content 27.6%) without any dilution. The results indicated that thermal treatment could reduce the organic matters and improve the performance of anaerobic digestion. When the thermal treatment time was 1d, 2d, 3d, 4d, the VS removal rates were 15.1%, 15.5%, 17.8% and 20.0%, respectively. The methane production rates (CH4/VSadd) were 284.4, 296.3, 309.2 and 264.4 mL x g(-1), which was enhanced by 49.7%, 55.9%, 62.7% and 39.2%, respectively. The highest methane production rate occurred when the thermal treatment time was 3d. The thermal treatment had an efficient impact on promoting the performance of methane production rate with a suitable energy consumption. On the other hand, thermal treatment could act as pasteurization. This showed that thermal treatment would be of great practical importance.

Anaerobic digestion of cellulosic wastes

International Nuclear Information System (INIS)

Donaldson, T.L.; Lee, D.D.

1984-01-01

Anaerobic digestion is a potentially attractive technology for volume reduction of cellulosic wastes. A substantial fraction of the waste is converted to off-gas and a relatively small volume of biologically stabilized sludge is produced. Process development work is underway using a 75-L digester to verify rates and conversions obtained at the bench scale, to develop start-up and operating procedures, and to generate effluent for characterization and disposal studies. Three runs using batch and batch-fed conditions have been made lasting 36, 90, and over 200 days. Solids solubilization and gas production rates and total solids destruction have met or exceeded the target values of 0.6 g cellulose per L of reactor per day, 0.5 L off-gas per L of reactor per day, and 80% destruction of solids, respectively. Successful start-up procedures have been developed, and preliminary effluent characterization and disposal studies have been done. A simple dynamic process model has been constructed to aid in further process development and for use in process monitoring and control of a large-scale digester. 7 references, 5 figures, 1 table

Anaerobic digestion for sustainable development: a natural approach

Energy Technology Data Exchange (ETDEWEB)

Gijzen, H.J.

2002-07-01

After the discovery of methane gas by Alessandro Volta in 1776, it took about 100 years before anaerobic processes for the treatment of wastewater and sludges were introduced. The development of high rate anaerobic digesters for the treatment of sewage and industrial wastewater took until the nineteen-seventies and for solid waste even till the nineteen-eighties. All digesters have in common that they apply natural anaerobic consortia of microorganisms for degradation and transformation processes. In view of this, it could be rewarding to evaluate the efficiency of natural ecosystems for their possible application. Examples of high rate anaerobic natural systems include the forestomach of ruminants and the hindgut of certain insects, such as termites and cockroaches. These ''natural reactors'' exhibit volumetric methane production rates as high as 35 l/l.d. The development of anaerobic reactors based on such natural anaerobic systems could produce eco-technologies for the effective management of a wide variety of solid wastes and industrial wastewater. Important limitations of anaerobic treatment of domestic sewage relate to the absence of nutrient and pathogen removal. A combination of anaerobic pre-treatment followed by photosynthetic post-treatment is proposed for the effective recovery of energy and nutrients from sewage. This eco-technology approach is based on the recognition that the main nutrient assimilating capacity is housed in photosynthetic plants. The proposed anaerobic-photosynthetic process is energy efficient, cost effective and applicable under a wide variety of rural and urban conditions. In conclusion: a natural systems approach towards waste management could generate affordable eco-technologies for effective treatment and resource recovery. (author)

Anaerobic digestion of buffalo dung: simulation of process kinetics

International Nuclear Information System (INIS)

Sahito, A.R.

2015-01-01

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)

Low-heat, mild alkaline pretreatment of switchgrass for anaerobic digestion.

Science.gov (United States)

Jin, Guang; Bierma, Tom; Walker, Paul M

2014-01-01

This study examines the effectiveness of alkaline pretreatment under mild heat conditions (100°C or 212°F) on the anaerobic co-digestion of switchgrass. The effects of alkaline concentration, types of alkaline, heating time and rinsing were evaluated. In addition to batch studies, continuous-feed studies were performed in triplicate to identify potential digester operational problems caused by switchgrass co-digestion while accounting for uncertainty due to digester variability. Few studies have examined anaerobic digestion of switchgrass or the effects of mild heating to enhance alkaline pretreatment prior to biomass digestion. Results indicate that pretreatment can significantly enhance digestion of coarse-ground (≤ 0.78 cm particle size) switchgrass. Energy conversion efficiency as high as 63% was observed, and was comparable or superior to fine-grinding as a pretreatment method. The optimal NaOH concentration was found to be 5.5% (wt/wt alkaline/biomass) with a 91.7% moisture level. No evidence of operational problems such as solids build-up, poor mixing, or floating materials were observed. These results suggest the use of waste heat from a generator could reduce the concentration of alkaline required to adequately pretreat lignocellulosic feedstock prior to anaerobic digestion.

Mixing effect on thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste

KAUST Repository

Ghanimeh, Sophia A.

2012-08-01

This paper examines the effect of mixing on the performance of thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste during the start-up phase and in the absence of an acclimated seed. For this purpose, two digesters were used under similar starting conditions and operated for 235days with different mixing schemes. While both digesters exhibited a successful startup with comparable specific methane yield of 0.327 and 0.314l CH 4/gVS, continuous slow stirring improved stability by reducing average VFA accumulation from 2890 to 825mg HAc/l, propionate content from 2073 to 488mg/l, and VFA-to-alkalinity ratio from 0.32 to 0.07. As a result, the startup with slow mixing was faster and smoother accomplishing a higher loading capacity of 2.5gVS/l/d in comparison to 1.9gVS/l/d for non-mixing. Mixing equally improved microbial abundance from 6.6 to 10gVSS/l and enhanced solids and soluble COD removal. © 2012 Elsevier Ltd.

Mixing effect on thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste

KAUST Repository

Ghanimeh, Sophia A.; El-Fadel, Mutasem E.; Saikaly, Pascal

2012-01-01

This paper examines the effect of mixing on the performance of thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste during the start-up phase and in the absence of an acclimated seed. For this purpose, two digesters were used under similar starting conditions and operated for 235days with different mixing schemes. While both digesters exhibited a successful startup with comparable specific methane yield of 0.327 and 0.314l CH 4/gVS, continuous slow stirring improved stability by reducing average VFA accumulation from 2890 to 825mg HAc/l, propionate content from 2073 to 488mg/l, and VFA-to-alkalinity ratio from 0.32 to 0.07. As a result, the startup with slow mixing was faster and smoother accomplishing a higher loading capacity of 2.5gVS/l/d in comparison to 1.9gVS/l/d for non-mixing. Mixing equally improved microbial abundance from 6.6 to 10gVSS/l and enhanced solids and soluble COD removal. © 2012 Elsevier Ltd.

Enzyme treatment to decrease solids and improve digestion of ...

African Journals Online (AJOL)

The aim of anaerobic digestion of primary sewage sludge is to convert the carbonaceous material contained in the solids into methane and carbon dioxide. The products of digestion are therefore gases, stabilised sludge solids which are subsequently dewatered and disposed of, and sludge liquor which is generally further ...

The challenges of anaerobic digestion and the role of biochar in optimizing anaerobic digestion.

Science.gov (United States)

Fagbohungbe, Michael O; Herbert, Ben M J; Hurst, Lois; Ibeto, Cynthia N; Li, Hong; Usmani, Shams Q; Semple, Kirk T

2017-03-01

Biochar, like most other adsorbents, is a carbonaceous material, which is formed from the combustion of plant materials, in low-zero oxygen conditions and results in a material, which has the capacity to sorb chemicals onto its surfaces. Currently, research is being carried out to investigate the relevance of biochar in improving the soil ecosystem, digestate quality and most recently the anaerobic digestion process. Anaerobic digestion (AD) of organic substrates provides both a sustainable source of energy and a digestate with the potential to enhance plant growth and soil health. In order to ensure that these benefits are realised, the anaerobic digestion system must be optimized for process stability and high nutrient retention capacity in the digestate produced. Substrate-induced inhibition is a major issue, which can disrupt the stable functioning of the AD system reducing microbial breakdown of the organic waste and formation of methane, which in turn reduces energy output. Likewise, the spreading of digestate on land can often result in nutrient loss, surface runoff and leaching. This review will examine substrate inhibition and their impact on anaerobic digestion, nutrient leaching and their environmental implications, the properties and functionality of biochar material in counteracting these challenges. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anaerobic co-digestion of cyanide containing cassava pulp with pig manure.

Science.gov (United States)

Glanpracha, Naraporn; Annachhatre, Ajit P

2016-08-01

Anaerobic co-digestion of cyanide-containing cassava pulp with pig manure was evaluated using laboratory scale mesophilic digester. The digester was operated in a semi-continuous mode with the mixed feedstock having C/N ratio of 35:1. Digester startup was accomplished in 60days with loading of 0.5-1kgVS/m(3)d. Subsequently, the loading to digester was increased step-wise from 2 to 9kgVS/m(3)d. Digester performance was stable at loading between 2 and 6kgVS/m(3)d with an average volatile solid removal and methane yield of 82% and 0.38m(3)/kgVSadded, respectively. However, beyond loading of 7kgVS/m(3)d, solubilization of particulate matter did not take place efficiently. Cyanide present in cassava pulp was successfully degraded indicating that anaerobic sludge in the digester was well acclimatized to cyanide. The results show that cassava pulp can be successfully digested anaerobically with pig manure as co-substrate without any inhibitory effect of cyanide present in the cassava pulp. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermal wet oxidation improves anaerobic biodegradability of raw and digested biowaste

DEFF Research Database (Denmark)

Lissens, G.; Thomsen, Anne Belinda; De Baere, L.

2004-01-01

Anaerobic digestion of solid biowaste generally results in relatively low methane yields of 50-60% of the theoretical maximum. Increased methane recovery from organic waste would lead to reduced handling of digested solilds, lower methane emissions to the environment, and higher green energy...

Feasibility of biogas production from anaerobic co-digestion of herbal-extraction residues with swine manure.

Science.gov (United States)

Li, Yan; Yan, Xi-Luan; Fan, Jie-Ping; Zhu, Jian-Hang; Zhou, Wen-Bin

2011-06-01

The objective of this work was to examine the feasibility of biogas production from the anaerobic co-digestion of herbal-extraction residues with swine manure. Batch and semi-continuous experiments were carried out under mesophilic anaerobic conditions. Batch experiments revealed that the highest specific biogas yield was 294 mL CH(4) g(-1) volatile solids added, obtained at 50% of herbal-extraction residues and 3.50 g volatile solids g(-1) mixed liquor suspended solids. Specific methane yield from swine manure alone was 207 mL CH(4) g(-1) volatile solid added d(-1) at 3.50 g volatile solids g(-1) mixed liquor suspended solids. Furthermore, specific methane yields were 162, 180 and 220 mL CH(4) g (-1) volatile solids added d(-1) for the reactors co-digesting mixtures with 10%, 25% and 50% herbal-extraction residues, respectively. These results suggested that biogas production could be enhanced efficiently by the anaerobic co-digestion of herbal-extraction residues with swine manure. Copyright © 2011 Elsevier Ltd. All rights reserved.

Evaluation of biogas production potential by dry anaerobic digestion of switchgrass--animal manure mixtures.

Science.gov (United States)

Ahn, H K; Smith, M C; Kondrad, S L; White, J W

2010-02-01

Anaerobic digestion is a biological method used to convert organic wastes into a stable product for land application with reduced environmental impacts. The biogas produced can be used as an alternative renewable energy source. Dry anaerobic digestion [>15% total solid (TS)] has an advantage over wet digestion (anaerobic digestion of animal manure-switchgrass mixture was evaluated under dry (15% TS) and thermophilic conditions (55 degrees C). Three different mixtures of animal manure (swine, poultry, and dairy) and switchgrass were digested using batch-operated 1-L reactors. The swine manure test units showed 52.9% volatile solids (VS) removal during the 62-day trial, while dairy and poultry manure test units showed 9.3% and 20.2%, respectively. Over the 62 day digestion, the swine manure test units yielded the highest amount of methane 0.337 L CH4/g VS, while the dairy and poultry manure test units showed very poor methane yield 0.028 L CH4/g VS and 0.002 L CH4/g VS, respectively. Although dairy and poultry manure performed poorly, they may still have high potential as biomass for dry anaerobic digestion if appropriate designs are developed to prevent significant volatile fatty acid (VFA) accumulation and pH drop.

Long-term high-solids anaerobic digestion of food waste: Effects of ammonia on process performance and microbial community.

Science.gov (United States)

Peng, Xuya; Zhang, ShangYi; Li, Lei; Zhao, Xiaofei; Ma, Yao; Shi, Dezhi

2018-04-22

A long-term high solids anaerobic digestion of food waste was conducted to identify microbial mechanisms of ammonia inhibition during digestion and to clarify correlations between ammonia accumulation, microbial community dynamics (diversity, composition, and interactions), and process stability. Results show that the effects of ammonia on process performance and microbial community were indirectly caused by volatile fatty acid accumulation. Excess free ammonia blocked acetate metabolism, leading to process instability. Accumulated acetate caused feedback inhibition at the acetogenesis stage, which resulted in considerable accumulation of propionate, valerate, and other long-chain fatty acids. This high concentration of volatile fatty acids reduced the abundance of syntrophic acetogenic bacteria and allowed hydrolytic fermentative bacteria to dominate. The normally interactive and orderly metabolic network was broken, which further exacerbated the process instability. These results improve the understanding of microbial mechanisms which contribute to process instability and provide guidance for the microbial management of anaerobic digesters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Anaerobic co-digestion of animal waste: swine manure and tuna fish waste

Energy Technology Data Exchange (ETDEWEB)

Otero, L.; Alvarez, J. A.; Lema, J. M.

2009-07-01

Anaerobic digestion has become an established and proven technology for the treatment of solid wastes. Co-digestion offers several possible ecological, technology and economical advantages. Anaerobic co-digestion can increase CH{sub 4} production of manure diesters in a 50-200% according to the operation conditions and the co-substrates used. Last September 2007, PROBIOGAS project started up with the objective of improving the production and use of biogas from co-digestion of farming, agricultural and industrial waste. Our research group takes part in the study of co-digestion of swine manure firstly with tuna fish waste and secondly with glycerine (bio diesel production waste). (Author)

[Agroindustrial wastes methanization and bacterial composition in anaerobic digestion].

Science.gov (United States)

González-Sánchez, María E; Pérez-Fabiel, Sergio; Wong-Villarreal, Arnoldo; Bello-Mendoza, Ricardo; Yañez-Ocampo, Gustavo

2015-01-01

The tons of organic waste that are annually generated by agro-industry, can be used as raw material for methane production. For this reason, it is important to previously perform biodegradability tests to organic wastes for their full scale methanization. This paper addresses biodegradability, methane production and the behavior of populations of eubacteria and archaeabacteria during anaerobic digestion of banana, mango and papaya agroindustrial wastes. Mango and banana wastes had higher organic matter content than papaya in terms of their volatile solids and total solid rate (94 and 75% respectively). After 63 days of treatment, the highest methane production was observed in banana waste anaerobic digestion: 63.89ml CH4/per gram of chemical oxygen demand of the waste. In the PCR-DGGE molecular analysis, different genomic footprints with oligonucleotides for eubacteria and archeobacteria were found. Biochemical methane potential results proved that banana wastes have the best potential to be used as raw material for methane production. The result of a PCR- DGGE analysis using specific oligonucleotides enabled to identify the behavior of populations of eubacteria and archaeabacteria present during the anaerobic digestion of agroindustrial wastes throughout the process. Copyright © 2015 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Mesophilic anaerobic co-digestion of the organic fraction of municipal solid waste with the liquid fraction from hydrothermal carbonization of sewage sludge.

Science.gov (United States)

De la Rubia, M A; Villamil, J A; Rodriguez, J J; Borja, R; Mohedano, A F

2018-06-01

In the present study, the influence of substrate pre-treatment (grinding and sieving) on batch anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) was first assessed, then followed by co-digestion experiments with the liquid fraction from hydrothermal carbonization (LFHTC) of dewatered sewage sludge (DSS). The methane yield of batch anaerobic digestion after grinding and sieving (20 mm diameter) the OFMSW was considerably higher (453 mL CH 4 STP g -1 VS added ) than that of untreated OFMSW (285 mL CH 4 STP g -1 VS added ). The modified Gompertz model adequately predicted process performance. The maximum methane production rate, R m , for ground and sieved OFMSW was 2.4 times higher than that of untreated OFMSW. The anaerobic co-digestion of different mixtures of OFMSW and LFHTC of DSS did not increase the methane yield above that of the anaerobic digestion of OFMSW alone, and no synergistic effects were observed. However, the co-digestion of both wastes at a ratio of 75% OFMSW-25% LFHTC provides a practical waste management option. The experimental results were adequately fitted to a first-order kinetic model showing a kinetic constant virtually independent of the percentage of LFHTC (0.52-0.56 d -1 ) and decreasing slightly for 100% LFHTC (0.44 d -1 ). Copyright © 2018 Elsevier Ltd. All rights reserved.

Improvement of anaerobic digestion of sludge

Energy Technology Data Exchange (ETDEWEB)

Dohanyos, Michael; Zabranska, Jana; Kutil, Josef; Jenicek, Pavel

2003-07-01

Anaerobic digestion improvement can be accomplished by different methods. Besides optimization of process conditions is frequently used pretreatment of input sludge and increase of process temperature. Thermophilic process brings a higher solids reduction and biogas production, the high resistance to foaming, no problems with odour, the higher effect of destroying pathogens and the improvement of the energy balance of the whole treatment plant. Disintegration of excess activated sludge in lysate centrifuge was proved in full-scale conditions causing increase of biogas production. The rapid thermal conditioning of digested sludge is acceptable method of particulate matter disintegration and solubilization. (author)

Thermal hydrolysis integration in the anaerobic digestion process of different solid wastes: energy and economic feasibility study.

Science.gov (United States)

Cano, R; Nielfa, A; Fdz-Polanco, M

2014-09-01

An economic assessment of thermal hydrolysis as a pretreatment to anaerobic digestion has been achieved to evaluate its implementation in full-scale plants. Six different solid wastes have been studied, among them municipal solid waste (MSW). Thermal hydrolysis has been tested with batch lab-scale tests, from which an energy and economic assessment of three scenarios is performed: with and without energy integration (recovering heat to produce steam in a cogeneration plant), finally including the digestate management costs. Thermal hydrolysis has lead to an increase of the methane productions (up to 50%) and kinetics parameters (even double). The study has determined that a proper energy integration design could lead to important economic savings (5 €/t) and thermal hydrolysis can enhance up to 40% the incomes of the digestion plant, even doubling them when digestate management costs are considered. In a full-scale MSW treatment plant (30,000 t/year), thermal hydrolysis would provide almost 0.5 M€/year net benefits. Copyright © 2014 Elsevier Ltd. All rights reserved.

Free nitrous acid pre-treatment of waste activated sludge enhances volatile solids destruction and improves sludge dewaterability in continuous anaerobic digestion.

Science.gov (United States)

Wei, Wei; Wang, Qilin; Zhang, Liguo; Laloo, Andrew; Duan, Haoran; Batstone, Damien J; Yuan, Zhiguo

2018-03-01

Previous work has demonstrated that pre-treatment of waste activated sludge (WAS) with free nitrous acid (FNA i.e. HNO 2 ) enhances the biodegradability of WAS, identified by a 20-50% increase in specific methane production in biochemical methane potential (BMP) tests. This suggests that FNA pre-treatment would enhance the destruction of volatile solids (VS) in an anaerobic sludge digester, and reduce overall sludge disposal costs, provided that the dewaterability of the digested sludge is not negatively affected. This study experimentally evaluates the impact of FNA pre-treatment on the VS destruction in anaerobic sludge digestion and on the dewaterability of digested sludge, using continuously operated bench-scale anaerobic digesters. Pre-treatment of full-scale WAS for 24 h at an FNA concentration of 1.8 mg NN/L enhanced VS destruction by 17 ± 1% (from 29.2 ± 0.9% to 34.2 ± 1.1%) and increased dewaterability (centrifuge test) from 12.4 ± 0.4% to 14.1 ± 0.4%. Supporting the VS destruction data, methane production increased by 16 ± 1%. Biochemical methane potential tests indicated that the final digestate stability was also improved with a lower potential from FNA treated digestate. Further, a 2.1 ± 0.2 log improvement in pathogen reduction was also achieved. With inorganic solids representing 15-22% of the full-scale WAS used, FNA pre-treatment resulted in a 16-17% reduction in the volume of dewatered sludge for final disposal. This results in significantly reduced costs as assessed by economic analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Long-term anaerobic digestion of food waste stabilized by trace elements

International Nuclear Information System (INIS)

Zhang Lei; Jahng, Deokjin

2012-01-01

Highlights: ► Korean food waste was found to contain low level of trace elements. ► Stable anaerobic digestion of food waste was achieved by adding trace elements. ► Iron played an important role in anaerobic digestion of food waste. ► Cobalt addition further enhanced the process performance in the presence of iron. - Abstract: The purpose of this study was to examine if long-term anaerobic digestion of food waste in a semi-continuous single-stage reactor could be stabilized by supplementing trace elements. Contrary to the failure of anaerobic digestion of food waste alone, stable anaerobic digestion of food waste was achieved for 368 days by supplementing trace elements. Under the conditions of OLR (organic loading rates) of 2.19–6.64 g VS (volatile solid)/L day and 20–30 days of HRT (hydraulic retention time), a high methane yield (352–450 mL CH 4 /g VS added ) was obtained, and no significant accumulation of volatile fatty acids was observed. The subsequent investigation on effects of individual trace elements (Co, Fe, Mo and Ni) showed that iron was essential for maintaining stable methane production. These results proved that the food waste used in this study was deficient in trace elements.

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.

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…

Dynamic effect of total solid content, low substrate/inoculum ratio and particle size on solid-state anaerobic digestion.

Science.gov (United States)

Motte, J-C; Escudié, R; Bernet, N; Delgenes, J-P; Steyer, J-P; Dumas, C

2013-09-01

Among all the process parameters of solid-state anaerobic digestion (SS-AD), total solid content (TS), inoculation (S/X ratio) and size of the organic solid particles can be optimized to improve methane yield and process stability. To evaluate the effects of each parameter and their interactions on methane production, a three level Box-Behnken experimental design was implemented in SS-AD batch tests degrading wheat straw by adjusting: TS content from 15% to 25%, S/X ratio (in volatile solids) between 28 and 47 and particle size with a mean diameter ranging from 0.1 to 1.4mm. A dynamic analysis of the methane production indicates that the S/X ratio has only an effect during the start-up phase of the SS-AD. During the growing phase, TS content becomes the main parameter governing the methane production and its strong interaction with the particle size suggests the important role of water compartmentation on SS-AD. Copyright © 2013 Elsevier Ltd. All rights reserved.

Strategies for the anaerobic digestion of the organic fraction of municipal solid waste: an overview

DEFF Research Database (Denmark)

Hartmann, H.; Ahring, Birgitte Kiær

2006-01-01

Different process strategies for anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) are reviewed weighing high-solids versus low-solids, mesophilic versus thermophilic and single-stage versus multi-stage processes. The influence of different waste characteristics...... such as composition of biodegradable fractions, C:N ratio and particle size is described. Generally, source sorting of OFMSW and a high content of food waste leads to higher biogas yields than the use of mechanically sorted OFMSW. Thermophilic processes are more efficient than mesophilic processes in terms of higher...... biogas yields at different organic loading rates (OLR). Highest biogas yields are achieved by means of wet thermophilic processes at OLRs lower than 6 kg-VS(.)m(-3) d(-1). High-solids processes appear to be relatively more efficient when OLRs higher than 6 kg-VS(.)m(-3) d(-1) are applied. Multi...

Environmental impact of rejected materials generated in organic fraction of municipal solid waste anaerobic digestion plants: Comparison of wet and dry process layout.

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Colazo, Ana-Belén; Sánchez, Antoni; Font, Xavier; Colón, Joan

2015-09-01

Anaerobic digestion of source separated organic fraction of municipal solid waste is an increasing waste valorization alternative instead of incineration or landfilling of untreated biodegradable wastes. Nevertheless, a significant portion of biodegradable wastes entering the plant is lost in pre-treatments and post-treatments of anaerobic digestion facilities together with other improper materials such as plastics, paper, textile materials and metals. The rejected materials lost in these stages have two main implications: (i) less organic material enters to digesters and, as a consequence, there is a loss of biogas production and (ii) the rejected materials end up in landfills or incinerators contributing to environmental impacts such as global warming or eutrophication. The main goals of this study are (i) to estimate potential losses of biogas in the rejected solid materials generated during the pre- and post-treatments of two full-scale anaerobic digestion facilities and (ii) to evaluate the environmental burdens associated to the final disposal (landfill or incineration) of these rejected materials by means of Life Cycle Assessment. This study shows that there is a lost of potential biogas production, ranging from 8% to 15%, due to the loss of organic matter during pre-treatment stages in anaerobic digestion facilities. From an environmental point of view, the Life Cycle Assessment shows that the incineration scenario is the most favorable alternative for eight out of nine impact categories compared with the landfill scenario. The studied impact categories are Climate Change, Fossil depletion, Freshwater eutrophication, Marine eutrophication, Ozone depletion, Particulate matter formation, Photochemical oxidant formation, Terrestrial acidification and Water depletion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of acid detergent fiber in hydrothermally pretreated sewage sludge on anaerobic digestion process

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Takasaki, Rikiya; Yuan, Lee Chang; Kamahara, Hirotsugu; Atsuta, Youichi; Daimon, Hiroyuki

2017-10-01

Hydrothermal treatment is one of the pre-treatment method for anaerobic digestion. The application of hydrothermal treatment to sewage sludge of wastewater treatment plant has been succeeded to enhance the biogas production. The purpose of this study is to quantitatively clarify the effect of hydrothermal treatment on anaerobic digestion process focusing on acid detergent fiber (ADF) in sewage sludge, which is low biodegradability. The hydrothermal treatment experiment was carried out for 15 minutes between 160 °C and 200 °C respectively. The ADF content was decreased after hydrothermal treatment compared with untreated sludge. However, ADF content was increased when raising the treatment temperature from 160 °C to 200 °C. During batch anaerobic digestion experiment, untreated and treated sludge were examined for 10 days under 38 °C, and all samples were fed once based on volatile solids of samples. From batch anaerobic digestion experiment, as ADF content in sewage sludge increased, the total biogas production decreased. It was found that ADF content in sewage sludge influence on anaerobic digestion. Therefore, ADF could be one of the indicator to evaluate the effect of hydrothermal treatment to sewage sludge on anaerobic digestion.

GM(1,N) method for the prediction of anaerobic digestion system and sensitivity analysis of influential factors.

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Ren, Jingzheng

2018-01-01

Anaerobic digestion process has been recognized as a promising way for waste treatment and energy recovery in a sustainable way. Modelling of anaerobic digestion system is significantly important for effectively and accurately controlling, adjusting, and predicting the system for higher methane yield. The GM(1,N) approach which does not need the mechanism or a large number of samples was employed to model the anaerobic digestion system to predict methane yield. In order to illustrate the proposed model, an illustrative case about anaerobic digestion of municipal solid waste for methane yield was studied, and the results demonstrate that GM(1,N) model can effectively simulate anaerobic digestion system at the cases of poor information with less computational expense. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of anaerobic digestion processes for short sludge-age waste activated sludge combined with anammox treatment of digestate liquor.

Science.gov (United States)

Ge, Huoqing; Batstone, Damien; Keller, Jurg

2016-01-01

The need to reduce energy input and enhance energy recovery from wastewater is driving renewed interest in high-rate activated sludge treatment (i.e. short hydraulic and solids retention times (HRT and SRT, respectively)). This process generates short SRT activated sludge stream, which should be highly degradable. However, the evaluation of anaerobic digestion of short SRT sludge has been limited. This paper assesses anaerobic digestion of short SRT sludge digestion derived from meat processing wastewater under thermophilic and mesophilic conditions. The thermophilic digestion system (55°C) achieved 60 and 68% volatile solids destruction at 8 day and 10 day HRT, respectively, compared with 50% in the mesophilic digestion system (35°C, 10 day HRT). The digestion effluents from the thermophilic (8-10 day HRT) and mesophilic systems were stable, as assessed by residual methane potentials. The ammonia rich sludge dewatering liquor was effectively treated by a batch anammox process, which exhibited comparable nitrogen removal rate as the tests using a control synthetic ammonia solution, indicating that the dewatering liquor did not have inhibiting/toxic effects on the anammox activity.

Municipal Development of Anaerobic Digestion/ Combined Heat and Power in Massachusetts

Science.gov (United States)

Pike, Brenda

With a commercial food waste ban going into effect in Massachusetts in October 2014, businesses, institutions, and municipalities are considering alternatives to landfills and incinerators for organic waste. Anaerobic digestion is one such alternative. Similar to composting, but in an environment devoid of oxygen, anaerobic digestion produces byproducts such as methane (which can be burned for heat or electricity) and liquid or solid digestate (which can be used as fertilizer, cattle bedding, and more). Thus, disposal of food waste and other organic materials can become a source of revenue rather than just an expense. Municipalities interested in developing anaerobic digestion/combined heat and power (AD/CHP) facilities have the benefit of desirable options for sites, such as landfill gas facilities and wastewater treatment plants, and potential feedstocks in source-separated residential or municipal food waste or wastewater. This thesis examines the opportunities and challenges for municipal development of AD/CHP facilities in Massachusetts.

Sequential batch anaerobic composting (SEBAC sup TM ) of solid wastes

Energy Technology Data Exchange (ETDEWEB)

Chynoweth, D.P.; O' Keefe, D.M.; Barkdoll, A.W.; Owens, J.M. (Department of Agricultural Engineering, University of Florida, Gainesville, Florida (US)); Legrand, R. (Radian Corporation, Austin, Texas (US))

1992-01-01

Anaerobic high-solids digestion (anaerobic composting) is an attractive option for treatment of organic wastes. The main advantages of anaerobic composting are the lack of aeration requirements and production of methane. An anaerobic composting design, sequential batch anaerobic composting (SEBAC{sup TM}), has been developed and demonstrated at the pilot scale which has proven to be stable and effective for treatment of the non-yeard waste and yard waste organic fractions of municipal solid waste (MSW). The design employs leachate recycle for wetting, inoculation, and removal of volatile organic acids during startup. Performance is similar to that of other designs requiring heavy solids inoculation and mixing and which do not have a mechanism for volatile organic acid removal during imbalance. (au) (12 refs.).

The influence of the anaerobic digestion process on the sewage sludges rheological behaviour

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Monteiro, P.S. [Porto Univ. (Portugal). Facultade de Engenharia. Inst. de Hidraulica e Recursos Hidricos

1998-12-31

During the anaerobic digestion process, a significant part of the organic matter is sewage sludge is decomposed to form other organic and inorganic compounds in dissolved form. The biological transformation of a substantial part of the organic solids has, certainly, a strong influence on the rheological characteristics of the sludges. In this paper a test facility was set up to simulate sewage sludge digestion and periodic observations on the evolution of the sludge characteristics were carried out. Results of this study show that important changes on the sludge rheological behaviour occur during anaerobic digestion and that the evolution of those changes is related with the degree of digestion. Moreover, it is shown that the verified high degree of physical changes can not be demonstrated only by the total solids concentration variation and two hypothesis are proposed to explain those changes.

Simulation of the Impact of SRT on Anaerobic Digestability of Ultrasonicated Hog Manure

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Elsayed Elbeshbishy

2010-05-01

Full Text Available Ultrasonication at a specific energy of 500 kJ/kgTS was applied to hog manure in a continuous mode completely mixed anaerobic digestion. A process model in BioWin was developed, calibrated and tested at different solids retention times (SRTs to evaluate the process economics. The results showed that there was a 36% increase in volatile suspended solids (VSS removal efficiency, a 20% increase in methane production rate, a 13.5% increase in destruction of bound proteins, and a reduction from 988 to 566 ppm in H2S concentration in the digester headspace. Furthermore, a calibrated model of the process using BioWin to assess the impact of SRTs on the economics of anaerobic digestion for unsonicated and sonicated hog manure revealed that ultrasonication resulted in a net benefit of $42–46/ton dry solids at SRTs of 15–30 days.

Simulation of the impact of SRT on anaerobic digestability of ultrasonicated hog manure

Energy Technology Data Exchange (ETDEWEB)

Elbeshbishy, E.; Hafez, H.; Nakhla, G. [Department of Civil and Environmental Engineering, University of Western Ontario, London, Ontario N6A 5B9 (Canada); Nakevski, A.; Ray, M. [Department of Chemical and Biochemical Engineering, University of Western Ontario, London, Ontario N6A 5B9 (Canada)

2010-07-01

Ultrasonication at a specific energy of 500 kJ/kgTS was applied to hog manure in a continuous mode completely mixed anaerobic digestion. A process model in BioWin was developed, calibrated and tested at different solids retention times (SRTs) to evaluate the process economics. The results showed that there was a 36% increase in volatile suspended solids (VSS) removal efficiency, a 20% increase in methane production rate, a 13.5% increase in destruction of bound proteins, and a reduction from 988 to 566 ppm in H{sub 2}S concentration in the digester headspace. Furthermore, a calibrated model of the process using BioWin to assess the impact of SRTs on the economics of anaerobic digestion for unsonicated and sonicated hog manure revealed that ultrasonication resulted in a net benefit of $42-46/ton dry solids at SRTs of 15-30 days. (author)

Understanding the impact of cationic polyacrylamide on anaerobic digestion of waste activated sludge.

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Wang, Dongbo; Liu, Xuran; Zeng, Guangming; Zhao, Jianwei; Liu, Yiwen; Wang, Qilin; Chen, Fei; Li, Xiaoming; Yang, Qi

2018-03-01

Previous investigations showed that cationic polyacrylamide (cPAM), a flocculant widely used in wastewater pretreatment and waste activated sludge dewatering, deteriorated methane production during anaerobic digestion of sludge. However, details of how cPAM affects methane production are poorly understood, hindering deep control of sludge anaerobic digestion systems. In this study, the mechanisms of cPAM affecting sludge anaerobic digestion were investigated in batch and long-term tests using either real sludge or synthetic wastewaters as the digestion substrates. Experimental results showed that the presence of cPAM not only slowed the process of anaerobic digestion but also decreased methane yield. The maximal methane yield decreased from 139.1 to 86.7 mL/g of volatile suspended solids (i.e., 1861.5 to 1187.0 mL/L) with the cPAM level increasing from 0 to 12 g/kg of total suspended solids (i.e., 0-236.7 mg/L), whereas the corresponding digestion time increased from 22 to 26 d. Mechanism explorations revealed that the addition of cPAM significantly restrained the sludge solubilization, hydrolysis, acidogenesis, and methanogenesis processes. It was found that ∼46% of cAPM was degraded in the anaerobic digestion, and the degradation products significantly affected methane production. Although the theoretically biochemical methane potential of cPAM is higher than that of protein and carbohydrate, only 6.7% of the degraded cPAM was transformed to the final product, methane. Acrylamide, acrylic acid, and polyacrylic acid were found to be the main degradation metabolites, and their amount accounted for ∼50% of the degraded cPAM. Further investigations showed that polyacrylic acid inhibited all the solubilization, hydrolysis, acidogenesis, and methanogenesis processes while acrylamide and acrylic acid inhibited the methanogenesis significantly. Copyright © 2017 Elsevier Ltd. All rights reserved.

ANAEROBIC BIODEGRADATION OF A BIODEGRADABLE MATERIAL UNDER ANAEROBIC - THERMOPHILIC DIGESTION

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RICARDO CAMACHO-MUÑOZ

2014-12-01

Full Text Available This paper dertermined the anaerobic biodegradation of a polymer obtained by extrusion process of native cassava starch, polylactic acid and polycaprolactone. Initially a thermophilic - methanogenic inoculum was prepared from urban solid waste. The gas final methane concentration and medium’s pH reached values of 59,6% and 7,89 respectively. The assay assembly was carried out according ASTM D5511 standard. The biodegradation percent of used materials after 15 day of digestion were: 77,49%, 61,27%, 0,31% for cellulose, sample and polyethylene respectively. Due cellulose showed biodegradation levels higher than 70% it’s deduced that the inoculum conditions were appropriate. A biodegradation level of 61,27%, 59,35% of methane concentration in sample’s evolved gas and a medium’s finale pH of 7,71 in sample’s vessels, reveal the extruded polymer´s capacity to be anaerobically degraded under thermophilic- high solid concentration conditions.

Modeling the performance of the anaerobic phased solids digester system for biogas energy production

International Nuclear Information System (INIS)

Rapport, Joshua L.; Zhang, Ruihong; Jenkins, Bryan M.; Hartsough, Bruce R.; Tomich, Thomas P.

2011-01-01

A process model was developed to predict the mass and energy balance for a full-scale (115 t d -1 ) high-solids anaerobic digester using research data from lab and pilot scale (1-3000 kg d -1 wet waste) systems. Costs and revenues were estimated in consultation with industry partners and the 20-year project cash flow, net present worth (NPW), simple payback, internal rate of return, and revenue requirements were calculated. The NPW was used to compare scenarios in order to determine the financial viability of using a generator for heat and electricity or a pressure swing adsorption unit for converting biogas to compressed natural gas (CNG). The full-scale digester consisted of five 786 m 3 reactors (one biogasification reactor and four hydrolysis reactors) treating a 50:50 mix (volatile solids basis) of food and green waste, of which 17% became biogas, 32% residual solids, and 51% wastewater. The NPW of the projects were similar whether producing electricity or CNG, as long as the parasitic energy demand was satisfied with the biogas produced. When producing electricity only, the power output was 1.2 MW, 7% of which was consumed parasitically. When producing CNG, the system produced 2 hm 3 y -1 natural gas after converting 22% of the biogas to heat and electricity which supplied the parasitic energy demand. The digester system was financially viable whether producing electricity or CNG for discount rates of up to 13% y -1 without considering debt (all capital was considered equity), heat sales, feed-in tariffs or tax credits.

Influence of feedstock-to-inoculum ratio on performance and microbial community succession during solid-state thermophilic anaerobic co-digestion of pig urine and rice straw.

Science.gov (United States)

Meng, Lingyu; Xie, Li; Kinh, Co Thi; Suenaga, Toshikazu; Hori, Tomoyuki; Riya, Shohei; Terada, Akihiko; Hosomi, Masaaki

2018-03-01

This study investigated the effect of the feedstock-to-inoculum (F/I) ratio on performance of the solid-state anaerobic co-digestion of pig urine and rice straw inoculated with a solid digestate, and clarified the microbial community succession. A 44-day biochemical methane potential test at F/I ratios of 0.5, 1, 2 and 3 at 55 °C and a 35-day large-scale batch test at F/I ratios of 0.5 and 3 at 55 °C were conducted to investigate the effects of F/I ratio on anaerobic digestibility and analyze microbial community succession, respectively. The highest cumulative methane yield was 353.7 m 3 /t VS in the large-scale batch test. Volatile fatty acids did not accumulate at any F/I ratios. The volatile solids reduction rate was highest at a F/I ratio of 0.5. Microbial community structures were similar between F/I ratios of 3 and 0.5, despite differences in digestion performance, suggesting that stable operation can be achieved at these ratios. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic digestion of solid waste in RAS: Effect of reactor type on the biochemical acidogenic potential (BAP) and assessment of the biochemical methane potential (BMP) by a batch assay

DEFF Research Database (Denmark)

Suhr, Karin Isabel; Letelier-Gordo, Carlos Octavio; Lund, Ivar

2015-01-01

the biochemical acidogenic potential of solid waste from juvenile rainbow trout was evaluated by measuring the yield of volatile fatty acids (VFA) during anaerobic digestion by batch or fed-batch reactor operation at hydrolysis time (HT) / hydraulic retention time (HRT) of 1, 5, or 10 days (and for batch......Anaerobic digestion is a way to utilize the potential energy contained in solid waste produced in recirculating aquaculture systems (RASs), either by providing acidogenic products for driving heterotrophic denitrification on site or by directly producing combustive methane. In this study...

Leachate properties as indicators of methane production process in MSW anaerobic digestion bioreactor landfill

Science.gov (United States)

Zeng, Yunmin; Wang, Li'ao; Xu, Tengtun; Li, Jiaxiang; Song, Xue; Hu, Chaochao

2018-03-01

In this paper, bioreactor was used to simulate the municipal solid waste (MSW) biodegradation process of landfill, tracing and testing trash methanogenic process and characteristics of leachate during anaerobic digestion, exploring the relationship between the two processes, aiming to screen out the indicators that can predict the methane production process of anaerobic digestion, which provides the support for real-time adjustment of technological parameters of MSW anaerobic digestion system and ensures the efficient operation of bioreactor landfill. The results showed that MSW digestion gas production rate constant is 0.0259 1/d, biogas production potential is 61.93 L/kg. The concentration of TN in leachate continued to increase, showing the trend of nitrogen accumulation. "Ammonia poisoning" was an important factor inhibiting waste anaerobic digestion gas production. In the anaerobic digestion system, although pH values of leachate can indicate methane production process to some degree, there are obvious lagging behind, so it cannot be used as indicator alone. The TOC/TN value of leachate has a certain indication on the stability of the methane production system. When TOC/TN value was larger than12, anaerobic digestion system was stable along with normal production of biogas. However, when TOC/TN value was lower than 12, the digestive system is unstable and the gas production is small. In the process of anaerobic digestion, the synthesis and transformation of valeric acid is more active. HAc/HVa changed greatly and had obvious inflection points, from which methane production period can be predicted.

Anaerobic digestion of thin stillage for energy recovery and water reuse in corn-ethanol plants.

Science.gov (United States)

Alkan-Ozkaynak, A; Karthikeyan, K G

2011-11-01

Recycling of anaerobically-digested thin stillage within a corn-ethanol plant may result in the accumulation of nutrients of environmental concern in animal feed coproducts and inhibitory organic materials in the fermentation tank. Our focus is on anaerobic digestion of treated (centrifugation and lime addition) thin stillage. Suitability of digestate from anaerobic treatment for reuse as process water was also investigated. Experiments conducted at various inoculum-to-substrate ratios (ISRs) revealed that alkalinity is a critical parameter limiting digestibility of thin stillage. An ISR level of 2 appeared optimal based on high biogas production level (763 mL biogas/g volatile solids added) and organic matter removal (80.6% COD removal). The digester supernatant at this ISR level was found to contain both organic and inorganic constituents at levels that would cause no inhibition to ethanol fermentation. Anaerobic digestion of treated-thin stillage can be expected to improve the water and energy efficiencies of dry grind corn-ethanol plants. Copyright © 2011 Elsevier Ltd. All rights reserved.

Application of Methanobrevibacter acididurans in anaerobic digestion.

Science.gov (United States)

Savant, D V; Ranade, D R

2004-01-01

To operate anaerobic digesters successfully under acidic conditions, hydrogen utilizing methanogens which can grow efficiently at low pH and tolerate high volatile fatty acids (VFA) are desirable. An acid tolerant hydrogenotrophic methanogen viz. Methanobrevibacter acididurans isolated from slurry of an anaerobic digester running on alcohol distillery wastewater has been described earlier by this lab. This organism could grow optimally at pH 6.0. In the experiments reported herein, M. acididurans showed better methanogenesis under acidic conditions with high VFA, particularly acetate, than Methanobacterium bryantii, a common hydrogenotrophic inhabitant of anaerobic digesters. Addition of M. acididurans culture to digesting slurry of acidogenic as well as methanogenic digesters running on distillery wastewater showed increase in methane production and decrease in accumulation of volatile fatty acids. The results proved the feasibility of application of M. acididurans in anaerobic digesters.

Design considerations and operational performance of Anaerobic Digester: A Review

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Muzaffar Ahmad Mir

2016-04-01

Full Text Available Due to the decline in fossil fuel reservoirs, the researchers emphasized more on the production of biogas from organic waste. Producing the renewable energy from biodegradable waste helps to overcome the energy crisis and solid waste management, done by anaerobic digestion. Anaerobic digestion is controlled breakdown of organic matter into methane gas (60%, carbon dioxide (40%, trace components along with digested used as soil conditioner. However there is vast dearth of literature regarding the design considerations. The batch digestion system yields a cost-effective and economically viable means for conversion of the food waste to useful energy. It is therefore recommended that such process can be increasingly employed in order to get and simultaneously protect the environment .This paper aims to draw key analysis and concern about the design considerations, analysis of gas production, substrates and inoculums utilization, uses and impacts of biogas.

Effect of different pH-values on process parameters in two-phase anaerobic digestion of high-solid substrates.

Science.gov (United States)

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

2015-01-01

In many publications, primary fermentation is described as a limiting step in the anaerobic digestion of fibre-rich biomass [Eastman JA, Ferguson JF. Solubilization of particulacte carbon during the anaerobic digeston. J WPCF. 1981;53:352-366; Noike T, Endo G, Chang J, Yaguchi J, Matsumoto J. Characteristics of carbohydrate degradation and the rate-limiting step in anaerobic digestion. Biotechnol Bioeng. 1985;27:1482-1489; Arntz HJ, Stoppok E, Buchholz K. Anaerobic hydroysis of beet pulp-discontiniuous experiments. Biotechnol Lett. 1985;7:113-118]. The microorganisms of the primary fermentation process differ widely from the methanogenic microorganisms [Pohland FG, Ghosh S. Developments in anaerobic stabilization of organic wastes-the two-phase concept. Environ Lett. 1971;1:255-266]. To optimize the biogas process, a separation in two phases is suggested by many authors [Fox P, Pohland GK. Anaerobic treatment applications and fundamentals: substrate specificity during phase separation. Water Environ Res. 1994;66:716-724; Cohen A, Zoetemeyer RJ, van Deursen A, van Andel JG. Anaerobic digestion of glucose with separated acid production and methane formation. Water Res. 1979;13:571-580]. To carry out the examination, a two-phase laboratory-scale biogas plant was established, with a physical phase separation. In previous studies, the regulation of the pH-value during the acid formation was usually carried out by the addition of sodium hydroxide [Cohen A, Zoetemeyer RJ, van Deursen A, van Andel JG. Anaerobic digestion of glucose with separated acid production and methane formation. Water Res. 1979;13:571-580; Ueno Y, Tatara M, Fukui H, Makiuchi T, Goto M, Sode K. Production of hydrogen and methane from organic solid wastes by phase separation of anaerobic process. Bioresour Technol. 2007;98:1861-1865; Zoetemeyer RJ, van den Heuvel JC, Cohen A. pH influence on acidogenic dissimilation of glucose in an anaerobic digestor. Water Res. 1982;16:303-311]. A new technology

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

Bacterial population of piggery-waste anaerobic digesters

Energy Technology Data Exchange (ETDEWEB)

Hobson, P N; Shaw, B G

1974-08-01

A survey was made of the anaerobic and facultatively anaerobic bacteria present in piggery waste, digesting piggery waste and domestic anaerobic sludge used to start a piggery waste digester. An influence of the input waste was shown in that streptococci, the predominant facultatively anaerobic bacteria in the piggery waste, were the predominant bacteria in the digesting waste, and they replaced Entrobacter, predominant in the domestic sludge, when a piggery waste digestion had been established from this latter material. Cellulolytic or methanogenic bacteria could not be detected in the piggery waste but populations of these, and other hydrolytic bacteria, became established at different times during the build-up of digestion by gradual addition of piggery waste to water. The bacteria concerned in degradation of the waste constituents were all anaerobes. Production of methane from H/sub 2//CO/sub 2/, formate and butyrate could be detected in mixed cultures from dilutions of digester contents, but the only methanogenic bacterium that could be isolated in pure culture was Methanobacterium formicicum, which uses H/sub 2//CO/sub 2/ or formate only.

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)

Renewable Biochemical Methane Potential through Anaerobic Co-digestion from Selective Feed Stocks

Science.gov (United States)

Thara, K.; Navis Karthika, Ignatius; Dheenadayalan, M. S., Dr

2017-08-01

Biochemical Methane Potential (BMP) analysis provides a measure of the anaerobic biodegradability of a given substrate. BMP test is also used to evaluate the potential biogas (methane) production between various Co-digestion substrates. This test is also used to determine the amount of organic carbon in a given material that can be an aerobically converted to methane-Biogas. Studies were carried out for the production of biogas from the leather solid waste. Co-digestion (simultaneous digestion of two or more substrates) studies were carried out in batch reactor using the fleshing (a solid waste generated during the processing of raw hides or skins into finished leather) along with the fruit and vegetable waste at mesophilic condition 35° C). The anaerobic methanogenic seed sludge prepared separately followed by standard BMP test, which was used as the seed inoculums. Recent research on this topic is reviewed in this current paper.

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...

Energy Generation from Horse Husbandry Residues by Anaerobic Digestion, Combustion, and an Integrated Approach

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Meike Nitsche

2017-02-01

Full Text Available Horse-related activities often occur close to urban areas, where acreage for horse manure disposal is scarce, and subsequently alternative recovery options are necessary. Anaerobic digestion, direct combustion, and the integrated generation of solid fuel and biogas from biomass (IFBB process are potential techniques focusing on energy provision. In this study, samples of horse faeces were analysed for chemical composition as pure feedstock and in mixture with straw or wood shavings, as well as for energy yield by biogas production or from combustion of solid fuel. It was observed that chemical properties of faeces, in a mixture with wood shavings, were promising for direct combustion, but achieved low methane yields. The methane yield of pure faeces and the straw mixture was 222.33 ± 13.60 and 233.01 ± 31.32 lN·kg-1 volatile solids (VSadded, respectively. The IFBB process divided the biomass into a press cake with reduced mineral concentration and a press fluid. Methane yields of press fluids were low (108.2 lN·kg-1 VSadded, on average. The chemical composition of the press cake allowed for combustion and led to a higher gross energy potential than anaerobic digestion (two-fold higher for pure manure and the mixture with straw, and five-fold higher for the mixture with shavings. Consequently, the gross energy potential of IFBB is higher compared to anaerobic digestion, however it should be noted that local conditions might favour the implementation of anaerobic digestion.

Pathogen inactivation in liquid dairy manure during anaerobic and aerobic digestions

Science.gov (United States)

Biswas, S.; Pandey, P.; Castillo, A. R.; Vaddella, V. K.

2014-12-01

Controlling manure-borne pathogens such as E. coli O157:H7, Salmonella spp. and Listeria monocytogenes are crucial for protecting surface and ground water as well as mitigating risks to human health. In California dairy farms, flushing of dairy manure (mainly animal feces and urine) from freestall barns and subsequent liquid-solid manure separation is a common practice for handling animal waste. The liquid manure fraction is generally pumped into the settling ponds and it goes into aerobic and/or anaerobic lagoons for extended period of time. Considering the importance of controlling pathogens in animal waste, the objective of the study was to understand the effects of anaerobic and aerobic digestions on the survival of three human pathogens in animal waste. The pathogen inactivation was assessed at four temperatures (30, 35, 42, and 50 °C), and the relationships between temperature and pathogen decay were estimated. Results showed a steady decrease of E. coli levels in aerobic and anaerobic digestion processes over the time; however, the decay rates varied with pathogens. The effect of temperature on Salmonella spp. and Listeria monocytogenes survival was different than the E. coli survival. In thermophilic temperatures (42 and 50 °C), decay rate was considerable greater compared to the mesophilic temperatures (30 and 35°C). The E. coli log reductions at 50 °C were 2.1 in both aerobic and anaerobic digestions after 13 days of incubation. The Salmonella spp. log reductions at 50 °C were 5.5 in aerobic digestion, and 5.9 in anaerobic digestion. The Listeria monocytogenes log reductions at 50 °C were 5.0 in aerobic digestion, and 5.6 in anaerobic digestion. The log reduction of E. coli, Salmonella spp., and Listeria monocytogens at 30 °C in aerobic environment were 0.1, 4.7, and 5.6, respectively. In anaerobic environment, the corresponding reductions were 0.4, 4.3, and 5.6, respectively. We anticipate that the outcomes of the study will help improving the

Aerobic treatment of swine manure to enhance anaerobic digestion and microalgal cultivation.

Science.gov (United States)

Bekoe, Dominic; Wang, Lijun; Zhang, Bo; Scott Todd, Matthew; Shahbazi, Abolghasem

2018-02-01

Aerobic treatment of swine manure was coupled with anaerobic digestion and microalgal cultivation. A 14-day aerobic treatment reduced the total solid content of swine manure by >15%. Ammonia and carbon dioxide were stripped by the air supplied, and this off-gas was further used to aerate the culture of Chlorella vulgaris. The microalgal growth rates in Bristol medium and the wastewater with the off-gas increased from 0.08 to 0.22 g/L/d and from 0.15 to 0.24 g/L/d, respectively. Meanwhile, the aerobically treated swine manure showed a higher methane yield during anaerobic digestion. The experimental results were used to establish a demonstration unit consisting of a 100 L composter, a 200 L anaerobic digester, a 60 L tubular photobioreactor, and a 300 L micro-open raceway pond.

Anaerobic digestion of cellulosic wastes: laboratory tests

International Nuclear Information System (INIS)

Lee, D.D.; Donaldson, T.L.

1984-11-01

Anaerobic digestion is a potentially attractive technology for volume reduction of cellulosic wastes. A substantial fraction of the waste is converted to off-gas and a relatively small volume of biologically stabilized sludge is produced. Process development work is underway using a 75-L digester to verify rates and conversions obtained at the bench scale, to develop start-up and operating procedures, and to generate effluent for characterization and disposal studies. Three runs using batch and batch-fed conditions have been made lasting 36, 90, and over 200 days. Solids solubilization and gas production rates and total solids destruction have met or exceeded the target values of 0.6 g cellulose per L of reactor per day, 0.5 L off-gas per L of reactor per day, and 80% destruction of solids, respectively. Successful start-up procedures have been developed, and preliminary effluent characterization and disposal studies have been done. A simple dynamic process model has been constructed to aid in further process development and for use in process monitoring and control of a large-scale digester. 10 references, 17 figures, 4 tables

Biomass hydrolysis inhibition at high hydrogen partial pressure in solid-state anaerobic digestion.

Science.gov (United States)

Cazier, E A; Trably, E; Steyer, J P; Escudie, R

2015-08-01

In solid-state anaerobic digestion, so-called ss-AD, biogas production is inhibited at high total solids contents. Such inhibition is likely caused by a slow diffusion of dissolved reaction intermediates that locally accumulate. In this study, we investigated the effect of H2 and CO2 partial pressure on ss-AD. Partial pressure of H2 and/or CO2 was artificially fixed, from 0 to 1 557mbars for H2 and from 0 to 427mbars for CO2. High partial pressure of H2 showed a significant effect on methanogenesis, while CO2 had no impact. At high [Formula: see text] , the overall substrate degradation decreased with no accumulation of metabolites from acidogenic bacteria, indicating that the hydrolytic activity was specifically impacted. Interestingly, such inhibition did not occur when CO2 was added with H2. This result suggests that CO2 gas transfer is probably a key factor in ss-AD from biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bio digester : anaerobic methanogenesis

NARCIS (Netherlands)

Bullema, Marten; Hulzen, Hans; Keizer, Melvin; Pruisscher, Gerlof; Smint, Martin; Vincent, Helene

2014-01-01

As part of the theme 13 and 14, our group have to realize a project in the field of the renewable energy. This project consist of the design of a bio-digester for the canteen of Zernikeplein. Gert Hofstede is our client. To produce energy, a bio-digester uses the anaerobic digestion, which is made

Covering Materials for Anaerobic Digesters Producing Biogas

International Nuclear Information System (INIS)

Itodo, I. N.; Philips, T. K.

2002-01-01

The suitability of foam, concrete and clay soil as covering material on anaerobic digesters producing biogas was investigated using four batch-type digesters of 20 litres volume. The methane yield from the digesters was of the order: foam >control> concrete > clay soil. The digester covered with foam had the highest methane yield, best temperature control and most favourable pH conditions. It is most suitable as cover material on anaerobic digesters

Evaluation of the 5 and 8 pH point titration methods for monitoring anaerobic digesters treating solid waste.

Science.gov (United States)

Vannecke, T P W; Lampens, D R A; Ekama, G A; Volcke, E I P

2015-01-01

Simple titration methods certainly deserve consideration for on-site routine monitoring of volatile fatty acid (VFA) concentration and alkalinity during anaerobic digestion (AD), because of their simplicity, speed and cost-effectiveness. In this study, the 5 and 8 pH point titration methods for measuring the VFA concentration and carbonate system alkalinity (H2CO3*-alkalinity) were assessed and compared. For this purpose, synthetic solutions with known H2CO3*-alkalinity and VFA concentration as well as samples from anaerobic digesters treating three different kind of solid wastes were analysed. The results of these two related titration methods were verified with photometric and high-pressure liquid chromatography measurements. It was shown that photometric measurements lead to overestimations of the VFA concentration in the case of coloured samples. In contrast, the 5 pH point titration method provides an accurate estimation of the VFA concentration, clearly corresponding with the true value. Concerning the H2CO3*-alkalinity, the most accurate and precise estimations, showing very similar results for repeated measurements, were obtained using the 8 pH point titration. Overall, it was concluded that the 5 pH point titration method is the preferred method for the practical monitoring of AD of solid wastes due to its robustness, cost efficiency and user-friendliness.

Evaluation of the rotary drum reactor process as pretreatment technology of municipal solid waste for thermophilic anaerobic digestion and biogas production.

Science.gov (United States)

Gikas, Petros; Zhu, Baoning; Batistatos, Nicolas Ion; Zhang, Ruihong

2018-06-15

Municipal solid waste (MSW) contains a large fraction of biodegradable organic materials. When disposed in landfills, these materials can cause adverse environmental impact due to gaseous emissions and leachate generation. This study was performed with an aim of effectively separating the biodegradable materials from a Mechanical Biological Treatment (MBT) facility and treating them in well-controlled anaerobic digesters for biogas production. The rotary drum reactor (RDR) process (a sub-process of the MBT facilities studied in the present work) was evaluated as an MSW pretreatment technology for separating and preparing the biodegradable materials in MSW to be used as feedstock for anaerobic digestion. The RDR processes used in six commercial MSW treatment plants located in the USA were surveyed and sampled. The samples of the biodegradable materials produced by the RDR process were analyzed for chemical and physical characteristics as well as anaerobically digested in the laboratory using batch reactors under thermophilic conditions. The moisture content, TS, VS and C/N of the samples varied between 64.7 and 44.4%, 55.6 to 35.3%, 27.0 to 41.3% and 24.5 to 42.7, respectively. The biogas yield was measured to be between 533.0 and 675.6 mL g -1 VS after 20 days of digestion. Approximately 90% of the biogas was produced during the first 13 days. The average methane content of the biogas was between 58.0 and 59.9%. The results indicated that the biodegradable materials separated from MSW using the RDR processes could be used as an excellent feedstock for anaerobic digestion. The digester residues may be further processed for compost production or further energy recovery by using thermal conversion processes such as combustion or gasification. Copyright © 2017. Published by Elsevier Ltd.

Enhanced primary treatment of concentrated black water and kitchen residues within DESAR concept using two types of anaerobic digesters

NARCIS (Netherlands)

Kujawa-Roeleveld, K.; Elmitwalli, T.A.; Zeeman, G.

2006-01-01

Anaerobic digestion of concentrated domestic wastewater streams - black or brown water, and solid fraction of kitchen waste is considered as a core technology in a source separation based sanitation concept (DESAR - decentralised sanitation and reuse). A simple anaerobic digester can be implemented

Enhanced dewaterability of sludge during anaerobic digestion with thermal hydrolysis pretreatment: New insights through structure evolution.

Science.gov (United States)

Zhang, Jingsi; Li, Ning; Dai, Xiaohu; Tao, Wenquan; Jenkinson, Ian R; Li, Zhuo

2017-12-19

Comprehensive insights into the sludge digestate dewaterability were gained through porous network structure of sludge. We measured the evolution of digestate dewaterability, represented by the solid content of centrifugally dewatered cake, in high-solids sequencing batch digesters with and without thermal hydrolysis pretreatment (THP). The results show that the dewaterability of the sludge after digestion was improved by 3.5% (±0.5%) for unpretreated sludge and 5.1% (±0.4%) for thermally hydrolyzed sludge. Compared to the unpretreated sludge digestate, thermal hydrolysis pretreatment eventually resulted in an improvement of dewaterability by 4.6% (±0.5%). Smaller particle size and larger surface area of sludge were induced by thermal hydrolysis and anaerobic digestion treatments. The structure strength and compactness of sludge, represented by elastic modulus and fractal dimension respectively, decreased with increase of digestion time. The porous network structure was broken up by thermal hydrolysis pretreatment and was further weakened during anaerobic digestion, which correspondingly improved the dewaterability of digestates. The logarithm of elastic modulus increased linearly with fractal dimension regardless of the pretreatment. Both fractal dimension and elastic modulus showed linear relationship with dewaterability. The rheological characterization combined with the analysis of fractal dimension of sewage sludge porous network structure was found applicable in quantitative evaluation of sludge dewaterability, which depended positively on both thermal hydrolysis and anaerobic digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Anaerobic Digestion: Mass Balances and Products

DEFF Research Database (Denmark)

Møller, Jacob; Christensen, Thomas Højlund; Jansen, Jes la Cour

2011-01-01

While the basic processes involved in anaerobic digestion of waste are described in Chapter 9.4 and the main digestion technologies are presented in Chapter 9.5, this chapter focuses on mass balances, gas production and energy aspects, environmental emissions and unit process inventories. Underst......While the basic processes involved in anaerobic digestion of waste are described in Chapter 9.4 and the main digestion technologies are presented in Chapter 9.5, this chapter focuses on mass balances, gas production and energy aspects, environmental emissions and unit process inventories...

Anaerobic Digestion Performance in the Energy Recovery of Kiwi Residues

Science.gov (United States)

Martins, Ramiro; Boaventura, Rui; Paulista, Larissa

2017-12-01

World production and trade of fruits generate losses in the harvest, post-harvest, handling, distribution and consumption phases, corresponding to 6.8% of total production. These residues present high potential as a substrate for the anaerobic digestion process and biogas generation. Thus, the energy valuation of the agro-industrial residues of kiwi production was evaluated by anaerobic digestion, aiming at optimizing the biogas production and its quality. Ten assays were carried out in a batch reactor (500 mL) under mesophilic conditions and varying a number of operational factors: different substrate/inoculum ratios; four distinct values for C: N ratio; inoculum from different digesters; and inoculum collected at different times of the year. The following parameters were used to control and monitor the process: pH, alkalinity, volatile fatty acids (VFA), volatile solids (VS) and chemical oxygen demand (COD). Among the tests performed, the best result obtained for the biogas production corresponded to the use of 2 g of substrate and 98 mL of inoculum of the anaerobic digester of the Wastewater Treatment Plant (WWTP) of Bragança, with addition of 150 mg of bicarbonate leading to a production of 1628 L biogas.kg-1 VS (57% methane). In relation to the biogas quality, the best result was obtained with 20 g of substrate and 380 mL of inoculum from the anaerobic digester sludge of WWTP of Ave (with addition 600 mg of sodium bicarbonate), presenting a value of 85% of CH4, with a production of 464 L biogas.kg-1 VS.

The IWA Anaerobic Digestion Model No 1 (ADM1)

NARCIS (Netherlands)

Batstone, D.J.; Keller, J.; Angelidaki, I.; Kalyuzhnyi, S.V.; Pavalostathis, S.G.; Rozzi, A.; Sanders, W.T.M.; Siegrist, H.; Vavilin, V.A.

2002-01-01

The IWA Anaerobic Digestion Modelling Task Group was established in 1997 at the 8th World Congress on Anaerobic Digestion (Sendai, Japan) with the goal of developing a generalised anaerobic digestion model. The structured model includes multiple steps describing biochemical as well as

The IWA Anaerobic digestion model no 1. (ADM1)

DEFF Research Database (Denmark)

Batstone, Damien J.; Keller, J.; Angelidaki, Irini

2002-01-01

The IWA Anaerobic Digestion Modelling Task Group was established in 1997 at the 8th World Congress on Anaerobic Digestion (Sendai, Japan) with the goal of developing a generalised anaerobic digestion model. The structured model includes multiple steps describing biochemical as well...

Anaerobic digestion of waste from an intensive pig unit. [NON

Energy Technology Data Exchange (ETDEWEB)

Hobson, P N; Shaw, B G

1973-03-01

Use was made of heated (35/sup 0/C), stirred, and daily fed laboratory digesters. It was found that digestion of undiluted feces-urine was impossible, but balanced digestion could be obtained in digesters originally seeded from a working domestic anaerobic digester or in digesters filled with water into which small amounts of waste were regularly added. The results from running two digesters for over 80 weeks at loading rates of 0.5 to 3.2 g VS/l/day at detention times of 37.5 to 14 days are given. Above a loading rate of about 2.6 g VS/l/day, at a detention time of 14 days, performance in terms of percentage reduction in solids, BOD and COD began to fall. Maximum BOD reduction of 80 to 90% was found at that loading rate. Volatile acids and ammonia remained below inhibitory levels. It was postulated that there was an upper limit of total solids of about 4.5% above which satisfactory performance cannot be expected.

Anaerobic digestion of low-level radioactive cellulosic and animal wastes

International Nuclear Information System (INIS)

Donaldson, T.L.; Strandberg, G.W.; Patton, B.D.; Harrington, F.E.

1983-02-01

A preliminary process design and a cost estimate have been made for a volume reduction plant for low-level, solid radioactive wastes generated at ORNL. The process is based on extension of existing anaerobic digestion technology and on laboratory studies indicating the feasibiity of this technology for digestion of the organic portion of low-level, solid radioactive wastes. A gaseous effluent (CO 2 and CH 4 ) is vented in the process, and a liquid ffluent containing undigested solids is filtered to remove solids, which are buried. The liquid is discharged to the low-level liquid waste system at ORNL. Overall volume reduction of solid waste by this process is estimated to be approximately 20:1. Costs appear to be comparable to costs for compaction. The process design is conservative, and several potential improvements which could increase efficiency are discussed in this report

Anaerobic digestion of solid slaughterhouse waste: study of biological stabilization by Fourier Transform infrared spectroscopy and thermogravimetry combined with mass spectrometry.

Science.gov (United States)

Cuetos, María José; Gómez, Xiomar; Otero, Marta; Morán, Antonio

2010-07-01

In this paper, Fourier Transform infrared spectroscopy (FTIR) along with thermogravimetric analysis together with mass spectrometry (TG-MS analysis) were employed to study the organic matter transformation attained under anaerobic digestion of slaughterhouse waste and to establish the stability of the digestates obtained when compared with fresh wastes. Digestate samples studied were obtained from successful digestion and failed systems treating slaughterhouse waste and the organic fraction of municipal solid wastes. The FTIR spectra and TG profiles from well stabilized products (from successful digestion systems) showed an increase in the aromaticity degree and the reduction of volatile content and aliphatic structures as stabilization proceeded. On the other hand, the FTIR spectra of non-stable reactors showed a high aliphaticity degree and fat content. When comparing differential thermogravimetry (DTG) profiles of the feed and digestate samples obtained from all successful anaerobic systems, a reduction in the intensity of the low-temperature range (approximately 300 degrees C) peak was observed, while the weight loss experienced at high-temperature (450-550 degrees C) was variable for the different systems. Compared to the original waste, the intensity of the weight loss peak in the high-temperature range decreased in the reactors with higher hydraulic retention time (HRT) whereas its intensity increased and the peak was displaced to higher temperatures for the digesters with lower HRT.

Perspectives for anaerobic digestion

DEFF Research Database (Denmark)

Ahring, Birgitte Kiær

2003-01-01

The modern society generates large amounts of waste that represent a tremendous threat to the environment and human and animal health. To prevent and control this, a range of different waste treatment and disposal methods are used. The choice of method must always be based on maximum safety...... 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...

Low intensity surplus activated sludge pretreatment before anaerobic digestion

Directory of Open Access Journals (Sweden)

Suschka Jan

2017-12-01

Full Text Available Sewage sludge (municipal, or industrial treatment is still a problem in so far that it is not satisfactorily resolved in terms of cost and final disposal. Two common forms of sludge disposal are possible; the first being direct disposal on land (including agriculture and the second being incineration (ash production, although neither of these methods are universally applied. Simplifying the issue, direct sludge disposal on land is seldom applied for sanitary and environmental reasons, while incineration is not popular for financial (high costs reasons. Very often medium and large wastewater treatment plants apply anaerobic digestion for sludge hygiene principles, reducing the amount to be disposed and for biogas (energy production. With the progress in sewage biological treatment aiming at nutrient removal, primary sludge has been omitted in the working processes and only surplus activated sludge requires handling. Anaerobic digestion of waste activated sludge (WAS is more difficult due to the presence of microorganisms, the decomposition of which requires a relatively long time for hydrolysis. In order to upgrade the hydrolysis effects, several different pre-treatment processes have already been developed and introduced. The additional pre-treatment processes applied are aimed at residual sludge bulk mass minimization, shortening of the anaerobic digestion process or higher biogas production, and therefore require additional energy. The water-energy-waste Nexus (treads of of the benefits and operational difficulties, including energy costs are discussed in this paper. The intensity of pre-treatment processes to upgrade the microorganism’s hydrolysis has crucial implications. Here a low intensity pre-treatment process, alkalisation and hydrodynamic disintegration - hybrid process - were presented in order to achieve sufficient effects of WAS anaerobic digestion. A sludge digestion efficiency increase expressed as 45% biogas additional

Anaerobic Digestion Modeling: from One to Several Bacterial Populations

Directory of Open Access Journals (Sweden)

Iván D. Ramírez-Rivas

2013-11-01

Full Text Available Anaerobic digestion systems are complex processes that unfortunately often suffer from instability causing digester failure. In order to be able to design, optimizing and operate efficiently anaerobic digestion systems, appropriate control strategies need to be designed. Such strategies require, in general, the development of mathematical models. The anaerobic digestion process comprises a complex network of sequential and parallel reactions of biochemical and physicochemical nature. Usually, such reactions contain a particular step, the so called rate-limiting step which, being the slowest, limits the reaction rate of the overall process. The first attempts for modeling anaerobic digestion led to models describing only the limiting step. However, over a wide range of operating conditions, the limiting step is not always the same. It may depend on wastewater characteristics, hydraulic loading, temperature, etc. It is apparent that the "limiting step hypothesis" leads to simple and readily usable models. Such models, however, do not describe very well the digester behavior, especially under transient operating conditions. This work reviews the current state-of-the-art in anaerobic digestion modeling. We give a brief description of the key anaerobic digestion models that have been developed so far for describing biomass growth systems, including the International Water Association’s Anaerobic Digestion Model 1 (ADM1 and we identify the areas that require further research endeavors.

Ultrasonic and Thermal Pretreatments on Anaerobic Digestion of Petrochemical Sludge: Dewaterability and Degradation of PAHs

Science.gov (United States)

Zhou, Jun; Xu, Weizhong; Wong, Jonathan W. C.; Yong, Xiaoyu; Yan, Binghua; Zhang, Xueying; Jia, Honghua

2015-01-01

Effects of different pretreatment methods on sludge dewaterability and polycyclic aromatic hydrocarbons (PAHs) degradation during petrochemical sludge anaerobic digestion were studied. Results showed that the total biogas production volume in the thermal pretreatment system was 4 and 5 times higher than that in the ultrasound pretreatment and in the control system, and the corresponding volatile solid removal efficiencies reached 28%, 15%, and 8%. Phenanthrene, paranaphthalene, fluoranthene, benzofluoranthene, and benzopyrene removal rates reached 43.3%, 55.5%, 30.6%, 42.9%, and 41.7%, respectively, in the thermal pretreatment system, which were much higher than those in the ultrasound pretreatment and in the control system. Moreover, capillary suction time (CST) of sludge increased after pretreatment, and then reduced after 20 days of anaerobic digestion, indicating that sludge dewaterability was greatly improved after anaerobic digestion. The decrease of protein and polysaccharide in the sludge could improve sludge dewaterability during petrochemical sludge anaerobic digestion. This study suggested that thermal pretreatment might be a promising enhancement method for petrochemical sludge solubilization, thus contributing to degradation of the PAHs, biogas production, and improvement of dewaterability during petrochemical sludge anaerobic digestion. PMID:26327510

Post-anaerobic digestion thermal hydrolysis of sewage sludge and food waste: Effect on methane yields, dewaterability and solids reduction.

Science.gov (United States)

Svensson, Kine; Kjørlaug, Oda; Higgins, Matthew J; Linjordet, Roar; Horn, Svein J

2018-04-01

Post-anaerobic digestion (PAD) treatment technologies have been suggested for anaerobic digestion (AD) to improve process efficiency and assure hygenization of organic waste. Because AD reduces the amount of organic waste, PAD can be applied to a much smaller volume of waste compared to pre-digestion treatment, thereby improving efficiency. In this study, dewatered digestate cakes from two different AD plants were thermally hydrolyzed and dewatered, and the liquid fraction was recirculated to a semi-continuous AD reactor. The thermal hydrolysis was more efficient in relation to methane yields and extent of dewaterability for the cake from a plant treating waste activated sludge, than the cake from a plant treating source separated food waste (SSFW). Temperatures above 165 °C yielded the best results. Post-treatment improved volumetric methane yields by 7% and the COD-reduction increased from 68% to 74% in a mesophilic (37 °C) semi-continuous system despite lowering the solid retention time (from 17 to 14 days) compared to a conventional system with pre-treatment of feed substrates at 70 °C. Results from thermogravimetric analysis showed an expected increase in maximum TS content of dewatered digestate cake from 34% up to 46% for the SSFW digestate cake, and from 17% up to 43% in the sludge digestate cake, after the PAD thermal hydrolysis process (PAD-THP). The increased dewatering alone accounts for a reduction in wet mass of cake leaving the plant of 60% in the case of sludge digestate cake. Additionaly, the increased VS-reduction will contribute to further reduce the mass of wet cake. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biomass stabilization in the anaerobic digestion of wastewater sludges

Energy Technology Data Exchange (ETDEWEB)

Arnaiz, C. [Universidad de Sevilla, Dept. de Ingenieria Quimica y Ambiental, Sevilla (Spain); Gutierrez, J.C. [Universidad Pablo de Olavide, Dept. de Ciencias Ambientales, Sevilla (Spain); Lebrato, J. [Universidad de Sevilla, Grupo Tratamiento de Aguas Residuales, Sevilla (Spain)

2005-07-01

Sludge stabilization processes include both volatile solid destruction and biomass stabilization. Traditionally, both processes have been considered together, in such a way that, when volatile solid destruction is achieved, the biomass is considered stabilized. In this study, volatile solids reduction and biomass stabilization in the anaerobic digestion of primary, secondary and mixed sludges from municipal wastewater treatment plants were researched in batch cultures by measurements of suspended solids and suspended lipid-phosphate. The estimated kinetic constants were higher in all sludge types tested for the biomass stabilization process, indicating that volatile solids destruction and biomass stabilization are not parallel processes, since the latter one is reached before the former. (Author)

Anaerobic digestion of tuna waste for the production of volatile fatty acids.

Science.gov (United States)

Bermúdez-Penabad, Noela; Kennes, Christian; Veiga, Maria C

2017-10-01

Fish canning industries generate a significant amount of solid waste that can be digested anaerobically into volatile fatty acids (VFA). The aim of this research was to study the effect of various pHs, ranging from 5.0 to 10.0, and percentage of total solids on the anaerobic digestion of tuna waste into VFA, both in batch assays and continuous reactor. The production of VFA was affected by pH and was significantly higher under alkaline conditions. At pH 8.0, the VFA production reached 30,611mgCOD/L. The VFA mainly consisted of acetic, propionic, n-butyric and i-valeric acids. Acetic acid was the main product at all the pHs tested. In terms of total solids (TS) the best results were obtained with 2.5% total solids, reaching 0.73gCOD VFA /gCOD waste . At higher TS concentrations (5 and 8% TS) lower yields were reached probably due to inhibition at high VFA concentration. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Evaluation of different types of anaerobic seed sludge for the high rate anaerobic digestion of pig slurry in UASB reactors.

Science.gov (United States)

Rico, Carlos; Montes, Jesús A; Rico, José Luis

2017-08-01

Three different types of anaerobic sludge (granular, thickened digestate and anaerobic sewage) were evaluated as seed inoculum sources for the high rate anaerobic digestion of pig slurry in UASB reactors. Granular sludge performance was optimal, allowing a high efficiency process yielding a volumetric methane production rate of 4.1LCH 4 L -1 d -1 at 1.5days HRT (0.248LCH 4 g -1 COD) at an organic loading rate of 16.4gCODL -1 d -1 . The thickened digestate sludge experimented flotation problems, thus resulting inappropriate for the UASB process. The anaerobic sewage sludge reactor experimented biomass wash-out, but allowed high process efficiency operation at 3days HRT, yielding a volumetric methane production rate of 1.7LCH 4 L -1 d -1 (0.236LCH 4 g -1 COD) at an organic loading rate of 7.2gCODL -1 d -1 . To guarantee the success of the UASB process, the settleable solids of the slurry must be previously removed. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Financial Feasibility of Anaerobic Digestion for Ontario's Livestock Industries

OpenAIRE

Weersink, Alfons; Mallon, Shawn

2007-01-01

This report is an investigation of the financial feasibility of farm based anaerobic digestion investments under Ontario's Standard Offer Contract electricity prices. Using Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) Agricultural Anaerobic Digestion Calculation Spreadsheet (AADCS) anaerobic digestion inputs, outputs, cost and revenues were estimated and used to conduct a financial analysis on the feasibility of four sized farm base anaerobic digestion investments. The res...

Review of enhanced processes for anaerobic digestion treatment of sewage sludge

Science.gov (United States)

Liu, Xinyuan; Han, Zeyu; Yang, Jie; Ye, Tianyi; Yang, Fang; Wu, Nan; Bao, Zhenbo

2018-02-01

Great amount of sewage sludge had been produced each year, which led to serious environmental pollution. Many new technologies had been developed recently, but they were hard to be applied in large scales. As one of the traditional technologies, anaerobic fermentation process was capable of obtaining bioenergy by biogas production under the functions of microbes. However, the anaerobic process is facing new challenges due to the low fermentation efficiency caused by the characteristics of sewage sludge itself. In order to improve the energy yield, the enhancement technologies including sewage sludge pretreatment process, co-digestion process, high-solid digestion process and two-stage fermentation process were widely studied in the literatures, which were introduced in this article.

Moorella stamsii sp. nov., a new anaerobic thermophilic hydrogenogenic carboxydotroph isolated from digester sludge

NARCIS (Netherlands)

Alves, J.I.; Gelder, van A.H.; Alves, M.M.; Sousa, D.Z.; Plugge, C.M.

2013-01-01

A novel anaerobic, thermophilic, carbon monoxide-utilizing bacterium, strain E3-O, was isolated from anaerobic sludge of a municipal solid waste digester. Cells were straight rods, 0.6 to 1µm in diameter and 2 to 3 µm in length, growing as single cells or in pairs. Cells formed round terminal

Energy recovery from wastewater treatment plants through sludge anaerobic digestion: effect of low-organic-content sludge.

Science.gov (United States)

Zhang, Yuyao; Li, Huan

2017-09-18

During anaerobic digestion, low-organic-content sludge sometimes is used as feedstock, resulting in deteriorated digestion performance. The operational experience of conventional anaerobic digestion cannot be applied to this situation. To investigate the feature of low-organic-content sludge digestion and explain its intrinsic mechanism, batch experiments were conducted using designed feedstock having volatile solids (VS) contents that were 30-64% of total solids (TS). The results showed that the accumulative biogas yield declined proportionally from 173.7 to 64.8 ml/g VS added and organic removal rate decreased from 34.8 to 11.8% with decreasing VS/TS in the substrate. The oligotrophic environment resulting from low-organic-content substrates led to decreased microbial activity and a switch from butyric fermentation to propionic fermentation. A first-order model described the biogas production from the batch experiments very well, and the degradation coefficient decreased from 0.159 to 0.069 day -1 , exhibiting a positive relation with organic content in substrate. The results observed here corroborated with data from published literature on anaerobic digestion of low-organic-content sludge and showed that it may not be feasible to recover energy from sludge with an organic content lower than 50% through mono digestion.

Comparison between ozone and ultrasound disintegration on sludge anaerobic digestion.

Science.gov (United States)

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

2012-03-01

This paper deals with the comparison of ultrasound (mechanical) and ozone (chemical) pre-treatment on the performances of excess sludge semi-continuous digestion. Sludge solubilisation has been investigated by varying specific energy input. For each pre-treatment, long anaerobic digestion tests were carried out by two parallel digesters: one reactor, as control unit, was fed with untreated waste activated sludge, and the other one was fed with disintegrated sludge. To evaluate and compare the efficacy of both pre-treatments, the specific energy was maintained approximately the same. The digestion tests were carried out to investigate the feasibility of anaerobic digestion performance (total biogas production, volatile solids removal, sludge dewaterability) and to assess the heat balance. Results obtained from the digestion of sonicated sludge at 4% disintegration degree (≈ 2500 kJ/kg TS) showed that the ultrasound pre-treatment may be effective both in increasing VS destruction (+19%) and cumulative biogas production (+26%). On the contrary, the digestion test with ozonized sludge (ozone dose of 0.05 g O(3)/g TS corresponding to ≈ 2000 kJ/kg TS) did not indicate a significant improvement on the digestion performances. By doubling the ozone dose an improvement in the organics removal and cumulative biogas production was observed. Relevant differences in terms of colloidal charge and filterability were discussed. Copyright © 2010 Elsevier Ltd. All rights reserved.

Redundancy in Anaerobic Digestion Microbiomes during Disturbances by the Antibiotic Monensin

Science.gov (United States)

Spirito, Catherine M.; Daly, Sarah E.; Werner, Jeffrey J.

2018-01-01

ABSTRACT The antibiotic monensin is fed to dairy cows to increase milk production efficiency. A fraction of this monensin is excreted into the cow manure. Previous studies have found that cow manure containing monensin can negatively impact the performance of anaerobic digesters, especially upon first introduction. Few studies have examined whether the anaerobic digester microbiome can adapt to monensin during the operating time. Here, we conducted a long-term time series study of four lab-scale anaerobic digesters fed with cow manure. We examined changes in both the microbiome composition and function of the anaerobic digesters when subjected to the dairy antibiotic monensin. In our digesters, monensin was not rapidly degraded under anaerobic conditions. The two anaerobic digesters that were subjected to manure from monensin feed-dosed cows exhibited relatively small changes in microbiome composition and function due to relatively low monensin concentrations. At higher concentrations of monensin, which we dosed directly to control manure (from dairy cows without monensin), we observed major changes in the microbiome composition and function of two anaerobic digesters. A rapid introduction of monensin to one of these anaerobic digesters led to the impairment of methane production. Conversely, more gradual additions of the same concentrations of monensin to the other anaerobic digester led to the adaptation of the anaerobic digester microbiomes to the relatively high monensin concentrations. A member of the candidate OP11 (Microgenomates) phylum arose in this anaerobic digester and appeared to be redundant with certain Bacteroidetes phylum members, which previously were dominating. IMPORTANCE Monensin is a common antibiotic given to dairy cows in the United States and is partly excreted with dairy manure. An improved understanding of how monensin affects the anaerobic digester microbiome composition and function is important to prevent process failure for farm

Environmental impacts of anaerobic digestion and the use of anaerobic residues as soil amendment

Energy Technology Data Exchange (ETDEWEB)

Mosey, F.E. [VFA Services Ltd., Herts (United Kingdom)

1996-01-01

This paper defines the environmental role of anaerobic digestion within the overall objective of recovering energy from renewable biomass resources. Examples and opportunities for incorporating anaerobic digestion into biomass-to-energy schemes are discussed, together with environmental aspects of anaerobic digestion plants. These include visual, public amenity, pathogens and public health, odor control, and gaseous emissions. Digestate disposal and the benefits of restrictions on recycling organic wastes and biomass residues back to the land are discussed, particularly as they relate to American and European codes of practice and environmental legislation. The paper concludes that anaerobic digestion, if performed in purpose-designed reactors that efficiently recover and use biogas, is an environmentally benign process that can enhance energy recovery and aid the beneficial land use of plant residues in many biomass-to-energy schemes.

Anaerobic digestion of cellulosic wastes: pilot plant studies

International Nuclear Information System (INIS)

Lee, D.D.; Donaldson, T.L.

1985-08-01

Anaerobic digestion is a potentially attractive technology for volume reduction of low-level radioactive cellulosic wastes. A substantial fraction of the waste is converted to off-gas, and a relatively small volume of biologically stabilized sludge is produced. Process development work has been completed using a 75-L digester to verify rates and conversions obtained at the bench scale. Start-up and operating procedures have been developed, and effluent was generated for characterization and disposal studies. Three runs lasting 36, 90, and 423 d were made using batch and batch-fed conditions. Solids solubilization rates and gas production rates were approximately double the target values of 0.6 g of cellulose per L of reactor volume per d and 0.5 L of off-gas per L of reactor per d. Greater than 80% destruction of solids was obtained. Preliminary effluent characterization and disposal studies were completed. A simple dynamic process model has been constructed to aid in process design and for use in process monitoring and control of a large-scale digester. 5 refs., 20 figs., 3 tabs

Characterization and BMP Tests of Liquid Substrates for High-rate Anaerobic Digestion

Directory of Open Access Journals (Sweden)

M. Mainardis

2018-01-01

Full Text Available This work was focused on the physicochemical characterization and biochemical methane potential (BMP tests of some liquid organic substrates, to verify if they were suitable for undergoing a process of high-velocity anaerobic digestion. The selected substrates were: first and second cheese whey, organic fraction of municipal solid waste (OFMSW leachate, condensate water and slaughterhouse liquid waste. Firstly, a physicochemical characterization was performed, using traditional and macromolecular parameters; then, batch anaerobic tests were carried out, and some continuous tests were planned. The results revealed that all the analyzed substrates have a potential to be anaerobically treated. Valuable information about treatment rate for a high-velocity anaerobic digestion process was obtained. Start-up of a lab-scale UASB reactor, treating diluted cheese whey, was successfully achieved with good COD removal efficiency. These preliminary results are expected to be further investigated in a successive phase, where continuous tests will be conducted on condensate water and OFMSW leachate.

Ultrasound pre-treatment for anaerobic digestion improvement.

Science.gov (United States)

Pérez-Elvira, S; Fdz-Polanco, M; Plaza, F I; Garralón, G; Fdz-Polanco, F

2009-01-01

Prior research indicates that ultrasounds can be used in batch reactors as pre-treatment before anaerobic digestion, but the specific energy required at laboratory-scale is too high. This work evaluates both the continuous ultrasound device performance (efficiency and solubilisation) and the operation of anaerobic digesters continuously fed with sonicated sludge, and presents energy balance considerations. The results of sludge solubilisation after the sonication treatment indicate that, applying identical specific energy, it is better to increase the power than the residence time. Working with secondary sludge, batch biodegradability tests show that by applying 30 kWh/m3 of sludge, it is possible to increase biogas production by 42%. Data from continuous pilot-scale anaerobic reactors (V=100 L) indicate that operating with a conventional HRT=20 d, a reactor fed with pre-treated sludge increases the volatile solids removal and the biogas production by 25 and 37% respectively. Operating with HRT=15 d, the removal efficiency is similar to the obtained with a reactor fed with non-hydrolysed sludge at HTR=20 d, although the specific biogas productivity per volume of reactor is higher for the pretreated sludge. Regarding the energy balance, although for laboratory-scale devices it is negative, full-scale suppliers state a net generation of 3-10 kW per kW of energy used.

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

New perspectives in anaerobic digestion.

NARCIS (Netherlands)

Lier, van J.B.; Tilche, A.; Ahring, B.K.; Macarie, H.; Moletta, R.; Dohanyos, M.; Hulshoff Pol, L.W.; Lens, P.N.L.; Verstraete, W.

2001-01-01

The IWA specialised group on anaerobic digestion (AD) is one of the oldest working groups of the former IAWQ organisation. Despite the fact that anaerobic technology dates back more than 100 years, the technology is still under development, adapting novel treatment systems to the modern

The hydrolytic stage in high solids temperature phased anaerobic digestion improves the downstream methane production rate.

Science.gov (United States)

Buffière, P; Dooms, M; Hattou, S; Benbelkacem, H

2018-07-01

The role of the hydrolytic stage in high solids temperature phased anaerobic digestion was investigated with a mixture of cattle slurry and maize silage with variable ratios (100, 70 and 30% volatile solids coming from cattle slurry). It was incubated for 48 h at 37, 55, 65 and 72 °C. Soluble chemical oxygen demand and biochemical methane potential were measured at 0, 24 and 48 h. Higher temperatures improved the amount of solubilized COD, which confirmed previously reported results. Nevertheless, solubilization mostly took place during the first 24 h. The rate of methane production in post-hydrolysis BMPs increased after 48 h hydrolysis time, but not after 24 h. The first order kinetic constant rose by 40% on average. No correlation was observed between soluble COD and downstream methane production rate, indicating a possible modification of the physical structure of the particulate solids during the hydrolytic stage. Copyright © 2018 Elsevier Ltd. All rights reserved.

Transforming anaerobic digestion with the Model T of digesters

Energy Technology Data Exchange (ETDEWEB)

Martin, J.F.; Ciotola, R.; Castano, J.; Eger, C.; Schlea, D. [Ohio State Univ., Columbus, OH (United States). Ecological Engineering Program

2010-07-01

Most livestock farmers in the United States do not take advantage of anaerobic digester technology because of the high cost and large scale. These limitations therefore reduce the production of renewable energy from farmlands. In order to expand anaerobic digestion methods and improve environmental quality, affordable and smaller-scale digesters should be developed to enable most livestock farmers to convert manure to methane. Doing so would improve their economic efficiency and environmental sustainability. This paper provided an analogy to the development of the Model T to better explain the need and potential for this technology. A modified fixed-dome digester was installed on the Ohio State University dairy in Columbus, Ohio. The digester was unheated, buried, had a volume of 1 m{sup 3} and received diluted dairy manure as feedstock. Biogas was produced at digester temperatures as low 10 degrees C during colder ambient temperatures. Water quality also improved. Results from the first year of operation will be analyzed to improve performance and enable future development of this technology.

Sequential ethanol fermentation and anaerobic digestion increases bioenergy yields from duckweed.

Science.gov (United States)

Calicioglu, O; Brennan, R A

2018-06-01

The potential for improving bioenergy yields from duckweed, a fast-growing, simple, floating aquatic plant, was evaluated by subjecting the dried biomass directly to anaerobic digestion, or sequentially to ethanol fermentation and then anaerobic digestion, after evaporating ethanol from the fermentation broth. Bioethanol yields of 0.41 ± 0.03 g/g and 0.50 ± 0.01 g/g (glucose) were achieved for duckweed harvested from the Penn State Living-Filter (Lemna obscura) and Eco-Machine™ (Lemna minor/japonica and Wolffia columbiana), respectively. The highest biomethane yield, 390 ± 0.1 ml CH 4 /g volatile solids added, was achieved in a reactor containing fermented duckweed from the Living-Filter at a substrate-to-inoculum (S/I) ratio (i.e., duckweed to microorganism ratio) of 1.0. This value was 51.2% higher than the biomethane yield of a replicate reactor with raw (non-fermented) duckweed. The combined bioethanol-biomethane process yielded 70.4% more bioenergy from duckweed, than if anaerobic digestion had been run alone. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of low solids retention time and focused pulsed pre-treatment on anaerobic digestion of waste activated sludge.

Science.gov (United States)

Lee, Il-Su; Rittmann, Bruce E

2011-02-01

The interacting effects of Focused Pulsed (FP) treatment and solids retention time (SRT) were evaluated in laboratory-scale digesters operated at SRTs of 2-20 days. Anaerobic digestion and methanogenesis of waste activated sludge (WAS) were stable for SRT ≥ 5 days, but the effluent soluble organic compounds increased significantly for SRT=2 days due to a combination of faster hydrolysis kinetics and washout of methanogens. FP treatment increased the CH(4) production rate and TCOD removal efficiency by up to 33% and 18%, respectively, at a SRT of 20 days. These effects were the result of an increase in the hydrolysis rate, since the concentrations of soluble components remained low for SRT ≥ 5 days. Alternately, FP pre-treatment of WAS allowed the same conversion of TCOD to CH(4) with a smaller SRT and digester size: e.g., 40% size savings with a CH(4) conversion of 0.23 g CH(4)-COD/g COD(in). Copyright © 2010 Elsevier Ltd. All rights reserved.

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

Methane fermentation process as anaerobic digestion of biomass ...

African Journals Online (AJOL)

Anaerobic decomposition of organic compounds is conducted in close cooperation of specialized bacteria of different types, including mostly hydrolyzing, digestive, acetogenic, homoacetogenic, sulfate-reducing (VI) and methanogenic bacteria. A great interest in the anaerobic digestion process results mainly from its ...

Using contaminated plants involved in phytoremediation for anaerobic digestion.

Science.gov (United States)

Cao, Zewei; Wang, Shengxiao; Wang, Ting; Chang, Zhizhou; Shen, Zhenguo; Chen, Yahua

2015-01-01

This study investigated the anaerobic digestion capability of five plants and the effects of copper (Cu) and S,S'-ethylenediaminedisuccinic acid (EDDS, a chelator widely used in chelant-assisted phytoremediation) on biogas production to determine a feasible disposal method for plants used in remediation. The results showed that in addition to Phytolacca americana L., plants such as Zea mays L., Brassica napus L., Elsholtzia splendens Nakai ex F. Maekawa, and Oenothera biennis L. performed well in biogas production. Among these, O. biennis required the shortest period to finish anaerobic digestion. Compared to normal plants with low Cu content, the plants used in remediation with increased Cu levels (100 mg kg(-1)) not only promoted anaerobic digestion and required a shorter anaerobic digestion time, but also increased the methane content in biogas. When the Cu content in plants increased to 500, 1000, and 5000 mg kg(-1), the cumulative biogas production decreased by 12.3%, 14.6%, and 41.2%, respectively. Studies also found that EDDS conspicuously restrained biogas production from anaerobic digestion. The results suggest that anaerobic digestion has great potential for the disposal of contaminated plants and may provide a solution for the resource utilization of plants used in remediation.

Microbial trophic interactions and mcrA gene expression in monitoring of anaerobic digesters

Directory of Open Access Journals (Sweden)

Alejandra eAlvarado

2014-11-01

Full Text Available Anaerobic digestion (AD is a biological process where different trophic groups of microorganisms break down biodegradable organic materials in the absence of oxygen. A wide range of anaerobic digestion technologies is being used to convert livestock manure, municipal and industrial wastewaters, and solid organic wastes into biogas. AD gains importance not only because of its relevance in waste treatment but also because of the recovery of carbon in the form of methane, which is a renewable energy and is used to generate electricity and heat. Despite the advances on the engineering and design of new bioreactors for anaerobic digestion, the microbiology component always poses challenges. Microbiology of AD processes is complicated as the efficiency of the process depends on the interactions of various trophic groups involved. Due to the complex interdependence of microbial activities for the functionality of the anaerobic bioreactors, the genetic expression of mcrA, which encodes a key enzyme in methane formation, is proposed as a parameter to monitor the process performance in real time. This review evaluates the current knowledge on microbial groups, their interactions and their relationship to the performance of anaerobic biodigesters with a focus on using mcrA gene expression as a tool to monitor the process.

Energy production from mechanical biological treatment and Composting plants exploiting solid anaerobic digestion batch: An Italian case study

International Nuclear Information System (INIS)

Di Maria, F.; Sordi, A.; Micale, C.

2012-01-01

Highlights: ► This work quantifies the Italian Composting and MBT facilities upgradable by SADB. ► The bioCH 4 from SADB of source and mechanical selected OFMSW is of 220–360 Nl/kg VS. ► The upgrading investment cost is 30% higher for Composting than for MBT. ► Electricity costs are 0.11–0.28 €/kW h, not influenced by differentiate collection. ► Electrical energy costs are constant for SADB treating more than 30 ktons/year. - Abstract: The energetic potential of the organic fraction of municipal solid waste processed in both existing Composting plants and Mechanical Biological Treatment (MBT) plants, can be successfully exploited by retrofitting these plants with the solid anaerobic digestion batch process. On the basis of the analysis performed in this study, about 50 MBT plants and 35 Composting plants were found to be suitable for retrofitting with Solid Anaerobic Digestion Batch (SADB) facilities. Currently the organic fraction of Municipal Solid Waste (OFMSW) arising from the MBT facilities is about 1,100,000 tons/year, whereas that arising from differentiated collection and treated in Composting plants is about 850,000 tons/year. The SADB performances were analyzed by the aid of an experimental apparatus and the main results, in agreement with literature data, show that the biogas yield ranged from 400 to 650 Nl/kg of Volatile Solids (VS), with a methane content ranging from 55% to 60% v/v. This can lead to the production of about 500 GW h of renewable energy per year, giving a CO 2 reduction of about 270,000 tons/year. From the economic point of view, the analysis shows that the mean cost of a kW h of electrical energy produced by upgrading MBT and Composting facilities with the SADB, ranges from 0.11 and 0.28 €/kW h, depending on the plant size and the amount of waste treated.

Application of Anaerobic Digestion Model No. 1 for simulating anaerobic mesophilic sludge digestion

International Nuclear Information System (INIS)

Mendes, Carlos; Esquerre, Karla; Matos Queiroz, Luciano

2015-01-01

Highlights: • The behavior of a anaerobic reactor was evaluated through modeling. • Parametric sensitivity analysis was used to select most sensitive of the ADM1. • The results indicate that the ADM1 was able to predict the experimental results. • Organic load rate above of 35 kg/m 3 day affects the performance of the process. - Abstract: Improving anaerobic digestion of sewage sludge by monitoring common indicators such as volatile fatty acids (VFAs), gas composition and pH is a suitable solution for better sludge management. Modeling is an important tool to assess and to predict process performance. The present study focuses on the application of the Anaerobic Digestion Model No. 1 (ADM1) to simulate the dynamic behavior of a reactor fed with sewage sludge under mesophilic conditions. Parametric sensitivity analysis is used to select the most sensitive ADM1 parameters for estimation using a numerical procedure while other parameters are applied without any modification to the original values presented in the ADM1 report. The results indicate that the ADM1 model after parameter estimation was able to predict the experimental results of effluent acetate, propionate, composites and biogas flows and pH with reasonable accuracy. The simulation of the effect of organic shock loading clearly showed that an organic shock loading rate above of 35 kg/m 3 day affects the performance of the reactor. The results demonstrate that simulations can be helpful to support decisions on predicting the anaerobic digestion process of sewage sludge

Application of Anaerobic Digestion Model No. 1 for simulating anaerobic mesophilic sludge digestion

Energy Technology Data Exchange (ETDEWEB)

Mendes, Carlos, E-mail: carllosmendez@gmail.com; Esquerre, Karla, E-mail: karlaesquerre@ufba.br; Matos Queiroz, Luciano, E-mail: lmqueiroz@ufba.br

2015-01-15

Highlights: • The behavior of a anaerobic reactor was evaluated through modeling. • Parametric sensitivity analysis was used to select most sensitive of the ADM1. • The results indicate that the ADM1 was able to predict the experimental results. • Organic load rate above of 35 kg/m{sup 3} day affects the performance of the process. - Abstract: Improving anaerobic digestion of sewage sludge by monitoring common indicators such as volatile fatty acids (VFAs), gas composition and pH is a suitable solution for better sludge management. Modeling is an important tool to assess and to predict process performance. The present study focuses on the application of the Anaerobic Digestion Model No. 1 (ADM1) to simulate the dynamic behavior of a reactor fed with sewage sludge under mesophilic conditions. Parametric sensitivity analysis is used to select the most sensitive ADM1 parameters for estimation using a numerical procedure while other parameters are applied without any modification to the original values presented in the ADM1 report. The results indicate that the ADM1 model after parameter estimation was able to predict the experimental results of effluent acetate, propionate, composites and biogas flows and pH with reasonable accuracy. The simulation of the effect of organic shock loading clearly showed that an organic shock loading rate above of 35 kg/m{sup 3} day affects the performance of the reactor. The results demonstrate that simulations can be helpful to support decisions on predicting the anaerobic digestion process of sewage sludge.

Energy production from agricultural residues: High methane yields in pilot-scale two-stage anaerobic digestion

International Nuclear Information System (INIS)

Parawira, W.; Read, J.S.; Mattiasson, B.; Bjoernsson, L.

2008-01-01

There is a large, unutilised energy potential in agricultural waste fractions. In this pilot-scale study, the efficiency of a simple two-stage anaerobic digestion process was investigated for stabilisation and biomethanation of solid potato waste and sugar beet leaves, both separately and in co-digestion. A good phase separation between hydrolysis/acidification and methanogenesis was achieved, as indicated by the high carbon dioxide production, high volatile fatty acid concentration and low pH in the acidogenic reactors. Digestion of the individual substrates gave gross energy yields of 2.1-3.4 kWh/kg VS in the form of methane. Co-digestion, however, gave up to 60% higher methane yield, indicating that co-digestion resulted in improved methane production due to the positive synergism established in the digestion liquor. The integrity of the methane filters (MFs) was maintained throughout the period of operation, producing biogas with 60-78% methane content. A stable effluent pH showed that the methanogenic reactors had good ability to withstand the variations in load and volatile fatty acid concentrations that occurred in the two-stage process. The results of this pilot-scale study show that the two-stage anaerobic digestion system is suitable for effective conversion of semi-solid agricultural residues as potato waste and sugar beet leaves

Continuous anaerobic digestion of swine manure: ADM1-based modelling and effect of addition of swine manure fibers pretreated with aqueous ammonia soaking

DEFF Research Database (Denmark)

Jurado, E.; Antonopoulou, G.; Lyberatos, G.

2016-01-01

pretreated manure fibers was performed in CSTR-type digesters, fed with swine manure and/or a mixtureof swine manure and AAS pretreated manure fibers (at a total solids based ratio of 0.52 manure per0.48 fibers). Two different simulations were performed. In the first place, the Anaerobic Digestion Model 1......Anaerobic digestion of manure fibers presents challenges due to their low biodegradability. Aqueous ammonia soaking (AAS) has been tested as a simple method to disrupt the lignocellulose and increase the methane yield of manure fibers. In the present study, mesophilic anaerobic digestion of AAS...... (ADM1) was fitted to a manure-fed, CSTR-type digester and validated by simulating the performance of a second reactor digesting manure. It was shown that disintegration and hydrolysis of the solid matter of manure was such a slow process that the organic particulate matter did not significantly...

Domestic solid waste and sewage improvement by anaerobic digestion: A stirred digester

Energy Technology Data Exchange (ETDEWEB)

Lebrato, J.; Perez-Rodriguez, J.L. [CSIC-UNSE, Instituto de Ciencia de Materiales, Sevilla (Spain); Maqueda, C. [CSIC Instituto de Recursos Naturales y Agrobiologia, Sevilla (Spain)

1995-05-01

The processing of the mixture of domestic solid waste and domestic sewage in an stirring digester was studied. The experimental set up consisted of six thermostatically controlled digesters of 1 l, each one in a bath at 35{+-}1oC and magnetically stirred. The best feeding for the culture was 1.7 g COD l{sup -1} day{sup -1}. The minimum hydraulic retention time was 6 days. The efficiency in COD removal of treatment varied between 90.1% and 72.4%. The biogas productivity was 0.19 l g{sup -1} COD day{sup -1}

New perspectives in anaerobic digestion

DEFF Research Database (Denmark)

van Lier, J.B.; Tilche, A.; Ahring, Birgitte Kiær

2001-01-01

The IWA specialised group on anaerobic digestion (AD) is one of the oldest working groups of the former IAWQ organisation. Despite the fact that anaerobic technology dates back more than 100 years, the technology is still under development, adapting novel treatment systems to the modern...... requirements. In fact, most advances were achieved during the last three decades, when high-rate reactor systems were developed and a profound insight was obtained in the microbiology of the anaerobic communities. This insight led to a better understanding of anaerobic treatment and, subsequently, to a broader...

Design and Fabrication of an Anaerobic Digester

Directory of Open Access Journals (Sweden)

M. S. Abubakar

2017-02-01

Full Text Available Anaerobic digester is a physical structure that provides a conducive environment for the multiplication of micro-organisms that degrades organic matter to generate biogas energy. Energy is required in agriculture for crop production, processing and storage, poultry production and electricity for farmstead and farm settlements. It is energy that propels agricultural mechanization, which minimizes the use of human and animal muscles and its inherent drudgery in agriculture. The energy demand required to meet up with the agricultural growth in Nigeria is high and growing every year. In this study the design and fabrication of an anaerobic digester was reported which is an attempt to boost energy requirement for small and medium dryland farmers in Nigeria. The design of the digester includes the following concept; the basic principles of anaerobic digestion processes, socio-economic status of the dryland farmers, amount of biogas to be produced. Finally, the digester was fabricated using locally available raw materials within the dryland area of Nigeria. At the end, preliminary flammability test was conducted and the biogas produced was found to be flammable.

Anaerobic Digestion Foaming Causes

OpenAIRE

Ganidi, Nafsika

2008-01-01

Anaerobic digestion foaming has been encountered in several sewage treatment plants in the UK. Foaming has raised major concerns for the water utilities due to significant impacts on process efficiency and operational costs. Several foaming causes have been suggested over the past few years by researchers. However, the supporting experimental information is limited and in some cases site specific. The present report aimed to provide a better understanding of the anaerobic di...

Economic Feasibility of Installing an Anaerobic Digester on a Department of Defense Installation

Science.gov (United States)

2010-03-01

permits anaerobic bacteria and enzymes to affect more waste than a lagoon does, as well as preventing a film or layer of scum forming on top of the waste...temperature classifications for anaerobic digestion. The three classes listed are: psychrophilic (4- 20 C), mesophilic (20-45 C), and thermophilic (45-60...operated at 55º C, 30 focusing on an optimum temperature for thermophilic bacteria. Despite previously discussed percentages for total solids in

Biokinetics and bacterial communities of propionate oxidizing bacteria in phased anaerobic sludge digestion systems.

Science.gov (United States)

Zamanzadeh, Mirzaman; Parker, Wayne J; Verastegui, Yris; Neufeld, Josh D

2013-03-15

Phased anaerobic digestion is a promising technology and may be a potential source of bio-energy production. Anaerobic digesters are widely used for sewage sludge stabilization and thus a better understanding of the microbial process and kinetics may allow increased volatile solids reduction and methane production through robust process operation. In this study, we analyzed the impact of phase separation and operational conditions on the bio-kinetic characteristics and communities of bacteria associated with four phased anaerobic digestion systems. In addition to significant differences between bacterial communities associated with different digester operating temperatures, our results also revealed that bacterial communities in the phased anaerobic digestion systems differed between the 1st and 2nd phase digesters and we identified strong community composition correlations with several measured physicochemical parameters. The maximum specific growth rates of propionate oxidizing bacteria (POB) in the mesophilic and thermophilic 1st phases were 11 and 23.7 mgCOD mgCOD(-1) d(-1), respectively, while those of the mesophilic and thermophilic 2nd-phase digesters were 6.7 and 18.6 mgCOD mgCOD(-1) d(-1), respectively. Hence, the biokinetic characteristics of the POB population were dependent on the digester loading. In addition, we observed that the temperature dependency factor (θ) values were higher for the less heavily loaded digesters as compared to the values obtained for the 1st-phase digesters. Our results suggested the appropriate application of two sets of POB bio-kinetic that reflect the differing growth responses as a function of propionate concentration (and/or organic loading rates). Also, modeling acetogenesis in phased anaerobic sludge digestion systems will be improved considering a population shift in separate phases. On the basis of the bio-kinetic values estimated in various digesters, high levels of propionate in the thermophilic digesters may be

Anaerobic co-digestion of the organic fraction of municipal solid waste with FOG waste from a sewage treatment plant: Recovering a wasted methane potential and enhancing the biogas yield

International Nuclear Information System (INIS)

Martin-Gonzalez, L.; Colturato, L.F.; Font, X.; Vicent, T.

2010-01-01

Anaerobic digestion is applied widely to treat the source collected organic fraction of municipal solid wastes (SC-OFMSW). Lipid-rich wastes are a valuable substrate for anaerobic digestion due to their high theoretical methane potential. Nevertheless, although fat, oil and grease waste from sewage treatment plants (STP-FOGW) are commonly disposed of in landfill, European legislation is aimed at encouraging more effective forms of treatment. Co-digestion of the above wastes may enhance valorisation of STP-FOGW and lead to a higher biogas yield throughout the anaerobic digestion process. In the present study, STP-FOGW was evaluated as a co-substrate in wet anaerobic digestion of SC-OFMSW under mesophilic conditions (37 o C). Batch experiments carried out at different co-digestion ratios showed an improvement in methane production related to STP-FOGW addition. A 1:7 (VS/VS) STP-FOGW:SC-OFMSW feed ratio was selected for use in performing further lab-scale studies in a 5 L continuous reactor. Biogas yield increased from 0.38 ± 0.02 L g VS feed -1 to 0.55 ± 0.05 L g VS feed -1 as a result of adding STP-FOGW to reactor feed. Both VS reduction values and biogas methane content were maintained and inhibition produced by long chain fatty acid (LCFA) accumulation was not observed. Recovery of a currently wasted methane potential from STP-FOGW was achieved in a co-digestion process with SC-OFMSW.

Study of physical mechanisms and their influence on dry anaerobic digestion kinetics: experimentations and modelization

International Nuclear Information System (INIS)

Bollon, Julien

2012-01-01

Anaerobic digestion is a biological process that converts organic matter into a methane rich gas (biogas). Among industrial technologies, dry processes (above 15 % total solid content) are more and more used because of their advantages in comparison with conventional wet processes. However, dry anaerobic digestion processes are poorly known and studied because of the 'pasty' nature of digestion media (rheological behavior, equilibria, transfers, biological kinetics). This thesis focuses on two major aspects: i) the nature of the chemical equilibria (sorption, diffusion) involved in digestion media, ii) the establishment and application of a kinetic model adapted to dry media. We first demonstrated that the diffusional mass transfer is highly reduced with increasing total solid without any agitation. One of the consequences is the importance of the liquid-gas transfer for the production of biogas. Then, we have developed a dedicated kinetic model that enables to understand the variability of the kinetic with total solid content. The impacts of this work are both at the laboratory scale, especially for the operation of Specific Methanogenic Activity tests, and at industrial scale, with the need to control total solid content for optimal efficiency, and to adapt the agitation to improve degradation yields. The developed model can be useful for the design and operation of bio-methanization facilities. (author) [fr

Anaerobic digestion and co-digestion of slaughterhouse wastes

Directory of Open Access Journals (Sweden)

Sonia Castellucci

2013-09-01

Full Text Available The use of renewable energy is becoming increasingly necessary in order to address the global warming problem and, as a consequence, has become an high priority for many countries. Biomass is a clean and renewable energy source with growing potential to replace conventional fossil fuels. Among biomass, residual and waste ones represent a great resource for energy generation since they permit both to eliminate a possible waste and to produce energy. In the present work, the case of slaughterhouse wastes (SHWs has been investigated. Anaerobic digestion is nowadays considered as one of the most important and sustainable conversion technology exploiting organic matter and biodegradable wastes. Biogas results from this bio-chemical process and mainly consists of methane and carbon dioxide, leading to produce thermal energy and/or electricity. In this paper, the European Regulations on animal by-products (ABPs are described, and some previous study on anaerobic digestion and co-digestion of ABPs - more precisely SHWs - are considered and compared in order to fix a starting point for future tests on their co-digestion in a micro-scale pilot digester. This is to define optimal feed ratio values which ensure an increasing content of methane in the outgoing biogas.

Improve biogas production from low-organic-content sludge through high-solids anaerobic co-digestion with food waste.

Science.gov (United States)

Liu, Chuanyang; Li, Huan; Zhang, Yuyao; Liu, Can

2016-11-01

Anaerobic co-digestion of sewage sludge and food waste was tested at two different total solid (TS) concentrations. In the low-solids group with TS 4.8%, the biogas production increased linearly as the ratio of food waste in substrate increased from 0 to 100%, but no synergetic effect was found between the two substrates. Moreover, the additive food waste resulted in the accumulation of volatile fatty acids and decelerated biogas production. Thus, the blend ratio of food waste should be lower than 50%. While in the high-solids group with TS 14%, the weak alkaline environment with pH 7.5-8.5 avoided excessive acidification but high concentration of free ammonia was a potential risk. However, good synergetic effect was found between the two substrates because the added food waste improved mass transfer in sludge cake. Thus, 50% was recommended as the optimum ratio of food waste in substrate because of the best synergetic effect. Copyright © 2016 Elsevier Ltd. All rights reserved.

Exposure to polystyrene nanoplastic leads to inhibition of anaerobic digestion system.

Science.gov (United States)

Fu, Shan-Fei; Ding, Jian-Nan; Zhang, Yun; Li, Yi-Fei; Zhu, Rong; Yuan, Xian-Zheng; Zou, Hua

2018-06-01

In this study, impacts of nanoplastic on the pure and mixed anaerobic digestion systems were investigated. Results showed the growth and metabolism of Acetobacteroides hydrogenigenes were partly inhibited by nanoplastic existed in the pure anaerobic digestion system. The anaerobic digestion of sewage sludge was also obviously inhibited by nanoplastic existed in the mixed anaerobic digestion system. Both the methane yield and methane production rate of the mixed anaerobic digestion system showed negative correlation with the nanoplastic concentration. Compared with anaerobic digestion system without nanoplastic, methane yield and maximum daily methane yield at the nanoplastic concentration of 0.2g/L decreased for 14.4% and 40.7%, respectively. In addition, the start-up of mixed anaerobic digestion system was prolonged by addition of nanoplastic. Microbial community structure analysis indicated the microbial community structures were also affected by nanoplastic existed in the system. At the nanoplastic concentration of 0.2g/L, the relative abundances of family Cloacamonaceae, Porphyromonadaceae, Anaerolinaceae and Gracilibacteraceae decreased partly. Conversely, the relative abundances of family Anaerolinaceae, Clostridiaceae, Geobacteraceae, Dethiosulfovibrionaceae and Desulfobulbaceae improved partly. Copyright © 2017 Elsevier B.V. All rights reserved.

Rapid establishment of thermophilic anaerobic microbial community during the one-step startup of thermophilic anaerobic digestion from a mesophilic digester.

Science.gov (United States)

Tian, Zhe; Zhang, Yu; Li, Yuyou; Chi, Yongzhi; Yang, Min

2015-02-01

The purpose of this study was to explore how fast the thermophilic anaerobic microbial community could be established during the one-step startup of thermophilic anaerobic digestion from a mesophilic digester. Stable thermophilic anaerobic digestion was achieved within 20 days from a mesophilic digester treating sewage sludge by adopting the one-step startup strategy. The succession of archaeal and bacterial populations over a period of 60 days after the temperature increment was followed by using 454-pyrosequencing and quantitative PCR. After the increase of temperature, thermophilic methanogenic community was established within 11 days, which was characterized by the fast colonization of Methanosarcina thermophila and two hydrogenotrophic methanogens (Methanothermobacter spp. and Methanoculleus spp.). At the same time, the bacterial community was dominated by Fervidobacterium, whose relative abundance rapidly increased from 0 to 28.52 % in 18 days, followed by other potential thermophilic genera, such as Clostridium, Coprothermobacter, Anaerobaculum and EM3. The above result demonstrated that the one-step startup strategy could allow the rapid establishment of the thermophilic anaerobic microbial community. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cultivation of Scenedesmus dimorphus using anaerobic digestate as a nutrient medium.

Science.gov (United States)

Abu Hajar, Husam A; Riefler, R Guy; Stuart, Ben J

2017-08-01

In this study, the microalga Scenedesmus dimorphus was cultivated phototrophically using unsterilized anaerobic digestate as a nutrient medium. A bench-scale experiment was conducted by inoculating the microalga S. dimorphus with 0.05-10% dilutions of the anaerobic digestate supernatant. It was found that 1.25-2.5% dilutions, which is equivalent to 50-100 mg N/L total nitrogen concentrations and 6-12 mg P/L total phosphorus concentrations, provided sufficient nutrients to maximize the growth rate along with achieving high concentrations of algal biomass. The microalgae cultivation was scaled up to 100 L open raceway ponds, where the effect of paddlewheel mixing on the growth was investigated. It was concluded that 0.3 m/s water surface velocity yielded the highest specific growth rate and biomass concentration compared to 0.1 and 0.2 m/s. The microalga S. dimorphus was then cultivated in the raceway ponds using 2.5% diluted anaerobic digestate at 317 and 454 μmol/(m 2  × s) average incident light intensities and 1.25% diluted anaerobic digestate at 234 and 384 μmol/(m 2  × s) average incident light intensities. The maximum biomass concentration was 446 mg/L which was achieved in the 2.5% dilution and 454 μmol/(m 2  × s) light intensity culture. Moreover, nitrogen, phosphorus, and COD removal efficiencies from the nutrient media were 65-72, 63-100, and 78-82%, respectively, whereas ammonia was completely removed from all cultures. For a successful and effective cultivation in open raceway ponds, light intensity has to be increased considerably to overcome the attenuation caused by the algal biomass as well as the suspended solids from the digestate supernatant.

Syntrophic acetate oxidation in two-phase (acid-methane) anaerobic digesters.

Science.gov (United States)

Shimada, T; Morgenroth, E; Tandukar, M; Pavlostathis, S G; Smith, A; Raskin, L; Kilian, R E

2011-01-01

The microbial processes involved in two-phase anaerobic digestion were investigated by operating a laboratory-scale acid-phase (AP) reactor and analyzing two full-scale, two-phase anaerobic digesters operated under mesophilic (35 °C) conditions. The digesters received a blend of primary sludge and waste activated sludge (WAS). Methane levels of 20% in the laboratory-scale reactor indicated the presence of methanogenic activity in the AP. A phylogenetic analysis of an archaeal 16S rRNA gene clone library of one of the full-scale AP digesters showed that 82% and 5% of the clones were affiliated with the orders Methanobacteriales and Methanosarcinales, respectively. These results indicate that substantial levels of aceticlastic methanogens (order Methanosarcinales) were not maintained at the low solids retention times and acidic conditions (pH 5.2-5.5) of the AP, and that methanogenesis was carried out by hydrogen-utilizing methanogens of the order Methanobacteriales. Approximately 43, 31, and 9% of the archaeal clones from the methanogenic phase (MP) digester were affiliated with the orders Methanosarcinales, Methanomicrobiales, and Methanobacteriales, respectively. A phylogenetic analysis of a bacterial 16S rRNA gene clone library suggested the presence of acetate-oxidizing bacteria (close relatives of Thermacetogenium phaeum, 'Syntrophaceticus schinkii,' and Clostridium ultunense). The high abundance of hydrogen consuming methanogens and the presence of known acetate-oxidizing bacteria suggest that acetate utilization by acetate oxidizing bacteria in syntrophic interaction with hydrogen-utilizing methanogens was an important pathway in the second-stage of the two-phase digestion, which was operated at high ammonium-N concentrations (1.0 and 1.4 g/L). A modified version of the IWA Anaerobic Digestion Model No. 1 (ADM1) with extensions for syntrophic acetate oxidation and weak-acid inhibition adequately described the dynamic profiles of volatile acid production

Anaerobic Digestion Alters Copper and Zinc Speciation.

Science.gov (United States)

Legros, Samuel; Levard, Clément; Marcato-Romain, Claire-Emmanuelle; Guiresse, Maritxu; Doelsch, Emmanuel

2017-09-19

Anaerobic digestion is a widely used organic waste treatment process. However, little is known on how it could alter the speciation of contaminants in organic waste. This study was focused on determining the influence of anaerobic digestion on the speciation of copper and zinc, two metals that generally occur at high concentration in organic waste. Copper and zinc speciation was investigated by X-ray absorption spectroscopy in four different raw organic wastes (predigestion) and their digested counterparts (postdigestion, i.e., digestates). The results highlighted an increase in the digestates of the proportion of amorphous or nanostructured copper sulfides as well as amorphous or nanostructured zinc sulfides and zinc phosphate as compared to raw waste. We therefore suggest that the environmental fate of these elements would be different when spreading either digestates or raw waste on cropland.

Substrate milling pretreatment as a key parameter for Solid-State Anaerobic Digestion optimization.

Science.gov (United States)

Motte, J-C; Escudié, R; Hamelin, J; Steyer, J-P; Bernet, N; Delgenes, J-P; Dumas, C

2014-12-01

The effect of milling pretreatment on performances of Solid-State Anaerobic Digestion (SS-AD) of raw lignocellulosic residue is still controverted. Three batch reactors treating different straw particle sizes (milled 0.25 mm, 1 mm and 10 mm) were followed during 62 days (6 sampling dates). Although a fine milling improves substrate accessibility and conversion rate (up to 30% compared to coarse milling), it also increases the risk of media acidification because of rapid and high acids production during fermentation of the substrate soluble fraction. Meanwhile, a gradual adaptation of microbial communities, were observed according to both reaction progress and methanogenic performances. The study concluded that particle size reduction affected strongly the performances of the reaction due to an increase of substrate bioaccessibility. An optimization of SS-AD processes thanks to particle size reduction could therefore be applied at farm or industrial scale only if a specific management of the soluble compounds is established. Copyright © 2014 Elsevier Ltd. All rights reserved.

Peracetic acid oxidation as an alternative pre-treatment for the anaerobic digestion of waste activated sludge.

Science.gov (United States)

Appels, Lise; Van Assche, Ado; Willems, Kris; Degrève, Jan; Van Impe, Jan; Dewil, Raf

2011-03-01

Anaerobic digestion is generally considered to be an economic and environmentally friendly technology for treating waste activated sludge, but has some limitations, such as the time it takes for the sludge to be digested and also the ineffectiveness of degrading the solids. Various pre-treatment technologies have been suggested to overcome these limitations and to improve the biogas production rate by enhancing the hydrolysis of organic matter. This paper studies the use of peracetic acid for disintegrating sludge as a pre-treatment of anaerobic digestion. It has been proved that this treatment effectively leads to a solubilisation of organic material. A maximum increase in biogas production by 21% is achieved. High dosages of PAA lead to a decrease in biogas production. This is due to the inhibition of the anaerobic micro-organisms by the high VFA-concentrations. The evolution of the various VFAs during digestion is studied and the observed trends support this hypothesis. Copyright © 2010 Elsevier Ltd. All rights reserved.

Methods of ammonia removal in anaerobic digestion: a review.

Science.gov (United States)

Krakat, Niclas; Demirel, Burak; Anjum, Reshma; Dietz, Donna

2017-10-01

The anaerobic digestion of substrates with high ammonia content has always been a bottleneck in the methanisation process of biomasses. Since microbial communities in anaerobic digesters are sensitive to free ammonia at certain conditions, the digestion of nitrogen-rich substrates such as livestock wastes may result in inhibition/toxicity eventually leading to process failures, unless appropriate engineering precautions are taken. There are many different options reported in literature to remove ammonia from anaerobic digesters to achieve a safe and stable process so that along with high methane yields, a good quality of effluents can also be obtained. Conventional techniques to remove ammonia include physical/chemical methods, immobilization and adaptation of microorganisms, while novel methods include ultrasonication, microwave, hollow fiber membranes and microbial fuel cell applications. This paper discusses conventional and novel methods of ammonia removal from anaerobic digesters using nitrogen-rich substrates, with particular focus on recent literature available about this topic.

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)

Rumen derived anaerobic digestion of water hyacinth (Eicchornia ...

African Journals Online (AJOL)

STORAGESEVER

2009-09-01

Sep 1, 2009 ... The agar plates were then incubated anaerobically at 37°C for 24 h. The digesters were seeded with rumen bacteria and immersed into water bath operated at 37°C. During the anaerobic digestion, volume of biogas produced was recorded accordingly. This paper, therefore, suggests ways by which water.

Test results for fuel cell operation on anaerobic digester gas

Science.gov (United States)

Spiegel, R. J.; Preston, J. L.

EPA, in conjunction with ONSI, embarked on a project to define, design, test, and assess a fuel cell energy recovery system for application at anaerobic digester waste water (sewage) treatment plants. Anaerobic digester gas (ADG) is produced at these plants during the process of treating sewage anaerobically to reduce solids. ADG is primarily comprised of methane (57-66%), carbon dioxide (33-39%), nitrogen (1-10%), and a small amount of oxygen (sulfur-bearing compounds (principally hydrogen sulfide) and halogen compounds (chlorides). The project has addressed two major issues: development of a cleanup system to remove fuel cell contaminants from the gas and testing/assessing of a modified ONSI PC25 C fuel cell power plant operating on the cleaned, but dilute, ADG. Results to date demonstrate that the ADG fuel cell power plant can, depending on the energy content of the gas, produce electrical output levels close to full power (200 kW) with measured air emissions comparable to those obtained by a natural gas fuel cell. The cleanup system results show that the hydrogen sulfide levels are reduced to below 10 ppbv and halides to approximately 30 ppbv.

Rumen derived anaerobic digestion of water hyacinth (Eicchornia ...

African Journals Online (AJOL)

The agar plates were then incubated anaerobically at 37°C for 24 h. The digesters were seeded with rumen bacteria and immersed into water bath operated at 37°C. During the anaerobic digestion, volume of biogas produced was recorded accordingly. This paper, therefore, suggests ways by which water hyacinth can be ...

Improved design of anaerobic digesters for household biogas production in indonesia: one cow, one digester, and one hour of cooking per day.

Science.gov (United States)

Usack, Joseph G; Wiratni, Wiratni; Angenent, Largus T

2014-01-01

A government-sponsored initiative in Indonesia to design and implement low-cost anaerobic digestion systems resulted in 21 full-scale systems with the aim to satisfy the cooking fuel demands of rural households owning at least one cow. The full-scale design consisted of a 0.3 m diameter PVC pipe, which was operated as a conventional plug-flow system. The system generated enough methane to power a cooking stove for ∼ 1 h. However, eventual clogging from solids accumulation inside the bioreactor proved to be a major drawback. Here, we improved the digester configuration to remedy clogging while maintaining system performance. Controlled experiments were performed using four 9-L laboratory-scale digesters operated at a temperature of 27 ± 1 °C, a volatile solids loading rate of 2.0 g VS · L(-1) · day(-1), and a 21-day hydraulic retention time. Two of the digesters were replicates of the original design (control digesters), while the other two digesters included internal mixing or effluent recycle (experimental digesters). The performance of each digester was compared based on methane yields, VS removal efficiencies, and steady-state solids concentrations during an operating period of 311 days. Statistical analyses revealed that internal mixing and effluent recycling resulted in reduced solids accumulation compared to the controls without diminishing methane yields or solids removal efficiencies.

Improved Design of Anaerobic Digesters for Household Biogas Production in Indonesia: One Cow, One Digester, and One Hour of Cooking per Day

Directory of Open Access Journals (Sweden)

Joseph G. Usack

2014-01-01

Full Text Available A government-sponsored initiative in Indonesia to design and implement low-cost anaerobic digestion systems resulted in 21 full-scale systems with the aim to satisfy the cooking fuel demands of rural households owning at least one cow. The full-scale design consisted of a 0.3 m diameter PVC pipe, which was operated as a conventional plug-flow system. The system generated enough methane to power a cooking stove for ∼1 h. However, eventual clogging from solids accumulation inside the bioreactor proved to be a major drawback. Here, we improved the digester configuration to remedy clogging while maintaining system performance. Controlled experiments were performed using four 9-L laboratory-scale digesters operated at a temperature of 27±1°C, a volatile solids loading rate of 2.0 g VS·L−1·day−1, and a 21-day hydraulic retention time. Two of the digesters were replicates of the original design (control digesters, while the other two digesters included internal mixing or effluent recycle (experimental digesters. The performance of each digester was compared based on methane yields, VS removal efficiencies, and steady-state solids concentrations during an operating period of 311 days. Statistical analyses revealed that internal mixing and effluent recycling resulted in reduced solids accumulation compared to the controls without diminishing methane yields or solids removal efficiencies.

Composting of the solid fraction of digestate derived from pig slurry: Biological processes and compost properties

Energy Technology Data Exchange (ETDEWEB)

Tambone, Fulvia, E-mail: fulvia.tambone@unimi.it; Terruzzi, Laura; Scaglia, Barbara; Adani, Fabrizio

2015-01-15

Highlights: • Anaerobic digestion leads to the production of a biologically stable digestate. • Solid–liquid separation produces a solid fraction having high fertilizer value. • Composting process shows low biological activity due to high biological stability of digestate. • Solid digestate fraction can be composted in a short time or used directly as organic fertilizer. - Abstract: The aim of this paper was to assess the characteristics of the solid fractions (SF) obtained by mechanical separation of digestate, their compostability and compost quality. To do so, the SF of digestates obtained from anaerobic digestion of pig slurry, energy crops and agro-industrial residues were sampled in five plants located in Northern Italy. Results obtained indicated that anaerobic digestion by itself promoted the high biological stability of biomasses with a Potential Dynamic Respiration Index (PDRI) close to 1000 mgO{sub 2} kg V S{sup −1} h{sup −1}. Subsequent composting of digestates, with an added bulking agent, did not give remarkably different results, and led only to a slight modification of the characteristics of the initial non-composted mixtures; the composts obtained fully respected the legal limits for high quality compost. Chemical studies of organic matter composition of the biomasses by using CP MAS {sup 13}C NMR, indicated that the compost was composed of a high relative content of O-alkyl-C (71.47% of total C) (cellulose and hemicelluloses) and a low alkyl-C (12.42%) (i.e. volatile fatty acids, steroid-like molecules, aliphatic biopolymers and proteins)

Composting of the solid fraction of digestate derived from pig slurry: Biological processes and compost properties

International Nuclear Information System (INIS)

Tambone, Fulvia; Terruzzi, Laura; Scaglia, Barbara; Adani, Fabrizio

2015-01-01

Highlights: • Anaerobic digestion leads to the production of a biologically stable digestate. • Solid–liquid separation produces a solid fraction having high fertilizer value. • Composting process shows low biological activity due to high biological stability of digestate. • Solid digestate fraction can be composted in a short time or used directly as organic fertilizer. - Abstract: The aim of this paper was to assess the characteristics of the solid fractions (SF) obtained by mechanical separation of digestate, their compostability and compost quality. To do so, the SF of digestates obtained from anaerobic digestion of pig slurry, energy crops and agro-industrial residues were sampled in five plants located in Northern Italy. Results obtained indicated that anaerobic digestion by itself promoted the high biological stability of biomasses with a Potential Dynamic Respiration Index (PDRI) close to 1000 mgO 2 kg V S −1 h −1 . Subsequent composting of digestates, with an added bulking agent, did not give remarkably different results, and led only to a slight modification of the characteristics of the initial non-composted mixtures; the composts obtained fully respected the legal limits for high quality compost. Chemical studies of organic matter composition of the biomasses by using CP MAS 13 C NMR, indicated that the compost was composed of a high relative content of O-alkyl-C (71.47% of total C) (cellulose and hemicelluloses) and a low alkyl-C (12.42%) (i.e. volatile fatty acids, steroid-like molecules, aliphatic biopolymers and proteins)

Psychrophilic dry anaerobic digestion of cow feces and wheat straw: Feasibility studies

International Nuclear Information System (INIS)

Massé, Daniel I.; Saady, N.M.C.; Gilbert, Yan

2015-01-01

This paper reports a novel psychrophilic dry anaerobic digestion (PDAD) of cow feces (feces) and wheat straw (WS). Three feeding strategies (WS, feces, and feces plus WS) were assessed in pseudo sequential batch reactors (PSBR) during three successive cycles of around 21 days hydraulic retention time (HRT). Average specific methane yields on VS fed (L kg −1 ) of 129 ± 17 (WS only), 164 ± 23 (feces only (10–11% TS)) and 152 ± 6 (a mixture of feces plus WS (16% TS)) were obtained during the last three successive cycles. The average methane production rates on VS fed were 3.5 ± 1.5 and 3.6 ± 1.3 and 4.1 ± 0.4 L kg −1  d −1 for the three feeding strategies, respectively. The successive cycles revealed that the psychrophilic anaerobic digestion of high-solid content of cow feces and wheat straw is a reproducible process, practically feasible, and as efficient as mesophilic dry anaerobic digestion given that a well-adapted inoculum is developed and maintained. - Highlights: • Cow feces and wheat straw (CFWS) psychrophilic dry anaerobic digestion (PDAD). • PDAD of CFWS (TS 16% mass fraction) is feasible and as efficient as mesophilic DAD. • VS OLR 1.5 g kg −1  d −1 produced VS-based SMY of 152 ± 6 L kg −1 • Inoculum adaptation is a prerequisite to a stable PDAD

Comparison of varying operating parameters on heavy metals ecological risk during anaerobic co-digestion of chicken manure and corn stover.

Science.gov (United States)

Yan, Yilong; Zhang, Liqiu; Feng, Li; Sun, Dezhi; Dang, Yan

2018-01-01

In this study, the potential ecological risk of heavy metals (Mn, Zn, Cu, Ni, As, Cd, Pb, Cr) accumulation from anaerobic co-digestion of chicken manure (CM) and corn stover (CS) was evaluated by comparing different initial substrate concentrations, digestion temperatures, and mixture ratios. Results showed that the highest volumetric methane yield of 20.3±1.4L/L reactor was achieved with a CS:CM ratio of 3:1 (on volatile solid basis) in mesophilic solid state anaerobic digestion (SS-AD). Although co-digestion increased the concentrations of all tested heavy metals and the direct toxicity of some heavy metals, the potential ecological risk index indicated that the digestates were all classified as low ecological risk. The biogasification and risk variation of heavy metals were affected by the operating parameters. These results are significant and should be taken into consideration when optimizing co-digestion of animal manure and crop residues during full-scale projects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Semi-continuous anaerobic co-digestion of cow manure and steam-exploded Salix with recirculation of liquid digestate.

Science.gov (United States)

Estevez, Maria M; Sapci, Zehra; Linjordet, Roar; Schnürer, Anna; Morken, John

2014-04-01

The effects of recirculating the liquid fraction of the digestate during mesophilic anaerobic co-digestion of steam-exploded Salix and cow manure were investigated in laboratory-scale continuously stirred tank reactors. An average organic loading rate of 2.6 g VS L(-1) d(-1) and a hydraulic retention time (HRT) of 30 days were employed. Co-digestion of Salix and manure gave better methane yields than digestion of manure alone. Also, a 16% increase in the methane yield was achieved when digestate was recirculated and used instead of water to dilute the feedstock (1:1 dilution ratio). The reactor in which the larger fraction of digestate was recirculated (1:3 dilution ratio) gave the highest methane yields. Ammonia and volatile fatty acids did not reach inhibitory levels, and some potentially inhibitory compounds released during steam explosion (i.e., furfural and 5-hydroxy methyl furfural) were only detected at trace levels throughout the entire study period. However, accumulation of solids, which was more pronounced in the recycling reactors, led to decreased methane yields in those systems after three HRTs. Refraining from the use of fresh water to dilute biomass with a high-solids content and obtaining a final digestate with increased dry matter content might offer important economic benefits in full-scale processes. To ensure long-term stability in such an approach, it would be necessary to optimize separation of the fraction of digestate to be recirculated and also perform proper monitoring to avoid accumulation of solids. Copyright © 2014 Elsevier Ltd. All rights reserved.

Anaerobic digestion of paunch in a CSTR for renewable energy production and nutrient mineralization

International Nuclear Information System (INIS)

Nkemka, Valentine Nkongndem; Marchbank, Douglas H.; Hao, Xiying

2015-01-01

Highlights: • Anaerobic digestion and nutrient mineralization of paunch in a CSTR. • Low CH 4 yield and high CH 4 productivity was obtained at an OLR of 2.8 g VS L −1 day −1. • Post-digestion of the digestate resulted in a CH 4 yield of 0.067 L g −1 VS. • Post-digestion is recommended for further digestate stabilization. - Abstract: A laboratory study investigated the anaerobic digestion of paunch in a continuous stirred tank reactor (CSTR) for the recovery of biogas and mineralization of nutrients. At an organic loading rate (OLR) of 2.8 g VS L −1 day −1 with a 30-day hydraulic retention time (HRT), a CH 4 yield of 0.213 L g −1 VS and CH 4 production rate of 0.600 L L −1 day −1 were obtained. Post-anaerobic digestion of the effluent from the CSTR for 30 days at 40 °C recovered 0.067 L g −1 VS as CH 4 , which was 21% of the batch CH 4 potential. Post-digestion of the effluent from the digestate obtained at this OLR is needed to meet the stable effluent criteria. Furthermore, low levels of soluble ions such as K + , Ca 2+ and Mg 2+ were found in the liquid fraction of the digestate and the remainder could have been retained in the solid digestate fraction. This study demonstrates the potential of biogas production from paunch in providing renewable energy. In addition, recovery of plant nutrients in the digestate is important for a sustainable agricultural system

Digesters and demographics: identifying support for anaerobic digesters on dairy farms.

Science.gov (United States)

Sanders, D J; Roberts, M C; Ernst, S C; Thraen, C S

2010-11-01

The dairy industry in the United States is amidst a long-running trend toward fewer, larger dairy farms. This development has created a backlash in some communities over concerns such as odor, waste management, and environmental degradation. Separately, anaerobic digestion has advanced as a waste management technology that potentially offers solutions to some of these issues, providing odor control and a combustible biogas among other things. These digesters require significant capital investments. Voluntary consumer premiums for the renewable energy produced have been used in some instances as a means to move adoption of such systems toward financial feasibility. This project employed a survey to measure Ohio consumers' willingness to pay a premium for renewable energy produced by anaerobic digesters on dairy farms. Cluster analysis was used to segment consumers by willingness to pay, age, education, income, self-identified political inclination, and a composite variable that served as a proxy for respondents' environmental stewardship. Four distinctive groups emerged from the data. Older, less educated respondents were found to have the least amount of support for digesters on dairy farms, whereas politically liberal, environmentally proactive respondents demonstrated the strongest support. Well-educated, affluent respondents and young respondents fell between these 2 groups. Most large dairy farms are generally met with fairly negative responses from their local communities; in contrast, this research finds some popular support for anaerobic digestion technology. Going forward, establishing a positive link between support for anaerobic digesters and for their use on large dairies could open up a new route for less-contested large dairy farm developments. Evaluation of community demographics could become an important part of finding an optimal location for a large dairy farm. Copyright © 2010 American Dairy Science Association. Published by Elsevier Inc. All

The pressure effects on two-phase anaerobic digestion

International Nuclear Information System (INIS)

Chen, Yuling; Rößler, Benjamin; Zielonka, Simon; Lemmer, Andreas; Wonneberger, Anna-Maria; Jungbluth, Thomas

2014-01-01

Highlights: • The pressure effect on anaerobic digestion up to 9 bar was examined. • Increasing pressure decreased pH value in the anaerobic filter. • Increasing pressure increased methane content. • Increasing pressure decreased specific methane yield slightly. • The pressurized methane reactor was very stable and performed well. - Abstract: Two-phase pressurized anaerobic digestion is a novel process aimed at facilitating injection of the produced biogas into the natural gas grid by integrating the fermentative biogas production and upgrading it to substitute natural gas. In order to understand the mechanisms, knowledge of pressure effects on anaerobic digestion is required. To examine the effects of pressure on the anaerobic digestion process, a two-phase anaerobic digestion system was built up in laboratory scale, including three acidogenesis-leach-bed-reactors and one pressure-resistant anaerobic filter. Four different pressure levels (the absolute pressure of 1 bar, 3 bar, 6 bar and 9 bar) were applied to the methane reactor in sequence, with the organic loading rate maintained at approximately 5.1 kgCOD m −3 d −1 . Gas production, gas quality, pH value, volatile fatty acids, alcohol, ammonium-nitrogen, chemical oxygen demand (COD) and alkaline buffer capacity were analyzed. No additional caustic chemicals were added for pH adjustment throughout the experiment. With the pressure increasing from 1.07 bar to 8.91 bar, the pH value decreased from 7.2 to 6.5, the methane content increased from 66% to 75%, and the specific methane yield was slightly reduced from 0.33 l N g −1 COD to 0.31 l N g −1 COD. There was almost no acid-accumulation during the entire experiment. The average COD-degradation grade was always more than 93%, and the average alkaline buffering capacity (VFA/TIC ratio) did not exceed 0.2 at any pressure level. The anaerobic filter showed a very stable performance, regardless of the pressure variation

Effect of mixture ratio, solids concentration and hydraulic retention time on the anaerobic digestion of the organic fraction of municipal solid waste.

Science.gov (United States)

Fongsatitkul, Prayoon; Elefsiniotis, Panagiotis; Wareham, David G

2010-09-01

This paper describes how the degradation of the organic fraction of municipal solid waste (OFMSW) is affected through codigestion with varying amounts of return activated sludge (RAS). Solid waste that had its inorganic fraction selectively removed was mixed with RAS in ratios of 100% OFMSW, 50% OFMSW/50% RAS, and 25% OFMSW/75% RAS. The total solids (TS) concentration was held at 8% and three anaerobic digester systems treating the mixtures were held (for the first run) at a total hydraulic retention time (HRT) of 28 days. Increasing amounts of RAS did not however improve the mixture's digestability, as indicated by little change and/or a drop in the main performance indices [including percentage volatile solids (VS) removal and specific gas production]. The optimum ratio in this research therefore appeared to be 100% OFMSW with an associated 85.1 ± 0.6% VS removal and 0.72 ± 0.01 L total gas g(- 1) VS. In the second run, the effect of increasing percentage of TS (8, 12% and 15%) at a system HRT of 28 days was observed to yield no improvement in the main performance indices (i.e. percentage VS removal and specific gas production). Finally, during the third run, variations in the total system HRT were investigated at an 8% TS, again using 100% OFMSW. Of the HRTs explored (23, 28 and 33 days), the longest HRT yielded the best performance overall, particularly in terms of specific gas production (0.77 ± 0.01 L total gas g(-1) VS).

Opportunities for optimization: fate of manure-borne pathogens during anaerobic digestion and solids separation

Science.gov (United States)

Anaerobic digestion can inactivate zoonotic pathogens present in cattle manure, which reduces transmission of these pathogens from farms to humans through the environment. However, the variability in extent of inactivation across farms and over time is unknown because most studies have examined pat...

Ultrasonic sludge disintegration for enhanced methane production in anaerobic digestion: effects of sludge hydrolysis efficiency and hydraulic retention time.

Science.gov (United States)

Kim, Dong-Jin; Lee, Jonghak

2012-01-01

Hydrolysis of waste activated sludge (WAS) has been regarded as the rate limiting step of anaerobic sludge digestion. Therefore, in this study, the effect of ultrasound and hydraulic residence time during sludge hydrolysis was investigated with the goal of enhancing methane production from anaerobic digestion (AD). WAS was ultrasonically disintegrated for hydrolysis, and it was semi-continuously fed to an anaerobic digesters at various hydraulic retention times (HRTs). The results of these experiments showed that the solids and chemical oxygen demand (COD) removal efficiencies when using ultrasonically disintegrated sludge were higher during AD than the control sludge. The longer the HRT, the higher the removal efficiencies of solids and COD, while methane production increased with lower HRT. Sludge with 30% hydrolysis produced 7 × more methane production than the control sludge. The highest methane yields were 0.350 m(3)/kg volatile solids (VS)(add) and 0.301 m(3)/kg COD(con) for 16 and 30% hydrolyzed sludge, respectively. In addition, we found that excess ultrasound irradiation may inhibit AD since the 50% hydrolyzed sludge produced lower methane yields than 16 and 30% hydrolyzed sludge.

Anaerobic co-digestion of dairy manure and potato waste

Science.gov (United States)

Yadanaparthi, Sai Krishna Reddy

Dairy and potato are two important agricultural commodities in Idaho. Both the dairy and potato processing industries produce a huge amount of waste which could cause environmental pollution. To minimize the impact of potential pollution associated with dairy manure (DM) and potato waste (PW), anaerobic co-digestion has been considered as one of the best treatment process. The purpose of this research is to evaluate the anaerobic co-digestion of dairy manure and potato waste in terms of process stability, biogas generation, construction and operating costs, and potential revenue. For this purpose, I conducted 1) a literature review, 2) a lab study on anaerobic co-digestion of dairy manure and potato waste at three different temperature ranges (ambient (20-25°C), mesophilic (35-37°C) and thermophilic (55-57°C) with five mixing ratios (DM:PW-100:0, 90:10, 80:20, 60:40, 40:60), and 3) a financial analysis for anaerobic digesters based on assumed different capital costs and the results from the lab co-digestion study. The literature review indicates that several types of organic waste were co-digested with DM. Dairy manure is a suitable base matter for the co-digestion process in terms of digestion process stability and methane (CH4) production (Chapter 2). The lab tests showed that co-digestion of DM with PW was better than digestion of DM alone in terms of biogas and CH4 productions (Chapter 3). The financial analysis reveals DM and PW can be used as substrate for full size anaerobic digesters to generate positive cash flow within a ten year time period. Based on this research, the following conclusions and recommendations were made: ▸ The ratio of DM:PW-80:20 is recommended at thermophilic temperatures and the ratio of DM:PW-90:10 was recommended at mesophilic temperatures for optimum biogas and CH4 productions. ▸ In cases of anaerobic digesters operated with electricity generation equipment (generators), low cost plug flow digesters (capital cost of 600/cow

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.

Effect of chemo-mechanical disintegration on sludge anaerobic digestion for enhanced biogas production.

Science.gov (United States)

Kavitha, S; Pray, S Saji; Yogalakshmi, K N; Kumar, S Adish; Yeom, Ick-Tae; Banu, J Rajesh

2016-02-01

The effect of combined surfactant-dispersion pretreatment on dairy waste activated sludge (WAS) reduction in anaerobic digesters was investigated. The experiments were performed with surfactant, Sodium dodecyl sulfate (SDS) in the range of 0.01 to 0.1 g/g suspended solids (SS) and disperser with rpm of 5000-25,000. The COD (chemical oxygen demand) solubilization, suspended solids reduction, and biogas generation increased for an energy input of 7377 kJ/kg total solids (TS) (12,000 rpm, 0.04 g/g SS, and 30 min) and were found to be 38, 32, and 75 %, higher than that of control. The pretreated sludge improved the performance of semicontinuous anaerobic digesters of 4 L working volume operated at four different SRTs (sludge retention time). SRT of 15 days was found to be appropriate showing 49 and 51 % reduction in SS and volatile solids (VS), respectively. The methane yield of the pretreated sample was observed to be 50 mL/g VS removed which was observed to be comparatively higher than the control (12 mL/g VS removed) at optimal SRT of 15 days. To the best of the authors' knowledge, this study is the first to be reported and not yet been documented in literature.

Enhancement of anaerobic sludge digestion by high-pressure homogenization.

Science.gov (United States)

Zhang, Sheng; Zhang, Panyue; Zhang, Guangming; Fan, Jie; Zhang, Yuxuan

2012-08-01

To improve anaerobic sludge digestion efficiency, the effects of high-pressure homogenization (HPH) conditions on the anaerobic sludge digestion were investigated. The VS and TCOD were significantly removed with the anaerobic digestion, and the VS removal and TCOD removal increased with increasing the homogenization pressure and homogenization cycle number; correspondingly, the accumulative biogas production also increased with increasing the homogenization pressure and homogenization cycle number. The optimal homogenization pressure was 50 MPa for one homogenization cycle and 40 MPa for two homogenization cycles. The SCOD of the sludge supernatant significantly increased with increasing the homogenization pressure and homogenization cycle number due to the sludge disintegration. The relationship between the biogas production and the sludge disintegration showed that the accumulative biogas and methane production were mainly enhanced by the sludge disintegration, which accelerated the anaerobic digestion process and improved the methane content in the biogas. Copyright © 2012 Elsevier Ltd. All rights reserved.

Operational strategies for thermophilic anaerobic digestion of organic fraction of municipal solid waste in continuously stirred tank reactors

DEFF Research Database (Denmark)

Angelidaki, Irini; Cui, J.; Chen, X.

2006-01-01

Three operational strategies to reduce inhibition due to ammonia during thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste (SS-OFMSW) rich in proteins were investigated. Feed was prepared by diluting SS-OFMSW (ratio of 1:4) with tap water or reactor process...... ammonium bicarbonate additions. Dilution of SS-OFMSW with fresh water showed a stable performance with volatile fatty acids of solids (VS). Use of recirculated process water after stripping ammonia showed even better performance with a methane yield...... of 0.43 m(3) kg(-1)VS. Recirculation of process water alone on the other hand, resulted in process inhibition at both TAN levels of 3.5 and 5.5 g-N l(-1). However, after a short period, the process recovered and adapted to the tested TAN levels. Thus, use of recirculated process water after stripping...

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

Psychrophilic dry anaerobic digestion of dairy cow feces: Long-term operation

Energy Technology Data Exchange (ETDEWEB)

Massé, Daniel I., E-mail: Daniel.masse@agr.gc.ca; Cata Saady, Noori M.

2015-02-15

Highlights: • Psychrophilic dry anaerobic digestion (PDAD) of cow feces (CF) is feasible. • PDAD of CF is as efficient as mesophilic and thermophilic AD at TCL 21 days. • CF (13–16% TS at OLR 5.0 g TCOD{sub fed} kg{sup −1} inoculum d{sup −1}) yielded 222 ± 27 {sub N}L CH{sub 4} kg{sup −1} VS fed. - Abstract: This paper reports experimental results which demonstrate psychrophilic dry anaerobic digestion of cow feces during long-term operation in sequence batch reactor. Cow feces (13–16% total solids) has been anaerobically digested in 12 successive cycles (252 days) at 21 days treatment cycle length (TCL) and temperature of 20 °C using psychrotrophic anaerobic mixed culture. An average specific methane yield (SMY) of 184.9 ± 24.0, 189.9 ± 27.3, and 222 ± 27.7 {sub N}L CH{sub 4} kg{sup −1} of VS fed has been achieved at an organic loading rate of 3.0, 4.0, and 5.0 g TCOD kg{sup −1} inoculum d{sup −1} and TCL of 21 days, respectively. The corresponding substrate to inoculum ratio (SIR) was 0.39 ± 0.06, 0.48 ± .02, 0.53 ± 0.05, respectively. Average methane production rate of 10 ± 1.4 {sub N}L CH{sub 4} kg{sup −1} VS fed d{sup −1} has been obtained. The low concentration of volatile fatty acids indicated that hydrolysis was the reaction limiting step.

[Distribution and removal of anaerobic antibiotic resistant bacteria during mesophilic anaerobic digestion of sewage sludge].

Science.gov (United States)

Tong, Juan; Wang, Yuan-Yue; Wei Yuan, Song

2014-10-01

Sewage sludge is one of the major sources that releasing antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG) into the environment since it contains large amount of ARB, but there is little information about the fate of the anaerobic ARB in the anaerobic digestion of sewage sludge. Therefore, the distribution, removal and seasonal changes of tetracycline and β-lactam antibiotics resistant bacteria in the mesophilic egg-shaped digesters of a municipal wastewater treatment plant were investigated for one year in this study. Results showed that there were higher amounts of ARB and higher resistance rate of β-lactam antibiotics than that of tetracycline antibiotics in the sewage sludge. All ARB could be significantly reduced during the mesophilic anaerobic digestion process by 1.48-1.64 log unit (P anaerobic digestion by 12.0% and 14.3%, respectively (P bacteria, there were more ARB in the sewage sludge in cold season than in warm season (P < 0.05).

Implementing Livestock Anaerobic Digestion Projects

Science.gov (United States)

Page provides information to help make an informed decision about installing an anaerobic digester. Is it a good match for a farm’s organic waste, project financing, development guidelines and permit requirements?

Optimization of methane production in anaerobic co-digestion of poultry litter and wheat straw at different percentages of total solid and volatile solid using a developed response surface model.

Science.gov (United States)

Shen, Jiacheng; Zhu, Jun

2016-01-01

Poultry litter (PL) can be good feedstock for biogas production using anaerobic digestion. In this study, methane production from batch co-digestion of PL and wheat straw (WS) was investigated for two factors, i.e., total solid (2%, 5%, and 10%) and volatile solid (0, 25, and 50% of WS), constituting a 3 × 3 experimental design. The results showed that the maximum specific methane volume [197 mL (g VS)(‑1)] was achieved at 50% VS from WS at 5% TS level. It was estimated that the inhibitory threshold of free ammonia was about 289 mg L(--1), beyond which reduction of methanogenic activity by at least 54% was observed. The specific methane volume and COD removal can be expressed using two response surface models (R(2) = 0.9570 and 0.9704, respectively). Analysis of variance of the experimental results indicated that the C/N ratio was the most significant factor influencing the specific methane volume and COD removal in the co-digestion of these two materials.

Anaerobic co-digestion of microalgal biomass and wheat straw with and without thermo-alkaline pretreatment.

Science.gov (United States)

Solé-Bundó, Maria; Eskicioglu, Cigdem; Garfí, Marianna; Carrère, Hélène; Ferrer, Ivet

2017-08-01

This study aimed at analyzing the anaerobic co-digestion of microalgal biomass grown in wastewater and wheat straw. To this end, Biochemical Methane Potential (BMP) tests were carried out testing different substrate proportions (20-80, 50-50 and 80-20%, on a volatile solid basis). In order to improve their biodegradability, the co-digestion of both substrates was also evaluated after applying a thermo-alkaline pretreatment (10% CaO at 75°C for 24h). The highest synergies in degradation rates were observed by adding at least 50% of wheat straw. Therefore, the co-digestion of 50% microalgae - 50% wheat straw was investigated in mesophilic lab-scale reactors. The results showed that the methane yield was increased by 77% with the co-digestion as compared to microalgae mono-digestion, while the pretreatment only increased the methane yield by 15% compared to the untreated mixture. Thus, the anaerobic co-digestion of microalgae and wheat straw was successful even without applying a thermo-alkaline pretreatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic digestion of sulfate-acidified cattle slurry: One-stage vs. two-stage.

Science.gov (United States)

Moset, Veronica; Ottosen, Lars Ditlev Mørck; Xavier, Cristiane de Almeida Neves; Møller, Henrik Bjarne

2016-05-15

Two strategies to include acidified cattle manure (AcCM) in co-digestion with normal cattle manure (CM) are presented in this work. The strategies are a single thermophilic (50 °C) continuous stirred tank reactor (CSTR) anaerobic digestion and a two-step (65 °C + 50 °C) CSTR process. In both strategies, two different inclusion levels of H2SO4-acidified CM (10% and 20%) in co-digestion with normal CM were tested and compared with a control CSTR fed only CM. Important enhancement of methane (CH4) yield and solid reductions were observed in the thermophilic one-step CSTR working with 10% AcCM. However, a higher inclusion level of AcCM (20%) caused volatile fatty acid accumulation in the reactor and a more than 30% reduction in CH4 production. In terms of CH4 production, when 10% of AcCM was co-digested with 90% of CM, the two-step anaerobic co-digestion yielded less than the single step. During the first step of the two-step CSTR process, acidogenesis and a partial sulfate reduction were achieved. However, sulfide stripping between the first and the second step must be promoted in order to advance this technology. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anaerobic digestion of paunch in a CSTR for renewable energy production and nutrient mineralization

Energy Technology Data Exchange (ETDEWEB)

Nkemka, Valentine Nkongndem; Marchbank, Douglas H.; Hao, Xiying, E-mail: xiying.hao@agr.gc.ca

2015-09-15

Highlights: • Anaerobic digestion and nutrient mineralization of paunch in a CSTR. • Low CH{sub 4} yield and high CH{sub 4} productivity was obtained at an OLR of 2.8 g VS L{sup −1} day{sup −1.} • Post-digestion of the digestate resulted in a CH{sub 4} yield of 0.067 L g{sup −1} VS. • Post-digestion is recommended for further digestate stabilization. - Abstract: A laboratory study investigated the anaerobic digestion of paunch in a continuous stirred tank reactor (CSTR) for the recovery of biogas and mineralization of nutrients. At an organic loading rate (OLR) of 2.8 g VS L{sup −1} day{sup −1} with a 30-day hydraulic retention time (HRT), a CH{sub 4} yield of 0.213 L g{sup −1} VS and CH{sub 4} production rate of 0.600 L L{sup −1} day{sup −1} were obtained. Post-anaerobic digestion of the effluent from the CSTR for 30 days at 40 °C recovered 0.067 L g{sup −1} VS as CH{sub 4}, which was 21% of the batch CH{sub 4} potential. Post-digestion of the effluent from the digestate obtained at this OLR is needed to meet the stable effluent criteria. Furthermore, low levels of soluble ions such as K{sup +}, Ca{sup 2+} and Mg{sup 2+} were found in the liquid fraction of the digestate and the remainder could have been retained in the solid digestate fraction. This study demonstrates the potential of biogas production from paunch in providing renewable energy. In addition, recovery of plant nutrients in the digestate is important for a sustainable agricultural system.

Recovery of ammonia from anaerobically digested manure using gas-permeable membranes

Directory of Open Access Journals (Sweden)

Maria Cruz García-González

Full Text Available ABSTRACT Nitrogen (N can be recovered from different types of wastewaters. Among these wastewaters, anaerobically digested swine manure (digestate has the highest N content in ammonia form (NH3. It is desirable to reduce N in digestate effluents to safely incorporate them in arable soil in N vulnerable zones (NVZ and to mitigate NH3 emissions during N land application. Additional benefit is to minimize inhibition of the anaerobic process by removing NH3 during the anaerobic digestion process. This work aimed to apply the gas-permeable membrane technology to evaluate ammonia (NH3 recovery from high-ammonia digested swine manure. Anaerobically digested swine manure with NH4+ content of 4,293 mg N L−1 was reduced by 91 % (to 381 mg N L−1 during the 32-day experiment. Although the results showed a total N recovery efficiency of 71 %, it is possible to increase this recovery efficiency to > 90 % by adjusting the area of the membrane system to match the high free ammonia concentration (FA in digested swine manure. Moreover, final digestate pH and alkalinity were kept around 8.1 and 8,923 mgCaCO3 L−1, which are convenient for the anaerobic process or incorporation in arable soil when the process is finished.

Enhanced biohydrogen production from oat straw co-digested with cow dung / sewage sludge by combined aerobic digestion and anaerobic fermentation

Directory of Open Access Journals (Sweden)

Loretta Li

2016-03-01

Full Text Available Hydrogen was produced from oat straw by combined aerobic and anaerobic fermentation with fungi and cow dung. With aerobic pre-digestion, the maximum hydrogen production rate reached 133 ml/g volatile suspended solids per hour. The maximum hydrogen yield was 71.5 ml/g straw in 6 days by biological process. The lignocellulosic conversion of oak-straw waste was 39%, with the complex component converting 68% of the hemi-cellulose and 61% of the cellulose, but only 34% of lignin conversion. Aerobic pre-digestion by Trichoderma viride and Saccharomyces cerevisiae was significantly effective for lignin degradation.  Combining aerobic and anaerobic fermentation is a promising low-cost efficient and environmentally friendly method, compared with hydrogen fermentation, not only for hydrogen production, but also for converting straw biomass.

Effect of microscale ZVI/magnetite on methane production and bioavailability of heavy metals during anaerobic digestion of diluted pig manure.

Science.gov (United States)

Liang, Yue-Gan; Li, Xiu-Juan; Zhang, Jin; Zhang, Li-Gan; Cheng, Beijiu

2017-05-01

Low methane production and high levels of heavy metal in pig slurries limit the feasibility of anaerobic digestion of pig manure. In this study, changes in the methane production and bioavailability of heavy metals in the anaerobic digestion of diluted pig manure were evaluated using single and combined action of microscale zero-valence iron (ZVI) and magnetite. After 30 days of anaerobic digestion, the methane yield ranged from 246.9 to 334.5 mL/g VS added, which increased by 20-26% in the group added with microscale ZVI and/or magnetite relative to that in the control group. Results of the first-order kinetic model revealed that addition of microscale ZVI and/or magnetite increased the biogas production potential, rather than the biogas production rate constant. These treatments also changed the distribution of chemical fractions for heavy metal. The addition of ZVI decreased the bioavailability of Cu and Zn in the solid digested residues. Moreover, a better performance was observed in the combined action of microscale ZVI and magnetite, and the ZVI anaerobic corrosion end-product, magnetite, might help enhance methane production through direct interspecies electron transfer in ZVI-anaerobic digestion process.

Comparative economic analysis: Anaerobic digester case study

International Nuclear Information System (INIS)

Lusk, P.D.

1991-01-01

An economic guide is developed to assess the value of anaerobic digesters used on dairy farms. Two varieties of anaerobic digesters, a conventional mixed-tank mesophilic and an innovative earthen psychrophilic, are comparatively evaluated using a cost-effectiveness index. The two case study examples are also evaluated using three other investment merit statistics: simple payback period, net present value, and internal rate of return. Life-cycle savings are estimated for both varieties, with sensitivities considered for investment risk. The conclusion is that an earthen psychrophilic digester can have a significant economic advantage over a mixed-tank mesophilic digester because of lower capital cost and reduced operation and maintenance expenses. Because of this economic advantage, additional projects are being conducted in North Carolina to increase the rate of biogas utilization. The initial step includes using biogas for milk cooling at the dairy farm where the existing psychrophilic digester is located. Further, a new project is being initiated for electricity production with thermal reclaim at a swine operation

Animal and industrial waste anaerobic digestion: USA status report

Energy Technology Data Exchange (ETDEWEB)

Lusk, P.D. [Resource Development Associates, Washington, DC (United States)

1996-01-01

Pollutants from unmanaged animal and bio-based industrial wastes can degrade the environment, and methane emitted from decomposing wastes may contribute to global climate change. One waste management system prevents pollution and converts a disposal problem into a new profit center. Case studies of operating systems indicate that the anaerobic digestion of animal and industrial wastes is a commercially available bioconversion technology with considerable potential for providing profitable coproducts, including a cost-effective renewable fuel. Growth and concentration of the livestock industry create opportunities to properly dispose of the large quantities of manures generated at dairy, swine, and poultry farms. Beyond the farm, extension of the anaerobic digestion process to recover methane has considerable potential for certain classified industries - with a waste stream characterization similar to livestock manures. More than 35 example industries have been identified, and include processors of chemicals, fiber, food, meat, milk, and pharmaceuticals. Some of these industries already recover methane for energy. This status report examines some current opportunities for recovering methane from the anaerobic digestion of animal and industrial wastes in the US. Case studies of operating digesters, including project and maintenance histories, and the operator`s {open_quotes}lessons learned,{close_quotes} are included as a reality check. Factors necessary for successful projects, as well as a list of reasons explaining why some anaerobic digestion projects fail, are provided. The role of management is key; not only must digesters be well engineered and built with high-quality components, they must also be sited at facilities willing to incorporate the uncertainties of a new technology. Anaerobic digestion can provide monetary benefits and mitigate possible pollution problems, thereby sustaining development while maintaining environmental quality.

Modeling flow inside an anaerobic digester by CFD techniques

Energy Technology Data Exchange (ETDEWEB)

Mendoza, Alexandra Martinez; Jimenez, P. Amparo Lopez [Departmento do Ingenieria Hidralica y Medio Ambiente, Universitat Politecnica de Valencia, Camino de Vera S/N 46022 (Spain); Martinez, Tatiana Montoya; Monanana, Vincente Fajardo [Grupo Aquas de Valencia. Avenida Marques del Turia 19 46005 Valencia (Spain)

2011-07-01

Anaerobic processes are used to treat high strength organic wastewater as well as for the treatment of primary and secondary sludge from conventional wastewater treatment plants. In these processes, heterotrophic microorganisms convert biodegradable organic matter to methane and carbon dioxide in the absence of dissolved oxygen and nitrate. Some of the most important aspects of the design of anaerobic digesters are related to hydraulic considerations. In spite of its important role in performance, hydraulics of flow inside digesters has not been quantified or adequately characterized. In this contribution a three-dimensional steady-state computational fluid dynamics (CFD) simulation has been performed for a particular anaerobic digester, in order to visualize the flow patterns. Flow and velocities profiles have been represented inside the digester to identify possible dead zones or stratifications. The geometry of a real digester installed in Valencia Waste Water Treatment Plant (located in Quart-Benager, Valencia, Spain) has been used in order to consider the proposed methodology.

Biogas generation from in-storage psychrophilic anaerobic digestion.

Science.gov (United States)

Giard, David; Choiniere, Denis; Cordeau, Sébastien; Barrington, Suzelle

2013-01-01

In-storage psychrophilic anaerobic digestion (ISPAD) is a technology allowing livestock producers to operate an anaerobic digester with minimum technological know-how and for the cost of a conventional storage cover. Nevertheless, the system is exposed to ambient temperatures and biogas production is expected to vary with climatic conditions. The objective of the project was therefore to measure ISPAD biogas production during the winter and fall seasons for a region east of Montreal, Canada. A calibrated biogas monitoring system was used to monitor biogas methane and carbon dioxide concentrations inside a two-year-old field installation with a 1000 m3 storage capacity. Despite a leaking pumping hatch, winter 2010 (January to March) methane concentrations varied directly with solar radiation and maximum exterior temperature, rather than with manure temperature at 2.4 and 1.2 m depths which remained relatively constant between 1 and 5 degrees C. During a six-month-period from November 2009 to April 2010, inclusively, the field ISPAD degraded 34% of the manure volatile solids corresponding to an average methane production of 40 m3/d. The ISPAD biogas production could be further increased by improving its air tightness and intrusion and by regularly pumping out the biogas.

Counteracting ammonia inhibition in anaerobic digestion by removal with a hollow fiber membrane contactor.

Science.gov (United States)

Lauterböck, B; Ortner, M; Haider, R; Fuchs, W

2012-10-01

The aim of the current study was to investigate the feasibility of membrane contactors for continuous ammonia (NH₃-N) removal in an anaerobic digestion process and to counteract ammonia inhibition. Two laboratory anaerobic digesters were fed slaughterhouse wastes with ammonium (NH₄⁺) concentrations ranging from 6 to 7.4 g/L. One reactor was used as reference reactor without any ammonia removal. In the second reactor, a hollow fiber membrane contactor module was used for continuous ammonia removal. The hollow fiber membranes were directly submerged into the digestate of the anaerobic reactor. Sulfuric acid was circulated in the lumen as an adsorbent solution. Using this set up, the NH₄⁺-N concentration in the membrane reactor was significantly reduced. Moreover the extraction of ammonia lowered the pH by 0.2 units. In combination that led to a lowering of the free NH₃-N concentration by about 70%. Ammonia inhibition in the reference reactor was observed when the concentration exceeded 6 g/L NH₄⁺-N or 1-1.2 g/L NH₃-N. In contrast, in the membrane reactor the volatile fatty acid concentration, an indicator for process stability, was much lower and a higher gas yield and better degradation was observed. The chosen approach offers an appealing technology to remove ammonia directly from media having high concentrations of solids and it can help to improve process efficiency in anaerobic digestion of ammonia rich substrates. Copyright © 2012 Elsevier Ltd. All rights reserved.

Biogas recovery in anaerobic digestion plants for pig wastewater

International Nuclear Information System (INIS)

Collivigarelli, C.; Sorlini, S.

2001-01-01

This work deals with a monitoring of thee anaerobic digestion plants in mesophilic conditions treating pig wastewater with the aim to study the treatment efficiency and energetic aspects. A good waste stabilization is reached in all plants, as shown by the high removal efficiency of total and volatile solids and COD, mainly due to the digestion process. On the contrary, Kjeldahl nitrogen and ammonia (low) removal takes place mainly in the final storage tank, thanks to ammonia stripping. The digestion process not only produces a well stabilized wastewater, that can be more surely reused for agricultural spreading, but it offers also an important energy recovery from the biogas combustion, whose specific production varies from 0,78 to 0,99 Nm 3 t - 1 (live weight) d - 1. It is used in cogeneration plants for the combined production of thermal energy (that is reused for waste heating in the digestion tank at mesophilic conditions and for other internal utilizations) and electric energy (that is used for internal requirements while the surplus is sent into the public grid) [it

Effect of silver nanoparticles and antibiotics on antibiotic resistance genes in anaerobic digestion.

Science.gov (United States)

Miller, Jennifer H; Novak, John T; Knocke, William R; Young, Katherine; Hong, Yanjuan; Vikesland, Peter J; Hull, Matthew S; Pruden, Amy

2013-05-01

Water resource recovery facilities have been described as creating breeding ground conditions for the selection, transfer, and dissemination of antibiotic resistance genes (ARGs) among various bacteria. The objective of this study was to determine the effect of direct addition of antibiotic and silver nanoparticles (Ag NPs, or nanosilver) on the occurrence of ARGs in thermophilic anaerobic digesters. Test thermophilic digesters were amended with environmentally-relevant concentrations of Ag NP (0.01, 0.1, and 1.0 mg-Ag/L; corresponding to approximately 0.7, 7.0, and 70 mg-Ag/kg total solids) and sulfamethoxazole (SMX) that span susceptible to resistant classifications (1, 5, and 50 mg/L) as potential selection pressures for ARGs. Tetracycline (tet(O), tet(W)) and sulfonamide (sulI, sulII) ARGs and the integrase enzyme gene (intI1) associated with Class 1 integrons were measured in raw sludge, test thermophilic digesters, a control thermophilic digester, and a control mesophilic digester. There was no apparent effect of Ag NPs on thermophilic anaerobic digester performance. The maximum SMX addition (50 mg/L) resulted in accumulation of volatile fatty acids and low pH, alkalinity, and volatile solids reduction. There was no significant difference between ARG gene copy numbers (absolute or normalized to 16S rRNA genes) in amended thermophilic digesters and the control thermophilic digester. Antibiotic resistance gene copy numbers in digested sludge ranged from 10(3) to 10(6) copies per microL (approximately 8 x10(1) to 8 x 10(4) copies per microg) of sludge as result of a 1-log reduction of ARGs (2-log reduction for intI1). Quantities of the five ARGs in raw sludge ranged from 10(4) to 10(8) copies per microL (approximately 4 x 10(2) to 4 x 10(6) per microg) of sludge. Test and control thermophilic digesters (53 degrees C, 12-day solids retention time [SRT]) consistently reduced but did not eliminate levels of all analyzed genes. The mesophilic digester (37 degrees C

Anaerobic digestion performance of sweet potato vine and animal manure under wet, semi-dry, and dry conditions.

Science.gov (United States)

Zhang, Enlan; Li, Jiajia; Zhang, Keqiang; Wang, Feng; Yang, Houhua; Zhi, Suli; Liu, Guangqing

2018-03-22

Sweet potato vine (SPV) is an abundant agricultural waste, which is easy to obtain at low cost and has the potential to produce clean energy via anaerobic digestion (AD). The main objectives of this study were to reveal methane production and process stability of SPV and the mixtures with animal manure under various total solid conditions, to verify synergetic effect in co-digestion of SPV and manure in AD systems, and to determine the kinetics characteristics during the full AD process. The results showed that SPV was desirable feedstock for AD with 200.22 mL/g VS added of methane yield in wet anaerobic digestion and 12.20 L methane /L working volume in dry anaerobic digestion (D-AD). Synergistic effects were found in semi-dry anaerobic digestion and D-AD with each two mixing feedstock. In contrast with SPV mono-digestion, co-digestion with manure increased methane yield within the range of 14.34-49.11% in different AD digesters. The values of final volatile fatty acids to total alkalinity (TA) were below 0.4 and the values of final pH were within the range of 7.4-8.2 in all the reactors, which supported a positive relationship between carbohydrate hydrolysis and methanogenesis during AD process. The mathematical modified first order model was applied to estimate substrate biodegradability and methane production potential well with conversion constant ranged from 0.0003 to 0.0953 1/day, which indicated that co-digestion increased hydrolysis efficiency and metabolic activity. This work provides useful information to improve the utilization and stability of digestion using SPV and livestock or poultry manure as substrates.

Anaerobic digestion of paunch in a CSTR for renewable energy production and nutrient mineralization.

Science.gov (United States)

Nkemka, Valentine Nkongndem; Marchbank, Douglas H; Hao, Xiying

2015-09-01

A laboratory study investigated the anaerobic digestion of paunch in a continuous stirred tank reactor (CSTR) for the recovery of biogas and mineralization of nutrients. At an organic loading rate (OLR) of 2.8gVSL(-1)day(-1) with a 30-day hydraulic retention time (HRT), a CH4 yield of 0.213Lg(-1)VS and CH4 production rate of 0.600LL(-1)day(-1) were obtained. Post-anaerobic digestion of the effluent from the CSTR for 30days at 40°C recovered 0.067Lg(-1)VS as CH4, which was 21% of the batch CH4 potential. Post-digestion of the effluent from the digestate obtained at this OLR is needed to meet the stable effluent criteria. Furthermore, low levels of soluble ions such as K(+), Ca(2+) and Mg(2+) were found in the liquid fraction of the digestate and the remainder could have been retained in the solid digestate fraction. This study demonstrates the potential of biogas production from paunch in providing renewable energy. In addition, recovery of plant nutrients in the digestate is important for a sustainable agricultural system. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Dynamic simulation model for anaerobic digestion of cellulose

International Nuclear Information System (INIS)

Lee, D.D.; Donaldson, T.L.

1984-01-01

A simple yet useful dynamic simulator for the anaerobic digestion of cellulosic feedstock has been developed. The incentive for this simulator is a need for guidance in design and optimization of an anaerobic digestin process for volume reduction and stabilization of low-level radioactive wastes generated at Oak Ridge National Laboratory. These wastes are primarily blotter and other paper and cotton/polyester clothing. Anaerobic digestion will convert a substantial mass (and hence volume) of waste to gaseous products which can be flared or simply released. The remaining sludge will contain the radionuclides and is expected to have only 5 to 10% of the original waste volume. This stabilized sludge will be more suitable for disposal by shallow land burial than is the original untreated waste. The liquid effluent will go to existing treatment facilities for hot liquids at Oak Ridge National Laboratory (ORNL). An anaerobic digestion process can be scaled to handle small or modest quantities of waste and is expected to be vastly superior to incineration in this regard

Winery waste recycling through anaerobic co-digestion with waste activated sludge.

Science.gov (United States)

Da Ros, C; Cavinato, C; Pavan, P; Bolzonella, D

2014-11-01

In this study biogas and high quality digestate were recovered from winery waste (wine lees) through anaerobic co-digestion with waste activated sludge both in mesophilic and thermophilic conditions. The two conditions studied showed similar yields (0.40 m(3)/kgCODfed) but different biological process stability: in fact the mesophilic process was clearly more stable than the thermophilic one in terms of bioprocess parameters. The resulting digestates showed good characteristics for both the tested conditions: heavy metals, dioxins (PCDD/F), and dioxin like bi-phenyls (PCBs) were concentred in the effluent if compared with the influent because of the important reduction of the solid dry matter, but remained at levels acceptable for agricultural reuse. Pathogens in digestate decreased. Best reductions were observed in thermophilic condition, while at 37°C the concentration of Escherichia coli was at concentrations level as high as 1000 UFC/g. Dewatering properties of digestates were evaluated by means of the capillary suction time (CST) and specific resistance to filtration (SRF) tests and it was found that a good dewatering level was achievable only when high doses of polymer (more than 25 g per kg dry solids) were added to sludge. Copyright © 2014 Elsevier Ltd. All rights reserved.

BIOESTABILIZATION ANAEROBIC SOLID WASTE ORGANIC:QUANTITATIVE ASPECTS

Directory of Open Access Journals (Sweden)

Valderi Duarte Leite

2015-01-01

Full Text Available It is estimated that in Brazil, the municipal solid waste produced are constituted on average 55% of fermentable organic solid waste and that this quantity can be applied in aerobic or anaerobic stabilization process. Anaerobic digestion is an important alternative for the treatment of different types of potentially fermentable waste, considering providing an alternative source of energy that can be used to replace fossil fuels. To perform the experimental part of this work was constructed and monitored an experimental system consisting of an anaerobic batch reactor, shredding unit of fermentable organic wastes and additional devices. Fermentable organic wastes consisted of leftover fruits and vegetables and were listed in EMPASA (Paraibana Company of Food and Agricultural Services, located in the city of Campina Grande- PB. The residues were collected and transported to the Experimental Station Biological Sewage Treatment (EXTRABES where they were processed and used for substrate preparation. The substrate consisted of a mixture of fermentable organic waste, more anaerobic sewage sludge in the proportion of 80 and 20 % respectively. In the specific case of this study, it was found that 1m3 of substrate concentration of total COD equal to 169 g L-1, considering the reactor efficiency equal to 80 %, the production of CH4 would be approximately 47.25 Nm3 CH4. Therefore, fermentable organic waste, when subjected to anaerobic treatment process produces a quantity of methane gas in addition to the partially biostabilized compound may be applied as a soil conditioning agent.

Effects of organic composition on mesophilic anaerobic digestion of food waste.

Science.gov (United States)

Li, Yangyang; Jin, Yiying; Borrion, Aiduan; Li, Hailong; Li, Jinhui

2017-11-01

Anaerobic digestion of food waste (FW) has been widely investigated, however, little is known about the influence of organic composition on the FW digestion process. This study aims to identify the optimum composition ratios of carbohydrate (CA), protein (CP) and lipid (EE) for maintaining high methane yield and process stability. The results show that the CA-CP-EE ratio was significantly correlated with performance and degradability parameters. Controlling the CA-CP-EE ratio higher than 1.89 (CA higher than 8.3%, CP lower than 5.0%, and EE lower than 5.6%) could be an effective way to maintain stable digestion and achieve higher methane production (385-627mL/gVS) and shorter digestion retention (196-409h). The CA-CP-EE ratio could be used as an important indicator for digestion performance. To effectively evaluate organic reduction, the concentration and removal efficiency of organic compositions in both solid phases and total FW should be considered. Copyright © 2017. Published by Elsevier Ltd.

Anaerobic digestion and co-digestion of slaughterhouse waste (SHW): influence of heat and pressure pre-treatment in biogas yield.

Science.gov (United States)

Cuetos, M J; Gómez, X; Otero, M; Morán, A

2010-10-01

Mesophilic anaerobic digestion (34+/-1 degrees C) of pre-treated (for 20 min at 133 degrees C, >3 bar) slaughterhouse waste and its co-digestion with the organic fraction of municipal solid waste (OFMSW) have been assessed. Semi-continuously-fed digesters worked with a hydraulic retention time (HRT) of 36 d and organic loading rates (OLR) of 1.2 and 2.6 kg VS(feed)/m(3)d for digestion and co-digestion, respectively, with a previous acclimatization period in all cases. It was not possible to carry out an efficient treatment of hygienized waste, even less so when OFMSW was added as co-substrate. These digesters presented volatile fatty acids (VFA), long chain fatty acids (LCFA) and fats accumulation, leading to instability and inhibition of the degradation process. The aim of applying a heat and pressure pre-treatment to promote splitting of complex lipids and nitrogen-rich waste into simpler and more biodegradable constituents and to enhance biogas production was not successful. These results indicate that the temperature and the high pressure of the pre-treatment applied favoured the formation of compounds that are refractory to anaerobic digestion. The pre-treated slaughterhouse wastes and the final products of these systems were analyzed by FTIR and TGA. These tools verified the existence of complex nitrogen-containing polymers in the final effluents, confirming the formation of refractory compounds during pre-treatment. (c) 2010 Elsevier Ltd. All rights reserved.

How Incentives Affect the Adoption of Anaerobic Digesters in the United States

Directory of Open Access Journals (Sweden)

Anh Sam

2017-07-01

Full Text Available Various government incentives support the adoption of anaerobic digester systems to manage farm waste and serve as a source of renewable energy in the United States. We examine the effectiveness of US state-level incentives promoting the adoption of anaerobic digester systems. We find that performance-based incentives and adoption of renewable portfolio standards best promote anaerobic digester system adoption.

Saponification pretreatment and solids recirculation as a new anaerobic process for the treatment of slaughterhouse waste.

Science.gov (United States)

Affes, R; Palatsi, J; Flotats, X; Carrère, H; Steyer, J P; Battimelli, A

2013-03-01

Different configurations of anaerobic process, adapted to the treatment of solid slaughterhouse fatty waste, were proposed and evaluated in this study. The tested configurations are based on the combination of anaerobic digestion with/without waste saponification pretreatment (70 °C during 60 min) and with/without recirculation of the digestate solid fraction (ratio=20% w/w). After an acclimation period of substrate pulses-feeding cycles, the reactors were operated in a semi-continuous feeding mode, increasing organic loading rates along experimental time. The degradation of the raw substrate was shown to be the bottleneck of the whole process, obtaining the best performance and process yields in the reactor equipped with waste pretreatment and solids recirculation. Saponification promoted the emulsification and bioavailability of solid fatty residues, while recirculation of solids minimized the substrate/biomass wash-out and induced microbial adaptation to the treatment of fatty substrates. Copyright © 2013 Elsevier Ltd. All rights reserved.

Horse manure as feedstock for anaerobic digestion.

Science.gov (United States)

Hadin, Sa; Eriksson, Ola

2016-10-01

Horse keeping is of great economic, social and environmental benefit for society, but causes environmental impacts throughout the whole chain from feed production to manure treatment. According to national statistics, the number of horses in Sweden is continually increasing and is currently approximately 360,000. This in turn leads to increasing amounts of horse manure that have to be managed and treated. Current practices could cause local and global environmental impacts due to poor performance or lack of proper management. Horse manure with its content of nutrients and organic material can however contribute to fertilisation of arable land and recovery of renewable energy following anaerobic digestion. At present anaerobic digestion of horse manure is not a common treatment. In this paper the potential for producing biogas and biofertiliser from horse manure is analysed based on a thorough literature review in combination with mathematical modelling and simulations. Anaerobic digestion was chosen as it has a high degree of resource conservation, both in terms of energy (biogas) and nutrients (digestate). Important factors regarding manure characteristics and operating factors in the biogas plant are identified. Two crucial factors are the type and amount of bedding material used, which has strong implications for feedstock characteristics, and the type of digestion method applied (dry or wet process). Straw and waste paper are identified as the best materials in an energy point of view. While the specific methane yield decreases with a high amount of bedding, the bedding material still makes a positive contribution to the energy balance. Thermophilic digestion increases the methane generation rate and yield, compared with mesophilic digestion, but the total effect is negligible. Copyright © 2016. Published by Elsevier Ltd.

Optimisation and inhibition of anaerobic digestion of livestock manure

Energy Technology Data Exchange (ETDEWEB)

Sutaryo, S.

2012-11-15

The optimisation process during this PhD study focused on mixed enzyme (ME) addition, thermal pre-treatment and co-digestion of raw manure with solid fractions of acidified manure, while for inhibition processes, ammonia and sulphide inhibition were studied. ME addition increased methane yield of both dairy cow manure (DCM) and solid fractions of DCM (by 4.44% and 4.15% respectively, compared to the control) when ME was added to manure and incubated prior to anaerobic digestion (AD). However, no positive effect was found when ME was added to manure and fed immediately to either mesophilic (35 deg. C) or thermophilic (50 deg. C) digesters. Low-temperature pre-treatment (65 deg. C to 80 deg. C for 20 h) followed by batch assays increased the methane yield of pig manure in the range from 9.5% to 26.4% at 11 d incubation. These treatments also increased the methane yield of solid-fractions pig manure in the range from 6.1% to 25.3% at 11 d of the digestion test. However, at 90 d the increase in methane yield of pig manure was only significant at the 65 deg. C treatment, thus low-temperature thermal pre-treatment increased the rate of gas production, but did not increase the ultimate yield (B{sub o}). High-temperature pre-treatment (100 deg. C to 225 deg. C for 15 min.) increased the methane yield of DCM by 13% and 21% for treatments at 175 deg. C and 200 deg. C, respectively, at 27 d of batch assays. For pig manure, methane yield was increased by 29% following 200 deg. C treatment and 27 d of a batch digestion test. No positive effect was found of high-temperature pre-treatment on the methane yield of chicken manure. At the end of the experiment (90 d), high-temperature thermal pre-treatment was significantly increasing the B{sub 0} of pig manure and DCM. Acidification of animal manure using sulphuric acid is a well-known technology to reduce ammonia emission of animal manure. AD of acidified manure showed sulphide inhibition and consequently methane production was 45

Effect of gamma-irradiation pretreatment on improvement of anaerobic digestive characteristic of sludge

International Nuclear Information System (INIS)

Mou Yanyan; Yuan Shoujun; Yu Xin; Zheng Zheng; Cui Lei; Zhao Yongfu

2005-01-01

A comparative study was made about main anaerobic digestive characteristics of sludge which was subjected to a 60 Co gamma-irradiation pretreatment. The results showed the gamma-irradiation pretreatment can clearly improve anaerobic digestibility of sludge and pick up the anaerobic digestion speed of sludge. (authors)

Startup and stability of thermophilic anaerobic digestion of OFMSW

KAUST Repository

El-Fadel, Mutasem E.; Saikaly, Pascal; Ghanimeh, Sophia A.

2013-01-01

Anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) is promoted as an energy source and more recently as a greenhouse gas (GHG) mitigation measure. In this context, AD systems operating at thermophilic temperatures (55-60°C)-compared to mesophilic temperatures (35-40°C)-have the unique feature of producing hygienic soil conditioners with greater process efficiency, higher energy yield, and more GHG savings. Startup of AD systems is often constrained by the lack of acclimated seeds, leading to process instability and failure. The authors focus on strategies to startup thermophilic digesters treating OFMSW in the absence of acclimated seeds and examines constraints associated with process stability and ways to overcome them. Relevant gaps in the literature and future research needs are delineated. © 2013 Taylor & Francis Group, LLC.

A comprehensive review on food waste anaerobic digestion: Research updates and tendencies.

Science.gov (United States)

Ren, Yuanyuan; Yu, Miao; Wu, Chuanfu; Wang, Qunhui; Gao, Ming; Huang, Qiqi; Liu, Yu

2018-01-01

Anaerobic digestion has been practically applied in agricultural and industrial waste treatment and recognized as an economical-effective way for food waste disposal. This paper presented an overview on the researches about anaerobic digestion of food waste. Technologies (e.g., pretreatment, co-digestion, inhibition and mitigation, anaerobic digestion systems, etc.) were introduced and evaluated on the basis of bibliometric analysis. Results indicated that ethanol and aerobic prefermentation were novel approaches to enhance substrates hydrolysis and methane yield. With the promotion of resource recovery, more attention should be paid to biorefinery technologies which can produce more useful products toward zero emissions. Furthermore, a technological route for food waste conversion based on anaerobic digestion was proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Continuous anaerobic digestion of swine manure: ADM1-based modelling and effect of addition of swine manure fibers pretreated with aqueous ammonia soaking

OpenAIRE

Jurado, E.; Antonopoulou, G.; Lyberatos, G.; Gavala, Hariklia N.; Skiadas, Ioannis V.

2016-01-01

Anaerobic digestion of manure fibers presents challenges due to their low biodegradability. Aqueous ammonia soaking (AAS) has been tested as a simple method to disrupt the lignocellulose and increase the methane yield of manure fibers. In the present study, mesophilic anaerobic digestion of AAS pretreated manure fibers was performed in CSTR-type digesters, fed with swine manure and/or a mixtureof swine manure and AAS pretreated manure fibers (at a total solids based ratio of 0.52 manure per0....

Effect of total solids content on methane and volatile fatty acid production in anaerobic digestion of food waste.

Science.gov (United States)

Liotta, Flavia; d'Antonio, Giuseppe; Esposito, Giovanni; Fabbricino, Massimiliano; van Hullebusch, Eric D; Lens, Piet N L; Pirozzi, Francesco; Pontoni, Ludovico

2014-10-01

This work investigates the role of the moisture content on anaerobic digestion of food waste, as representative of rapidly biodegradable substrates, analysing the role of volatile fatty acid production on process kinetics. A range of total solids from 4.5% to 19.2% is considered in order to compare methane yields and kinetics of reactors operated under wet to dry conditions. The experimental results show a reduction of the specific final methane yield of 4.3% and 40.8% in semi-dry and dry conditions compared with wet conditions. A decreasing trend of the specific initial methane production rate is observed when increasing the total solids concentration. Because of lack of water, volatile fatty acids accumulation occurs during the first step of the process at semi-dry and dry conditions, which is considered to be responsible for the reduction of process kinetic rates. The total volatile fatty acids concentration and speciation are proposed as indicators of process development at different total solids content. © The Author(s) 2014.

Comparison of the microbial communities in solid-state anaerobic digestion (SS-AD) reactors operated at mesophilic and thermophilic temperatures.

Science.gov (United States)

Li, Yueh-Fen; Nelson, Michael C; Chen, Po-Hsu; Graf, Joerg; Li, Yebo; Yu, Zhongtang

2015-01-01

The microbiomes involved in liquid anaerobic digestion process have been investigated extensively, but the microbiomes underpinning solid-state anaerobic digestion (SS-AD) are poorly understood. In this study, microbiome composition and temporal succession in batch SS-AD reactors, operated at mesophilic or thermophilic temperatures, were investigated using Illumina sequencing of 16S rRNA gene amplicons. A greater microbial richness and evenness were found in the mesophilic than in the thermophilic SS-AD reactors. Firmicutes accounted for 60 and 82 % of the total Bacteria in the mesophilic and in the thermophilic SS-AD reactors, respectively. The genus Methanothermobacter dominated the Archaea in the thermophilic SS-AD reactors, while Methanoculleus predominated in the mesophilic SS-AD reactors. Interestingly, the data suggest syntrophic acetate oxidation coupled with hydrogenotrophic methanogenesis as an important pathway for biogas production during the thermophilic SS-AD. Canonical correspondence analysis (CCA) showed that temperature was the most influential factor in shaping the microbiomes in the SS-AD reactors. Thermotogae showed strong positive correlation with operation temperature, while Fibrobacteres, Lentisphaerae, Spirochaetes, and Tenericutes were positively correlated with daily biogas yield. This study provided new insight into the microbiome that drives SS-AD process, and the findings may help advance understanding of the microbiome in SS-AD reactors and the design and operation of SS-AD systems.

Simulation of the Impact of SRT on Anaerobic Digestability of Ultrasonicated Hog Manure

OpenAIRE

Elbeshbishy; Nakevski; Hafez; Ray; Nakhla

2010-01-01

Ultrasonication at a specific energy of 500 kJ/kgTS was applied to hog manure in a continuous mode completely mixed anaerobic digestion. A process model in BioWin was developed, calibrated and tested at different solids retention times (SRTs) to evaluate the process economics. The results showed that there was a 36% increase in volatile suspended solids (VSS) removal efficiency, a 20% increase in methane production rate, a 13.5% increase in destruction of bound proteins, and a reduction from ...

Comparative analyses of microbial structures and gene copy numbers in the anaerobic digestion of various types of sewage sludge.

Science.gov (United States)

Hidaka, Taira; Tsushima, Ikuo; Tsumori, Jun

2018-04-01

Anaerobic co-digestion of various sewage sludges is a promising approach for greater recovery of energy, but the process is more complicated than mono-digestion of sewage sludge. The applicability of microbial structure analyses and gene quantification to understand microbial conditions was evaluated. The results show that information from gene analyses is useful in managing anaerobic co-digestion and damaged microbes in addition to conventional parameters like total solids, pH and biogas production. Total bacterial 16S rRNA gene copy numbers are the most useful tools for evaluating unstable anaerobic digestion of sewage sludge, rather than mcrA and total archaeal 16S rRNA gene copy numbers, and high-throughput sequencing. First order decay rates of gene copy numbers during pH failure were higher than typical decay rates of microbes in stable operation. The sequencing analyses, including multidimensional scaling, showed very different microbial structure shifts, but the results were not consistent. Copyright © 2017 Elsevier Ltd. All rights reserved.

Renewable methane from anaerobic digestion of biomass

International Nuclear Information System (INIS)

Chynoweth, D.P.; Owens, J.M.

2001-01-01

Production of methane via anaerobic digestion of energy crops and organic wastes would benefit society by providing a clean fuel from renewable feedstocks. This would replace fossil fuel-derived energy and reduce environmental impacts including global warming and acid rain. Although biomass energy is more costly than fossil fuel-derived energy, trends to limit carbon dioxide and other emissions through emission regulations, carbon taxes, and subsidies of biomass energy would make it cost competitive. Methane derived from anaerobic digestion is competitive in efficiencies and costs to other biomass energy forms including heat, synthesis gases, and ethanol. (author)

Anaerobic digestion of industrial activated aerobic sludge

International Nuclear Information System (INIS)

Goodloe, J.G.; Roberts, R.S.

1990-04-01

The Tennessee Eastman Company manufactures a variety of organic chemicals, plastics and fibers at their Kingsport Tennessee Facility. The wastewater generated during the manufacture of these compounds is currently treated using an activated sludge process. The objective of the project is to evaluate the economic potential of an anaerobic digestion process to convert industrial sludge at the Tennessee Eastman Company into biogas. The evaluation will require collection and analysis of experimental data on the anaerobic digestion of industrial sludge obtained from Kingsport. Although the experiments will be conducted using Tennessee Eastman sludge, these results should be also generally applicable to similar industrial sludge

Techno-economic assessment of anaerobic digestion systems for agri-food wastes

Energy Technology Data Exchange (ETDEWEB)

Lau, A.; Baldwin, S.; Wang, M. [British Colombia Univ., Vancouver, BC (Canada)

2010-07-01

Activities in British Columbia's Fraser Valley generate an estimated 3 million tones of agriculture and food wastes annually, of which 85 per cent are readily available for anaerobic digestion. The potential for energy generation from biogas through anaerobic digestion is approximately 30 MW. On-farm manure-based systems represent the most likely scenario for the development of anaerobic digestion in British Columbia in the near future. Off-farm food processing wastes may be an alternative option to large centralized industrial complexes. Odour control, pathogen reduction, improved water quality, reduced greenhouse gas emissions and reduced landfill usage are among the environmental benefits of anaerobic digestion. The economical benefits include power and heat generation, biogas upgrading, and further processing of the residues to produce compost or animal bedding. This paper described a newly developed anaerobic digestion (AD) calculator that helps users regarding their investment decision in AD facilities. The calculator classifies various technology options into several major types of AD systems. It also constructs kinetic and economic models for these systems and provides a fair estimation on biogas yield, digester volume, capital cost and annual income. The calculator takes into consideration factors such as the degradability of wastes with different compositions and different operating parameters.

Process performance and modelling of anaerobic digestion using source-sorted organic household waste

DEFF Research Database (Denmark)

Khoshnevisan, Benyamin; Tsapekos, Panagiotis; Alvarado-Morales, Merlin

2018-01-01

Three distinctive start-up strategies of biogas reactors fed with source-sorted organic fraction of municipal solid waste were investigated to reveal the most reliable procedure for rapid process stabilization. Moreover, the experimental results were compared with mathematical modeling outputs....... The combination of both experimental and modelling/simulation succeeded in optimizing the start-up process for anaerobic digestion of biopulp under mesophilic conditions....

Siloxane removal and sludge disintegration using thermo-alkaline treatments with air stripping prior to anaerobic sludge digestion

International Nuclear Information System (INIS)

Oshita, Kazuyuki; Fujime, Motochika; Takaoka, Masaki; Fujimori, Takashi; Appels, Lise; Dewil, Raf

2015-01-01

Highlights: • Siloxanes hamper the energy-use of anaerobic digestion biogas. • D5 siloxane was considered as target compound in this study. • The treatment removed 80% of D5 in sewage sludge at 55 °C and 135 g-NaOH kg −1 -VTS. • D5 removal and the disintegration of VSS in the sludge were correlated. • At the optimal conditions, the costs of anaerobic digestion were notably diminished. - Abstract: A thermo-alkaline treatment with air stripping was applied before anaerobic sludge digestion for both siloxane removal and sludge disintegration. The treatment was expected to increase the amount of biogas produced and to reduce the amount of siloxane in the gas. Adding sodium hydroxide (NaOH) to the sludge improved the removal of siloxane from the sludge, with approximately 90% of the siloxane removed to the gas phase using a thermo-alkaline treatment. Over 80% of decamethylcyclopentasiloxane (D5) could be removed under the following conditions: 55 °C treatment temperature, 135 g-NaOH kg −1 volatile total solids (VTS), and 0.5 L min −1 air-stripping rate. The disintegration ratio of volatile suspended solids (VSS) in the sludge was correlated with the D5 removal ratio. Because most of the siloxane was adsorbed to, or was contained in the VSS, the siloxane removal ratio increased with VSS disintegration. Finally, the energy consumption and operational costs of this system were evaluated for several scenarios. Thermo-alkaline treatment at the indicated operational conditions had the lowest operating costs for a 400 m 3 day −1 anaerobic sludge digestion system

Kinetic study of thermophilic anaerobic digestion of solid wastes from potato processing

International Nuclear Information System (INIS)

Linke, Bernd

2006-01-01

Anaerobic treatment of solid wastes from potato processing was studied in completely stirred tank reactors (CSTR) at 55 o C. Special attention was paid to the effect of increased organic loading rate (OLR) on the biogas yield in long-term experiments. Both biogas yield and CH 4 in the biogas decreased with the increase in OLR. For OLR in the range of 0.8 gl -1 d -1 -3.4 gl -1 d -1 , biogas yield and CH 4 obtained were 0.85 l g -1 -0.65 l g -1 and 58%-50%, respectively. Biogas yield y as a function of maximum biogas yield y m , reaction rate constant k and HRT are described on the basis of a mass balance in a CSTR and a first order kinetic. The value of y m can be obtained from curve fitting or a simple batch test and k results from plotting y/(y m -y) against 1/OLR from long-term experiments. In the present study values for y m and k were obtained as 0.88 l g -1 and 0.089 d -1 , respectively. The simple model equations can apply for dimensioning completely stirred tank reactors (CSTR) digesting organic wastes from food processing industries, animal waste slurries or biogas crops

Making lignin accessible for anaerobic digestion by wet-explosion pretreatment

DEFF Research Database (Denmark)

Ahring, Birgitte Kiær; Biswas, Rajib; Ahamed, Aftab

2015-01-01

of lignin during anaerobic digestion processes. The pretreatment of feedlot manure was performed in a 10 L reactor at 170 C for 25 min using 4 bars oxygen and the material was fed to a continuous stirred tank reactor operated at 55 C for anaerobic digestion. Methane yield of untreated and pretreated...... material was 70 ± 27 and 320 ± 36 L/kg-VS/day, respectively, or 4.5 times higher yield as a result of the pretreatment. Aliphatic acids formed during the pretreatment were utilized by microbes. 44.4% lignin in pretreated material was actually converted in the anaerobic digestion process compared to 12...

Start-up strategies for thermophilic anaerobic digestion of pig manure

International Nuclear Information System (INIS)

Moset, V.; Bertolini, E.; Cerisuelo, A.; Cambra, M.; Olmos, A.; Cambra-López, M.

2014-01-01

Sludge physicochemical composition, methane (CH 4 ) yield, and methanogenic community structure and dynamics using quantitative real-time polymerase chain reaction were determined after start-up of anaerobic digestion of pig manure. Eight thermophilic continuous stirred anaerobic digesters were used during 126 days. Four management strategies were investigated: a feedless and a non-feedless period followed by a gradual or an abrupt addition of pig manure (two digesters per strategy). During the first 43 days, VFA (volatile fatty acids) accumulations and low CH 4 yield were observed in all digesters. After this period, digesters recovered their initial status being propionic acid the last parameter to be re-established. Non-feedless digesters with an abrupt addition of pig manure showed the best performances (lower VFA accumulation and higher CH 4 yield). Differences in microbial orders and dynamics, however, were less evident among treatments. Hydrogenotrophic methanogenesis, Methanomicrobiales first and Methanobacteriales second, was the dominant metabolic pathway in all digesters. Further research is needed to clarify the role and activity of hydrogenotrophic methanogens during the recovery start-up period and to identify the best molecular tools and methodologies to monitor microbial populations and dynamics reliably and accurately in anaerobic digesters. - Highlights: • Four start-up strategies for thermophilic anaerobic digestion of pig manure were tested. • Physicochemical composition, methane yield and methanogenic community were determined. • During the first 43 days, a decline in reactor's performance occurred. • The best start-up strategy was non-feedless with an abrupt addition of pig slurry. • Hydrogenotrophic methanogenesis was the dominant metabolic pathway

Ammonia and temperature determine potential clustering in the anaerobic digestion microbiome.

Science.gov (United States)

De Vrieze, Jo; Saunders, Aaron Marc; He, Ying; Fang, Jing; Nielsen, Per Halkjaer; Verstraete, Willy; Boon, Nico

2015-05-15

Anaerobic digestion is regarded as a key environmental technology in the present and future bio-based economy. The microbial community completing the anaerobic digestion process is considered complex, and several attempts already have been carried out to determine the key microbial populations. However, the key differences in the anaerobic digestion microbiomes, and the environmental/process parameters that drive these differences, remain poorly understood. In this research, we hypothesized that differences in operational parameters lead to a particular composition and organization of microbial communities in full-scale installations. A total of 38 samples were collected from 29 different full-scale anaerobic digestion installations, showing constant biogas production in function of time. Microbial community analysis was carried out by means of amplicon sequencing and real-time PCR. The bacterial community in all samples was dominated by representatives of the Firmicutes, Bacteroidetes and Proteobacteria, covering 86.1 ± 10.7% of the total bacterial community. Acetoclastic methanogenesis was dominated by Methanosaetaceae, yet, only the hydrogenotrophic Methanobacteriales correlated with biogas production, confirming their importance in high-rate anaerobic digestion systems. In-depth analysis of operational and environmental parameters and bacterial community structure indicated the presence of three potential clusters in anaerobic digestion. These clusters were determined by total ammonia concentration, free ammonia concentration and temperature, and characterized by an increased relative abundance of Bacteroidales, Clostridiales and Lactobacillales, respectively. None of the methanogenic populations, however, could be significantly attributed to any of the three clusters. Nonetheless, further experimental research will be required to validate the existence of these different clusters, and to which extent the presence of these clusters relates to stable or sub

Optimization of inoculum to substrate ratio for bio-energy generation in co-digestion of tannery solid wastes

Energy Technology Data Exchange (ETDEWEB)

Sri Bala Kameswari, K.; Chitra Kalyanaraman,; Porselvam, S. [Central Leather Research Institute (CLRI), Environmental Technology Division, Chennai (India); Thanasekaran, K. [Anna University, Centre for Environmental Studies, Chennai (India)

2012-04-15

The inoculum to substrate (I/S) ratio is an important factor which influences the anaerobic digestion process. In this study, the effect of different I/S ratios on the performance of co-digestion of fleshings along with mixture of sludge generated during treatment of tannery wastewater was investigated. The parameters studied were biogas generation, volatile solids reduction, volatile fatty acid (VFA) production, and the stability of the digestion process based on VFA to alkalinity ratio was evaluated for various I/S ratios. Economical significance of I/S ratio as related to the volume of the anaerobic digester and the potential benefit of bio-energy generated are discussed in detail. (orig.)

Continuously-stirred anaerobic digester to convert organic wastes into biogas: system setup and basic operation.

Science.gov (United States)

Usack, Joseph G; Spirito, Catherine M; Angenent, Largus T

2012-07-13

Anaerobic digestion (AD) is a bioprocess that is commonly used to convert complex organic wastes into a useful biogas with methane as the energy carrier. Increasingly, AD is being used in industrial, agricultural, and municipal waste(water) treatment applications. The use of AD technology allows plant operators to reduce waste disposal costs and offset energy utility expenses. In addition to treating organic wastes, energy crops are being converted into the energy carrier methane. As the application of AD technology broadens for the treatment of new substrates and co-substrate mixtures, so does the demand for a reliable testing methodology at the pilot- and laboratory-scale. Anaerobic digestion systems have a variety of configurations, including the continuously stirred tank reactor (CSTR), plug flow (PF), and anaerobic sequencing batch reactor (ASBR) configurations. The CSTR is frequently used in research due to its simplicity in design and operation, but also for its advantages in experimentation. Compared to other configurations, the CSTR provides greater uniformity of system parameters, such as temperature, mixing, chemical concentration, and substrate concentration. Ultimately, when designing a full-scale reactor, the optimum reactor configuration will depend on the character of a given substrate among many other nontechnical considerations. However, all configurations share fundamental design features and operating parameters that render the CSTR appropriate for most preliminary assessments. If researchers and engineers use an influent stream with relatively high concentrations of solids, then lab-scale bioreactor configurations cannot be fed continuously due to plugging problems of lab-scale pumps with solids or settling of solids in tubing. For that scenario with continuous mixing requirements, lab-scale bioreactors are fed periodically and we refer to such configurations as continuously stirred anaerobic digesters (CSADs). This article presents a general

Biogas from mesophilic anaerobic digestion of cow dung using gelatin as additive

Science.gov (United States)

Salam, Bodius; Rahman, Md Mizanur; Sikder, Md Asif R.; Islam, Majedul

2017-06-01

A research work was conducted to investigate the enhanced production ability of biogas from mesophilic anaerobic digestions of cow dung (CD) using gelatin as additive. Five laboratory scale digesters were constructed to digest cow dung, where one set up was used for digestion of cow dung without additive and the other set up were used for digestion with additive. Gelatin additive was added in the slurry of amount 0.29, 0,57, 0.85 and 1.14% (wt.). The digesters were made of glass conical flask of 1-liter capacity each. Cow dung was used 335 gm and water was used 365 gm in each experiment. In the slurry, total solid content was maintained 8% (wt.) for all the observations. The digesters were fed on batch basis. The digesters were operated at ambient temperatures of 26 - 35°C. The total gas yield was obtained about 14.4 L/kg CD for digestion without additive and about 65% more biogas for digestion with 0.29% gelatin additive. The retention time for digestion without additive was 38 days and with additive retention time varied between 24 and 52 days.

Electricity purchase agreements and distributed energy policies for anaerobic digesters

International Nuclear Information System (INIS)

Binkley, David; Harsh, Stephen; Wolf, Christopher A.; Safferman, Steven; Kirk, Dana

2013-01-01

Anaerobic digestion is increasingly recognized for its ability to produce renewable energy and reduce greenhouse gas emissions from livestock operations. In 2010, there were 2645 U.S. dairy farms with herd sizes large enough to support anaerobic digesters, yet only 156 systems were in operation (U.S. Environmental Protection Agency (U.S. EPA), 2010a. Market Opportunities for Biogas Recovery Systems at U.S. Livestock Facilities. AgSTAR Program; U.S. Environmental Protection Agency (U.S. EPA), 2011. Operational Anaerobic Digesters, Sorted by State (Dairy). AgSTAR Program.). This study analyzes the net present value of digester systems under alternative electricity purchase agreements and how returns are affected by standby charges, net metering policies and the use of feed-in-tariffs. In order for digester potential to be fully realized on a state or national level, changes to distributed energy policy are required. Results indicated that standby charges can reduce revenues from offsetting electricity by an average of nearly 20%. Net metering rules limit participation among larger farms and negatively affect profitability by restricting engine–generator size. Lastly, the effectiveness of a fixed price feed-in-tariff policy for digesters is significantly affected by project size differentiation. Digester energy policies are similar nationwide, making this study useful for government regulatory agencies and digester owners throughout the U.S. - Highlights: ► Anaerobic digester net present value was examined over a range of herd sizes. ► Standby charges reduce electricity sales revenues by an average of nearly 20%. ► Net metering rules reduce profitability by restricting engine–generator size. ► Feed-in-tariffs for digesters are significantly affected by project size.

The effects of temperature, organic matter and time-dependency on rheological properties of dry anaerobic digested swine manure.

Science.gov (United States)

Liu, Gang-Jin; Liu, Yi; Wang, Zhi-Yong; Lei, Yun-Hui; Chen, Zi-Ai; Deng, Liang-Wei

2015-04-01

An efficient way to avoid the pollution of swine wastewater is the application of dry anaerobic digestion, which needs rheological parameter for stirring and pipe designing. The rheological properties of this kind of sludge have been studied for many decades, yet their effects only solid concentration has been investigated widely. In this paper, the influences of temperature, organic and time-dependency on the efficiency of anaerobic digested swine manure were studied. The viscosity decreased with temperature arranged from 10 to 60 °C which caused increase in protein from 7.18 to 8.49 g/kg. 60 °C can make the digested swine manure with TS from 16.6% to 21.5% reach to the same rheology state. The added peptone decreased the viscosity because of its function of water-reducing admixture and air entraining mixture. Time-dependent experiment showed the decrease of shear stress over time. The first and the second yield stress of dry anaerobic digested swine manure were evaluated through time-dependent model. Copyright © 2015 Elsevier Ltd. All rights reserved.

Laboratory scale studies on the mesophilic anaerobic digestion of cheese whey in different digester configurations

Energy Technology Data Exchange (ETDEWEB)

Lo, K.V.; Liao, P.H.

1988-02-01

A two-phase system consisting of two reactors in series was used to study the mesophilic anaerobic digestion of cheese whey. A completely-mixed reactor and an anaerobic rotating biological contact reactor were used in series. The results indicated that ethanol and volatile fatty acids were the major products in the first reactor. Acidogenic pretreatment prior to the methanogenic phase resulted in an increase in methane production in the second reactor over that in one-stage digestion. High treatment efficiency in terms of reduction of chemical oxygen demand was also obtained for the two-phase digestion than that of the one-stage digestion. When comparing the system's performance in terms of methane production rate, the two-phase digestion had no advantage over the one-stage digestion.

Microbial community analysis of ambient temperature anaerobic digesters

Energy Technology Data Exchange (ETDEWEB)

Ciotola, R. [Ohio State Univ., Columbus, OH (United States). Dept. of Food, Agriculture and Biological Engineering

2010-07-01

This paper reported on a study in which designs for Chinese and Indian fixed-dome anaerobic digesters were modified in an effort to produce smaller and more affordable digesters. While these types of systems are common in tropical regions of developing countries, they have not been used in colder climates because of the low biogas yield during the winter months. Although there is evidence that sufficient biogas production can be maintained in colder temperatures through design and operational changes, there is a lack of knowledge about the seasonal changes in the composition of the microbial communities in ambient temperature digesters. More knowledge is needed to design and operate systems for maximum biogas yield in temperate climates. The purpose of this study was to cultivate a microbial community that maximizes biogas production at psychrophilic temperatures. The study was conducted on a 300 gallon experimental anaerobic digester on the campus of Ohio State University. Culture-independent methods were used on weekly samples collected from the digester in order to examine microbial community response to changes in ambient temperature. Microbial community profiles were established using universal bacterial and archaeal primers that targeted the 16S rRNA gene. In addition to the methanogenic archaea, this analysis also targeted some of the other numerically and functionally important microbial taxa in anaerobic digesters, such as hydrolytic, fermentative, acetogenic and sulfate reducing bacteria. According to preliminary results, the composition of the microbial community shifts with changes in seasonal temperature.

Evaluating the effects of activated carbon on methane generation and the fate of antibiotic resistant genes and class I integrons during anaerobic digestion of solid organic wastes.

Science.gov (United States)

Zhang, Jingxin; Mao, Feijian; Loh, Kai-Chee; Gin, Karina Yew-Hoong; Dai, Yanjun; Tong, Yen Wah

2018-02-01

The effects of activated carbon (AC) on methane production and the fate of antibiotic resistance genes (ARGs) were evaluated through comparing the anaerobic digestion performance and transformation of ARGs among anaerobic mono-digestion of food waste, co-digestion of food waste and chicken manure, and co-digestion of food waste and waste activated sludge. Results showed that adding AC in anaerobic digesters improved methane yield by at least double through the enrichment of bacteria and archaea. Conventional digestion process showed ability in removing certain types of ARGs, such as tetA, tetX, sul1, sul2, cmlA, floR, and intl1. Supplementing AC in anaerobic digester enhanced the removal of most of the ARGs in mono-digestion of food waste. The effects tended to be minimal in co-digestion of co-substrates such as chicken manure and waste activated sludge, both of which contain a certain amount of antibiotics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Importance of storage time in mesophilic anaerobic digestion of food waste.

Science.gov (United States)

Lü, Fan; Xu, Xian; Shao, Liming; He, Pinjing

2016-07-01

Storage was used as a pretreatment to enhance the methanization performance of mesophilic anaerobic digestion of food waste. Food wastes were separately stored for 0, 1, 2, 3, 4, 5, 7, and 12days, and then fed into a methanogenic reactor for a biochemical methane potential (BMP) test lasting up to 60days. Relative to the methane production of food waste stored for 0-1day (285-308mL/g-added volatile solids (VSadded)), that after 2-4days and after 5-12days of storage increased to 418-530 and 618-696mL/g-VSadded, respectively. The efficiency of hydrolysis and acidification of pre-stored food waste in the methanization reactors increased with storage time. The characteristics of stored waste suggest that methane production was not correlated with the total hydrolysis efficiency of organics in pre-stored food waste but was positively correlated with the storage time and acidification level of the waste. From the results, we recommend 5-7days of storage of food waste in anaerobic digestion treatment plants. Copyright © 2016. Published by Elsevier B.V.

Anaerobic Digestion Scale Levels and Their Energy Yields. A comparison of energy yields of different manure-and co-digestion scale levels

NARCIS (Netherlands)

Konneman, Bram

2007-01-01

Anaerobic digestion is a biological process whereby, in the absence of oxygen, organic matter is converted into biogas and digestate. In recent years anaerobic digestion has received re-newed attention in the Dutch agricultural sector. Co-digestion, in wh

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 enhance...... hydrolysis of recalcitrant organic matter, improve sanitation and ease the stripping of ammonia from the reactor. The efficiency of the combined system was studied in terms of methane yield, volatile solids (VS) reduction and volatile fatty acid (VFA) production at different hydraulic retention times (HRT...

A strict anaerobic extreme thermophilic hydrogen-producing culture enriched from digested household waste

DEFF Research Database (Denmark)

Karakashev, Dimitar Borisov; Kotay, Shireen Meher; Trably, Eric

2009-01-01

The aim of this study was to enrich, characterize and identify strict anaerobic extreme thermophilic hydrogen (H-2) producers from digested household solid wastes. A strict anaerobic extreme thermophilic H-2 producing bacterial culture was enriched from a lab-scale digester treating household...... wastes at 70 degrees C. The enriched mixed culture consisted of two rod-shaped bacterial members growing at an optimal temperature of 80 degrees C and an optimal pH 8.1. The culture was able to utilize glucose, galactose, mannose, xylose, arabinose, maltose, sucrose, pyruvate and glycerol as carbon...... sources. Growth on glucose produced acetate, H-2 and carbon dioxide. Maximal H-2 production rate on glucose was 1.1 mmol l(-1) h(-1) with a maximum H-2 yield of 1.9 mole H-2 per mole glucose. 16S ribosomal DNA clone library analyses showed that the culture members were phylogenetically affiliated...

Site-specific management of miscanthus genotypes for combustion and anaerobic digestion

NARCIS (Netherlands)

Kiesel, Andreas; Nunn, Christopher; Iqbal, Yasir; Weijde, Van der Tim; Wagner, Moritz; Özgüven, Mensure; Tarakanov, Ivan; Kalinina, Olena; Trindade, Luisa M.; Clifton-Brown, John; Lewandowski, Iris

2017-01-01

In Europe, the perennial C4 grass miscanthus is currently mainly cultivated for energy generation via combustion. In recent years, anaerobic digestion has been identified as a promising alternative utilization pathway. Anaerobic digestion produces a higher-value intermediate (biogas), which can be

Efficient Anaerobic Digestion of Microalgae Biomass: Proteins as a Key Macromolecule.

Science.gov (United States)

Magdalena, Jose Antonio; Ballesteros, Mercedes; González-Fernandez, Cristina

2018-05-06

Biogas generation is the least complex technology to transform microalgae biomass into bioenergy. Since hydrolysis has been pointed out as the rate limiting stage of anaerobic digestion, the main challenge for an efficient biogas production is the optimization of cell wall disruption/hydrolysis. Among all tested pretreatments, enzymatic treatments were demonstrated not only very effective in disruption/hydrolysis but they also revealed the impact of microalgae macromolecular composition in the anaerobic process. Although carbohydrates have been traditionally recognized as the polymers responsible for the low microalgae digestibility, protease addition resulted in the highest organic matter solubilization and the highest methane production. However, protein solubilization during the pretreatment can result in anaerobic digestion inhibition due to the release of large amounts of ammonium nitrogen. The possible solutions to overcome these negative effects include the reduction of protein biomass levels by culturing the microalgae in low nitrogen media and the use of ammonia tolerant anaerobic inocula. Overall, this review is intended to evidence the relevance of microalgae proteins in different stages of anaerobic digestion, namely hydrolysis and methanogenesis.

Stimulation of the anaerobic digestion of the dry organic fraction of municipal solid waste (OFMSW) with carbon-based conductive materials.

Science.gov (United States)

Dang, Yan; Sun, Dezhi; Woodard, Trevor L; Wang, Li-Ying; Nevin, Kelly P; Holmes, Dawn E

2017-08-01

Growth of bacterial and archaeal species capable of interspecies electron exchange was stimulated by addition of conductive materials (carbon cloth or granular activated carbon (GAC)) to anaerobic digesters treating dog food (a substitute for the dry-organic fraction of municipal solid waste (OFMSW)). Methane production (772-1428mmol vs carbon cloth than controls. OFMSW degradation was also significantly accelerated and VFA concentrations were substantially lower in reactors amended with conductive materials. These results suggest that both conductive materials (carbon cloth and GAC) can promote conversion of OFMSW to methane even in the presence of extremely high VFA concentrations (∼500mM). Copyright © 2017 Elsevier Ltd. All rights reserved.

A new multiple-stage electrocoagulation process on anaerobic digestion effluent to simultaneously reclaim water and clean up biogas.

Science.gov (United States)

Liu, Zhiguo; Stromberg, David; Liu, Xuming; Liao, Wei; Liu, Yan

2015-03-21

A new multiple-stage treatment process was developed via integrating electrocoagulation with biogas pumping to simultaneously reclaim anaerobic digestion effluent and clean up biogas. The 1st stage of electrocoagulation treatment under the preferred reaction condition led to removal efficiencies of 30%, 81%, 37% and >99.9% for total solids, chemical oxygen demand, total nitrogen and total phosphorus, respectively. Raw biogas was then used as a reactant and pumped into the effluent to simultaneously neutralize pH of the effluent and remove H2S in the biogas. The 2nd stage of electrocoagulation treatment on the neutralized effluent showed that under the selected reaction condition, additional 60% and 10% of turbidity and chemical oxygen demand were further removed. The study concluded a dual-purpose approach for the first time to synergistically combine biogas purification and water reclamation for anaerobic digestion system, which well addresses the downstream challenges of anaerobic digestion technology. Copyright © 2014 Elsevier B.V. All rights reserved.

Potential of brown algae for sustainable electricity production through anaerobic digestion

International Nuclear Information System (INIS)

Fasahati, Peyman; Saffron, Christopher M.; Woo, Hee Chul; Liu, J. Jay

2017-01-01

Highlights: • Electricity production through anaerobic digestion of brown algae was assessed. • Breakeven electricity selling price of 18.81 ¢/kWh was calculated. • AD unit has highest energy consumption of 14% of generated electricity. • Seaweed cost has largest cost contribution of 11.95 ¢/kWh to the calculated BESP. • Impact of economic and process parameters on BESP was assessed. - Abstract: This paper assesses the economics of heat and power production from the anaerobic digestion (AD) of brown algae (Laminaria japonica) at a plant scale of 400,000 dry tons/year. The conversion process was simulated in Aspen Plus v.8.6 to obtain rigorous heat and material balance for energy assessments and the development of a techno-economic model. The breakeven electricity selling price (BESP) was found to be 18.81 ¢/kWh assuming 30 years of plant life and a 10% internal rate of return. The results show that the AD unit has the highest energy demand in the entire process and consumes approximately 14% of all electricity produced. In addition, the seaweed cost of 11.95 ¢/kWh is the largest cost component that contributes to the calculated BESP, which means that a reduction in the cost of seaweed cultivation can significantly decrease the electricity production cost. A sensitivity analysis was performed on the economic and process parameters in order to assess the impact of possible variations and uncertainties in these parameters. Results showed that solids loading, anaerobic digestion yield, and time, respectively, have the highest impact on BESP.

Effect of Cambi Thermal Hydrolysis Process-Anaerobic digestion treatment on concentrations on phthalate plasticisers in wastewater sludge

Science.gov (United States)

The impact of the recently implemented Cambi Thermal Hydrolysis Process™-Anaerobic Digestion (TH-AD) solids treatment method on concentrations of 4 phthalate plasticisers in wastewater sludge samples was explored in this study. Samples were analysed for diisononyl phthalate (DiNP), diisodecyl phthal...

Biochar-mediated reductions in greenhouse gas emissions from soil amended with anaerobic digestates

International Nuclear Information System (INIS)

Martin, Sarah L.; Clarke, Michèle L.; Othman, Mukhrizah; Ramsden, Stephen J.; West, Helen M.

2015-01-01

This investigation examines nitrous oxide (N 2 O) fluxes from soil with simultaneous amendments of anaerobic digestates and biochar. The main source of anthropogenic emissions of N 2 O is agriculture and in particular, manure and slurry application to fields. Anaerobic digestates are increasingly used as a fertiliser and interest is growing in their potential as sources of N 2 O via nitrification and denitrification. Biochar is a stable product of pyrolysis and may affect soil properties such as cation exchange capacity and water holding capacity. Whilst work has been conducted on the effects of biochar amendment on N 2 O emissions in soils fertilised with mineral fertilisers and raw animal manures, little work to date has focused on the effects of biochar on nitrogen transformations within soil amended with anaerobic digestates. The aim of the current investigation was to quantify the effects of biochar application on ammonification, nitrification and N 2 O fluxes within soil amended with three anaerobic digestates derived from different feedstocks. A factorial experiment was undertaken in which a sandy loam soil (Dunnington Heath series) was either left untreated, or amended with three different anaerobic digestates and one of three biochar treatments; 0%, 1% or 3%. Nitrous oxide emissions were greatest from soil amended with anaerobic digestate originating from a maize feedstock. Biochar amendment reduced N 2 O emissions from all treatments, with the greatest effect observed in treatments with maximum emissions. The degree of N 2 O production and efficacy of biochar amelioration of gas emissions is discussed in context of soil microbial biomass and soil available carbon. - Highlights: • Nitrous oxide was emitted from anaerobic digestates applied to soil. • Simultaneous amendment of soil with biochar and anaerobic digestate reduced N 2 O emissions. • Soil nitrate accumulation occurred but was digestate dependent

Leaching characteristics of poultry litter in first phase of multistage anaerobic digestion

Directory of Open Access Journals (Sweden)

Surya P Sunkavalli

2014-05-01

Full Text Available Poultry litter is highly biodegradable in nature. Therefore, it could be subjected to biomethanation to produce valuable biogas and bio-manure as byproducts. Some studies have been conducted along these lines in India by utilizing the poultry litter as a substrate in batch type dung digesters of KVIC and DENABANDHU models. However, these reactors have the drawbacks of high residence time (30 – 35 days, scum formation problems etc. Moreover, these batch type plants are not suitable for the treatment of large quantities of solid waste. Multistage anaerobic digestion has the potential to overcome some of the aforesaid issues. Anaerobic leaching experiments were conducted at different total solids concentration and pH using poultry litter in order to evaluate the leachate quality for a period of 7 days. The increase in Total solids (TS % from 15 to 20% show inverse effect on VFA and Alkalinity. The change in pH from 8.5 to 5.5 didn’t show much impact on VFA but there is a small impact on alkalinity. It was also observed that the leaching of the organic matter in the solid to the liquid phase is very fast and it is taking place approximately in three to four days and subsequently leachate getting saturated. Therefore, reactor set up was made in the last phase to regularly remove the water from the reactor so that higher driving force is available for leaching. The study resulted in leaching of maximum organic content in the solid to liquid within three days. DOI: http://dx.doi.org/10.3126/ije.v3i2.10516 International Journal of the Environment Vol.3(2 2014: 76-82

Simulation of anaerobic digestion processes using stochastic algorithm.

Science.gov (United States)

Palanichamy, Jegathambal; Palani, Sundarambal

2014-01-01

The Anaerobic Digestion (AD) processes involve numerous complex biological and chemical reactions occurring simultaneously. Appropriate and efficient models are to be developed for simulation of anaerobic digestion systems. Although several models have been developed, mostly they suffer from lack of knowledge on constants, complexity and weak generalization. The basis of the deterministic approach for modelling the physico and bio-chemical reactions occurring in the AD system is the law of mass action, which gives the simple relationship between the reaction rates and the species concentrations. The assumptions made in the deterministic models are not hold true for the reactions involving chemical species of low concentration. The stochastic behaviour of the physicochemical processes can be modeled at mesoscopic level by application of the stochastic algorithms. In this paper a stochastic algorithm (Gillespie Tau Leap Method) developed in MATLAB was applied to predict the concentration of glucose, acids and methane formation at different time intervals. By this the performance of the digester system can be controlled. The processes given by ADM1 (Anaerobic Digestion Model 1) were taken for verification of the model. The proposed model was verified by comparing the results of Gillespie's algorithms with the deterministic solution for conversion of glucose into methane through degraders. At higher value of 'τ' (timestep), the computational time required for reaching the steady state is more since the number of chosen reactions is less. When the simulation time step is reduced, the results are similar to ODE solver. It was concluded that the stochastic algorithm is a suitable approach for the simulation of complex anaerobic digestion processes. The accuracy of the results depends on the optimum selection of tau value.

Effect of ultrasonic pretreatment on anaerobic digestion and its sludge dewaterability.

Science.gov (United States)

Xu, Huacheng; He, Pinjing; Yu, Guanghui; Shao, Liming

2011-01-01

To investigate the effect of ultrasonic pretreatment on anaerobic digestion and sludge dewaterability and further to probe into the influencing factors on sludge dewaterability, sludge flocs were stratified into four fractions: (1) slime; (2) loosely bound extracellular polymeric substances (LB-EPS); (3) tightly bound EPS (TB-EPS); and (4) EPS-free pellets. The results showed that ultrasonic pretreatment increased the anaerobic digestion efficiency by 7%-8%. Anaerobic digestion without ultrasonic pretreatment deteriorated the sludge dewaterability, with the capillary suction time (CST) increased from 1.42 to 47.3 (sec x L)/g-TSS. The application of ultrasonic pretreatment firstly deteriorated the sludge dewaterability (normalized CST increased to 44.4 (sec x L)/g-TSS), while subsequent anaerobic digestion offset this effect and ultimately decreased the normalized CST to 23.2 (sec x L)/g-TSS. The dewaterability of unsonicated sludge correlated with protein (p = 0.003) and polysaccharide (p = 0.004) concentrations in the slime fraction, while that of sonicated sludge correlated with protein concentrations in the slime and LB-EPS fractions (p anarobic digestion.

Anaerobic digestion of spent mushroom substrate under thermophilic conditions: performance and microbial community analysis.

Science.gov (United States)

Xiao, Zheng; Lin, Manhong; Fan, Jinlin; Chen, Yixuan; Zhao, Chao; Liu, Bin

2018-01-01

Spent mushroom substrate (SMS) is the residue of edible mushroom production occurring in huge amounts. The SMS residue can be digested for biogas production in the mesophilic anaerobic digestion. In the present study, performance of batch thermophilic anaerobic digestion (TAD) of SMS was investigated as well as the interconnected microbial population structure changes. The analyzed batch TAD process lasted for 12 days with the cumulative methane yields of 177.69 mL/g volatile solid (VS). Hydrolytic activities of soluble sugar, crude protein, and crude fat in SMS were conducted mainly in the initial phase, accompanied by the excessive accumulation of volatile fatty acids and low methane yield. Biogas production increased dramatically from days 4 to 6. The degradation rates of cellulose and hemicellulose were 47.53 and 55.08%, respectively. The high-throughput sequencing of 16S rRNA gene amplicons revealed that Proteobacteria (56.7%-62.8%) was the dominant phylum in different fermentative stages, which was highly specific compared with other anaerobic processes of lignocellulosic materials reported in the literature. Crenarchaeota was abundant in the archaea. The most dominant genera of archaea were retrieved as Methanothermobacter and Methanobacterium, but the latter decreased sharply with time. This study shows that TAD is a feasible method to handle the waste SMS.

Dry anaerobic digestion of lignocellulosic and protein residues

Directory of Open Access Journals (Sweden)

Maryam M Kabir

2015-12-01

Full Text Available Utilisation of wheat straw and wool textile waste in dry anaerobic digestion (AD process was investigated. Dry-AD of the individual substrates as well as co-digestion of those were evaluated using different total solid (TS contents ranging between 6 to 30%. Additionally, the effects of the addition of nutrients and cellulose- or protein-degrading enzymes on the performance of the AD process were also investigated. Dry-AD of the wheat straw resulted in methane yields of 0.081 – 0.200 Nm3CH4/kgVS with the lowest and highest values obtained at 30 and 21% TS, respectively. The addition of the cellulolytic enzymes could significantly increase the yield in the reactor containing 13% TS (0.231 Nm3CH4/kg VS. Likewise, degradation of wool textile waste was enhanced significantly at TS of 13% with the addition of the protein-degrading enzyme (0.131 Nm3CH4/kg VS. Furthermore, the co-digestion of these two substrates showed higher methane yields compared with the methane potentials calculated for the individual fractions at all the investigated TS contents due to synergetic effects and better nutritional balance.

Continuous anaerobic digestion of swine manure: ADM1-based modelling and effect of addition of swine manure fibers pretreated with aqueous ammonia soaking

International Nuclear Information System (INIS)

Jurado, E.; Antonopoulou, G.; Lyberatos, G.; Gavala, H.N.; Skiadas, I.V.

2016-01-01

Highlights: • Aqueous ammonia soaking (AAS) effect on methane yield: verification in continuously fed digesters. • AAS resulted in 98% increase of the methane yield of swine manure fibers in continuously fed digesters. • ADM1 was successfully adapted to simulating anaerobic digestion of swine manure. • Modification of hydrolysis kinetics was necessary for an adequate simulation of the digestion of AAS-treated fibers. - Abstract: Anaerobic digestion of manure fibers presents challenges due to their low biodegradability. Aqueous ammonia soaking (AAS) has been tested as a simple method to disrupt the lignocellulose and increase the methane yield of manure fibers. In the present study, mesophilic anaerobic digestion of AAS pretreated manure fibers was performed in CSTR-type digesters, fed with swine manure and/or a mixture of swine manure and AAS pretreated manure fibers (at a total solids based ratio of 0.52 manure per 0.48 fibers). Two different simulations were performed. In the first place, the Anaerobic Digestion Model 1 (ADM1) was fitted to a manure-fed, CSTR-type digester and validated by simulating the performance of a second reactor digesting manure. It was shown that disintegration and hydrolysis of the solid matter of manure was such a slow process that the organic particulate matter did not significantly contribute to the methane production. In the second place, ADM1 was used to describe biogas production from the codigestion of manure and AAS pretreated manure fibers. The model predictions regarding biogas production and methane content were in good agreement with the experimental data. It was shown that, AAS treatment significantly increased the disintegration and hydrolysis rate of the carbohydrate compounds of the fibers. The effect of the addition of AAS treated fibers on the kinetics of the conversion of other key compounds such as volatile fatty acids was negligible.

Speciation modeling of ammonia and other major solutes in anaerobic digesters

Science.gov (United States)

Anaerobic digestion of high-nitrogen wastes can be inhibited by high concentrations of un-ionized ammonia, NH**3 (aq). Understanding the toxicity of NH**3 (aq) to anaerobic digestion requires an understanding of the mechanisms controlling its concentration. Previous work on ammonia toxicity in an...

Inactivation of dairy manure-borne pathogens by anaerobic digestion

Science.gov (United States)

Background: Anaerobic digestion of animal manure has the potential to inactivate enteric pathogens, thereby reducing exposures to livestock and humans when the products of digestion are disposed by land-spreading or irrigation or returned to livestock uses such as bedding. Data on digester effectiv...

Energetic and biochemical valorization of cork boiling wastewater by anaerobic digestion.

Science.gov (United States)

Marques, Isabel Paula; Gil, Luís; La Cara, Francesco

2014-01-01

In addition to energy benefits, anaerobic digestion offers other interesting advantages. The cork industry is of great environmental, economic and social significance in the western Mediterranean region, with Portugal being the world-leading producer and exporter. Cork boiling wastewater (CBW) is a toxic and recalcitrant organic effluent produced by this sector, which constitutes a serious environmental hazard. However, there is no documented research on anaerobic treatment/valorization performed with this effluent. The work presented here was developed with the aim to use the anaerobic digestion process to convert the CBW polluting organic load into an energy carrier gas and valuable molecules for industry. No lag phases were observed and a methane yield of 0.126 to 0.142 m(3) kg(-1) chemical oxygen demand (COD)added was registered in the mesophilic consortium experiments carried out in batch flasks at 37 ± 1°C. Anaerobic digestion can be advantageously connected to ultrafiltration or electrochemical processes, due to the following: 1) reduction of ellagic acid content and consequent decrease of CBW viscosity; and 2) increase in conductivity after the anaerobic process, avoiding the electrolyte application of the electrochemical process. The improvement of several CBW biochemical features shows that anaerobic digestion may provide additionally useful molecules. The rise in concentration of some of these compounds, belonging to the benzoic acid family (gallic, protocatechuic, vanillic and syringic acids), is responsible for the increase of antiradical activity of the phenolic fraction. Additionally, some enzymatic activity was also observed and while the laccase activity increased in the digested effluent by anaerobiosis, xylanase was formed in the process. The multidisciplinary approach adopted allowed the valorization of CBW in terms of energy and valuable biomolecules. By exploiting the anaerobic digestion process potential, a novel methodology to toxic

[Anaerobic co-digestion of corn stalk and vermicompost].

Science.gov (United States)

Chen, Guang-yin; Zheng, Zheng; Zou, Xing-xing; Fang, Cai-xia; Luo, Yan

2010-02-01

The characteristics of corn stalk digested alone at different total solid (TS) loading rates and co-digestion of various proportions of corn stalk and vermicompost were investigated by batch model at 35 degrees C +/- 1 degrees C. The organic loading rates (OLRs) studied were in the range of 1.2%-6.0% TS and increasing proportions of vermicompost from 20% to 80% TS. A maximum methane yield of corn stalk digested alone was 217.60 mL/g obtained at the TS loading rate of 4.8%. However, when the TS loading rate was 6.0%, the anaerobic system was acidified and the lowest pH value was 5.10 obtained on day 4 and the biogas productivity decreased. Furthermore, co-digestion of vermicompost and corn stalk in varying proportions were investigated at constant of 6.0% TS. Co-digestion with vermicompost improved the biodegradability of corn stalk and the methane yield was improved by 4.42%-58.61%, and led to higher pH values, higher volatile fatty acids (VFAs) concentration and lower alkalinity content compared with corn stalk digested alone. The maximum biogas yield and methane yield of 410.30 mL/g and 259. 35 mL/g were obtained for 40% vermicompost and 60% corn stalk respectively. Compared with corn stalk digested alone, co-digested with vermicompost didn' t affect methane content and the fermentation type, but promoted the destruction of crystalline of cellulose and the highest destruction rate was 29.36% for 40% vermicompost and 60% corn stalk. Therefore, adding vermicompost was beneficial for the decomposition and increasing the biotransformation rate of corn stalk.

Nitrogen availability and indirect measurements of greenhouse gas emissions from aerobic and anaerobic biowaste digestates applied to agricultural soils

International Nuclear Information System (INIS)

Rigby, H.; Smith, S.R.

2013-01-01

Highlights: • Nitrogen release in digestate-amended soil depends on the digestate type. • Overall N release is modulated by digestate mineral and mineralisable N contents. • Microbial immobilisation does not influence overall release of digestate N in soil. • Digestate physical properties and soil type interact to affect overall N recovery. • High labile C inputs in digestate may promote denitrification in fine-textured soil. - Abstract: Recycling biowaste digestates on agricultural land diverts biodegradable waste from landfill disposal and represents a sustainable source of nutrients and organic matter (OM) to improve soil for crop production. However, the dynamics of nitrogen (N) release from these organic N sources must be determined to optimise their fertiliser value and management. This laboratory incubation experiment examined the effects of digestate type (aerobic and anaerobic), waste type (industrial, agricultural and municipal solid waste or sewage sludge) and soil type (sandy loam, sandy silt loam and silty clay) on N availability in digestate-amended soils and also quantified the extent and significance of the immobilisation of N within the soil microbial biomass, as a possible regulatory mechanism of N release. The digestate types examined included: dewatered, anaerobically digested biosolids (DMAD); dewatered, anaerobic mesophilic digestate from the organic fraction of municipal solid waste (DMADMSW); liquid, anaerobic co-digestate of food and animal slurry (LcoMAD) and liquid, thermophilic aerobic digestate of food waste (LTAD). Ammonium chloride (NH 4 Cl) was included as a reference treatment for mineral N. After 48 days, the final, maximum net recoveries of mineral N relative to the total N (TN) addition in the different digestates and unamended control treatments were in the decreasing order: LcoMAD, 68%; LTAD, 37%, DMAD, 20%; and DMADMSW, 11%. A transient increase in microbial biomass N (MBN) was observed with LTAD application

Nitrogen availability and indirect measurements of greenhouse gas emissions from aerobic and anaerobic biowaste digestates applied to agricultural soils

Energy Technology Data Exchange (ETDEWEB)

Rigby, H.; Smith, S.R., E-mail: s.r.smith@imperial.ac.uk

2013-12-15

Highlights: • Nitrogen release in digestate-amended soil depends on the digestate type. • Overall N release is modulated by digestate mineral and mineralisable N contents. • Microbial immobilisation does not influence overall release of digestate N in soil. • Digestate physical properties and soil type interact to affect overall N recovery. • High labile C inputs in digestate may promote denitrification in fine-textured soil. - Abstract: Recycling biowaste digestates on agricultural land diverts biodegradable waste from landfill disposal and represents a sustainable source of nutrients and organic matter (OM) to improve soil for crop production. However, the dynamics of nitrogen (N) release from these organic N sources must be determined to optimise their fertiliser value and management. This laboratory incubation experiment examined the effects of digestate type (aerobic and anaerobic), waste type (industrial, agricultural and municipal solid waste or sewage sludge) and soil type (sandy loam, sandy silt loam and silty clay) on N availability in digestate-amended soils and also quantified the extent and significance of the immobilisation of N within the soil microbial biomass, as a possible regulatory mechanism of N release. The digestate types examined included: dewatered, anaerobically digested biosolids (DMAD); dewatered, anaerobic mesophilic digestate from the organic fraction of municipal solid waste (DMADMSW); liquid, anaerobic co-digestate of food and animal slurry (LcoMAD) and liquid, thermophilic aerobic digestate of food waste (LTAD). Ammonium chloride (NH{sub 4}Cl) was included as a reference treatment for mineral N. After 48 days, the final, maximum net recoveries of mineral N relative to the total N (TN) addition in the different digestates and unamended control treatments were in the decreasing order: LcoMAD, 68%; LTAD, 37%, DMAD, 20%; and DMADMSW, 11%. A transient increase in microbial biomass N (MBN) was observed with LTAD application

Performance of thermophilic anaerobic digesters using inoculum mixes with enhanced methanogenic diversity

KAUST Repository

Ghanimeh, Sophia; El-Fadel, Mutasem; Saikaly, Pascal

2017-01-01

Reportedly, various mixes of seeds were quasi-randomly selected to startup anaerobic digesters. In contrast, this study examines the impact of inoculating thermophilic anaerobic digesters with a designed mix of non-acclimated seeds based

A Review of the Anaerobic Digestion of Fruit and Vegetable Waste.

Science.gov (United States)

Ji, Chao; Kong, Chui-Xue; Mei, Zi-Li; Li, Jiang

2017-11-01

Fruit and vegetable waste is an ever-growing global question. Anaerobic digestion techniques have been developed that facilitate turning such waste into possible sources for energy and fertilizer, simultaneously helping to reduce environmental pollution. However, various problems are encountered in applying these techniques. The purpose of this study is to review local and overseas studies, which focus on the use of anaerobic digestion to dispose fruit and vegetable wastes, discuss the acidification problems and solutions in applying anaerobic digestion for fruit and vegetable wastes and investigate the reactor design (comparing single phase with two phase) and the thermal pre-treatment for processing raw wastes. Furthermore, it analyses the dominant microorganisms involved at different stages of digestion and suggests a focus for future studies.

Dynamic real-time substrate feed optimization of anaerobic co-digestion plants

NARCIS (Netherlands)

Gaida, Daniel

2014-01-01

In anaerobic co-digestion plants a mix of organic materials is converted to biogas using the anaerobic digestion process. These organic materials, called substrates, can be crops, sludge, manure, organic wastes and many more. They are fed on a daily basis and significantly affect the biogas

Solar pond for heating anaerobic digesters

International Nuclear Information System (INIS)

Song Kehui; Li Shensheng

1991-10-01

A theoretical analysis and numerical results calculated for solar pond heating anaerobic digesters in Beijing area in China are presented. The effect of temperature rise is evident and rather steady. 3 refs, 1 fig., 1 tab

Household anaerobic digester for bioenergy production in developing countries: opportunities and challenges.

Science.gov (United States)

Surendra, K C; Takara, Devin; Jasinski, Jonas; Khanal, Samir Kumar

2013-01-01

Access to clean and affordable energy is vital for advancing development objectives, particularly in rural areas of developing countries. There are some three billion people in these regions, however, who lack consistent access to energy and rely on traditional solid fuels such as firewood, cattle manure, and crop residues for meeting cooking and heating needs. Excessive use of such highly polluting resources creates serious environmental, social and public health issues. In this context, household digesters (which convert readily available feedstocks such as cattle manure, human excreta, and crop residues into biogas) have the potential to play a significant role in supplying methane as a clean, renewable energy resource for remote geographies. In addition to bioenergy production, the slurry generated from anaerobic digestion is rich in nutrients and can improve the physical, chemical, and biological attributes of soil when applied to agricultural land. This type of approach has the potential to significantly reduce greenhouse gas emissions while simultaneously improving the quality of life. Despite a long history of research and innovation for the development and optimization of household digesters, little is known and has been reported for the application of these systems in decentralized communities. The primary purpose of this paper seeks to review the dearth of literature pertaining to small-scale anaerobic digesters in remote geographies and in regions where much of the world's population reside.

Pretreatment and Anaerobic Co-digestion of Selected PHB and PLA Bioplastics

Directory of Open Access Journals (Sweden)

Nicholas Benn

2018-01-01

Full Text Available Conventional petroleum-derived plastics are recalcitrant to biodegradation and can be problematic as they accumulate in the environment. In contrast, it may be possible to add novel, biodegradable bioplastics to anaerobic digesters at municipal water resource recovery facilities along with primary sludge to produce more biomethane. In this study, thermal and chemical bioplastic pretreatments were first investigated to increase the rate and extent of anaerobic digestion. Subsequently, replicate, bench-scale anaerobic co-digesters fed synthetic primary sludge with and without PHB bioplastic were maintained for over 170 days. Two polyhydroxybutyrate (PHB, one poly(3-hydroxybutyrate-co-4-hydroxybutyrate and one polylactic acid (PLA bioplastic were investigated. Biochemical methane potential (BMP assays were performed using both untreated bioplastic as well as bioplastic pretreated at elevated temperature (35–90°C under alkaline conditions (8anaerobic co-digesters fed synthetic primary sludge with PHB bioplastic resulted in 80–98% conversion of two PHB bioplastics to biomethane and a 5% biomethane production increase at the organic loadings employed (sludge OLR = 3.6 g COD per L of reactor volume per day [g COD/LR-d]; bioplastic OLR = 0.75 g theoretical oxygen demand per L of reactor volume per day [ThOD/LR-d] compared to digesters not fed bioplastics. Anaerobic digestion or co-digestion is a feasible management option for biodegradable plastics.

On the effect of aqueous ammonia soaking pretreatment on batch and continuous anaerobic digestion of digested swine manure fibers

OpenAIRE

Mirtsou Xanthopoulou, Chrysoula; Jurado, Esperanza; Skiadas, Ioannis; Gavala, Hariklia N.

2012-01-01

The continuously increasing demand for renewable energy sources renders anaerobic digestion to one of the most promising technologies for renewable energy production. Due to the animal production intensification, manure is being used as the primary feedstock for most of the biogas plants. Thus, their economical profitable operation relies on increasing the methane yield from manure, and especially of its solid fraction which is not so easily degradable. Aqueous Ammonia Soaking (AAS) has been ...

An automated medium scale prototype for anaerobic co-digestion of olive mill wastewater

Directory of Open Access Journals (Sweden)

B. Bernardi

2017-12-01

Full Text Available Olive oil production constitutes one of the most important agro-industrial business for Mediterranean countries, where 97% of the international production is focused. Such an activity, mainly carried out through three phase olive oil mill plants, generates huge amounts of solid and liquid by-products further than olive oil. Physico-chemical features of these by-products depend on various factors such as soil and climatic conditions, agricultural practices and processing. As currently carried out, the disposal of these by-products may lead to numerous problems taking into account management, economic and particularly environmental aspects. Indeed, olive mill wastewater is not easily biodegradable due to its high chemical and biochemical oxygen demand, its high content in phenolic compounds, high ratio C/N and low pH, leading consequently to soil and water source pollution. Considering, the above-mentioned statements, olive mill waste disposal constitutes nowadays a challenge for oil industry stakeholders. It becomes necessary to look for alternative solutions in order to overcome environmental problems and ensure the sustainability of oil industry. Anaerobic co-digestion of olive mill wastewater with other agro-industrial matrices could be one of these solutions; since it offers the possibility to produce green energy and break down toxicological compounds contained in these wastewater for a better disposal of the digested matrices as soil conditioner. In this contest, this note reports the functioning principle of an automated medium scale plant for anaerobic co-digestion of olive mill wastewater. Keywords: Medium scale prototype, Olive mill wastewater (OMWW, Anaerobic co-digestion (AcoD, Automatic process

Two-stage anaerobic digestion of cheese whey

Energy Technology Data Exchange (ETDEWEB)

Lo, K V; Liao, P H

1986-01-01

A two-stage digestion of cheese whey was studied using two anaerobic rotating biological contact reactors. The second-stage reactor receiving partially treated effluent from the first-stage reactor could be operated at a hydraulic retention time of one day. The results indicated that two-stage digestion is a feasible alternative for treating whey. 6 references.

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)

Enhanced primary treatment of concentrated black water and kitchen residues within DESAR concept using two types of anaerobic digesters.

Science.gov (United States)

Kujawa-Roeleveld, K; Elmitwalli, T; Zeeman, G

2006-01-01

Anaerobic digestion of concentrated domestic wastewater streams--black or brown water, and solid fraction of kitchen waste is considered as a core technology in a source separation based sanitation concept (DESAR--decentralised sanitation and reuse). A simple anaerobic digester can be implemented for an enhanced primary treatment or, in some situations, as a main treatment. Two reactor configurations were extensively studied; accumulation system (AC) and UASB septic tank at 15, 20 and 25 degrees C. Due to long retention times in an AC reactor, far stabilisation of treated medium can be accomplished with methanisation up to 60%. The AC systems are the most suitable to apply when the volume of waste to be treated is minimal and when a direct reuse of a treated medium in agriculture is possible. Digested effluent contains both liquid and solids. In a UASB septic tank, efficient separation of solids and liquid is accomplished. The total COD removal was above 80% at 25 degrees C. The effluent contains COD and nutrients, mainly in a soluble form. The frequency of excess sludge removal is low and sludge is well stabilised due to a long accumulation time.

Development and validation of a simplified titration method for monitoring volatile fatty acids in anaerobic digestion.

Science.gov (United States)

Sun, Hao; Guo, Jianbin; Wu, Shubiao; Liu, Fang; Dong, Renjie

2017-09-01

The volatile fatty acids (VFAs) concentration has been considered as one of the most sensitive process performance indicators in anaerobic digestion (AD) process. However, the accurate determination of VFAs concentration in AD processes normally requires advanced equipment and complex pretreatment procedures. A simplified method with fewer sample pretreatment procedures and improved accuracy is greatly needed, particularly for on-site application. This report outlines improvements to the Nordmann method, one of the most popular titrations used for VFA monitoring. The influence of ion and solid interfering subsystems in titrated samples on results accuracy was discussed. The total solid content in titrated samples was the main factor affecting accuracy in VFA monitoring. Moreover, a high linear correlation was established between the total solids contents and VFA measurement differences between the traditional Nordmann equation and gas chromatography (GC). Accordingly, a simplified titration method was developed and validated using a semi-continuous experiment of chicken manure anaerobic digestion with various organic loading rates. The good fitting of the results obtained by this method in comparison with GC results strongly supported the potential application of this method to VFA monitoring. Copyright © 2017. Published by Elsevier Ltd.

Factors controlling pathogen destruction during anaerobic digestion of biowastes

International Nuclear Information System (INIS)

Smith, S.R.; Lang, N.L.; Cheung, K.H.M.; Spanoudaki, K.

2005-01-01

Anaerobic digestion is the principal method of stabilising biosolids from urban wastewater treatment in the UK, and it also has application for the treatment of other types of biowaste. Increasing awareness of the potential risks to human and animal health from environmental sources of pathogens has focused attention on the efficacy of waste treatment processes at destroying pathogenic microorganisms in biowastes recycled to agricultural land. The degree of disinfection achieved by a particular anaerobic digester is influenced by a variety of interacting operational variables and conditions, which can often deviate from the ideal. Experimental investigations demonstrate that Escherichia coli and Salmonella spp. are not damaged by mesophilic temperatures, whereas rapid inactivation occurs by thermophilic digestion. A hydraulic, biokinetic and thermodynamic model of pathogen inactivation during anaerobic digestion showed that a 2 log 10 reduction in E. coli (the minimum removal required for agricultural use of conventionally treated biosolids) is likely to challenge most conventional mesophilic digesters, unless strict maintenance and management practices are adopted to minimise dead zones and by-pass flow. Efficient mixing and organic matter stabilisation are the main factors controlling the rate of inactivation under mesophilic conditions and not a direct effect of temperature per se on pathogenic organisms

Simulation of the anaerobic digestion process

Energy Technology Data Exchange (ETDEWEB)

Maia, C A.M.

1981-01-01

The dynamic model of anaerobic fermentation includes an inhibition function to relate volatile acid concentration to a specific growth rate for the methane bacteria and also includes the interactions between the liquid, gaseous, and biology phases of the digester.

Low-temperature anaerobic digestion of swine manure in a plug-flow reactor.

Science.gov (United States)

Massé, Daniel I; Gilbert, Yan; Saady, N M C; Liu, Charle

2013-01-01

A low-temperature (25 degrees C) anaerobic eight-compartment (PF01 to PF08) cascade reactor simulating a plug-flow reactor (PFR) treating pig manure was monitored for a year. The bioreactor was fed at an average loading rate of 2.4 +/- 0.2 g of total chemical oxygen demand (TCOD) per litre of reactor per day for a theoretical hydraulic retention time (HRT) of 67 +/- 7 d. An average of 79% of TCOD was removed from pig manure (converted into biogas and in sediments), whereas specific methane yields ranging from 397 to 482 NL CH4 kg(-1) VS (148.6 to 171.4 NL CH4 kg(-1) TCOD) were obtained. After 150 d, fluctuating performances of the process were observed, associated with solids accumulation in the upstream compartments, preventing the complete anaerobic digestion of swine manure in the compartments PF01 to PF04. Low-temperature anaerobic PFR represents an interesting alternative for the treatment of pig manure and recovery of green energy. Further investigations regarding a modified design, with better accumulating solids management, are needed to optimize the performance of this low-temperature PFR treating pig manure.

State-of-the-art of anaerobic digestion technology for industrial wastewater treatment

Energy Technology Data Exchange (ETDEWEB)

Rajeshwari, K.V.; Balakrishnan, M.; Kansal, A.; Kusum Lata; Kishore, V.V.N. [Tata Energy Research Institute, New Delhi (India). Darbari Seth Block

2000-06-01

Anaerobic digestion is the most suitable option for the treatment of high strength organic effluents. The presence of biodegradable components in the effluents coupled with the advantages of anaerobic process over other treatment methods makes it an attractive option. This paper reviews the suitability and the status of development of anaerobic reactors for the digestion of selected organic effluents from sugar and distillery, pulp and paper, slaughterhouse and dairy units. In addition, modifications in the existing reactor designs for improving the efficiency of digestion has also been suggested. (author)

Improving the stability of thermophilic anaerobic digesters treating SS-OFMSW through enrichment with compost and leachate seeds

KAUST Repository

Ghanimeh, Sophia A.

2013-03-01

This paper examines the potential of improving the stability of thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste (SS-OFMSW) by adding leachate and compost during inoculation. For this purpose, two stable thermophilic digesters, A (control) and B (with added leachate and compost), were subjected to a sustained substrate shock by doubling the organic loading rate for one week. Feeding was suspended then gradually resumed to reach the pre-shock loading rate (2. gVS/l/d). Digester A failed, exhibiting excessive increase in acetate and a corresponding decrease in pH and methane generation, and lower COD and solids removal efficiencies. In contrast, digester B was able to restore its functionality with 90% recovery of pre-shock methane generation rate at stable pH, lower hydrogen levels, and reduced VFAs and ammonia accumulation. © 2012 Elsevier Ltd.

Improving the stability of thermophilic anaerobic digesters treating SS-OFMSW through enrichment with compost and leachate seeds

KAUST Repository

Ghanimeh, Sophia A.; El-Fadel, Mutasem E.; Saikaly, Pascal

2013-01-01

This paper examines the potential of improving the stability of thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste (SS-OFMSW) by adding leachate and compost during inoculation. For this purpose, two stable thermophilic digesters, A (control) and B (with added leachate and compost), were subjected to a sustained substrate shock by doubling the organic loading rate for one week. Feeding was suspended then gradually resumed to reach the pre-shock loading rate (2. gVS/l/d). Digester A failed, exhibiting excessive increase in acetate and a corresponding decrease in pH and methane generation, and lower COD and solids removal efficiencies. In contrast, digester B was able to restore its functionality with 90% recovery of pre-shock methane generation rate at stable pH, lower hydrogen levels, and reduced VFAs and ammonia accumulation. © 2012 Elsevier Ltd.

Fuel gas production by anaerobic digestion of kelp

Energy Technology Data Exchange (ETDEWEB)

Troiano, R.A. (Dynatech R/D Co., Cambridge, MA); Wise, D.L.; Augenstein, D.C.; Kispert, R.G.; Cooney, C.L.

1976-12-01

The purpose of the experimental program was to explore the feasibility of the anaerobic digestion of kelp to produce methane. Experiments were carried out with freshly harvested U.S. East Coast kelp, Laminaria saccharina. The use for fuel conversion of the rapidly growing U.S. West Coast kelp, the so-called ''giant kelp,'' Macrocystis pyrifera, has been elsewhere. L. saccharina is similar to M. pyrifera in physical structure as well as chemical composition. Both are brown algae (phaeophyta) of the order Laminariales (kelp). Their principal products of photosynthesis are the sugar alcohol, mannitol, and the polysaccharide, laminarin. The cell walls are composed mostly of algin with some cellulose and fucoidin (a phycocolloid-like algin) and the brown color is due to fucoxanthin pigment. It was anticipated that all these constituents of kelp would be subject to anaerobic digestion. The digester operation, alkali pretreatment of kelp, and a comparison of kelp digestion with other substrates are discussed.

Multivariate monitoring of anaerobic co-digestion

DEFF Research Database (Denmark)

Madsen, Michael; Holm-Nielsen, Jens Bo

Anaerobic digestion processes for production of renewable energy in the form of biogas, and in the future hydrogen, are becoming increasingly important worldwide. Sustainable solutions for renewable energy production systems are given high political priority, amongst other things due to global...

The effect of anaerobic digestion on the survival of salmonella and ...

African Journals Online (AJOL)

The decline in viable number of salmonella and coliform bacteria was investigated in laboratory based anaerobic and aerobic digesters using cow dung. The results indicated that unheated anaerobic digestion had greater reduction in the viable number of salmonella and coliform bacteria 1.05x104 and 1.26 x 104 cells/ml ...

Anaerobic digestion of Chinese cabbage waste silage with swine manure for biogas production: batch and continuous study.

Science.gov (United States)

Kafle, Gopi Krishna; Bhattarai, Sujala; Kim, Sang Hun; Chen, Lide

2014-01-01

The aim of this study was to investigate the potential for anaerobic co-digestion of Chinese cabbage waste silage (CCWS) with swine manure (SM). Batch and continuous experiments were carried out under mesophilic anaerobic conditions (36-38°C). The batch test evaluated the effect of CCWS co-digestion with SM (SM: CCWS=100:0; 25:75; 33:67; 0:100, % volatile solids (VS) basis). The continuous test evaluated the performance of a single stage completely stirred tank reactor with SM alone and with a mixture of SM and CCWS. Batch test results showed no significant difference in biogas yield up to 25-33% of CCWS; however, biogas yield was significantly decreased when CCWS contents in feed increased to 67% and 100%. When testing continuous digestion, the biogas yield at organic loading rate (OLR) of 2.0 g VSL⁻¹ d⁻¹ increased by 17% with a mixture of SM and CCWS (SM:CCWS=75:25) (423 mL g⁻¹ VS) than with SM alone (361 mL g⁻¹ VS). The continuous anaerobic digestion process (biogas production, pH, total volatile fatty acids (TVFA) and TVFA/total alkalinity ratios) was stable when co-digesting SM and CCWS (75:25) at OLR of 2.0 g VSL⁻¹ d⁻¹ and hydraulic retention time of 20 days under mesophilic conditions.

Combining protein extraction and anaerobic digestion to produce feed, fuel and fertilizer from green biomass – An organic biorefinery concept

DEFF Research Database (Denmark)

Fernandez, Maria Santamaria; Salces, Beatriz Molinuevo; Lübeck, Mette

Organically grown green biomass (red clover, clover grass) was investigated as a resource for organic feed and organic fertilizer by combination of proteins extraction and anaerobic digestion of the residues. Extraction of proteins from both crops revealed very favourable amino acid composition...... for the use as animal feed. The residual 90% of organic matter, leaving the separation as solid press cake and brown juice was subjected to anaerobic digestion to produce biogas and fertilizer. Methane yields of 220-310 and 430-540 ml CH4/g VS were obtained for press cake and brown juice, respectively...

Microbiology of anaerobic digestion; Microbiologia da digestao anaerobica

Energy Technology Data Exchange (ETDEWEB)

Novaes, Rosana Filomena Vazoller [CETESB, Sao Paulo, SP (Brazil)

1988-12-31

Considerations was made about the microorganisms involved in the anaerobic digestion of wastes. Are also presented, the main results on this subject obtained, until now, in the studies carried on the group of anaerobic microbiology researchers from the Sanitary Company of Sao Paulo State, Brazil. (author) 23 refs., 8 figs., 3 tabs.

[Enhancement of anaerobic digestion of excess sludge by acid-alkali pretreatment].

Science.gov (United States)

Yuan, Guang-Huan; Zhou, Xing-Qiu; Wu, Jian-Dong

2012-06-01

In order to enhance the efficiency of anaerobic digestion of excess sludge, acid-alkali pretreatment method was studied. Three different pretreatment methods (alkali alone,acid-alkali, alkali-acid) were compared to investigate their impacts on hydrolysis and acidification of activated sludge. In addition, their influences on methane-producing in subsequent anaerobic digestion process were also studied. The results showed that the soluble chemical oxygen demand (SCOD) of alkaline treatment alone was about 16% higher than the combining of acid and alkali treatment, SCOD concentration increased to 5406.1 mg x L(-1) after 8 d pretreatment. After treated by acid (pH 4.0, 4 d) and alkali (pH 10.0, 4 d), the acetic acid production and its content in short-chain fatty acids (SCFAs) were higher than other pretreatment methods. And the acetic acid production (as COD/VSS) could reach 74.4 mg x g(-1), accounting for 60.5% of SCFAs. After acid-alkali pretreatment, the C: N ratio of the sludge mixed liquor was about 25, and the C: P ratio was between 35-40, which was more favorable than C: N and C: P ratio of alkali alone and alkali-acid to subsequent anaerobic digestion. The control experiments showed that, after acid-alkali pretreatment, anaerobic digestion cumulative methane yield (CH4/VSS(in)) reached to 136.1 mL x g(-1) at 15 d, which was about 2.5-, 1.6-, and 1.7-fold of the blank (unpretreated), alkali alone pretreatment and alkali-acid pretreatment, respectively. After acid-alkali pretreatment for 8 d and anaerobic digestion for 15 d, the removal efficiency of VSS was about 60.9%, and the sludge reduction effect was better than other pretreatments. It is obvious that the acid-alkali pretreatment method was more favorable to anaerobic digestion and sludge reduction.

Evaluation and characterization during the anaerobic digestion of high-strength kitchen waste slurry via a pilot-scale anaerobic membrane bioreactor.

Science.gov (United States)

Xiao, Xiaolan; Huang, Zhenxing; Ruan, Wenquan; Yan, Lintao; Miao, Hengfeng; Ren, Hongyan; Zhao, Mingxing

2015-10-01

The anaerobic digestion of high-strength kitchen waste slurry via a pilot-scale anaerobic membrane bioreactor (AnMBR) was investigated at two different operational modes, including no sludge discharge and daily sludge discharge of 20 L. The AnMBR provided excellent and reliable permeate quality with high COD removal efficiencies over 99%. The obvious accumulations of long chain fatty acids (LCFAs) and Ca(2+) were found in the anaerobic digester by precipitation and agglomeration. Though the physicochemical process contributed to attenuating the free LCFAs toxicity on anaerobic digestion, the digestion efficiency was partly influenced for the low bioavailability of those precipitates. Moreover, higher organic loading rate (OLR) of 5.8 kg COD/(m(3) d) and digestion efficiency of 78% were achieved as the AnMBR was stably operated with sludge discharge, where the membrane fouling propensity was also alleviated, indicating the crucial significance of SRT control on the treatment of high-strength kitchen waste slurry via AnMBRs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Anaerobic digestion of cider apple residues

Energy Technology Data Exchange (ETDEWEB)

Contreras Lopez, A. (E.T.S.I.I., U.N.E.D., Madrid (Spain). Dept. Quimica Applicada a la Ingenieria); Lopez Bobo, R. (E.T.S. Ingeneiros Industriales, Asturias (Spain). Dept. de Energia)

1992-12-01

Apple residue from the cider industry is used here for anaerobic fermentation. The effect of retention time and volatile solids concentration on the production of biogas and methane was investigated by using continuously mixed anaerobic fermentors with a working volume of 1 1. The maximum proportions of biogas and methane obtained were 430 1 biogas/kg per day (12 days' retention time and 3% of volatile solids) and 281 1 of methane per day (a retention time of 30 days and 2% of volatile solids), respectively. (author)

A fuzzy logic approach to control anaerobic digestion.

Science.gov (United States)

Domnanovich, A M; Strik, D P; Zani, L; Pfeiffer, B; Karlovits, M; Braun, R; Holubar, P

2003-01-01

One of the goals of the EU-Project AMONCO (Advanced Prediction, Monitoring and Controlling of Anaerobic Digestion Process Behaviour towards Biogas Usage in Fuel Cells) is to create a control tool for the anaerobic digestion process, which predicts the volumetric organic loading rate (Bv) for the next day, to obtain a high biogas quality and production. The biogas should contain a high methane concentration (over 50%) and a low concentration of components toxic for fuel cells, e.g. hydrogen sulphide, siloxanes, ammonia and mercaptanes. For producing data to test the control tool, four 20 l anaerobic Continuously Stirred Tank Reactors (CSTR) are operated. For controlling two systems were investigated: a pure fuzzy logic system and a hybrid-system which contains a fuzzy based reactor condition calculation and a hierachial neural net in a cascade of optimisation algorithms.

Biogas generation potential by anaerobic digestion for sustainable energy development in India

International Nuclear Information System (INIS)

Rao, P. Venkateswara; Baral, Saroj S.; Dey, Ranjan; Mutnuri, Srikanth

2010-01-01

The potential of biogas generation from anaerobic digestion of different waste biomass in India has been studied. Renewable energy from biomass is one of the most efficient and effective options among the various other alternative sources of energy currently available. The anaerobic digestion of biomass requires less capital investment and per unit production cost as compared to other renewable energy sources such as hydro, solar and wind. Further, renewable energy from biomass is available as a domestic resource in the rural areas, which is not subject to world price fluctuations or the supply uncertainties as of imported and conventional fuels. In India, energy demand from various sectors is increased substantially and the energy supply is not in pace with the demand which resulted in a deficit of 11,436 MW which is equivalent to 12.6% of peak demand in 2006. The total installed capacity of bioenergy generation till 2007 from solid biomass and waste to energy is about 1227 MW against a potential of 25,700 MW. The bioenergy potential from municipal solid waste, crop residue and agricultural waste, wastewater sludge, animal manure, industrial waste which includes distilleries, dairy plants, pulp and paper, poultry, slaughter houses, sugar industries is estimated. The total potential of biogas from all the above sources excluding wastewater has been estimated to be 40,734 Mm 3 /year. (author)