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1

FCPP application to utilize anaerobic digester gas  

SciTech Connect

Toshiba and a municipal organization of Yokohama city are jointly conducting a program to utilize ADG (Anaerobic Digester Gas) more effectively. ADG which contains about 60% methane is produced by anaerobic digestion of waste water treatment sludge and has been used as an energy source for heating digestion tanks in sewage treatment plants and/or for combustion engine fuel. This program is focused on operating a commercial Phosphoric Acid Fuel Cell (PAFC) power plant on ADG because of its inherently high fuel efficiency and low emissions characteristics. According to the following joint program, we have successfully demonstrated an ADG fueled FCPP The success of this study promises that the ADG fueled FCPP, an environment-friendly power generation system, will be added to the line-up of PC25{trademark}C applications.

Nakayama, Yoshio; Kusama, Nobuyuki; Wada, Katsuya [Toshiba Corp., Tokyo (Japan)

1996-12-31

2

TEST RESULTS FOR FUEL CELL OPERATION ON ANAEROBIC DIGESTER GAS  

EPA Science Inventory

EPA, in conjunction with ONSI Corp., 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 proce...

3

Greenhouse gas emission reductions from domestic anaerobic digesters linked with sustainable sanitation in rural China.  

PubMed

Anaerobic digesters provide clean, renewable energy (biogas) by converting organic waste to methane, and are a key part of China's comprehensive rural energy plan. Here, experimental and modeling results are used to quantify the net greenhouse gas (GHG) reduction from substituting a household anaerobic digester for traditional energy sources in Sichuan, China. Tunable diode laser absorption spectroscopy and radial plume mapping were used to estimate the mass flux of fugitive methane emissions from active digesters. Using household energy budgets, the net improvement in GHG emissions associated with biogas installation was estimated using global warming commitment (GWC) as a consolidated measure of the warming effects of GHG emissions from cooking. In all scenarios biogas households had lower GWC than nonbiogas households, by as much as 54%. Even biogas households with methane leakage exhibited lower GWC than nonbiogas households, by as much as 48%. Based only on the averted GHG emissions over 10 years, the monetary value of a biogas installation was conservatively estimated at US$28.30 ($16.07 ton(-1) CO(2)-eq), which is available to partly offset construction costs. The interaction of biogas installation programs with policies supporting improved stoves, renewable harvesting of biomass, and energy interventions with substantial health cobenefits are discussed. PMID:21348471

Dhingra, Radhika; Christensen, Erick R; Liu, Yang; Zhong, Bo; Wu, Chang-Fu; Yost, Michael G; Remais, Justin V

2011-03-15

4

Greenhouse gas emission reductions from domestic anaerobic digesters linked with sustainable sanitation in rural China  

PubMed Central

Anaerobic digesters provide clean, renewable energy (biogas) by converting organic waste to methane, and are a key part of China's comprehensive rural energy plan. Here, experimental and modeling results are used to quantify the net greenhouse gas (GHG) reduction from substituting a household anaerobic digester for traditional energy sources in Sichuan, China. Tunable diode laser absorption spectroscopy and radial plume mapping were used to estimate the mass flux of fugitive methane emissions from active digesters. Using household energy budgets, the net improvement in GHG emissions associated with biogas installation was estimated using global warming commitment (GWC) as a consolidated measure of the warming effects of GHG emissions from cooking. In all scenarios biogas households had lower GWC than non-biogas households, by as much as 54%. Even biogas households with methane leakage exhibited lower GWC than non-biogas households, by as much as 48%. Based only on the averted GHG emissions over 10 years, the monetary value of a biogas installation was conservatively estimated at US$28.30 ($16.07 ton?1 CO2-eq.), which is available to partly offset construction costs. The interaction of biogas installation programs with policies supporting improved stoves, renewable harvesting of biomass, and energy interventions with substantial health co-benefits, are discussed. PMID:21348471

DHINGRA, RADHIKA; CHRISTENSEN, ERICK R.; LIU, YANG; ZHONG, BO; WU, CHANG-FU; YOST, MICHAEL G.; REMAIS, JUSTIN V.

2013-01-01

5

Perspectives for anaerobic digestion.  

PubMed

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, minimum environmental impact and, as far as possible, on valorization of the waste and final recycling of the end products. One of the main trends of today's waste management policies is to reduce the stream of waste going to landfills and to recycle the organic material and the plant nutrients back 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 as well as future perspectives will be discussed. PMID:12747559

Ahring, Birgitte K

2003-01-01

6

Anaerobic Digestion of Agricultural Solid Residues  

Microsoft Academic Search

Agricultural residues can be converted to methane-rich gas mixture. Anaerobic biomethane production is an effective process for conversion of a broad variety of agricultural residues to methane to substitute natural gas and medium calorific value gases. Methane generating bacteria (methanogens) and other microbes that help digest dying plants in anaerobic conditions. Agricultural solid residues (ASR) represent a potential energy resource

Ayhan Demirbas; Temel Ozturk

2005-01-01

7

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

PubMed

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 (NH4Cl) 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, indicating greater microbial activity in amended soil and reflecting the lower stability of this OM source, compared to the other, anaerobic digestate types, which showed no consistent effects on MBN compared to the control. Thus, the overall net release of digestate N in different soil types was not regulated by N transfer into the soil microbial biomass, but was determined primarily by digestate properties and the capacity of the soil type to process and turnover digestate N. In contrast to the sandy soil types, where nitrate (NO3-) concentrations increased during incubation, there was an absence of NO3- accumulation in the silty clay soil amended with LTAD and DMADMSW. This provided indirect evidence for denitrification activity and the gaseous loss of N, and the associated increased risk of greenhouse gas emissions under certain conditions of labile C supply and/or digestate physical structure in fine-textured soil types. The significance and influence of the interaction between soil type and digestate stability and physical properties on denitrification processes in digestate-amended soils require urgent investigation to ensure management practices are appropriate to minimise greenhouse gas emissions from land applied biowastes. PMID:24035244

Rigby, H; Smith, S R

2013-12-01

8

TECHNICAL ASSESSMENT OF FUEL CELL OPERATION ON ANAEROBIC DIGESTER GAS AT THE YONKERS, NY, WASTEWATER TREATMENT PLANT  

EPA Science Inventory

The paper summarizes the results of a 2-year field test to assess the performance of a specially modified commercial phosphoric acid 200 kW fuel cell power plant to recover energy from anaerobic digester gas (ADG) which has been cleansed of contaminants (sulfur and halide compoun...

9

Anaerobic digestion in rural China  

SciTech Connect

The People`s Republic of China has been promoting underground, individual, anaerobic digesters to process rural organic materials. This strategy has resulted in approximately five million household anaerobic digesters installed in China today. Simple reactors provide energy and fertilizer for Chinese farms and villages. Another benefit includes improved household sanitation. Reactor design has evolved over time. In the standard modern design, effluent is removed from the reactor at the top of the water column, meaning that supernatant is collected rather than sludge. Additionally, no mixing of the system occurs when effluent is removed. In some systems, a vertical cylindrical pull-rod port is added to the base of the effluent port. Effluent is removed by moving the pull-rod - simply a wooden shaft with a metal disk on the bottom - up and down in the port. A bucket can be placed directly under the pull-rod port, simplifying effluent removal, while the movement of the wooden shaft provides some mixing in the reactor. The gas primarily is used for cooking and lighting. A digester can provide approximately 60 percent of a family`s energy needs. Effluent from the reactors is an odorless, dark colored slurry, primarily used as an agricultural fertilizer. 3 figs.

Henderson, J.P. [City of Vancouver (Canada)

1997-01-01

10

Anaerobic digestion of agricultural and other substrates--implications for greenhouse gas emissions.  

PubMed

The greenhouse gas (GHG) emissions, expressed in carbon dioxide equivalents (CO2-eq), of different Austrian biogas systems were analyzed and evaluated using life-cycle assessment (LCA) as part of a national project. Six commercial biogas plants were investigated and the analysis included the complete process chain: viz., the production and collection of substrates, the fermentation of the substrates in the biogas plant, the upgrading of biogas to biomethane (if applicable) and the use of the biogas or biomethane for heat and electricity or as transportation fuel. Furthermore, the LCA included the GHG emissions of construction, operation and dismantling of the major components involved in the process chain, as well as the use of by-products (e.g. fermentation residues used as fertilizers). All of the biogas systems reduced GHG emissions (in CO2-eq) compared with fossil reference systems. The potential for GHG reduction of the individual biogas systems varied between 60% and 100%. Type of feedstock and its reference use, agricultural practices, coverage of storage tanks for fermentation residues, methane leakage at the combined heat and power plant unit and the proportion of energy used as heat were identified as key factors influencing the GHG emissions of anaerobic digestion processes. PMID:23739470

Pucker, J; Jungmeier, G; Siegl, S; Pötsch, E M

2013-06-01

11

Module 12: Biogas/Anaerobic Digesters  

NSDL National Science Digital Library

Eastern Iowa Community College provides this learning module to teach students anaerobic digester basics, the benefits of anaerobic digesters, the anaerobic digester process, and a variety of related topics. Users can download a zip file in which they will find a syllabus, student handouts, a quiz, and 55 slide PowerPoint presentation.

2014-09-02

12

The Anaerobic Digestion of Organic  

E-print Network

occurs naturally in landfills that contain organic waste, such as food scraps, paper products, and yardThe Anaerobic Digestion of Organic Municipal Solid Waste in California, these energy alternatives could provide a number of benefits, including reducing the United States' dependence

Iglesia, Enrique

13

Arnold Schwarzenegger ANAEROBIC DIGESTER  

E-print Network

rights. This report has not been approved or disapproved by the California Energy Commission nor has to reduce odor and use the digested solids as animal bedding. Neither of these factors was a motivator

14

Economic Analysis of Anaerobic Digestion Systems and the Financial Incentives Provided by the New York State Renewable Portfolio Standard (RPS) Customer-Sited Tier (CST) Anaerobic Digester Gas (ADG)-to-Electricity Program  

Microsoft Academic Search

This paper conducts a financial analysis of anaerobic digestion systems on dairy farms and describes a financial model developed for this purpose. The model is flexible and can be utilized with farm-specific data to assist in the evaluation of an anaerobic digestion system. The model is illustrated with two sources of data. The “base” case is the more flexible model

Dolapo K. Enahoro; Brent A. Gloy

2008-01-01

15

Kinetics and Modeling of Anaerobic Digestion Process  

Microsoft Academic Search

Anaerobic digestion modeling started in the early 1970s when the need for design and efficient operation of anaerobic systems\\u000a became evident. At that time not only was the knowledge about the complex process of anaerobic digestion inadequate but also\\u000a there were computational limitations. Thus, the first models were very simple and consisted of a limited number of equations.\\u000a During the

Hariklia Gavala; Irini Angelidaki; Birgitte Ahring

16

Anaerobic digestion of cattail by rumen cultures  

Microsoft Academic Search

The anaerobic digestion of aquatic plants could serve the dual roles for producing renewable energy and reducing waste. In this study, the anaerobic digestion of cattail (Typha latifolia linn), a lignocellulosic aquatic plant, by rumen microorganisms in batch cultures was investigated. At a substrate level of 12.4g\\/l volatile solids (VS) and pH 6.7, maximum VS conversion of 66% was achieved

Zhen-Hu Hu; Han-Qing Yu

2006-01-01

17

Mitigation of greenhouse gas emissions by anaerobic digestion of cattle slurry  

Microsoft Academic Search

Biogas treatment of animal manures is an upcoming technology because it is a way of producing renewable energy (biogas). However, little is known about effects of this management strategy on greenhouse gas (GHG) emissions during fermentation, storage, and field application of the substrates compared to untreated slurries. In this study, we compared cattle slurry and cattle slurry with potato starch

Joachim Clemens; Manfred Trimborn; Peter Weiland; Barbara Amon

2006-01-01

18

Waste-to-wheel analysis of anaerobic-digestion-based renewable natural gas pathways with the GREET model.  

SciTech Connect

In 2009, manure management accounted for 2,356 Gg or 107 billion standard cubic ft of methane (CH{sub 4}) emissions in the United States, equivalent to 0.5% of U.S. natural gas (NG) consumption. Owing to the high global warming potential of methane, capturing and utilizing this methane source could reduce greenhouse gas (GHG) emissions. The extent of that reduction depends on several factors - most notably, how much of this manure-based methane can be captured, how much GHG is produced in the course of converting it to vehicular fuel, and how much GHG was produced by the fossil fuel it might displace. A life-cycle analysis was conducted to quantify these factors and, in so doing, assess the impact of converting methane from animal manure into renewable NG (RNG) and utilizing the gas in vehicles. Several manure-based RNG pathways were characterized in the GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) model, and their fuel-cycle energy use and GHG emissions were compared to petroleum-based pathways as well as to conventional fossil NG pathways. Results show that despite increased total energy use, both fossil fuel use and GHG emissions decline for most RNG pathways as compared with fossil NG and petroleum. However, GHG emissions for RNG pathways are highly dependent on the specifics of the reference case, as well as on the process energy emissions and methane conversion factors assumed for the RNG pathways. The most critical factors are the share of flared controllable CH{sub 4} and the quantity of CH{sub 4} lost during NG extraction in the reference case, the magnitude of N{sub 2}O lost in the anaerobic digestion (AD) process and in AD residue, and the amount of carbon sequestered in AD residue. In many cases, data for these parameters are limited and uncertain. Therefore, more research is needed to gain a better understanding of the range and magnitude of environmental benefits from converting animal manure to RNG via AD.

Han, J.; Mintz, M.; Wang, M. (Energy Systems)

2011-12-14

19

The IWA Anaerobic Digestion Model No 1 (ADM1)  

Microsoft Academic Search

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 physicochemical processes. The biochemical steps include disintegration from homogeneous particulates to carbohydrates, proteins and lipids; extracellular hydrolysis of

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

2002-01-01

20

Use of biochars in anaerobic digestion.  

PubMed

This study investigated the behavior of biochars from pyrolysis (pyrochar) and hydrothermal carbonization (hydrochar) in anaerobic digestion regarding their degradability and their effects on biogas production and ammonia inhibition. A batch fermentation experiment (42°C, 63 days) was conducted in 100mL syringes filled with 30 g inoculum, 2g biochar and four levels of total ammonium nitrogen (TAN). For pyrochar, no clear effect on biogas production was observed, whereas hydrochar increased the methane yield by 32%. This correlates with the hydrochar's larger fraction of anaerobically degradable carbon (10.4% of total carbon, pyrochar: 0.6%). Kinetic and microbiota analyses revealed that pyrochar can prevent mild ammonia inhibition (2.1 g TANk g(-1)). Stronger inhibitions (3.1-6.6 g TAN kg(-1)) were not mitigated, neither by pyrochar nor by hydrochar. Future research should pay attention to biochar-microbe interactions and the effects in continuously-fed anaerobic digesters. PMID:24859210

Mumme, Jan; Srocke, Franziska; Heeg, Kathrin; Werner, Maja

2014-07-01

21

In storage psychrophilic anaerobic digestion of swine slurry  

Microsoft Academic Search

Anaerobic digestion of manures induces deodorization and conserves nitrogen. Livestock producers could transform their long-term (250–300 day) manure storages into psychrophilic anaerobic digesters, thus greatly reducing the investment, operational and technical cost associated with the treatment. But, sufficient inoculation is required and the feeding regime differs from that of a fixed volume digester, as the fed manure volume to digester

J. Abou Nohra; S. Barrington; J. C. Frigon; S. R. Guiot

2003-01-01

22

Pulse power enhancement of the anaerobic digester process  

SciTech Connect

A pilot study of the effects of Pulse Power Processing on an anaerobic digester system was completed at the Decatur Utilities Dry Creek Wastewater Treatment Plant, in Decatur Alabama, in September, 1995. This patented method generates several significant effects when all biosolids material is treated as it enters the anaerobic system. Intense, high peak-power plasma arcs are created, one at each end of the parabolic processing chamber, to produce an amplified synergy of alterations to the digester sludge flowing between them. The millisecond electric discharges generate localized temperatures as high as 30,000 K{degrees}, followed by a rapid cooling of the flowing liquid, which produces acoustic shock waves with pressures approaching 5,000 atmospheres. This destructive force: ruptures many of the cell walls of the bacteria and other single-cell organisms, releasing their vacuole fluids; breaks carbon bonds to form smaller organic compounds; and pulverizes large particle conglomerates, increasing the overall surface area of the solids. These beneficial results serve to boost the nutrient source for the anaerobes in the digester. In conjunction with LTV radiation, the formation of excited chemical radicals (including OH{sup -}), and the changes in ionic charge through alteration of the zeta potential, the bioreactor system is turbocharged to enhance the conversion of volatile biosolids to methane gas, which is the natural respiratory by-product of anaerobic digestion.

Greene, H.W. [Scientific Utilization, Inc., Huntsville, AL (United States)

1996-12-31

23

Anaerobic digestion for household organics  

SciTech Connect

Considerable success in using anaerobic technology for processing household organics is being reported by several recently constructed facilities in Europe. Organic residuals collected separately in a Belgian town are processed to produce biogas and a compost-like material in less than one month. The dry anaerobic conversion process (DRANCO) was developed by Organic Waste Systems (OWS) in the 1980s, with the collaboration of Professor Willy Verstraete at the University of Ghent`s Laboratory of Applied Microbial Ecology. The patented process converts solid and semisolid organic residuals into biogas (for energy recovery) and a stable humus like product. The plant has competing odor sources such as the active landfill and the surrounding farmland - in fact, the smell of livestock manure is quite prevalent in this heavily agricultural area. Addition of the nonrecyclable paper fraction to the feedstock improves the carbon/nitrogen ratio, soaks up moisture, and absorbs odor. The entire Brecht facility does not occupy much space and total material retention time at the site is one month, compared to a number of months for aerobic systems. It also has a low staffing requirement, provides energy self-sufficiency, and the final soil enhancement product meets established quality standards.

Sinclair, R.; Kelleher, M.

1995-04-01

24

A methane production feasibility model for central anaerobic digesters  

NASA Astrophysics Data System (ADS)

A mathematical model was developed for prediction of the practicability of building and operating large centrally located anaerobic digesters for producing methane gas from animal manure. The assumptions were that the manure would be collected from the feedlots and that the product gas would be supplied to an existing pipeline. The model takes account of the farm locations and calculates transportation costs for various numbers of digesters. Digester sizes for each distribution and installation and operating costs are computed. Revenue was then determined on the basis of methane production and fertilizer value recovery. The utility of the model is shown through a study of farms in southwestern Ontario where many small feedlots exist. The results of the study indicate a gas production cost of roughly $0.18/cu m.

Sullivan, J. L.; Peters, N.; Ostrovski, C. M.

1981-01-01

25

Anaerobic digestion of slaughterhouse by-products  

Microsoft Academic Search

Anaerobic digestion of animal by-products was investigated in batch and semi-continuously fed, reactor experiments at 55°C and for some experiments also at 37°C. Separate or mixed by-products from pigs were tested. The methane potential measured by batch assays for meat- and bone flour, fat, blood, hair, meat, ribs, raw waste were: 225, 497, 487, 561, 582, 575, 359, 619dm3kg?1 respectively,

Anette Hejnfelt; Irini Angelidaki

2009-01-01

26

Anaerobic digestion of extruded OFMSW.  

PubMed

Organic fraction of municipal solid waste (OFMSW) was used to feed two pilot plants of 1000 l working in anaerobic conditions. The OFMSW had previously been treated using a system of extrusion which, due to exerted pressure, separates the undesired fractions of waste from organic waste and reduces the organic fraction in a kind of homogeneous jam. Pilot tests were performed in semi-continuous conditions with a stepwise progressive increase of the total solids content (TS) of the input material from 3% TS w/w (1.5 g VS l(-1) d(-1) organic loading rate) to 10% TS w/w (4.3 g VS l(-1) d(-1) organic loading rate) using activated sludge as diluting agent. The average specific biogas production obtained was 600 l kg(-1)VS. When the input TS content was increased to 10% w/w, the biogas average specific production went up to 800 l kg(-1)VS. The methane content in the biogas was always higher than 60% measured by volume. PMID:22074901

Novarino, Daniel; Zanetti, Maria Chiara

2012-01-01

27

The anaerobic digestion of solid organic waste.  

PubMed

The accumulation of solid organic waste is thought to be reaching critical levels in almost all regions of the world. These organic wastes require to be managed in a sustainable way to avoid depletion of natural resources, minimize risk to human health, reduce environmental burdens and maintain an overall balance in the ecosystem. A number of methods are currently applied to the treatment and management of solid organic waste. This review focuses on the process of anaerobic digestion which is considered to be one of the most viable options for recycling the organic fraction of solid waste. This manuscript provides a broad overview of the digestibility and energy production (biogas) yield of a range of substrates and the digester configurations that achieve these yields. The involvement of a diverse array of microorganisms and effects of co-substrates and environmental factors on the efficiency of the process has been comprehensively addressed. The recent literature indicates that anaerobic digestion could be an appealing option for converting raw solid organic wastes into useful products such as biogas and other energy-rich compounds, which may play a critical role in meeting the world's ever-increasing energy requirements in the future. PMID:21530224

Khalid, Azeem; Arshad, Muhammad; Anjum, Muzammil; Mahmood, Tariq; Dawson, Lorna

2011-08-01

28

Contribution of Anaerobic Digesters to Emissions Mitigation and Electricity Generation Under U.S. Climate Policy  

E-print Network

Livestock husbandry in the U.S. significantly contributes to many environmental problems, including the release of methane, a potent greenhouse gas (GHG). Anaerobic digesters (ADs) break down organic wastes using bacteria ...

Zaks, David P. M.

29

Methane enrichment digestion experiments at the anaerobic experimental test unit at Walt Disney World. Final report, March 1989August 1990  

Microsoft Academic Search

The goal of the project was to determine the technical feasibility of utilizing a novel concept in anaerobic digestion, in-situ methane enrichment digestion or MED for producing utility-grade gas from a pilot-scale anaerobic digester. MED tests conducted during this program consistently achieved digester product gas with a methane (CH4) content of greater than 90% (on a dry-, nitrogen-free basis). The

V. J. Srivastava; A. H. Hill

1993-01-01

30

Balancing hygienization and anaerobic digestion of raw sewage sludge.  

PubMed

The anaerobic digestion of raw sewage sludge was evaluated in terms of process efficiency and sludge hygienization. Four different scenarios were analyzed, i.e. mesophilic anaerobic digestion, thermophilic anaerobic digestion and mesophilic anaerobic digestion followed by a 60 °C or by an 80 °C hygienization treatment. Digester performance (organic matter removal, process stability and biogas yield) and the hygienization efficiency (reduction of Escherichia coli, somatic coliphages and F-specific RNA phages) were the main examined factors. Moreover, a preliminary economical feasibility study of each option was carried out throughout an energy balance (heat and electricity). The obtained results showed that both thermophilic anaerobic digestion and mesophilic anaerobic digestion followed by a hygienization step were able to produce an effluent sludge that fulfills the American and the European legislation for land application. However, higher removal efficiencies of indicators were obtained when a hygienization post-treatment was present. Regarding the energy balance, it should be noted that all scenarios have a significant energy surplus. Particularly, positive heat balances will be obtained for the thermophilic anaerobic digestion and for the mesophilic anaerobic digestion followed by 60 °C hygienization post-treatment if an additional fresh-sludge/digested sludge heat exchanger is installed for energy recovery. PMID:23063441

Astals, S; Venegas, C; Peces, M; Jofre, J; Lucena, F; Mata-Alvarez, J

2012-12-01

31

Effects of turbulence modelling on prediction of flow characteristics in a bench-scale anaerobic gas-lift digester.  

PubMed

Flow in a gas-lift digester with a central draft-tube was investigated using computational fluid dynamics (CFD) and different turbulence closure models. The k-? Shear-Stress-Transport (SST), Renormalization-Group (RNG) k-?, Linear Reynolds-Stress-Model (RSM) and Transition-SST models were tested for a gas-lift loop reactor under Newtonian flow conditions validated against published experimental work. The results identify that flow predictions within the reactor (where flow is transitional) are particularly sensitive to the turbulence model implemented; the Transition-SST model was found to be the most robust for capturing mixing behaviour and predicting separation reliably. Therefore, Transition-SST is recommended over k-? models for use in comparable mixing problems. A comparison of results obtained using multiphase Euler-Lagrange and singlephase approaches are presented. The results support the validity of the singlephase modelling assumptions in obtaining reliable predictions of the reactor flow. Solver independence of results was verified by comparing two independent finite-volume solvers (Fluent-13.0sp2 and OpenFOAM-2.0.1). PMID:23624047

Coughtrie, A R; Borman, D J; Sleigh, P A

2013-06-01

32

Development of anaerobic digestion methods for palm oil mill effluent (POME) treatment  

Microsoft Academic Search

Palm oil mill effluent (POME) is a highly polluting wastewater that pollutes the environment if discharged directly due to its high chemical oxygen demand (COD) and biochemical oxygen demand (BOD) concentration. Anaerobic digestion has been widely used for POME treatment with large emphasis placed on capturing the methane gas released as a product of this biodegradation treatment method. The anaerobic

P. E. Poh; M. F. Chong

2009-01-01

33

Anaerobic Digestion II. Sludge Treatment and Disposal Course #166. Instructor's Guide [and] Student Workbook.  

ERIC Educational Resources Information Center

This lesson is the second of a two-part series on anaerobic digestion. Topics discussed include classification of digester by function, roof design, and temperature range, mixing systems, gas system components, operational control basics, and general safety considerations. The lesson includes an instructor's guide and student workbook. The…

Arasmith, E. E.

34

State Of The Science On Cogeneration Of Heat And Power From Anaerobic Digestion Of Municipal Biosolids  

EPA Science Inventory

This presentation will report on work underway to inventory facilities currently utilizing biogas from anaerobic digestion and speak with practitioners to learn: techniques for preparing residuals for digestion, methods to use for cleaning biogas (e.g., of siloxane), and how gas...

35

Tumble-mix anaerobic digestion of dry beef manure  

SciTech Connect

Anaerobic digestion of beef manure at an influent total solids concentration of 26% was demonstrated using an innovative tumble-mix fermenter. At an organic loading rate of 4.7 kg VS m-/sup 3/ d-/sup 1/ and a 23% VS influent concentration, a 54% volatile solids reduction was achieved. The average biogas production was 1.37 m/sup 3/ m-/sup 3/ d-/sup 1/ with a gas quality of 54% CH/sub 4/.

Kottwitz, D.; Schulte, D.D.

1982-12-01

36

Low-temperature anaerobic digestion for wastewater treatment.  

PubMed

Methanogenesis is an important biogeochemical process for the degradation of organic matter within cold environments, and is associated with the release of the potent greenhouse gas, methane. Cold methanogenesis has been harnessed, in engineered systems, as low-temperature anaerobic digestion (LTAD) for wastewater treatment and bioenergy generation. LTAD represents a nascent wastewater treatment biotechnology, which offers an attractive alternative to conventional aerobic and anaerobic processes. Successful, high-rate, LTAD of sewage and industrial wastewaters (e.g. from the brewery, food-processing and pharmaceutical sectors), with concomitant biogas generation, has been demonstrated at laboratory-scale and pilot-scale. A holistic, polyphasic approach, which integrates bioprocess, physiological and molecular biological datasets has been critical to the development of the LTAD concept. PMID:22176749

McKeown, Rory M; Hughes, Dermot; Collins, Gavin; Mahony, Thérèse; O'Flaherty, Vincent

2012-06-01

37

Cellulase production by the anaerobic digestion process  

SciTech Connect

An anaerobic digestion process is described for the production of cellulolytic enzymes using a methanogenic cellulose-enrichment culture. After a heat treatment designed to destroy all but spore-forming bacteria, this culture produced cellulase from a variety of cellulosic materials as well as from cellobiose. The enzyme system contained endo- and exoglucanase, acted on filter paper, and showed cellobiase and xylanase activities. It was stable at 2/sup 0/C under aerobic conditions and showed a pH optimum at 5 and a temperature optimum at 50/sup 0/C. Endoglucanase and filter paper activities were mostly exogenic, whereas cellobiase and xylanase activities were cell associated. The cellulolytic activity produced by this mixed culture was comparable to that of commercially available fungal preparations, and the process could be useful as an alternate source for these enzymes.

Khan, A.W.; van den Berg, L.

1981-01-01

38

Methane production by anaerobic digestion of Bermuda grass  

SciTech Connect

Bermuda grass (Cynodon dactylon) is one of the high-yield warm-season grasses that has been suggested as a promising raw material for conversion to methane. Experimental work performed with laboratory digesters to study the anaerobic digestion of Coastal Bermuda grass harvested in Louisiana and having a C/N ratio of 24 is described. Methane yields of about 1.9 SCF/lb of volatile solids (VS) added were observed under conventional mesophilic high-rate conditions. When supplemental nitrogen additions were made, the methane yields increased. This observation along with the compositional data compiled on the grass used in this work indicated that the nitrogen content of the unsupplemented grass was insufficient to sustain high-rate digestion at the higher yield level. However, as the C/N ratio was reduced by addition of ammonium chloride, the methane yield continually increased up to 3.5 SCF/lb added at the lowest C/N ratio examined (6.3) even after relatively high concentrations of ammonium nitrogen were measured in the effluent. It appears that the added nutrient had a stimulatory effect on methane production above the point where nitrogen was not limiting. Thermophilic digestion with supplemental nitrogen additions afforded methane yields of about 2.7 SCF/lb VS added. Carbon and energy balances were calculated and the relative biodegradabilities of the organics were estimated. It was concluded from this work that Coastal Bermuda grass can be converted to high-methane gas under conventional anaerobic digestion conditions. The performance of the particular lot of grass studied was substantially improved by supplemental nitrogen additions. (Refs. 12).

Klass, D.L.; Ghosh, S.

1981-01-01

39

Parasite ova in anaerobically digested sludge  

SciTech Connect

The Metropolitan Sanitary District of Greater Chicago produces anaerobically digested wastewater sludge from a 14-day continuous-flow process maintained at 35 degrees Celcius. Some of the sludge is ultimately applied to strip-mined lands in Central Illinois (Fulton County) as a soil conditioner and fertilizer. Parasitic nematode ova were isolated from freshly processed samples, as well as from samples collected from storage lagoons, using a system of continuous sucrose solution gradients. The mean number of ova per 100 g of dry sludge was 203 Ascaris spp., 173 Toxocara spp., 48 Toxascaris leonina, and 36 Trichuris spp. An assessment of the viability of these ova was determined by subjecting the ova to conditions favorable for embryonation. Recovered ova were placed in 1.5% formalin and aerated at 22 degrees Celcius for 21 to 28 days. Development of ova isolated from freshly digested sludge occurred in 64% of the Ascaris spp., 53% of the Toxocara, 63% of the Toxascaris leonina, and 20% of the Trichuris spp. Viability was also demonstrated in ova recovered from sludge samples held in storage lagoons for a period of up to 5 years; embryonation occurred in 24% of the Ascaris spp., 10% of the Toxocara spp., 43% of the Toxascaris leonina, and 6% of the Trichuris spp. (Refs. 24).

Arther, R.G.; Fitzgerald, P.R.; Fox, J.C.

1981-08-01

40

Autogenerative high pressure digestion: anaerobic digestion and biogas upgrading in a single step reactor system.  

PubMed

Conventional anaerobic digestion is a widely applied technology to produce biogas from organic wastes and residues. The biogas calorific value depends on the CH, content which generally ranges between 55 and 65%. Biogas upgrading to so-called 'green gas', with natural gas quality, generally proceeds with add-on technologies, applicable only for biogas flows > 100 m3/h. In the concept of autogenerative high pressure digestion (AHPD), methanogenic biomass builds up pressure inside the reactor. Since CO2 has a higher solubility than CH4, it will proportion more to the liquid phase at higher pressures. Therefore, AHPD biogas is characterised by a high CH4 content, reaching equilibrium values between 90 and 95% at a pressure of 3-90 bar. In addition, also H2S and NH3 are theoretically more soluble in the bulk liquid than CO2. Moreover, the water content of the already compressed biogas is calculated to have a dew point <--10 degrees C. Ideally, high-quality biogas can be directly used for electricity and heat generation, or injected in a local natural gas distribution net. In the present study, using sodium acetate as substrate and anaerobic granular sludge as inoculum, batch-fed reactors showed a pressure increase up to 90 bars, the maximum allowable value for our used reactors. However, the specific methanogenic activity (SMA) of the sludge decreased on average by 30% compared to digestion at ambient pressure (1 bar). Other results show no effect of pressure exposure on the SMA assessed under atmospheric conditions. These first results show that the proposed AHPD process is a highly promising technology for anaerobic digestion and biogas upgrading in a single step reactor system. PMID:22097043

Lindeboom, R E F; Fermoso, F G; Weijma, J; Zagt, K; van Lier, J B

2011-01-01

41

Methane enrichment digestion experiments at the anaerobic experimental test unit at Walt Disney World. Final report, March 1989-August 1990  

SciTech Connect

The goal of the project was to determine the technical feasibility of utilizing a novel concept in anaerobic digestion, in-situ methane enrichment digestion or MED for producing utility-grade gas from a pilot-scale anaerobic digester. MED tests conducted during this program consistently achieved digester product gas with a methane (CH4) content of greater than 90% (on a dry-, nitrogen-free basis). The MED concept, because it requires relatively simple equipment and modest energy input, has the potential to simplify gas cleanup requirements and substantially reduce the cost of converting wastes and biomass to pipeline quality gas.

Srivastava, V.J.; Hill, A.H.

1993-06-01

42

40 CFR Table Jj-6 to Subpart Jj of... - Collection Efficiencies of Anaerobic Digesters  

...Efficiencies of Anaerobic Digesters Anaerobic digester type Cover type Methane collection efficiency Covered anaerobic lagoon (biogas capture) Bank to bank, impermeable 0.975 Modular, impermeable 0.70 Complete mix, fixed film, or plug...

2014-07-01

43

40 CFR Table Jj-6 to Subpart Jj of... - Collection Efficiencies of Anaerobic Digesters  

Code of Federal Regulations, 2013 CFR

...Efficiencies of Anaerobic Digesters Anaerobic digester type Cover type Methane collection efficiency Covered anaerobic lagoon (biogas capture) Bank to bank, impermeable 0.975 Modular, impermeable 0.70 Complete mix, fixed film, or plug...

2013-07-01

44

Improving products of anaerobic sludge digestion by microaeration.  

PubMed

Biogas, digested sludge and sludge liquor are the main products of anaerobic sludge digestion. Each of the products is influenced significantly by specific conditions of the digestion process. Therefore, any upgrade of the digestion technology must be considered with regard to quality changes in all products. Microaeration is one of the methods used for the improvement of biogas quality. Recently, microaeration has been proved to be a relatively simple and highly efficient biological method of sulfide removal in the anaerobic digestion of biosolids, but little attention has been paid to comparing the quality of digested sludge and sludge liquor in the anaerobic and microaerobic digestion and that is why this paper primarily deals with this area of research. The results of the long-term monitoring of digested sludge quality and sludge liquor quality in the anaerobic and microaerobic digesters suggest that products of both technologies are comparable. However, there are several parameters in which the 'microaerobic' products have a significantly better quality such as: sulfide (68% lower) and soluble chemical oxygen demand (COD) (33% lower) concentrations in the sludge liquor and the lower foaming potential of the digested sludge. PMID:24569280

Jenicek, P; Celis, C A; Krayzelova, L; Anferova, N; Pokorna, D

2014-01-01

45

Modeling anaerobic digestion of microalgae using ADM1.  

PubMed

The coupling between a microalgal pond and an anaerobic digester is a promising alternative for sustainable energy production by transforming carbon dioxide into methane using solar energy. In this paper, we demonstrate the ability of the original ADM1 model and a modified version (based on Contois kinetics for the hydrolysis steps) to represent microalgae anaerobic digestion. Simulations were compared to experimental data of an anaerobic digester fed with Chlorella vulgaris. The modified ADM1 fits adequately the data for the considered 140 day experiment encompassing a variety of influent load and flow rates. It turns out to be a reliable predictive tool for optimising the coupling of microalgae with anaerobic digestion processes. PMID:21536430

Mairet, Francis; Bernard, Olivier; Ras, Monique; Lardon, Laurent; Steyer, Jean-Philippe

2011-07-01

46

Design of an anaerobic digester in Quebec, Canada  

E-print Network

.In response to the future Quebec, Canada regulations prohibiting landfilling of organic matter by 2020, EBI, a waste management company located near Montreal is considering constructing an anaerobic digester. This thesis ...

Bouaziz, Alexandre N. (Alexandre Nathanel)

2014-01-01

47

INCREASE OF INDICATOR ORGANISMS FOLLOWING ANAEROBIC DIGESTION AND CENTRIFUGE DEWATERING.  

EPA Science Inventory

The Water Environment Research Foundation (WERF) recently published a report titled ?Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges?. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bac...

48

Anaerobic digestion of water hyacinth and sludge  

SciTech Connect

The Institute of Gas Technology (IGT) has been operating an experimental test unit (ETU) at the Walt Disney World (WDW) wastewater treatment plant to demonstrate the conversion of water hyacinth and sludge to methane in a solids concentrating (SOLCON) digester. Results from 2 years to operation have confirmed earlier laboratory observations that this digester achieves higher methane yields and solids conversion than those observed in continuous stirred tank reactors. Methane yields as high as 0.49 m/sup 3/ kg/sup -1/ (7.9 SCF/lb) volatile solids added have been obtained during steady-state operation on a blend of water hyacinth and sludge. 9 refs., 5 figs., 5 tabs.

Biljetina, R.; Srivastava, V.J.; Chynoweth, D.P.; Hayes, T.D.

1986-01-01

49

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

NASA Astrophysics Data System (ADS)

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.

Pike, Brenda

50

Thermal pretreatment of algae for anaerobic digestion.  

PubMed

The objective of this work was to determine the benefit of thermal pretreatment on biogas yield from microalgae-fed anaerobic digester mesocosms. Replicate Nanochloropsis oculata cultures were heated for 4h at 30, 60, and 90°C, as well as at a constant temperature of 90°C for 1, 3.5, and 12h. Net biogas production increased from 0.28L biogas/g volatile solids added (VSa) for the control to 0.39 L biogas/g VSa (p<0.01) when heated at 90°C, but there was no improvement at 30 or 60°C. Increased biogas production correlated with increased soluble chemical oxygen demand (COD). Net biogas production increased as a function of heating time, from 0.32 L biogas/g VSa for the control, to 0.41, 0.43, and 0.44 L biogas/g VSa (p<0.05 for all combinations vs. control) when preheated at 90°C for 1, 3.5, and 12h, respectively. However, despite enhanced biogas production the energy balance is negative for thermal pretreatment. PMID:24189036

Marsolek, Michael D; Kendall, Elizabeth; Thompson, Phillip L; Shuman, Teodora Rutar

2014-01-01

51

Anaerobic digestion of sludge from intensive recirculating aquaculture systems: Review  

Microsoft Academic Search

Intensive recirculating aquaculture systems (RAS) produce high volumes of biosolid waste which is a potential source of pollution if not properly treated. A reduction in sludge-mass would therefore minimize the potential environmental hazard and economic burden stemming from its disposal. Recently, anaerobic digestion was suggested as an alternative to aquaculture sludge digestion and stabilization in RAS. This practice results not

Natella Mirzoyan; Yossi Tal; Amit Gross

2010-01-01

52

Heat and energy requirements in thermophilic anaerobic sludge digestion  

Microsoft Academic Search

The heating requirements of the thermophilic anaerobic digestion process were studied. Biogas production was studied in laboratory experiments at retention times from 1 to 10 days. The data gathered in the experiments was then used to perform a heat and energy analysis. The source of heat was a conventional CHP unit system. The results showed that thermophilic digestion is much

G. D. Zupan?i?; M. Roš

2003-01-01

53

Effect of alkaline pretreatment on anaerobic digestion of solid wastes  

SciTech Connect

The introduction of the anaerobic digestion for the treatment of the organic fraction of municipal solid waste (OFMSW) is currently of special interest. The main difficulty in the treatment of this waste fraction is its biotransformation, due to the complexity of organic material. Therefore, the first step must be its physical, chemical and biological pretreatment for breaking complex molecules into simple monomers, to increase solubilization of organic material and improve the efficiency of the anaerobic treatment in the second step. This paper describes chemical pretreatment based on lime addition (Ca(OH){sub 2}), in order to enhance chemical oxygen demand (COD) solubilization, followed by anaerobic digestion of the OFMSW. Laboratory-scale experiments were carried out in completely mixed reactors, 1 L capacity. Optimal conditions for COD solubilization in the first step of pretreatment were 62.0 mEq Ca(OH){sub 2}/L for 6.0 h. Under these conditions, 11.5% of the COD was solubilized. The anaerobic digestion efficiency of the OFMSW, with and without pretreatment, was evaluated. The highest methane yield under anaerobic digestion of the pretreated waste was 0.15 m{sup 3} CH{sub 4}/kg volatile solids (VS), 172.0% of the control. Under that condition the soluble COD and VS removal were 93.0% and 94.0%, respectively. The results have shown that chemical pretreatment with lime, followed by anaerobic digestion, provides the best results for stabilizing the OFMSW.

Lopez Torres, M. [National Center for Scientific Researcher (CNIC), Environmental Pollution Department (DECA), Ave. 25 y 158, Cubanacan, Playa, Havana City (Cuba)], E-mail: matilde.lopez@cnic.edu.cu; Espinosa Llorens, Ma. del C. [National Center for Scientific Researcher (CNIC), Environmental Pollution Department (DECA), Ave. 25 y 158, Cubanacan, Playa, Havana City (Cuba)

2008-11-15

54

Biogasification of sorghum in a novel anaerobic digester  

SciTech Connect

The Institute of Gas Technology (IGT) conducted pilot-scale anaerobic digestion experiments with ensiled sorghum in a 160 ft/sup 3/ digester at the experimental test unit (ETU) facility at the Walt Disney World Resort Complex in Florida. The study focused on improving bioconversion efficiencies and process stability by employing a novel reactor concept developed at IGT. Steady-state performance data were collected from the ETU as well as from a laboratory-scale conventional stirred tank reactor (CSTR) at loading rates of 0.25 and 0.50 lb organic matter/ft/sup 3/-day at mesophilic and thermophilic temperatures, respectively. This paper will describe the ETU facility, novel digester design and operating techniques, and the results obtained during 12 months of stable and uninterrupted operation of the ETU and the CSTR which showed that methane yields anad rates from the ETU were 20% to 50% higher than those of the CSTR. 10 refs., 7 figs., 5 tabs.

Srivastava, V.J.; Biljetina, R.; Isaacson, H.R.; Hayes, T.D.

1987-01-01

55

Thermochemical liquidization of anaerobically digested and dewatered sludge and anaerobic retreatment  

Microsoft Academic Search

The pretreatment effect of thermochemical liquidization for the anaerobic retreatment of anaerobically digested and dewatered sludge was studied. The digested sludge (dry matter; 15.7%) was thermochemically liquidized at 175°C and 4 MPa with a holding time of 1 h. The liquidized sludge was separated by centrifugation to produce a supernatant of 44.7% (w\\/w) and precipitate of 52.3%. The liquidized sludge

Shigeki Sawayama; Seiichi Inoue; Kenichiro Tsukahara; Tomoko Ogi

1996-01-01

56

Enhanced anaerobic digestion of food waste by thermal and ozonation pretreatment methods.  

PubMed

Treatment of food waste by anaerobic digestion can lead to an energy production coupled to a reduction of the volume and greenhouse gas emissions from this waste type. According to EU Regulation EC1774/2002, food waste should be pasteurized/sterilized before or after anaerobic digestion. With respect to this regulation and also considering the slow kinetics of the anaerobic digestion process, thermal and chemical pretreatments of food waste prior to mesophilic anaerobic digestion were studied. A series of batch experiments to determine the biomethane potential of untreated as well as pretreated food waste was carried out. All tested conditions of both thermal and ozonation pretreatments resulted in an enhanced biomethane production. The kinetics of the anaerobic digestion process were, however, accelerated by thermal pretreatment at lower temperatures (<120 °C) only. The best result of 647.5 ± 10.6 mlCH4/gVS, which is approximately 52% higher as compared to the specific biomethane production of untreated food waste, was obtained with thermal pretreatment at 80 °C for 1.5 h. On the basis of net energy calculations, the enhanced biomethane production could cover the energy requirement of the thermal pretreatment. In contrast, the enhanced biomethane production with ozonation pretreatment is insufficient to supply the required energy for the ozonator. PMID:25169646

Ariunbaatar, Javkhlan; Panico, Antonio; Frunzo, Luigi; Esposito, Giovanni; Lens, Piet N L; Pirozzi, Francesco

2014-12-15

57

Anaerobic Digestion and Combined Heat and Power Study  

SciTech Connect

One of the underlying objectives of this study is to recover the untapped energy in wastewater biomass. Some national statistics worth considering include: (1) 5% of the electrical energy demand in the US is used to treat municipal wastewater; (2) This carbon rich wastewater is an untapped energy resource; (3) Only 10% of wastewater treatment plants (>5mgd) recover energy; (4) Wastewater treatment plants have the potential to produce > 575 MW of energy nationwide; and (5) Wastewater treatment plants have the potential to capture an additional 175 MW of energy from waste Fats, Oils and Grease. The WSSC conducted this study to determine the feasibility of utilizing anaerobic digestion and combined heat and power (AD/CHP) and/or biosolids gasification and drying facilities to produce and utilize renewable digester biogas. Digester gas is considered a renewable energy source and can be used in place of fossil fuels to reduce greenhouse gas emissions. The project focus includes: (1) Converting wastewater Biomass to Electricity; (2) Using innovative technologies to Maximize Energy Recovery; and (3) Enhancing the Environment by reducing nutrient load to waterways (Chesapeake Bay), Sanitary Sewer Overflows (by reducing FOG in sewers) and Greenhouse Gas Emissions. The study consisted of these four tasks: (1) Technology screening and alternative shortlisting, answering the question 'what are the most viable and cost effective technical approaches by which to recover and reuse energy from biosolids while reducing disposal volume?'; (2) Energy recovery and disposal reduction potential verification, answering the question 'how much energy can be recovered from biosolids?'; (3) Economic environmental and community benefit analysis, answering the question 'what are the potential economic, environmental and community benefits/impacts of each approach?'; and (4) Recommend the best plan and develop a concept design.

Frank J. Hartz; Rob Taylor; Grant Davies

2011-12-30

58

Animal digestive strategies versus anaerobic digestion bioprocesses for biogas production from lignocellulosic biomass  

Microsoft Academic Search

Herbivorous mammals and wood-eating insects are fairly effective in the digestion of plant polymers, such as lignocellulosics.\\u000a In order to improve methane production from the lignocellulosic biomass, several kinds of anaerobic digestion processes derived\\u000a from animal models have been devised. However, the rates of biodegradation occurring in the anaerobic bioreactors still remain\\u000a lower than in animal guts. The effectiveness of

Ali Bayané; Serge R. Guiot

2011-01-01

59

Anaerobic digestion of secondary residuals from an anaerobic bioreactor at a brewery to enhance bioenergy generation  

Microsoft Academic Search

Many beer breweries use high-rate anaerobic digestion (AD) systems to treat their soluble high-strength wastewater. Biogas\\u000a from these AD systems is used to offset nonrenewable energy utilization in the brewery. With increasing nonrenewable energy\\u000a costs, interest has mounted to also digest secondary residuals from the high-rate digester effluent, which consists of yeast\\u000a cells, bacteria, methanogens, and small (hemi)cellulosic particles. Mesophilic

Benjamin T. Bocher; Matthew T. Agler; Marcelo L. Garcia; Allen R. Beers; Largus T. Angenent

2008-01-01

60

Biogas production from anaerobic digestion of Spirulina maxima algal biomass  

SciTech Connect

Spirulina maxima algal biomass could be used as the sole nutrient for the production of biogas by anaerobic digestion process. It is relatively simple to adapt the municipal sewage sludge to this new substrate. The adapted sludge is very stable. Under nonoptimal conditions, the methane yield and productivity obtained were 0.26 m/sup 3//(kg VS added day) and 0.26 m/sup 3//(kg VS added day), respectively, with the semicontinuous, daily fed, anaerobic digestion having loading rate of 0.97 kg VS/(m/sup 3/ day), retention time of 33 days and temperature of 30/sup 0/C.

Rejean Samson; Anh LeDuy

1982-08-01

61

Comparative analysis of anaerobically digested wastes flow properties.  

PubMed

The flow curve of anaerobically digested wastes from different origins was determined through rheological measurements. Regardless of their origin, samples can be divided into two families: simple non-Newtonian liquids well modelled by basic power law below 10%DC and viscoelastic liquids with a yield stress, well modelled by a Herschel-Bulkley model above. In all the cases, the rheological behaviour is driven by both the organic content and the volatile fraction (organic content/solid content), indicating that anaerobic digestion tends to smooth the rheological characteristics of organic wastes, whichever their origins. PMID:25052338

Mbaye, S; Dieudé-Fauvel, E; Baudez, J C

2014-11-01

62

Detoxifying CO2 capture reclaimer waste by anaerobic digestion.  

PubMed

The decrease in toxicity of carbon capture reclaimer monoethanolamine (MEA) waste (MEAw) during anaerobic degradation of such waste together with easily degradable organics was investigated. Samples were collected from a bioreactor at steady state with 86 % organic chemical oxygen demand removal at room temperature, which had been running on MEAw for 2 years. The toxicity of the digester effluents were 126, 42 and 10 times lower than that of the MEAw to the tested freshwater trophic groups of Pseudokirchneriella subcapitata, Daphnia magna and embryos of Danio rerio, respectively. The toxicity of the tested taxonomic groups after anaerobic digestion was mainly attributed to the ammonia generated by the degradation of MEAw. PMID:24122630

Wang, Shuai; Hovland, Jon; Brooks, Steven; Bakke, Rune

2014-01-01

63

Animal and industrial waste anaerobic digestion: USA status report  

SciTech Connect

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.

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

1996-01-01

64

Anaerobic digestion and wastewater treatment systems  

Microsoft Academic Search

Upflow Anaerobic Sludge Bed (UASB) wastewater (pre-)treatment systems represent a proven sustainable technology for a wide range of very different industrial effluents, including those containing toxic\\/inhibitory compounds. The process is also feasible for treatment of domestic wastewater with temperatures as low as 14–16° C and likely even lower. Compared to conventional aerobic treatment systems the anaerobic treatment process merely offers

G. Lettinga

1995-01-01

65

Single stage anaerobic digester at Tarleton State University. Final report  

SciTech Connect

The design and operation of the demonstration plant facilities at Tarleton State University to produce methane in a single stage anaerobic digester are described. A combination of manures from hogs and poultry are used as feedstock. Uses for the methane, cost of the digester, and value of the energy produced are discussed. During the 21 months of operation, 310 people have visited the project. (DMC)

Not Available

1980-01-01

66

Assessing solid digestate from anaerobic digestion as feedstock for ethanol production  

Microsoft Academic Search

Ethanol production using solid digestate (AD fiber) from a completely stirred tank reactor (CSTR) anaerobic digester was assessed comparing to an energy crop of switchgrass, and an agricultural residue of corn stover. A complete random design was fulfilled to optimize the reaction conditions of dilute alkali pretreatment. The most effective dilute alkali pretreatment conditions for raw CSTR AD fiber were

Charles Teater; Zhengbo Yue; James MacLellan; Yan Liu; Wei Liao

2011-01-01

67

Experimental digester facility modifications and digester gas upgrading research  

SciTech Connect

The Institute of Gas Technology (IGT) has been participating in an experimental program at the Community Waste Research Facility (CWRF) located at the Walt Disney World Resort Complex, Orlando, Florida. Four institutions have formed a team to provide solutions to community waste treatment and disposal programs. Of primary importance to this research effort is the implementation of low-cost, energy-efficient waste treatment and recovery technologies and the net production of energy (methane) from biomass and waste resources. The production of methane is being studied in a novel, high-rate digester. During 1988, we were responsible for modifying the Experimental Test Unit (ETU) to permit dry solids feeding of refuse-derived fuel (RDF) and for conducting bench-scale experiments to evaluate techniques for efficient removal of carbon dioxide produced during anaerobic digestion.

Srivastava, V.J.; Biljetina, R.; Akin, C.

1989-01-01

68

Comparison between ozone and ultrasound disintegration on sludge anaerobic digestion.  

PubMed

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. PMID:20719427

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

2012-03-01

69

Anaerobic digestion of municipal, industrial, and livestock wastes for energy recovery and disposal  

SciTech Connect

The degradation of carbonaceous organic material by anaerobic bacteria leads to the production of methane gas (biogas) at the theoretical stoichiometric conversion rate of 0.35-cubic meters of methane per kilogram of Chemical Oxygen Demand (COD) reasonably close proximity to the site of this digestion process. The untreated biogas generated from anaerobic digestion typically contains from 55% to 75% methane content, with the balance consisting mainly of carbon dioxide and a small, but important, amount of hydrogen sulfide. The untreated biogas is normally saturated with water vapor at the temperature of the digestion process which typically is in the mesophilic range 25 to 38 degrees Celsius. This overview paper describes the types of anaerobic technologies which are presently used for the digestion of various type of municipal, industrial and livestock manure wastes, summarizes the principal developments which have taken place in the field during the past several years, and discusses the energy recovery economics for each of the three usage applications. The paper stratifies the use of anaerobic digestion technology for the treatment of wastewaters from industry (an application which has increased dramatically during the past decade) by geographical region, by industry type, very various categories of food processing, and by technology type, in all cases taking account of system size to emphasize the economics of energy production.

Sax, R.I. [Biothane Corporation, Camden, NJ (United States); Lusk, P.D. [Resource Development Associates, Washington, DC (United States)

1995-11-01

70

Modeling anaerobic digestion of aquatic plants by rumen cultures: Cattail as an example  

Microsoft Academic Search

Despite of the significance of the anaerobic digestion of lignocellulosic materials, only a limited number of studies have been carried out to evaluate the lignocellulosic digestion kinetics, and information about the modeling of this process is limited. In this work, a mathematical model, based on the Anaerobic Digestion Model No.1 (ADM1), was developed to describe the anaerobic conversion of lignocellulose-rich

Bai-Hang Zhao; Zheng-Bo Yue; Bing-Jie Ni; Yang Mu; Han-Qing Yu; Hideki Harada

2009-01-01

71

Biogas production from anaerobic digestion of Spirulina maxima algal biomass  

SciTech Connect

The photosynthetic spectrum of solar energy could be exploited for the production of chemical energy of methane through the combined algal-bacterial process. In this process, the algae are mass produced from light and from carbon in the first step. The algal biomass is then used as a nutrient for feeding the anaerobic digester, in the second step, for the production of methane by anaerobic bacteria. The carbon source for the production of algal biomass could be either organic carbon from wastewaters (for eucaryotic algae), or carbon dioxide from the atmosphere or from the combustion exhaust gases (for both prokaryotic and eukaryotic algae). The technical feasibility data on the anaerobic digestion of algal biomass have been reported for many species of algae including macroscopic algae and microscopic algae. Research being conducted in the authors' laboratory consists of using the semimicroscopic blue-green alga Spirulina maxima as the sole substrate for this combined algal-bacterial process. This species of alga is very attractive for the process because of its capability of using the atmospheric carbon dioxide as carbon source and its simple harvesting methods. Furthermore, it appeared that the fermentability of S. maxima is significantly higher than other microscopic algae. This communication presents the results on the anaerobic inoculum development by the adaptation technique. This inoculum was then used for the semicontinuous anaerobic digestion of S. maxima algal biomass. The evolutions of biogas production and composition, biogas yield, total volatile fatty acids, alkalinity, ammonia nitrogen, pH, and electrode potential were followed.

Samson, R.; LeDuy, A.

1982-08-01

72

STABILIZATION OF SEWAGE SLUDGE BY TWO-PHASE ANAEROBIC DIGESTION  

EPA Science Inventory

The research described in the report was concerned with evaluation of alternative approaches to anaerobic digestion, a process commonly used on the residual stream from wastewater treatment. The principal approach studied was that of separating the acid- and methane-forming phase...

73

Two-phase anaerobic digestion of unscreened dairy manure  

Microsoft Academic Search

Concentrated animal feeding operations along with a corresponding absence of suitable manure disposal methods have been shown to cause significant environmental and public health problems, including odors and nutrient enrichment and pathogen contamination of surface and ground waters. Anaerobic digestion (AD) of manure can offer substantial benefits, both economic and intangible, to animal feeding operators and surrounding communities, such as

G. N. Demirer; S. Chen

2005-01-01

74

Anaerobic digestion of the liquid fraction of dairy manure  

SciTech Connect

The authors tested several solid liquid separation systems suitable for processing dairy manure prior to anaerobic digestion. None of the systems tried have completely satisfied the requirements. Evaluated effects of separation on biogas production. Unseparated dairy manure produced more biogas than the liquid fraction.

Haugen, V.; Dahlberg, S.; Lindley, J.A.

1983-06-01

75

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

ERIC Educational Resources Information Center

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

Carnegie, John W., Ed.

76

Biogas production from anaerobic digestion of Spirulina maxima algal biomass  

Microsoft Academic Search

The photosynthetic spectrum of solar energy could be exploited for the production of chemical energy of methane through the combined algal-bacterial process. In this process, the algae are mass produced from light and from carbon in the first step. The algal biomass is then used as a nutrient for feeding the anaerobic digester, in the second step, for the production

Rejean Samson; Anh LeDuy

1982-01-01

77

Inactivation of Selected Bacterial Pathogens in Dairy Cattle Manure by Mesophilic Anaerobic Digestion (Balloon Type Digester)  

PubMed Central

Anaerobic digestion of animal manure in biogas digesters has shown promise as a technology in reducing the microbial load to safe and recommended levels. We sought to treat dairy manure obtained from the Fort Hare Dairy Farm by investigating the survival rates of bacterial pathogens, through a total viable plate count method, before, during and after mesophilic anaerobic digestion. Different microbiological media were inoculated with different serial dilutions of manure samples that were withdrawn from the biogas digester at 3, 7 and 14 day intervals to determine the viable cells. Data obtained indicated that the pathogens of public health importance were 90%–99% reduced in the order: Campylobacter sp. (18 days) < Escherichia coli sp. (62 days) < Salmonella sp. (133 days) from a viable count of 10.1 × 103, 3.6 × 105, 7.4 × 103 to concentrations below the detection limit (DL = 102 cfu/g manure), respectively. This disparity in survival rates may be influenced by the inherent characteristics of these bacteria, available nutrients as well as the stages of the anaerobic digestion process. In addition, the highest p-value i.e., 0.957 for E. coli showed the statistical significance of its model and the strongest correlation between its reductions with days of digestion. In conclusion, the results demonstrated that the specific bacterial pathogens in manure can be considerably reduced through anaerobic digestion after 133 days. PMID:25026086

Manyi-Loh, Christy E.; Mamphweli, Sampson N.; Meyer, Edson L.; Okoh, Anthony I.; Makaka, Golden; Simon, Michael

2014-01-01

78

Anaerobic digestion of polyelectrolyte flocculated waste activated sludge.  

PubMed

This work examined how adding one of three polyelectrolyte flocculants (T3052: cationic, T2000: non-ionic, and T1052: anionic) affected the anaerobic digestion of wastewater sludge. Methane production, floc characteristics (morphology and zeta-potential) and process parameters (soluble chemical oxygen demands (SCODs) and reductive potentials) were monitored along the digestion tests. The digestion rates of T2000- and T1052-conditioned sludge resembled that for original sludge. The T3052-flocculated sludge generated methane at a higher rate during the first 6 days of digestion than did the original one. In the following stage, the digestion rate of sludge flocculated with T3052 at dosage exceeding 15 g/kg dried solids declined. For example, at 40 days of digestion the methane production amounts for original, 15 g/kg DS flocculated, and 40 g/kg flocculated sludge were of 136, 105, and 85 g/kg DS, respectively. The role of flocculants could change in different stages of digestion. The dosed polymers had no apparent toxicity to the inoculum used. The changes in SCOD, adenosintriphosphate concentrations, oxidative and reductive potential, and zeta-potentials did not correlate with the noted hindered digestion for T3052-conditioned sludge. Microphotographic observation revealed that the flocs of T3052-conditioned sludge were not only of a large size, but also were resistant to structural deterioration during digestion. Therefore, mass transfer resistance was proposed to account for the hindered digestion efficiency observed for T3052-conditioned sludge. PMID:13129515

Chu, C P; Lee, D J; Chang, Bea-Ven; You, C H; Liao, C S; Tay, J H

2003-11-01

79

Anaerobic digestion of microalgal biomass after ultrasound pretreatment.  

PubMed

High rate algal ponds are an economic and sustainable alternative for wastewater treatment, where microalgae and bacteria grow in symbiosis removing organic matter and nutrients. Microalgal biomass produced in these systems can be valorised through anaerobic digestion. However, microalgae anaerobic biodegradability is limited by the complex cell wall structure and therefore a pretreatment step may be required to improve the methane yield. In this study, ultrasound pretreatment at a range of applied specific energy (16-67MJ/kgTS) was investigated prior to microalgae anaerobic digestion. Experiments showed how organic matter solubilisation (16-100%), hydrolysis rate (25-56%) and methane yield (6-33%) were improved as the pretreatment intensity increased. Mathematical modelling revealed that ultrasonication had a higher effect on the methane yield than on the hydrolysis rate. A preliminary energy assessment indicated that the methane yield increase was not high enough as to compensate the electricity requirement of ultrasonication without biomass dewatering (8% VS). PMID:25002372

Passos, Fabiana; Astals, Sergi; Ferrer, Ivet

2014-11-01

80

Anaerobic digestion of crude glycerol: a review  

Microsoft Academic Search

Several researchers have used crude glycerol as a source of substrate for methane production and power generation, which is a way of adding value to this residue that has a high chemical oxygen demand (COD) and is rich in impurities. This review article summarizes recent data and discussions on the use of crude glycerol as substrate and co-substrate for anaerobic

M. B. Viana; A. V. Freitas; R. C. Leitão; G. A. S. Pinto; S. T. Santaella

2012-01-01

81

Anaerobic digestion of organic waste for biogas production  

SciTech Connect

A low solids aqueous suspensions of organic waste is treated in greater than or equal to 4, e.g., 6 serial anaerobic zones at less than 40/sup 0/ and under quiescent conditions to provide CH/sub 4/, fertilizer, and a clean liquid effluent. Thus, a fermentation system together with a biogas storage system, a generating plant, and an effluent-holding tank were installed on a pig farm. The digester constituted 3 tanks, sharing 2 common walls. The solids constituted 2% of the liquid-solid suspension added twice daily to the tanks. The system was operated for 6 mo. without removal of solids. Thereafter, solids were removed every 21 days and used as fertilizer. Cu sulfate (approximately 1 lb/10,000 gal) was added periodically every 2-3 wk, scrap Fe (approximately 3 ton) was added once, and Mo (2-3 lb.) was added once. The system generated 10,000-11,000 cubic feet gas/day and gas contained 75% CH/sub 4/. About 600 kW electricity/day was generated. BOD and COD of material entering the system and material exiting the system were measured, BOD and COD were reduced by 90-95%.

Paton, R.

1984-01-31

82

Combined anaerobic and aerobic digestion for increased solids reduction and nitrogen removal.  

PubMed

A unique sludge digestion system consisting of anaerobic digestion followed by aerobic digestion and then a recycle step where thickened sludge from the aerobic digester was recirculated back to the anaerobic unit was studied to determine the impact on volatile solids (VS) reduction and nitrogen removal. It was found that the combined anaerobic/aerobic/anaerobic (ANA/AER/ANA) system provided 70% VS reduction compared to 50% for conventional mesophilic anaerobic digestion with a 20 day SRT and 62% for combined anaerobic/aerobic (ANA/AER) digestion with a 15 day anaerobic and a 5 day aerobic SRT. Total Kjeldahl nitrogen (TKN) removal for the ANA/AER/ANA system was 70% for sludge wasted from the aerobic unit and 43.7% when wasted from the anaerobic unit. TKN removal was 64.5% for the ANA/AER system. PMID:20801476

Novak, John T; Banjade, Sarita; Murthy, Sudhir N

2011-01-01

83

Early warning indicators for monitoring the process failure of anaerobic digestion system of food waste.  

PubMed

To determine reliable state parameters which could be used as early warning indicators of process failure due to the acidification of anaerobic digestion of food waste, three mesophilic anaerobic digesters of food waste with different operation conditions were investigated. Such parameters as gas production, methane content, pH, concentrations of volatile fatty acid (VFA), alkalinity and their combined indicators were evaluated. Results revealed that operation conditions significantly affect the responses of parameters and thus the optimal early warning indicators of each reactor differ from each other. None of the single indicators was universally valid for all the systems. The universally valid indicators should combine several parameters to supply complementary information. A combination of total VFA, the ratio of VFA to total alkalinity (VFA/TA) and the ratio of bicarbonate alkalinity to total alkalinity (BA/TA) can reflect the metabolism of the digesting system and realize rapid and effective early warning. PMID:25218457

Li, Lei; He, Qingming; Wei, Yunmei; He, Qin; Peng, Xuya

2014-11-01

84

Anaerobic digestion of stillage to produce bioenergy in the sugarcane-to-ethanol industry.  

PubMed

Stillage is the main wastewater from ethanol production, containing a high chemical oxygen demand in addition to acidic and corrosive characteristics. Though stillage may be used as a soil fertilizer, its land application may be considered problematic due its high polluting potential. Anaerobic digestion represents an effective alternative treatment to reduce the pollution load of stillage. In addition, the methane gas produced within the process may be converted to energy, which can be directly applied to the treatment plant. The objective of this paper was to investigate the energetic potential of anaerobic digestion applied to stillage in the sugarcane ethanol industry. An overall analysis of the results indicates energy recovery capacity (ERC) values for methane ranging from 3.5% to 10%, respectively, for sugarcane juice and molasses. The processes employed to obtain the fermentable broth, as well as the distillation step, represent the main limiting factors to the energetic potential feasibility. Considering financial aspects the annual savings could reach up to US$ 30 million due to anaerobic digestion of stillage in relatively large-scale distilleries (365,000 m3 of ethanol per year). The best scenarios were verified for the association between anaerobic digestion of stillage and combustion of bagasse. In this case, the fossil fuels consumption in distilleries could be fully ceased, such the ERC of methane could reach values ranging from 140% to 890%. PMID:24600872

Fuess, Lucas Tadeu; Garcia, Marcelo Loureiro

2014-01-01

85

Extracellular polymeric substances and dewaterability of waste activated sludge during anaerobic digestion.  

PubMed

Anaerobic digestion of waste activated sludge was conducted to gain insight into the mechanisms underlying change in sludge dewaterability during its anaerobic digestion. Unexpectedly, the results indicated that sludge dewatering properties measured by capillary suction time only deteriorated after 10 days of anaerobic digestion, after which dewaterability recovered and remained stable. The loosely bound extracellular polymeric substance (LB-EPS) content increased three-fold after 20 days of anaerobic digestion, and did not change significantly during the remaining 30 days. The tightly bound EPS (TB-EPS) content reduced slightly after 20 days of anaerobic digestion, and stabilized during the last 30 days. Polysaccharides (PS) and proteins (PN) content in LB-EPS increased after 10 days of anaerobic digestion. However, PS and PN contents in TB-EPS decreased slightly. The relationship analysis showed that only LB-EPS correlated with dewaterability of the sludge during anaerobic digestion. PMID:25401321

Ye, Fenxia; Liu, Xinwen; Li, Ying

2014-01-01

86

Anaerobic digestion of pulp and paper mill wastewater and sludge.  

PubMed

Pulp and paper mills generate large amounts of waste organic matter that may be converted to renewable energy in form of methane. The anaerobic treatment of mill wastewater is widely accepted however, usually only applied to few selected streams. Chemical oxygen demand (COD) removal rates in full-scale reactors range between 30 and 90%, and methane yields are 0.30-0.40 m(3) kg(-1) COD removed. Highest COD removal rates are achieved with condensate streams from chemical pulping (75-90%) and paper mill effluents (60-80%). Numerous laboratory and pilot-scale studies have shown that, contrary to common perception, most other mill effluents are also to some extent anaerobically treatable. Even for difficult-to-digest streams such as bleaching effluents COD removal rates range between 15 and 90%, depending on the extent of dilution prior to anaerobic treatment, and the applied experimental setting. Co-digestion of different streams containing diverse substrate can level out and diminish toxicity, and may lead to a more robust microbial community. Furthermore, the microbial population has the ability to become acclimated and adapted to adverse conditions. Stress situations such as toxic shock loads or temporary organic overloading may be tolerated by an adapted community, whereas they could lead to process disturbance with an un-adapted community. Therefore, anaerobic treatment of wastewater containing elevated levels of inhibitors or toxicants should be initiated by an acclimation/adaptation period that can last between a few weeks and several months. In order to gain more insight into the underlying processes of microbial acclimation/adaptation and co-digestion, future research should focus on the relationship between wastewater composition, reactor operation and microbial community dynamics. The potential for engineering and managing the microbial resource is still largely untapped. Unlike in wastewater treatment, anaerobic digestion of mill biosludge (waste activated sludge) and primary sludge is still in its infancy. Current research is mainly focused on developing efficient pretreatment methods that enable fast hydrolysis of complex organic matter, shorter sludge residence times and as a consequence, smaller sludge digesters. Previous experimental studies indicate that the anaerobic digestibility of non-pretreated biosludge from pulp and paper mills varies widely, with volatile solids (VS) removal rates of 21-55% and specific methane yields ranging between 40 and 200 mL g(-1) VS fed. Pretreatment can increase the digestibility to some extent, however in almost all reported cases, the specific methane yield of pretreated biosludge did not exceed 200 mL g(-1) VS fed. Increases in specific methane yield mostly range between 0 and 90% compared to non-pretreated biosludge, whereas larger improvements were usually achieved with more difficult-to-digest biosludge. Thermal treatment and microwave treatment are two of the more effective methods. The heat required for the elevated temperatures applied in both methods may be provided from surplus heat that is often available at pulp and paper mills. Given the large variability in specific methane yield of non-pretreated biosludge, future research should focus on the links between anaerobic digestibility and sludge properties. Research should also involve mill-derived primary sludge. Although biosludge has been the main target in previous studies, primary sludge often constitutes the bulk of mill-generated sludge, and co-digestion of a mixture between both types of sludge may become practical. The few laboratory studies that have included mill primary sludge indicate that, similar to biosludge, the digestibility can range widely. Long-term studies should be conducted to explore the potential of microbial adaptation to lignocellulosic material which can constitute more than half of the organic matter in pulp and paper mill sludge. PMID:25150519

Meyer, Torsten; Edwards, Elizabeth A

2014-11-15

87

Novel anaerobic digestion process with sludge ozonation for economically feasible power production from biogas.  

PubMed

A novel process scheme was developed to achieve economically feasible energy recovery from anaerobic digestion. The new process scheme employs a hybrid configuration of mesophilic and thermophilic anaerobic digestion with sludge ozonation: the ozonated sludge is first degraded in a thermophilic digester and then further degraded in a mesophilic digester. In small-scale pilot experiments of the new process scheme, degradation of VSS improved by 3.5% over the control (mesophilic-only configuration) with 20% less ozone consumption. Moreover, biogas conversion also improved by 7.1% over the control. Selective enrichment of inorganic compounds during centrifugation produced a dewatered sludge cake with very low water content (59.4%). This low water content in the sludge cake improved its auto-thermal combustion potential during incineration and added to the overall energy savings. We conducted a case study to evaluate power generation from biogas for a municipal wastewater treatment plant with an average dry weather flow of 43,000 m3/d. Electricity production cost was 5.2 ¢/kWh for the advanced process with power generation, which is lower than the current market price of 7.2 ¢/kWh. The new anaerobic digestion scheme with power generation may reduce greenhouse gas emissions by about 1,000 t-CO(2)/year compared with the conventional process without power generation. PMID:21508552

Komatsu, K; Yasui, H; Goel, R; Li, Y Y; Noike, T

2011-01-01

88

Methane production from and beneficiation of anaerobic digestion of aquatic plant material  

SciTech Connect

A process is disclosed for improved CH/sub 4/ production by anaerobic digestion of aquatic plant material, at least a portion or all which was grown in organically polluted water. Mixtures of aquatic plant material whose 1 portion was grown in nonpolluted and a 2nd portion comprising approximately 10 wt.% or more grown in organically polluted water can be used. The liquid effluent from the digester may be advantageously returned to the aquatic plant-growing pond to maintain the desired organic pollution. The process provides for improved CH/sub 4/ production from aquatic plant material which is, by itself, recalcitrant to anaerobic digestion. Thus, 2 digesters were operated under the same conditions, the 1st being fed with water hyacinth grown in nonorganic polluted hardwater of BOD 5 mg/l and hardness of 20 grains/gal. and the 2nd being fed with water hyacinth grown in sewage-polluted water of BOD 20 mg/l. Each digester was operated in a semicontinuous completely mixed anaerobic manner with a culture volume of 5 liters for a detention time of 12 days, a loading of 0.1 lb volatile solid/cubic feet-day, and 35/sup 0/ at pH of 6.8-7.1. The runs were contained for several detention times and exhibited stable performance. CH/sub 4/ yield increased approximately 69% and the gas-production rate increased approximately 82% by using water hyacinth feed grown in sewage-polluted water.

Klass, D.L.; Ghosh, S.

1984-01-03

89

Improving thermophilic anaerobic digestion of swine manure  

Microsoft Academic Search

Thermophilic (55°C) anaerobic degradation of swine manure was found possible even at an ammonia content of 6g-N\\/l, with a low methane yield of only 67ml CH4\\/g-VS and a high concentration of volatile fatty acids (11.5g acetate\\/l). Several methods were tested in order to increase the methane yield. Addition of 1.5% (w\\/w) activated carbon, 10% (w\\/w) glauconite or 1.5% (w\\/w) activated

Kaare Hvid Hansen; Irini Angelidaki; Birgitte KiÆr Ahring

1999-01-01

90

Anaerobic digestion of livestock manures: A current opportunities casebook  

SciTech Connect

Growth and concentration of the livestock industry creates new opportunities for proper disposal of the large quantities of manures generated at dairy, swine, and poultry farms. One manure management system provides not only pollution prevention but also converts a problem into a new profit center. Economic evaluations and case studies of operating systems indicate that the anaerobic digestion of livestock manures is a commercially-available bioconversion technology with considerable potential for providing profitable co-products, including a renewable fuel. An introduction to the engineering economies of these technologies is provided, based on estimates of digesters that generate electricity from the recovered methane. Regression models used to estimate digester cost and internal rate of return are developed from the evaluations. Case studies of operating digesters, including project and maintenance histories, and the operator`s {open_quotes}lessons learned{close_quotes}, are provided as a reality check.

Lusk, P.D.

1995-08-01

91

Batch load anaerobic digestion of dairy manure  

E-print Network

and medium size dairy operations unless the pro- cess can be made more efficient or some other economic benefit can be derived from the manure. A recent study indicated that a batch load process might be more efficient in waste stabilization and biogas... rate of biogas production was 0. 69 liters biogas/liter digester/ day. This volumetric biogas production increased with increasing influent total solids concentration. Influent concentration had little effect on other biogas production parameters...

Egg, Richard P

2012-06-07

92

The effects of digestion temperature and temperature shock on the biogas yields from the mesophilic anaerobic digestion of swine manure  

Microsoft Academic Search

In order to obtain basic design criteria for anaerobic digesters of swine manure, the effects of different digesting temperatures, temperature shocks and feed loads, on the biogas yields and methane content were evaluated. The digester temperatures were set at 25, 30 and 35°C, with four feed loads of 5%, 10%, 20% and 40% (feed volume\\/digester volume). At a temperature of

K. J. Chae; Am Jang; S. K. Yim; In S. Kim

2008-01-01

93

CFD simulation of anaerobic digester with variable sewage sludge rheology.  

PubMed

A computational fluid dynamics (CFD) model that evaluates mechanical mixing in a full-scale anaerobic digester was developed to investigate the influence of sewage sludge rheology on the steady-state digester performance. Mechanical mixing is provided through an impeller located in a draft tube. Use is made of the Multiple Reference Frame model to incorporate the rotating impeller. The non-Newtonian sludge is modeled using the Hershel-Bulkley law because of the yield stress present in the fluid. Water is also used as modeling fluid to illustrate the significant non-Newtonian effects of sewage sludge on mixing patterns. The variation of the sewage sludge rheology as a result of the digestion process is considered to determine its influence on both the required impeller torque and digester mixing patterns. It was found that when modeling the fluid with the Hershel-Bulkley law, the high slope of the sewage stress-strain curve at high shear rates causes significant viscous torque on the impeller surface. Although the overall fluid shear stress property is reduced during digestion, this slope is increased with sludge age, causing an increase in impeller torque for digested sludge due to the high strain rates caused by the pumping impeller. Consideration should be given to using the Bingham law to deal with high strain rates. The overall mixing flow patterns of the digested sludge do however improve slightly. PMID:23764598

Craig, K J; Nieuwoudt, M N; Niemand, L J

2013-09-01

94

Anaerobic digestion of two biodegradable municipal waste streams.  

PubMed

Landfill avoidance for organic wastes is now a high priority worldwide. Two fractions of the municipal waste stream were considered with respect to their potential for diversion through controlled anaerobic digestion. The physical and chemical properties of source segregated domestic food waste (ss-FW) and of the mechanically-recovered organic fraction of municipal solid waste (mr-OFMSW) were analysed, and their methane yields determined in both batch and semi-continuous digestion. Methane potentials were compared with predicted values based on biochemical composition, elemental analysis and carbon mass balance, and the differences explained by compositional analysis of feedstocks and digestates. The ss-FW had a higher percentage biodegradability and higher energy potential on a dry weight basis due to the high proportion of proteins and fats in this waste, although the energy potential of the mr-OFMSW was slightly higher on a wet weight (WW) basis. The mr-OFMSW showed very stable digestion characteristics, whereas the ss-FW had a high digestate ammoniacal-N concentration and volatile fatty acid accumulation leading to some process instability. Digestates from semi-continuous trials with mr-OFMSW had high concentrations of potentially toxic elements (PTE) and a lower nutrient content than ss-FW digestate, making the former unsuitable for application to land used in food production. PMID:22504715

Zhang, Yue; Banks, Charles J; Heaven, Sonia

2012-08-15

95

Characteristics of carbohydrate degradation and the rate-limiting step in anaerobic digestion  

Microsoft Academic Search

The characteristics of the degradation of cellulose, soluble starch, and glucose in the acidogenic phase and the effects of the substrate loading rate and biological solids retention time on the methanogenic phase of anaerobic digestion were investigated. The results obtained from continuous experiments using laboratory-scale anaerobic chemostat reactors elucidated the true rate-limiting step of anaerobic digestion. The specific rate of

Tatsuya Noike; Ginro Endo; Juu-En Chang; Jun-Ichi Yaguchi; Jun-Ichiro Matsumoto

1985-01-01

96

Anaerobic Digestion for Mitigation of Biodiesel Production Byproducts  

NSDL National Science Digital Library

The Advanced Technology Environmental and Energy Center (ATEEC) provides this document, which was part of a workshop held on anaerobic digestion for mitigation of biodiesel production byproducts. It would be useful for instructors looking to develop their own curriculum on biofuels and biodiesel byproducts. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

2011-04-19

97

Production of Methane Biogas as Fuel Through Anaerobic Digestion  

Microsoft Academic Search

\\u000a Anaerobic digestion (AD) is a biotechnology by which biomass is converted by microbes to methane (CH4) biogas, which can then be utilized as a renewable fuel to generate heat and electricity. A genetically and metabolically\\u000a diverse community of microbes (mainly bacteria and methanogens) drives the AD process through a series of complex microbiological\\u000a processes in the absence of oxygen. During

Zhongtang Yu; Floyd L. Schanbacher

98

The action of antibiotics on the anaerobic digestion process.  

PubMed

Antibiotics can disturb the production of biogas during anaerobic digestion. This study shows a systematic approach to understanding how the different bacterial populations involved in the final conversion of organic matter into methane are inhibited by 15 antimicrobial agents with different specificities and modes of action. The results obtained show the following trends: (i) some inhibitors, such as the macrolide erythromycin, lack any inhibitory effect on biogas production; (ii) some antibiotics, with different specificities, have partial inhibitory effects on anaerobic digestion and decrease methane production by interfering with the activity of propionic-acid- and butyric-acid-degrading bacteria, (e.g. antibiotics that interfere with cell wall synthesis, RNA polymerase activity and protein synthesis, especially the aminoglycosides); (iii) the protein synthesis inhibitors chlortetracycline (IC50 40 mg l-1) and chloramphenicol (IC50 15-20 mg l-1) are very powerful inhibitors of anaerobic digestion. The majority of the antibiotics tested lacked activity against acetoclastic methanogens, being active only on the acetogenic bacteria. However, chloramphenicol and chlortetracycline could cause the complete inhibition of the acetoclastic methanogenic archaea. PMID:9008891

Sanz, J L; Rodríguez, N; Amils, R

1996-12-01

99

Anaerobic digestion of dairy cattle manure autoheated by aerobic pretreatment  

SciTech Connect

A novel way to heat anaerobic digesters was investigated. Dairy cattle manure was autoheated by an aerobic pretreatment process and then fed to the anaerobic digester. Important physical properties of the dairy cattle manure were determined. These included bulk density, specific heat, thermal conductivity and the rheological properties; consistency coefficient, behavior index and apparent viscosity. These parameters were used to calculate the overall heat transfer coefficients, and to estimate the heat losses from the aerobic reactor to the outside environment. The total energy balance of the aerobic treatment system was then established. An optimization study of the main parameters influencing the autoheating process showed that the total solids, the air flow rate and the stirring speed for operation of the aerobic pretreatment should be approximately 7%, 70 L/H and 1,400 rpm respectively. Temperatures as high as 65C were reached in 40 hours of aerobic treatment. At the above recommended levels of total solids, the air flow rate and the stirring speed, there was little difference in the energy requirements for heating the influent by aeration and heating the influent by a conventional heating system. In addition to the temperature increase, the aerobic pretreatment assisted in balancing the anaerobic digestion process and increased the methanogenesis of the dairy cattle manure. Despite the 8% decomposition of organic matter that occurred during the aerobic pretreatment process, methane production of the digester started with the aerobically heated manure was significantly higher (at least 20% higher) than of the digester started with conventionally heated manure. The aerobic system successfully autoheated the dairy cattle manure with an energy cost equal to that of conventionally heated influent.

Achkari-Begdouri, A.

1989-01-01

100

Anaerobic Co-digestion of Brown Water and Food Waste for Energy Recovery  

E-print Network

LIM J.W. Anaerobic Co-digestion of Brown Water and Food Waste for Energy Recovery Jun Wei LIM waste. Keywords Anaerobic digestion; food waste; brown water; biogas; co-digestion INTRODUCTION water and kitchen food waste in urban decentralised units hal-00607958,version1-11Jul2011 Author

Paris-Sud XI, Université de

101

Pretreatment technologies for advancing anaerobic digestion of pulp and paper biotreatment residues  

Microsoft Academic Search

While anaerobic digestion is commonly practiced in the municipal sector, it has not gained popularity in the pulp and paper industry mainly because of its long sludge residence time requirement of 20–30 days. The construction of large digesters to provide such extended residence times is capital-intensive and thus the implementation of anaerobic digestion has remained economically prohibitive. A review of

Allan Elliott; Talat Mahmood

2007-01-01

102

Biogas production from anaerobic digestion of Spirulina maxima algal biomass  

SciTech Connect

The semimicroscopic blue-green alga Spirulina maxima makes an ideal substrate for anaerobic digestion because it is easy to harvest, it can use carbon dioxide from the atmosphere as its carbon source, and its fermentability is higher than that of other small algae. Digestion experiments demonstrated that S. maxima can serve as the sole nutrient for biogas production and that municipal sewage sludge, when adapted to this new substrate, is very stable. During semicontinuous daily-fed trials under non-optimal conditions at an 0.06 lb volatile solids (VS)/ft/sup 3/ (0.97 kg VS/m/sup 3/) loading rate, 33-day retention time, and 86/sup 0/F (30/sup 0/C) digestion temperature, the daily methane yield was 4.2 CF/lb (0.26 m/sup 3//kg) VS added, which represents 47% of the maximum theoretical yield. Studies on optimizing the process are underway.

Samson, R.; LeDuy, A.

1982-08-01

103

Enhanced anaerobic digestion of waste activated sludge digestion by the addition of zero valent iron.  

PubMed

Anaerobic digestion is promising technology to recover energy from waste activated sludge. However, the sludge digestion is limited by its low efficiency of hydrolysis-acidification. Zero valent iron (ZVI) as a reducing material is expected to enhance anaerobic process including the hydrolysis-acidification process. Considering that, ZVI was added into an anaerobic sludge digestion system to accelerate the sludge digestion in this study. The results indicated that ZVI effectively enhanced the decomposition of protein and cellulose, the two main components of the sludge. Compared to the control test without ZVI, the degradation of protein increased 21.9% and the volatile fatty acids production increased 37.3% with adding ZVI. More acetate and less propionate are found during the hydrolysis-acidification with ZVI. The activities of several key enzymes in the hydrolysis and acidification increased 0.6-1 time. ZVI made the methane production raise 43.5% and sludge reduction ratio increase 12.2 percent points. Fluorescence in situ hybridization analysis showed that the abundances of hydrogen-consuming microorganisms including homoacetogens and hydrogenotrophic methanogens with ZVI were higher than the control, which reduced the H2 accumulation to create a beneficial condition for the sludge digestion in thermodynamics. PMID:24275106

Feng, Yinghong; Zhang, Yaobin; Quan, Xie; Chen, Suo

2014-04-01

104

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

PubMed

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. PMID:20965366

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

2010-11-01

105

Development of a new bioethanol feedstock – Anaerobically digested fiber from confined dairy operations using different digestion configurations  

Microsoft Academic Search

Two types of digesters, continuous stirring-tank reactor (CSTR) and plug flow reactor (PFR), were integrated into a biorefining concept to generate a new cellulosic ethanol feedstock –anaerobically digested fiber (AD fiber) from dairy cow feces. Cellulose content in AD fibers was significantly increased during the anaerobic digestion. CSTR and PFR AD fibers had cellulose contents of 357 and 322 g kg?1 dried

Zhengbo Yue; Charles Teater; James MacLellan; Yan Liu; Wei Liao

2011-01-01

106

Anaerobic digestion of solid wastes of cane sugar industry  

SciTech Connect

The cane sugar manufacturing industry generates large quantities of lignocellulosic solid wastes, namely bagasse and cachaza. Bagasse is the fibrous residue of the cane after extracting the juice. Cachaza is the filter cake of the precipitated insoluble sugars. This research investigates the feasibility of anaerobic digestion of a mixture of bagasse and cachaza to produce methane. Two rations of bagasse-cachaza mix as substrates were investigated. The first one was 8:1 which represents the average ratio of bagasse and cachaza produced in a raw sugar mill. The second ratio investigated was 2.4:1 which represents the proportion of bagasse and cachaza wastes after 70% of the bagasse is burned in sugar mill boilers. An acclimated microbial culture for this substrate was developed. Organic Loading-Detention Time relationships were established for an optimum system. Pre-treatment techniques of the substrate were investigated as a means of enhancing the digestibility of the cellulosic substrate. Recirculation of the filtrate was evaluated as a method for increasing solids retention time without increasing hydraulic detention time. The kinetics of the digestion process for bagasse-cachaza mixed substrate was investigated and growth constants were determined. The bionutritional characteristics of the substrate used for the digestion were evaluated. Based on the results obtained, mass balances and preliminary economic analysis of the digestion system were developed.

Dasgupta, A.

1983-01-01

107

Psychrophilic anaerobic digestion of guinea pig manure in low-cost tubular digesters at high altitude.  

PubMed

Guinea pig is one of the most common livestock in rural communities of the Andes. The aim of this research was to study the anaerobic digestion of guinea pig manure in low-cost unheated tubular digesters at high altitude. To this end, the performance of two pilot digesters was monitored during 7 months; and two greenhouse designs were compared. In the dome roof digester the temperature and biogas production were significantly higher than in the shed roof digester. However, the biogas production rate was low (0.04 m(biogas)(3)m(digester)(-3) d(-1)), which is attributed to the low organic loading rate (0.6 kg(VS)m(digester)(-3)d(-1)) and temperature (23°C) of the system, among other factors. In a preliminary fertilization study, the potato yield per hectare was increased by 100% using the effluent as biofertilizer. Improving manure management techniques, increasing the organic loading rate and co digesting other substrates may be considered to enhance the process. PMID:21450457

Garfí, Marianna; Ferrer-Martí, Laia; Villegas, Vidal; Ferrer, Ivet

2011-05-01

108

DIGESTER GAS - FUEL CELL - PROJECT  

SciTech Connect

GEW has been operating the first fuel cell in Europe producing heat and electricity from digester gas in an environmentally friendly way. The first 9,000 hours in operation were successfully concluded in August 2001. The fuel cell powered by digester gas was one of the 25 registered ''Worldwide projects'' which NRW presented at the EXPO 2000. In addition to this, it is a key project of the NRW State Initiative on Future Energies. All of the activities planned for the first year of operation were successfully completed: installing and putting the plant into operation, the transition to permanent operation as well as extended monitoring till May 2001.

Dr.-Eng. Dirk Adolph; Dipl.-Eng. Thomas Saure

2002-03-01

109

Biogas plasticization coupled anaerobic digestion: batch test results.  

PubMed

Biogas has unique properties for improving the biodegradability of biomass solids during anaerobic digestion (AD). This report presents batch test results of the first investigation into utilizing biogas plasticization to "condition" organic polymers during active digestion of waste activated sludge (WAS). Preliminary design calculations based on polymer diffusion rate limitation are presented. Analysis of the 20 degrees C batch test data determined the first order (k(1)) COD conversion coefficient to be 0.167 day(-1) with a maximum COD utilization rate of 11.25 g L(-1) day(-1). Comparison of these batch test results to typical conventional AD performance parameters showed orders of magnitude improvement. These results show that biogas plasticization during active AD could greatly improve renewable energy yields from biomass waste materials such as MSW RDF, STP sludges, food wastes, animal manure, green wastes, and agricultural crop residuals. PMID:17054122

Schimel, Keith A

2007-06-01

110

Feasibility and strategies for anaerobic digestion of solid waste for energy production in Dar es Salaam city, Tanzania  

Microsoft Academic Search

In Tanzania, the most serious solid waste management problem currently is disposal, but since the largest fraction of the waste is organics which are amenable to anaerobic digestion and composting, it makes environmental and economic sense to explore these options. This prompted the conception of the Taka (waste) Gas Project which is meant to utilise organic solid waste from Dar

Stephen E Mbuligwe; Gabriel R Kassenga

2004-01-01

111

The effect of direct addition of iron(III) on anaerobic digestion efficiency and odor causing compounds.  

PubMed

The role of iron addition to sewage sludge prior to anaerobic digestion was evaluated to determine the effect of iron on digestion performance and generation of odor-causing compounds. Hydrogen sulfide (H2S) and volatile organic sulfur compounds (VOSCs) were the odorous gases evaluated in this study. Samples were obtained from seven municipal wastewater treatment plants (WWTPs), and batch anaerobic digestion tests were conducted using primary and secondary sludges at 30 day solids retention time (SRT) under mesophilic conditions. Volatile solid removal (VSR) was highly predictable with background iron concentrations measured in the combined sludge. They were likely to increase as influent iron content increased. 1.25% w/w ferric chloride (FeCl3) was added to the anaerobic digester feed in order to simulate iron addition for sulfide control in full-scale WWTPs. The results showed that it had a positive impact on digestion performance with higher VSR and odor control with reduced H2S and TVOSCs in the headspace gas of dewatered biosolids considered in the tests. Ferric chloride is considered a beneficial additive as a strategy for an odor mitigation, not to mention more efficient digestion under anaerobic conditions. PMID:24334887

Park, Chang Min; Novak, John T

2013-01-01

112

Investigation of Poultry Waste for Anaerobic Digestion: A Case Study  

NASA Astrophysics Data System (ADS)

Anaerobic Digestion (AD) is a biological conversion technology which is being used to produce bioenergy all over the world. This energy is created from biological feedstocks, and can often use waste products from various food and agricultural processors. Biogas from AD can be used as a fuel for heating or for co-generation of electricity and heat and is a renewable substitute to using fossil fuels. Nutrient recycling and waste reduction are additional benefits, creating a final product that can be used as a fertilizer in addition to energy benefits. This project was conducted to investigate the viability of three turkey production wastes as AD feedstock: two turkey litters and a material separated from the turkey processing wastewater using dissolved air flotation (DAF) process. The DAF waste contained greases, oils and other non-commodity portions of the turkey. Using a variety of different process methods, types of bacteria, loading rates and food-to-microorganism ratios, optimal loading rates for the digestion of these three materials were obtained. In addition, the co-digestion of these materials revealed additional energy benefits. In this study, batch digestion tests were carried out to treat these three feedstocks, using mesophilic and thermophilic bacteria, using loading rates of 3 and 6 gVS/L They were tested separately and also as a mixture for co-digestion. The batch reactor used in this study had total and working volumes of 1130 mL and 500 mL, respectively. The initial organic loading was set to be 3 gVS/L, and the food to microorganism ratio was either 0.6 or 1.0 for different treatments based on the characteristics of each material. Only thermophilic (50 +/- 2ºC) temperatures were tested for the litter and DAF wastes in continuous digestion, but mesophilic and thermophilic batch digestion experiments were conducted. The optimum digestion time for all experiments was 14 days. The biogas yields of top litter, mixed litter, and DAF waste under mesophilic batch conditions all at 3 gVS/L loading were determined to be 148.6 +/- 7.82, 176.5 +/- 11.1 and 542.0 +/- 37.9 mL/ gVS, respectively and were 201.9 +/- 10.0, 210.4 +/- 29.3, and 419.3 +/- 12.1 mL/gVS, respectively, for initial loading of 6 gVS/L. Under thermophilic batch conditions, the top litter, mixed litter, and DAF waste had the biogas yields of 255.3 +/- 7.9, 313.4 +/- 30.1and 297.4 +/- 33.8 mL/gVS for loading rate of 3 gVS/L and 233.8 +/- 45.3, 306.5 +/- 11.8 and 185.1 +/- 0.85 mL/gVS for loading rate of 6 gVS/L. The biogas yields from co-digestion of the mixed litter and DAF waste at 3 gVS/L were 461.8 +/- 41.3 mL/gVS under thermophilic conditions. The results from batch anaerobic digestion tests were then used for designing continuous digestion experiments. All the continuous digestion experiments were conducted by using an Anaerobic Phase Solids (APS) digester system operated at a thermophilic temperature. The total volume of the continuous digester system was 4.8 L and the working volume was around 4.4 L. The APS digester system had two hydrolysis reactors and one biogasification reactor. Feedstock was loaded into the hydrolysis reactors in batches. The feedstock digestion time was 14 days and the average organic loading rate (OLR) of the system was 3 gVS/L/day. The experiment has three distinct feedstock stages, first with turkey litter waste, a co-digestion of DAF and turkey litter waste, followed by DAF waste. The biogas yields were determined to be 305.2 +/- 70.6 mL/gVS/d for turkey mixed litter, 455.8 +/- 77.2 mL/gVS/d during the mixture of mixed litter and DAF waste, and 382.0 +/- 39.6 mL/gVS for DAF waste. The biogas yields from the thermophilic batch test yields compare with that of the continuous digester yields. For experiments utilizing turkey litter, batch tests yielded 313.4 +/- 30.1mL/gVS biogas and 305.2 +/- 70.6 mL/gVS/d for continuous experiments. For experiments using codigestion of turkey litter and DAF waste, batches yielded 461.8 +/- 41.3 mL/gVS biogas comparing well to continuous digester operation that yielded 455.8 +/- 77.

Salam, Christopher R.

113

Repeated pulse feeding induces functional stability in anaerobic digestion.  

PubMed

Anaerobic digestion is an environmental key technology in the future bio-based economy. To achieve functional stability, a minimal microbial community diversity is required. This microbial community should also have a certain 'elasticity', i.e. the ability to rapidly adapt to suboptimal conditions or stress. In this study it was evaluated whether a higher degree of functional stability could be achieved by changing the feeding pattern, which can change the evenness, dynamics and richness of the bacterial community. The first reactor (CSTR stable ) was fed on daily basis, whereas the second reactor (CSTR dynamic ) was fed every 2 days. Average biogas production was 0.30 l CH4 l(-1) day(-1) in both reactors, although daily variation was up to four times higher in the CSTR dynamic compared with the CSTR stable during the first 50 days. Bacterial analysis revealed that this CSTR dynamic had a two times higher degree of bacterial community dynamics. The CSTR dynamic also appeared to be more tolerant to an organic shock load of 8 g COD l(-1) and ammonium levels up to 8000 mg TAN l(-1). These results suggest that the regular application of a limited pulse of organic material and/or a variation in the substrate composition might promote higher functional stability in anaerobic digestion. PMID:23302421

De Vrieze, Jo; Verstraete, Willy; Boon, Nico

2013-07-01

114

Controlled struvite crystallisation for removing phosphorus from anaerobic digester sidestreams.  

PubMed

Enhanced biological phosphorus removal wastewater treatment plants that use anaerobic digesters for sludge treatment, have high phosphorus concentrations in the sidestreams from their sludge dewatering equipment. To remove phosphorus from such sidestreams controlled struvite crystallisation can be used. Struvite (or MAP) is a naturally occurring crystal of magnesium, ammonium and phosphate. We present operational results obtained with a continuously operated pilot-scale MAP reactor. The pilot-scale reactor (143 l) was an air agitated column reactor with a reaction and a settling zone, based on the Phosnix process of Unitika Ltd., Japan. The influent to the MAP reactor was centrate from the centrifuge that dewaters anaerobically digested sludge at the Oxley Creek wastewater treatment plant in Brisbane. We used a 60% magnesium hydroxide slurry to add the required magnesium to the process and to obtain the alkaline pH value required. The pilot-scale MAP process achieved an ortho-P removal ratio of 94% from an average influent ortho-P concentration of 61 mg/l. The reactor was operated at a pH of around 8.5. Insufficient dosing of magnesium reduced the P removal performance. There was no influence of the hydraulic residence time on the process in the range of 1-8 h. The dry MAP product had cadmium, lead and mercury concentrations well below the legal limits for fertilisers in Queensland, Australia and can be reused as a valuable slow-release fertiliser. PMID:11257869

Münch, E V; Barr, K

2001-01-01

115

Repeated pulse feeding induces functional stability in anaerobic digestion  

PubMed Central

Summary Anaerobic digestion is an environmental key technology in the future bio-based economy. To achieve functional stability, a minimal microbial community diversity is required. This microbial community should also have a certain ‘elasticity’, i.e. the ability to rapidly adapt to suboptimal conditions or stress. In this study it was evaluated whether a higher degree of functional stability could be achieved by changing the feeding pattern, which can change the evenness, dynamics and richness of the bacterial community. The first reactor (CSTRstable) was fed on daily basis, whereas the second reactor (CSTRdynamic) was fed every 2 days. Average biogas production was 0.30?l CH4 l?1 day?1 in both reactors, although daily variation was up to four times higher in the CSTRdynamic compared with the CSTRstable during the first 50 days. Bacterial analysis revealed that this CSTRdynamic had a two times higher degree of bacterial community dynamics. The CSTRdynamic also appeared to be more tolerant to an organic shock load of 8?g COD l?1 and ammonium levels up to 8000?mg TAN l?1. These results suggest that the regular application of a limited pulse of organic material and/or a variation in the substrate composition might promote higher functional stability in anaerobic digestion. PMID:23302421

De Vrieze, Jo; Verstraete, Willy; Boon, Nico

2013-01-01

116

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

PubMed

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. PMID:24350427

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

2013-01-01

117

In-storage psychrophilic anaerobic digestion of swine manure: Acclimation of the microbial community  

Microsoft Academic Search

Covering a concrete manure storage tank with an air-tight floating membrane should induce anaerobic digestion of the stored manure. If the microbial community in the manure can acclimate to the ambient conditions, then In-Storage Psychrophilic Anaerobic Digestion (ISPAD) could be used by Canadian livestock producers to produce methane and stabilize manure. The objective of this study was to determine whether

Susan M. King; Suzelle Barrington; Serge R. Guiot

2011-01-01

118

The fate of crop nutrients during digestion of swine manure in psychrophilic anaerobic sequencing batch reactors  

Microsoft Academic Search

The objectives of the study were to measure the levels of manure nutrients retained in psychrophilic anaerobic sequencing batch reactors (PASBRs) digesting swine manure, and to determine the distribution of nutrients in the sludge and supernatant zones of settled bioreactor effluent. Anaerobic digestion reduced the total solids (TS) concentration and the soluble chemical oxygen demand (SCOD) of manure by 71.4%

D. I. Massé; F. Croteau; L. Masse

2007-01-01

119

Development of an advanced anaerobic digester design and a kinetic model for biogasification of water hyacinth/sludge blends  

SciTech Connect

The Institute of Gas Technology (IGT) conducted a comprehensive laboratory-scale research program to develop and optimize the anaerobic digestion process for producing methane from water hyacinth and sludge blends. This study focused on digester design and operating techniques, which gave improved methane yields and production rates over those observed using conventional digesters. The final digester concept and the operating experience was utilized to design and operate a large-scale experimentla test unit (ETU) at Walt Disney World, Florida. This paper describes the novel digester design, operating techniques, and the results obtained in the laboratory. The paper also discusses a kinetic model which predicts methane yield, methane production rate, and digester effluent solids as a function of retention time. This model was successfully utilized to predict the performance of the ETU. 15 refs., 6 figs., 6 tabs.

Srivastava, V.; Fannin, K.F.; Biljetina, R.; Chynoweth, D.P.; Hayes, T.D.

1986-07-01

120

Anaerobic digestion of high-strength cheese whey utilizing semicontinuous digesters and chemical flocculant addition  

SciTech Connect

Semicontinuous digesters were used to anaerobically treat high-strength whey (70 kg/cubic m COD). A maximum loading of 16.1 kg COD/cubic m/day was obtained with soluble COD removal efficiencies greater than 99%. The use of a chemical flocculant resulted in an increased biomass concentration in the digester compared to a control, thus enabling correspondingly higher space loadings to be applied. With the onset of substantial levels of granulation of the biomass, flocculant dosage was able to be discontinued. This article discusses the performance of the digesters in detail and, briefly, the long-term operational difficulties experienced and the control strategies employed on such systems. 24 references.

Barford, J.P.; Cail, R.G.; Callander, I.J.; Floyd, E.J.

1986-11-01

121

Autotrophic nitrogen removal from anaerobic supernatant of Florence's WWTP digesters.  

PubMed

In municipal WWTP with anaerobic sludge digestion, 10-20% of total nitrogen load comes from the return supernatant produced by the final sludge dewatering. In recent years a completely autotrophic nitrogen removal process based on Anammox biomass has been tested in a few European countries, in order to treat anaerobic supernatant and to increase the COD/N ratio in municipal wastewater. This work reports the experimental results of the SHARON-ANAMMOX process application to anaerobic supernatant taken from the urban Florentine area wastewater treatment plant (S. Colombano WWTP). A nitritation labscale chemostat (7.4 L) has been started-up seeded with the S. Colombano WWTP nitrifying activated sludge. During the experimental period, nitrite oxidising bacteria wash-out was steadily achieved with a retention time ranging from 1 to 1.5 d at 35 degrees C. The Anammox inoculum sludge was taken from a pilot plant at EAWAG (Zurich). Anammox biomass has been enriched at 33 degrees C with anaerobic supernatant diluted with sodium nitrite solution until reaching a maximum specific nitrogen removal rate of 0.065 kgN kg(-1) VSS d(-1), which was 11 times higher than the one found in inoculum sludge (0.005 kgN kg(-1) VSS d(-1). In a lab-scale SBR reactor (4 L), coupled with nitritation bioreactor, specific nitrogen removal rate (doubling time equal to 26 d at 35 degrees C and at nitrite-limiting condition) reached the value of 0.22 kgN kg(-1) VSS d(-1), which was approximately 44 times larger than the rate measured in the inoculum Anammox sludge. PMID:16889249

Caffaz, S; Lubello, C; Canziani, R; Santianni, D

2006-01-01

122

Anaerobic digestion of food waste: Comparing leachate exchange rates in sequential batch systems digesting food waste and biosolids  

Microsoft Academic Search

Over 35,000 tonnes of food waste are generated from high concentration point sources (i.e., restaurants, hospitals and markets) in metropolitan Adelaide (Australia) each year. Anaerobic digestion is a preferred method of treatment to degrade highly putrescible waste streams such as food waste due its high methane potential. To maximise methane yield, a sequential batch anaerobic system was chosen as the

B. Dearman; R. H. Bentham

2007-01-01

123

Microalgae to biofuels: life cycle impacts of methane production of anaerobically digested lipid extracted algae.  

PubMed

This study presents experimental measurements of the biochemical methane production for whole and lipid extracted Nannochloropsis salina. Results show whole microalgae produced 430 cm(3)-CH4 g-volatile solids(-1) (g-VS) (?=60), 3 times more methane than was produced by the LEA, 140 cm(3)-CH4 g-VS(-1) (?=30). Results illustrate current anaerobic modeling efforts in microalgae to biofuel assessments are not reflecting the impact of lipid removal. On a systems level, the overestimation of methane production is shown to positively skew the environmental impact of the microalgae to biofuels process. Discussion focuses on a comparison results to those of previous anaerobic digestion studies and quantifies the corresponding change in greenhouse gas emissions of the microalgae to biofuels process based on results from this study. PMID:25181698

Quinn, Jason C; Hanif, Asma; Sharvelle, Sybil; Bradley, Thomas H

2014-11-01

124

Biomass production, anaerobic digestion, and nutrient recycling of small benthic or floating seaweeds  

SciTech Connect

A number of experiments have been carried out supporting the development of a seaweed-based ocean energy farm. Beginning in 1976, forty-two species of seaweed indigenous to the coastal waters of Central Florida were screened for high biomass yields in intensive culture. Gracilaria tikvahiae achieved the highest annual yield of 34.8 g dry wt/m/sup 2/ day. Yield has been found to vary inversely with seawater exchange rate, apparently because of carbon dioxide limitation at low exchange rates. Gracilaria was anaerobically digested in 120 liter and 2 liter reactors. Gas yields in the large digesters averaged 0.4 1/g volatile solids (.24 1 CH/sub 4//gv.s.) with a bioconversion efficiency of 48%. Studies of the suitability of digester residue as a nutrient source for growing Gracilaria have been conducted. Nitrogen recycling efficiency from harvested plant through liquid digestion residue to harvested plant approached 75%. Studies of nutrient uptake and storage by Gracilaria, Ascophyllum, and Sargassum showed that nutrient starved plants are capable of rapidly assimilating and storing inorganic nutrients which may be used later for growth when no nutrients are present in the medium. A shallow water seaweed farm was proposed which would produce methane from harvested seaweed and use digester residues as a concentrated source of nutrients for periodic fertilizations.

Ryther, J.H.

1982-02-01

125

Microbial kinetic for In-Storage-Psychrophilic Anaerobic Digestion (ISPAD).  

PubMed

In-Storage-Psychrophilic-Anaerobic-Digestion (ISPAD) is a wastewater storage tank converted into an anaerobic digestion (AD) system by means of an airtight floating geo-membrane. For process optimization, ISPAD requires modelling with well-established microbial kinetics coefficients. The present objectives were to: obtain kinetics coefficients for the modelling of ISPAD; compare the prediction of the conventional and decomposition fitting approach, an innovative fitting technique used in other fields of science, and; obtain equations to predict the maximum growth rate (?max) of microbial communities as a function of temperature. The method consisted in conducting specific Substrate Activity Tests (SAT) using ISPAD inoculum to monitor the rate of degradation of specific substrates at 8, 18 and 35 °C. Microbial kinetics coefficients were obtained by fitting the Monod equations to SAT. The statistical procedure of Least Square Error analysis was used to minimize the Sum of Squared Errors (SSE) between the measured ISPAD experimental data and the Monod equation values. Comparing both fitting methods, the decomposition approach gave higher correlation coefficient (R) for most kinetics values, as compared to the conventional approach. Tested to predict ?max with temperature, the Square Root equation better predicted temperature dependency of both acidogens and propionate degrading acetogens, while the Arrhenius equation better predicted that of methanogens and butyrate degrading acetogens. Increasing temperature from 18 to 35 °C did not affect butyrate degrading acetogens, likely because of their dominance, as demonstrated by microbial population estimation. The estimated ISPAD kinetics coefficients suggest a robust psychrophilic and mesophilic coexisting microbial community demonstrating acclimation to ambient temperature. PMID:25156266

Madani-Hosseini, Mahsa; Mulligan, Catherine N; Barrington, Suzelle

2014-12-15

126

Survey of the Anaerobic Biodegradation Potential of Organic Chemicals in Digesting Sludge  

PubMed Central

The degradation potential of 77 organic chemicals under methanogenic conditions was examined with an anaerobic digesting sludge from the United Kingdom. Degradation was assessed in terms of net total gas (CH4 plus CO2) produced, expressed as a percentage of the theoretical production (ThGP). The compounds tested were selected from various chemical groups and included substituted phenols and benzoates, pesticides, phthalic acid esters, homocyclic and heterocyclic ring compounds, glycols, and monosubstituted benzenes. The results obtained were in good agreement with published surveys of biodegradability in U.S. digesting sludges and other methanogenic environments. In general, the presence of chloro or nitro groups inhibited anaerobic gas production, while carboxyl and hydroxyl groups facilitated biodegradation. The relationship between substituent position and susceptibility to methanogenic degradation was compound dependent. The following chemicals were completely degraded (?80% ThGP) at a concentration of 50 mg of carbon per liter: phenol, 2-aminophenol, 4-cresol, catechol, sodium benzoate, 4-aminobenzoic acid, 3-chlorobenzoic acid, phthalic acid, ethylene glycol, diethylene glycol, triethylene glycol, sodium stearate, and quinoline. 3-Cresol, 4-chlorobenzoic acid, dimethyl phthalate, and pyridine were partially degraded. Although the remaining chemicals tested were either persistent or toxic, their behavior may differ at more environmentally realistic chemical-to-biomass ratios. Our findings suggest that biodegradability assessments made with sludge from one source can be extrapolated to sludge from another source with a reasonable degree of confidence and should help in predicting the fate of an organic chemical during the anaerobic digestion of sewage sludge. PMID:16347851

Battersby, Nigel S.; Wilson, Valerie

1989-01-01

127

Anaerobic treatment of intensive fish culture effluents: digestion of fish feed and release of volatile fatty acids  

Microsoft Academic Search

Removal of organic matter and nitrate was studied in a laboratory-scale treatment system consisting of a digestion basin and a fluidized bed reactor. Fish feed was anaerobically degraded in the digestion basin and supernatant from the digestion basin, rich in dissolved organic degradation products, was used to fuel nitrate removal by denitrifying organisms in the fluidized bed reactor. Anaerobic digestion

Jaap van Rijn; Nicolai Fonarev; Brian Berkowitz

1995-01-01

128

Enhancement of the conventional anaerobic digestion of sludge: comparison of four different strategies.  

PubMed

Anaerobic digestion (AD) is the preferred option to stabilize sludge. However, the rate limiting step of solids hydrolysis makes it worth modifing the conventional mesophilic AD in order to increase the performance of the digester. The main strategies are to introduce a hydrolysis pre-treatment, or to modify the digestion temperature. Among the different pre-treatment alternatives, the thermal hydrolysis (TH) at 170 degrees C for 30 min, and the ultrasounds pre-treatment (US) at 30 kJ/kg TS were selected for the research, while for the non-conventional anaerobic digestion, the thermophilic (TAD) and the two-stage temperature phased AD (TPAD) were considered. Four pilot plants were operated, with the same configuration and size of anaerobic digester (200 L, continuously fed). The biogas results show a general increase compared to the conventional digestion, being the highest production per unit of digester for the process combining the thermal pre-treatment and AD (1.4 L biogas/L digester day compared to the value of 0.26 obtained in conventional digesters). The dewaterability of the digestate became enhanced for processes TH + AD and TPAD when compared with the conventional digestate, while it became worse for processes US + AD and TAD. In all the research lines, the viscosity in the digester was smaller compared to the conventional (which is a key factor for process performance and economics), and both thermal pre-treatment and thermophilic digestion (TAD and TPAD) assure a pathogen free digestate. PMID:22097010

Pérez-Elvira, S I; Fdz-Polanco, M; Fdz-Polanco, F

2011-01-01

129

Fermentative hydrogen production from tofu-processing waste and anaerobic digester sludge using microbial consortium.  

PubMed

The combination of tofu-processing waste and anaerobic digester sludge was studied for its fermentative H(2) production capacity in batch and continuous modes using a thermophilic mixed culture. Heat-treatment (110 degrees C, 30 min) in the presence of 0.5% HCl increased the soluble carbohydrate content of the tofu waste from 2.2 to 10.4 g/l. Anaerobic digester sludge was added to the tofu waste for supplementary nutrients with the optimal mixing ratio of 20% (v/v) under batch conditions. In continuous experiments, the effects of HRT(hydraulic retention time) and pH were investigated for the ranges of 2-6h and 5.0-6.0, respectively. The maximal H(2) production rate (12.0 l H(2)/l/day) and yield (2.3 mol H(2)/mol glucose equivalent) were obtained at HRT 4h and pH 5.5 while maintaining the head space gas at 50-60% (v/v) of H(2) without CH(4). This study indicates that the combination of tofu-processing waste and digester sludge can be considered to be one of the most promising forms of organic waste for continuous H(2) production. PMID:19394818

Kim, Mi-Sun; Lee, Dong-Yeol

2010-01-01

130

Anaerobic digestion of glycerol and co-digestion of glycerol and pig manure.  

PubMed

The potential of glycerol obtained from transesterification of waste cooking oil as a main carbon source for biogas production was investigated. The glycerol was highly contaminated with oils and fats and was pretreated with sulfuric acid. Using a carbon source of glucose as a control, we compared biogas production from the acid-treated glycerol in a synthetic medium and the acid-treated glycerol mixed with pig manure. The anaerobic digestion of acid-treated glycerol with supplement in a synthetic medium was found to be satisfactory at organic loading rates (OLR) between 1.3, 1.6 and 2.6 g chemical oxygen demand (COD) L(-1) d(-1). The maximum methane yield of 0.32 L at Standard temperature and pressure (STP) g(-1) COD removal was achieved at an OLR of 1.6 g COD L(-1) d(-1) and the methane content was 54% on an average. At a higher organic loading rate of 5.4 g COD L(-1) d(-1), the propionic acid to acetic acid ratio was higher than the critical threshold limit for metabolic imbalance. Anaerobic digestion of acid-treated glycerol with pig manure was also investigated at the COD ratio of 80:20 (glycerol:pig manure). The anaerobic digestion of acid-treated glycerol with pig manure was found to be satisfactory at organic loading rates between 1.3, 1.7, 2.9 and 5.0 g COD L(-1) d(-1) in terms of COD reduction (>80%) and methane content of (62% on an average). However, the biogas production rate was found to significantly decrease at the highest load. The maximum methane yield of 0.24 L STP g(-1) COD removal was achieved at an OLR of 1.3 g COD L(-1) d(-1). PMID:22417895

Nuchdang, Sasikarn; Phalakornkule, Chantaraporn

2012-06-30

131

CFD simulation of mixing for high-solids anaerobic digestion.  

PubMed

A computational fluid dynamics (CFD) model that simulates mechanical mixing for high-solids anaerobic digestion was developed. Numerical simulations of mixing manure slurry which exhibits non-Newtonian pseudo-plastic fluid behavior were performed for six designs: (i) one helical ribbon impeller; (ii) one anchor impeller; (iii) one curtain-type impeller; (iv) three counterflow (CF-2) impellers; (v) two modified high solidity (MHS 3/39°) impellers; and (vi) two pitched blade turbine impellers. The CFD model was validated against measurements for mixing a Herschel-Bulkley fluid by ribbon and anchor impellers. Based on mixing time with respect to mixing energy level, three impeller types (ribbon, CF-2, and MHS 3/39°) stand out when agitating highly viscous fluids, of these mixing with two MHS 3/39° impellers requires the lowest power input to homogenize the manure slurry. A comparison of digestion material demonstrates that the mixing energy varies with manure type and total solids concentration to obtain a given mixing time. Moreover, an in-depth discussion about the CFD strategy, the influences of flow regime and impeller type on mixing characteristics, and the intrinsic relation between mixing and flow field is included. PMID:22422446

Wu, Binxin

2012-08-01

132

Anaerobic digestion of spent bedding from deep litter piggery housing.  

PubMed

This paper investigates spent litter from deep litter piggery housing as a potential substrate for farm-scale anaerobic digestion. Degradability and degradation rates were evaluated under mesophilic conditions for unused, lightly soiled (used by weaner/small pigs), and heavily soiled (used by finishing/large pigs) wheat straw, barley straw, and rice husks bedding. Apparent first order hydrolysis rate coefficients varied, but were comparable across all samples analysed (<0.1 day(-1)). Spent wheat straw was generally more degradable (approximately 60%) than spent barley straw, while spent barley straw was comparable to raw straw (40-50%), but with higher hydrolysis rates, indicating better accessibility. Rice husks were relatively poorly degradable (<20%), but degradability was improved by weathering in a pig shed. Digestion of spent barley and wheat straw litter was significantly faster (approximately twice the rate) at low (8% solids) than high (14% solids) solids loading. Rice husks degradation kinetics were not significantly influenced by solids concentration. Intrinsic methanogenic activity of heavily soiled spent wheat straw and rice husks bedding was initially poor, but achieved full activity after 40-60 days, indicating that reactor operation without external inoculum may be possible with care. PMID:19097776

Tait, Stephan; Tamis, Jelmer; Edgerton, Bruce; Batstone, Damien J

2009-04-01

133

Efficiency of the anaerobic digestion of amine wastes.  

PubMed

Laboratory-scale anaerobic degradation of monoethanolamine waste (MEAw) with co-substrate organics was conducted at room temperature and organic loading rates from 0.19 to 5.03 kg COD/m(3) day for 486 days in a hybrid digester. 90 % feed COD conversion to methane was obtained at the lower loads and only 45 % at the highest MEA waste/COD ratio (MEAwr) of 0.62 due to inhibition of methanogenesis. Inhibition at comparable loads decreased with time, implying that the culture adapted to the challenging feed. Methane yield was negatively correlated to MEAwr applied and inhibition avoided at MEAwr <0.5. Acetate accumulation implies inhibition of acetoclastic methanogenesis that can be caused by ammonia, a product of MEAw degradation. Moderate total ammonia nitrogen and free ammonia nitrogen accumulation, maximum 2.2 g N/l and 90 mg N/l, respectively suggests, however, that other components of MEAw, and/or degradation products of such, also inhibit methanogenesis, disturbing the digester performance. PMID:23912885

Wang, Shuai; Hovland, Jon; Bakke, Rune

2013-12-01

134

Kinetics and advanced digester design for anaerobic digestion of water hyacinth and primary sludge  

SciTech Connect

A research program centered around a facility located at Walt Disney World (WDW) is in progress to evaluate the use of water hyacinth (WH) for secondary and tertiary wastewater treatment, to optimize growth of WH under these conditions, and to convert the resultant primary sludge (PS) and WH to methane via anaerobic digestion. This article describes the status of the biogasification component of this program, which includes baseline and advanced digestion experiments with individual feeds and blends and the design of an experimental test unit (ETU) to be installed at WDW. Experiments with several blends demonstrated that methane yields can be predicted from the fractional content and methane yield of each component. The process was found to adhere to the Monod kinetic model for microbial growth, and associated kinetic parameters were developed for various feed combinations. A novel upflow digester is achieving significantly higher conversion than a stirred-tank digester. Of several pretreatment techniques used, only alkaline treatment resulted in increased biodegradability. A larger scale (4.5 m/sup 3/) experimental test unit is being designed for installation at WDW in 1982. 13 figures, 4 tables.

Chynoweth, D.P.; Dolenc, D.A.; Ghosh, S.; Henry, M.P.; Jerger, D.E.; Srivastava, V.J.

1982-01-01

135

Pretreatment of sludge with microwaves for pathogen destruction and improved anaerobic digestion performance.  

PubMed

A new way of generating Class A sludge using microwaves was evaluated through a series of laboratory-scale experiments. Microwaves provide rapid and uniform heating throughout the material. Other benefits of microwave treatment include instant and accurate control and selective and concentrated heating on materials, such as sludge, that have a high dielectric loss factor. Sludge was irradiated with 2450-MHz microwaves, and fecal coliforms were counted. Fecal coliforms were not detected at 65 degrees C for primary sludge and anaerobic digester sludge and at 85 degrees C for waste activated sludge when sludge was irradiated with 2450-MHz microwaves. During the bench-scale anaerobic digester operation, the highest average log reduction of fecal coliforms was achieved by the anaerobic digester fed with microwave-pretreated sludge (> or = 2.66 log removal). The anaerobic digester fed with microwave-irradiated sludge was more efficient in inactivation of fecal coliforms than the other two digesters fed with raw sludge and externally heated sludge, respectively. It took more than three hydraulic retention times for a bench-scale mesophilic anaerobic digester to meet Class A sludge requirements after feeding microwave-irradiated sludge. Class A sludge can be produced consistently with a continuously fed mesophilic anaerobic digester if sludge is pretreated with microwaves to reach 65 degrees C. PMID:16553169

Hong, Seung M; Park, Jae K; Teeradej, N; Lee, Y O; Cho, Y K; Park, C H

2006-01-01

136

DESTRUCTION BY ANAEROBIC MESOPHILIC AND THERMOPHILIC DIGESTION OF VIRUSES AND INDICATOR BACTERIA INDIGENOUS TO DOMESTIC SLUDGES  

EPA Science Inventory

In raw sludges and in mesophilically and thermophilically digested anaerobic sludges, large variations in numbers of viruses occurred over narrow ranges of numbers of fecal coliforms, total coliforms, and fecal streptococci, demonstrating that the bacteria are poor quantitative r...

137

Effect of natural and modified zeolite addition on anaerobic digestion of piggery waste.  

PubMed

The effect of natural and modified zeolites on the anaerobic degradation of acetate and methanol was evaluated by the determination of specific methane productivity (SMP) in batch minidigesters of 50 mL at doses of 0.01, 0.05 and 0.1 g of zeolite/g of VSS. The effects of the different zeolite concentrations were determined by the results of the SMP. A kinetic characterization with data of accumulated methane gas volume was also carried out. In the second phase of the study, the effects of natural and nickel zeolite concentrations were tested with piggery waste in laboratory scale digesters of 2.5 L operating at semi continuous mode, by increasing the organic load applied from 0.2 to 22.0 g TCOD/d corresponding to organic loading rates (OLR) of 0.1-8.8 g TCOD/l x d. A greater effect of modified zeolite on SMP was observed, with an increase of 8.5 times with magnesium zeolite, 4.4 times with cobalt zeolite and 2.8 times with nickel zeolite. Two phases were defined in the kinetic study and an increase of more than 2 times the apparent constant of digesters with modified zeolites was observed in the second phase when compared to unmodified natural zeolite. Modified natural zeolite addition to digesters can allow an increase in the potential biodegradability of piggery waste solid fraction and/or a considerable reduction of digestion volume. PMID:14640227

Milán, Z; Villa, P; Sánchez, E; Montalvo, S; Borja, R; Ilangovan, K; Briones, R

2003-01-01

138

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

PubMed Central

Background Replacing the energy-intensive evaporation of stillage by anaerobic digestion is one way of decreasing the energy demand of the lignocellulosic biomass to the ethanol process. The biogas can be upgraded and sold as transportation fuel, injected directly into the gas grid or be incinerated on-site for combined heat and power generation. A techno-economic evaluation of the spruce-to-ethanol process, based on SO2-catalysed steam pretreatment followed by simultaneous saccharification and fermentation, has been performed using the commercial flow-sheeting program Aspen Plus™. Various process configurations of anaerobic digestion of the stillage, with different combinations of co-products, have been evaluated in terms of energy efficiency and ethanol production cost versus the reference case of evaporation. Results Anaerobic digestion of the stillage showed a significantly higher overall energy efficiency (87-92%), based on the lower heating values, than the reference case (81%). Although the amount of ethanol produced was the same in all scenarios, the production cost varied between 4.00 and 5.27 Swedish kronor per litre (0.38-0.50 euro/L), including the reference case. Conclusions Higher energy efficiency options did not necessarily result in lower ethanol production costs. Anaerobic digestion of the stillage with biogas upgrading was demonstrated to be a favourable option for both energy efficiency and ethanol production cost. The difference in the production cost of ethanol between using the whole stillage or only the liquid fraction in anaerobic digestion was negligible for the combination of co-products including upgraded biogas, electricity and district heat. PMID:20843330

2010-01-01

139

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

Microsoft Academic Search

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

I. Angelidaki; B. K. Ahring; H. Deng; J. E. Schmidt

2002-01-01

140

Anaerobic Digesters: From Waste to Energy Crops as an Alternative Energy Source  

Microsoft Academic Search

The main objective of the present study is to investigate the integrated organic waste-anaerobic digester-energy crop production system as a eco-agricultural system and to use anaerobically digested cattle slurry as fertilizer for safflower production. The value of slurry as fertilizer for growing safflower was compared with commercial organic and chemical fertilizers. According to the results of this study, higher yields

G. Kocar

2008-01-01

141

Anaerobic digestion of distillery spent wash: Influence of enzymatic pre-treatment of intact yeast cells.  

PubMed

The potential benefits of enzymatic digestion of intact yeast cells on anaerobic digestion of Scotch whisky distillery spent wash and pot ale were investigated. Various yeast cell wall hydrolytic enzymes were studied based on their effect on dissolution of cell wall glucan and mannoprotein. The synergistic activity of beta-glucanase and protease showed greater than 90% yeast cell digestion at 37 degrees C in 24h. The widely-used industrial enzyme papain showed 95% yeast cell digestion in spent wash at 1% enzyme concentration within 22h at 50 degrees C. Anaerobic digestion of pot ale residues containing intact yeast cells pre-treated with lytic enzymes showed COD reductions of 87%, compared with only 13% without enzymes. Similar results were observed with distillery spent wash centrate. The hydrolysis of intact yeast cells in distillery liquid residues was found to be a rate-limiting step in anaerobic treatment of such residues. PMID:19884003

Mallick, P; Akunna, J C; Walker, G M

2010-03-01

142

Biogas plasticization coupled anaerobic digestion: continuous flow anaerobic pump test results.  

PubMed

In this investigation, the Anaerobic Pump (TAP) and a conventional continuous flow stirred tank reactor (CFSTR) were tested side by side to compare performance. TAP integrates anaerobic digestion (AD) with biogas plasticization-disruption cycle to improve mass conversion to methane. Both prototypes were fed a "real world" 50:50 mixture of waste-activated sludge (WAS) and primary sludge and operated at room temperature (20 degrees Celsius). The quantitative results from three steady states show TAP peaked at 97% conversion of the particulate COD in a system hydraulic residence time (HRT) of only 6 days. It achieved a methane production of 0.32 STP cubic meter CH(4) per kilogram COD fed and specific methane yield of 0.78 m(3) CH(4) per cubic meter per day. This was more than three times the CFSTR specific methane yield (0.22 m(3) CH(4) per cubic meter per day) and more than double the CFSTR methane production (0.15 m(3) CH(4) per kilogram COD fed). A comparative kinetics analysis showed the TAP peak substrate COD removal rate (R (o)) was 2.24 kg COD per cubic meter per day, more than three times the CFSTR substrate removal rate of 0.67 kg COD per cubic meter per day. The three important factors contributing to the superior TAP performance were (1) effective solids capture (96%) with (2) mass recycle and (3) stage II plasticization-disruption during active AD. The Anaerobic Pump (TAP) is a high rate, high efficiency-low temperature microbial energy engine that could be used to improve renewable energy yields from classic AD waste substrates like refuse-derived fuels, treatment plant sludges, food wastes, livestock residues, green wastes and crop residuals. PMID:19455433

Schimel, Keith A; Boone, David R

2010-03-01

143

Biodegradability and change of physical characteristics of particles during anaerobic digestion of domestic sewage  

Microsoft Academic Search

At the high-rate anaerobic treatment of domestic sewage, both biological and physical processes play an important role. Therefore, the anaerobic biodegradability of raw, paper-filtered and membrane-filtered sewage and black water has been investigated in batch experiments. Additionally, the effect of anaerobic digestion on physical characteristics, like particle size, surface tension and zeta-potential, of the present particles is studied. The biodegradability

Tarek A Elmitwalli; Jesko Soellner; Arie De Keizer; Harry Bruning; Grietje Zeeman; Gatze Lettinga

2001-01-01

144

Supercritical Fluid Extraction of Bacterial and Archaeal Lipid Biomarkers from Anaerobically Digested Sludge  

PubMed Central

Supercritical fluid extraction (SFE) was used in the analysis of bacterial respiratory quinone (RQ), bacterial phospholipid fatty acid (PLFA), and archaeal phospholipid ether lipid (PLEL) from anaerobically digested sludge. Bacterial RQ were determined using ultra performance liquid chromatography (UPLC). Determination of bacterial PLFA and archaeal PLEL was simultaneously performed using gas chromatography-mass spectrometry (GC-MS). The effects of pressure, temperature, and modifier concentration on the total amounts of RQ, PLFA, and PLEL were investigated by 23 experiments with five settings chosen for each variable. The optimal extraction conditions that were obtained through a multiple-response optimization included a pressure of 23.6 MPa, temperature of 77.6 °C, and 10.6% (v/v) of methanol as the modifier. Thirty nine components of microbial lipid biomarkers were identified in the anaerobically digested sludge. Overall, the SFE method proved to be more effective, rapid, and quantitative for simultaneously extracting bacterial and archaeal lipid biomarkers, compared to conventional organic solvent extraction. This work shows the potential application of SFE as a routine method for the comprehensive analysis of microbial community structures in environmental assessments using the lipid biomarkers profile. PMID:22489140

Hanif, Muhammad; Atsuta, Yoichi; Fujie, Koichi; Daimon, Hiroyuki

2012-01-01

145

Anaerobic digestion of giant reed for methane production.  

PubMed

As a fast growing plant, giant reed has good potential to be used as a feedstock for methane production via anaerobic digestion (AD). The effect of total solids (TS) content, an AD operating parameter, was studied. Results showed that increasing TS from 8% to 38% decreased methane yield, due to the inhibition of volatile fatty acids (VFAs) and total ammonia nitrogen (TAN); while the maximum volumetric methane production was obtained at 20-23% TS. Comparison of solid-state AD (SS-AD) at 20% TS and liquid AD (L-AD) at 8% TS was conducted at feedstock to effluent (F/E) ratios of 2.0, 3.5, and 5.0. The best performance was achieved at an F/E of 2.0, with methane yields of 129.7 and 150.8L-CH4/kg-VS for SS-AD and L-AD, respectively. Overall organic components were degraded by 17.7-28.5% and 24.0-26.6% in SS-AD and L-AD, respectively; among which cellulose showed the highest degradation rate and the highest contribution to methane production. PMID:25203231

Yang, Liangcheng; Li, Yebo

2014-11-01

146

Mechanisms of floc destruction during anaerobic and aerobic digestion and the effect on conditioning and dewatering of biosolids  

Microsoft Academic Search

Laboratory anaerobic and aerobic digestion studies were conducted using waste activated sludges from two municipal wastewater treatment plants in order to gain insight into the mechanisms of floc destruction that account for changes in sludge conditioning and dewatering properties when sludges undergo anaerobic and aerobic digestion. Batch digestion studies were conducted at 20°C and the dewatering properties, solution biopolymer concentration

John T. Novak; Mary E. Sadler; Sudhir N. Murthy

2003-01-01

147

Anaerobic digestibility of marine microalgae Phaeodactylum tricornutum in a lab-scale anaerobic membrane bioreactor.  

PubMed

The biomass of industrially grown Phaeodactylum tricornutum was subjected in a novel way to bio-methanation at 33°C, i.e., in an anaerobic membrane bioreactor (AnMBR) at a hydraulic retention time of 2.5 days, at solid retention times of 20 to 10 days and at loading rates in the range of 2.6-5.9 g biomass-COD L(-1) day(-1) with membrane fluxes ranging from 1 to 0.8 L m(-2) h(-1). The total COD recovered as biogas was in the order of 52%. The input suspension was converted to a clear effluent rich in total ammonium nitrogen (546 mg TAN L(-1)) and phosphate (141 mg PO(4)-P L(-1)) usable as liquid fertilizer. The microbial community richness, dynamics, and organization in the reactor were interpreted using the microbial resource management approach. The AnMBR communities were found to be moderate in species richness and low in dynamics and community organization relative to UASB and conventional CSTR sludges. Quantitative polymerase chain reaction analysis revealed that Methanosaeta sp. was the dominant acetoclastic methanogen species followed by Methanosarcina sp. This work demonstrated that the use of AnMBR for the digestion of algal biomass is possible. The fact that some 50% of the organic matter is not liquefied means that the algal particulates in the digestate constitute a considerable fraction which should be valorized properly, for instance as slow release organic fertilizer. Overall, 1 kg of algae dry matter (DM) could be valorized in the form of biogas ( euro 2.07), N and P in the effluent (euro 0.02) and N and P in the digestate (euro 0.04), thus totaling about euro 2.13 per kilogram algae DM. PMID:22005739

Zamalloa, Carlos; De Vrieze, Jo; Boon, Nico; Verstraete, Willy

2012-01-01

148

COMPARATIVE EVALUATION OF MESOPHILIC AND THERMOPHILIC ANAEROBIC DIGESTION. PHASE 2. STEADY STATE STUDIES  

EPA Science Inventory

A study was conducted of the relative performance of anaerobic digestion systems under mesophilic and thermophilic conditions. Fifty liter laboratory scale digesters were fed primary sludge from the Allentown, PA Waste Water Treatment Plant. Long-term, steady-state performance da...

149

Decentralized direct adaptive Fuzzy-Neural control of an anaerobic digestion bioprocess plant  

Microsoft Academic Search

The paper proposed to use Fuzzy-Neural Multi-Model (FNMM) identification and control system for decentralized control of distributed parameter anaerobic wastewater treatment digestion bioprocess, carried out in a fixed bed and a recirculation tank. The distributed parameter analytical model of the digestion bioprocess is reduced to a lumped system using the orthogonal collocation method, applied in three collocation points (plus the

Ieroham S. Baruch; Rosalba Galvan-Guerra

2008-01-01

150

Decentralized Adaptive Fuzzy-Neural Control of an Anaerobic Digestion Bioprocess Plant  

Microsoft Academic Search

The paper proposed to use recurrent Fuzzy-Neural Multi-Model (FNMM) identifier for decentralized identification of a distributed parameter anaerobic wastewater treatment digestion bioprocess, carried out in a fixed bed and a recirculation tank. The distributed parameter analytical model of the digestion bioprocess is used as a plant data generator. It is reduced to a lumped system using the orthogonal collocation method,

Ieroham S. Baruch; Rosalba Galvan-guerra

2009-01-01

151

ENERGY AND ECONOMIC ASSESSMENT OF ANAEROBIC DIGESTERS AND BIOFUELS FOR RURAL WASTE MANAGEMENT  

EPA Science Inventory

A technological and socioeconomic assessment of anaerobic digester feasibility for small to mid-size livestock operations was undertaken. Three full scale digesters and one pilot scale facility were under various degrees of monitoring and evaluation to assess design and operation...

152

Mixing in large-scale municipal solid waste-sewage sludge anaerobic digesters  

SciTech Connect

Operational problems were encountered in the anaerobic digestion of municipal solid waste and municipal sewage sludge in a 10.7-m-diam. digester. Use on increased mixing power would probably improve the operability of the system, but at the expense of increased energy costs.

James, S.C. (Environmental Protection Agency, Cincinnati, OH); Wiles, C.C.; Swartzbaugh, J.T.; Smith, R.B.

1980-01-01

153

The environmental sustainability of anaerobic digestion as a biomass valorization technology.  

PubMed

This paper studies the environmental sustainability of anaerobic digestion from three perspectives. First, reference electricity is compared to electricity production from domestic organic waste and energy crop digestion. Second, different digester feed possibilities in an agricultural context are studied. Third, the influence of applying digestate as fertilizer is investigated. Results highlight that biomass is converted at a rational exergy (energy) efficiency ranging from 15.3% (22.6) to 33.3% (36.0). From a life cycle perspective, a saving of over 90% resources is achieved in most categories when comparing biobased electricity to conventional electricity. However, operation without heat valorization results in 32% loss of this performance while using organic waste (domestic and agricultural residues) as feedstock avoids land resources. The use of digestate as a fertilizer is beneficial from a resource perspective, but causes increased nitrogen and methane emissions, which can be reduced by 50%, making anaerobic digestion an environmentally competitive bioenergy technology. PMID:22864176

De Meester, Steven; Demeyer, Jens; Velghe, Filip; Peene, Andy; Van Langenhove, Herman; Dewulf, Jo

2012-10-01

154

Anaerobic digestion of Jatropha curcas L. press cake and effects of an iron-additive.  

PubMed

Oil production from Jatropha curcas L. seeds generates large amounts of Jatropha press cake (JPC) which can be utilized as a substrate for biogas production. The objective of this work was to investigate anaerobic mono-digestion of JPC and the effects of an iron additive (IA) on gas quality and process stability during the increase of the organic loading rate (OLR). With the increase of the OLR from 1.3 to 3.2 g(VS) L(-1) day(-1), the biogas yield in the reference reactor (RR) without IA decreased from 512 to 194 L(N) kg(VS) (-1) and the CH? concentration decreased from 69.3 to 44.4%. In the iron additive reactor (IAR), the biogas yield decreased from 530 to 462 L(N) kg(VS) (-1) and the CH? concentration decreased from 69.4 to 61.1%. The H?S concentration in the biogas was reduced by addition of the IA to values below 258 ppm in the IAR while H?S concentration in the RR increased and exceeded the detection limit of 5000 ppm. The acid capacity (AC) in the RR increased to more than 20 g L(-1), indicating an accumulation of organic acids caused by process instability. AC values in the IAR remained stable at values below 5 g L(-1). The results demonstrate that JPC can be used as sole substrate for anaerobic digestion up to an OLR of 2.4 g(VS) l(-1) day(-1). The addition of IA has effectively decreased the H(2)S content in the biogas and has improved the stability of the anaerobic process and the biogas quality. PMID:21987413

Schmidt, Thomas

2011-11-01

155

Thermophilic anaerobic digestion of pulp and paper mill primary sludge and co-digestion of primary and secondary sludge.  

PubMed

Anaerobic digestion of pulp and paper mill primary sludge and co-digestion of primary and secondary sludge were studied for the first time in semi-continuously fed continuously stirred tank reactors (CSTR) in thermophilic conditions. Additionally, in batch experiments, methane potentials of 210 and 230 m³CH?/t volatile solids (VS)(added) were obtained for primary, and 50 and 100 m³CH?/tVS(added) for secondary sludge at 35 °C and 55 °C, respectively. Anaerobic digestion of primary sludge was shown to be feasible with organic loading rates (OLR) of 1-1.4 kgVS/m³d and hydraulic retention times (HRT) of 16-32 d resulting in methane yields of 190-240 m³CH?/tVS(fed). Also the highest tested OLR of 2 kgVS/m³d and the shortest HRT of 14-16 d could be feasible, if pH stability is confirmed. Co-digestion of primary and secondary sludge with an OLR of 1 kgVS/m³d and HRTs of 25-31 d resulted in methane yields of 150-170 m³CH?/tVS(fed). In the digestion processes, cellulose and hemicellulose degraded while lignin did not. pH adjustment and nitrogen deficiency needs to be considered when planning anaerobic digestion of pulp and paper mill wastewater sludges. PMID:22795957

Bayr, Suvi; Rintala, Jukka

2012-10-01

156

Mesophilic anaerobic digestion of waste activated sludge: influence of the solid retention time in the wastewater treatment process  

Microsoft Academic Search

The performance of mesophilic anaerobic digesters of four large Italian wastewater treatment plants without primary sedimentation were studied. Only the waste activated sludge is stabilised by means of the mesophilic (35–37°C) anaerobic digestion process. The anaerobic digesters generally worked with a hydraulic retention time in a range of 20–40 days and an organic loading rate of some 1kgVS\\/mreactor3day. The solids

David Bolzonella; Paolo Pavan; Paolo Battistoni; Franco Cecchi

2005-01-01

157

Evaluation of a microwave-heating anaerobic digester treating municipal secondary sludge.  

PubMed

This work experimentally determined the effect of microwave irradiation on the anaerobic digestion of municipal secondary sludge in semi-continuous mesophilic digesters at hydraulic retention times (HRT) of 15, 10 and 5 days when microwaves were used as a heating source. A microwave-heating anaerobic digester (MHAD) was compared with a water-heating reactor (control). Biogas production increased in both digesters as the HRT decreased except for the control with a HRT of 5 days. Improvement in removal efficiency of volatile solid and biogas production of the MHAD relative to the control increased as the HRT decreased. The results show that the MHAD was more effective than the control in increasing mesophilic anaerobic biodegradability and biogas production treating secondary sludge. PMID:23837339

Jang, Joo-Hyun; Ahn, Johng-Hwa

2013-01-01

158

Retooling the ethanol industry: thermophilic anaerobic digestion of thin stillage for methane production and pollution prevention.  

PubMed

Anaerobic digestion of corn ethanol thin stillage was tested at thermophilic temperature (55 degrees C) with two completely stirred tank reactors. The thin stillage wastestream was organically concentrated with 100 g/L total chemical oxygen demand and 60 g/L volatiles solids and a low pH of approximately 4.0. Steady-state was achieved at 30-, 20-, and 15-day hydraulic retention times (HRTs) and digester failure at a 12-day HRT. Significant reduction of volatile solids was achieved, with a maximum reduction (89.8%) at the 20-day HRT. Methane yield ranged from 0.6 to 0.7 L methane/g volatile solids removed during steady-state operation. Effluent volatile fatty acids below 200 mg/L as acetic acid were achieved at 20- and 30-day HRTs. Ultrasonic pretreatment was used for one digester, although no significant improvement was observed. Ethanol plant natural gas consumption could be reduced 43 to 59% with the methane produced, while saving an estimated $7 to $17 million ($10 million likely) for a facility producing 360 million L ethanol/y. PMID:18330219

Schaefer, Scott H; Sung, Shihwu

2008-02-01

159

Effect of seasonal changes in quantities of biowaste on full scale anaerobic digester performance  

SciTech Connect

A 750,000 l digester located in Roppen/Austria was studied over a 2-year period. The concentrations and amounts of CH{sub 4}, H{sub 2}, CO{sub 2} and H{sub 2}S and several other process parameters like temperature, retention time, dry weight and input of substrate were registered continuously. On a weekly scale the pH and the concentrations of NH{sub 4}{sup +}-N and volatile fatty acids (acetic, butyric, iso-butyric, propionic, valeric and iso-valeric acid) were measured. The data show a similar pattern of seasonal gas production over 2 years of monitoring. The consumption of VFA and not the hydrogenotrophic CH{sub 4} production appeared to be the limiting factor for the investigated digestion process. Whereas the changes in pH and the concentrations of most VFA did not correspond with changes in biogas production, the ratio of acetic to propionic acid and the concentration of H{sub 2} appeared to be useful indicators for reactor performance. However, the most influential factors for the anaerobic digestion process were the amount and the quality of input material, which distinctly changed throughout the year.

Illmer, P. [University of Innsbruck, Institute of Microbiology, Technikerstr. 25, A-6020 Innsbruck (Austria)], E-mail: Paul.Illmer@uibk.ac.at; Gstraunthaler, G. [Abfallbeseitigungsverband Westtirol, Breite Mure, A-6426 Roppen (Austria)

2009-01-15

160

Feasibility assessment tool for urban anaerobic digestion in developing countries.  

PubMed

This paper describes a method developed to support feasibility assessments of urban anaerobic digestion (AD). The method not only uses technical assessment criteria but takes a broader sustainability perspective and integrates technical-operational, environmental, financial-economic, socio-cultural, institutional, policy and legal criteria into the assessment tool developed. Use of the tool can support decision-makers with selecting the most suitable set-up for the given context. The tool consists of a comprehensive set of questions, structured along four distinct yet interrelated dimensions of sustainability factors, which all influence the success of any urban AD project. Each dimension answers a specific question: I) WHY? What are the driving forces and motivations behind the initiation of the AD project? II) WHO? Who are the stakeholders and what are their roles, power, interests and means of intervention? III) WHAT? What are the physical components of the proposed AD chain and the respective mass and resource flows? IV) HOW? What are the key features of the enabling or disabling environment (sustainability aspects) affecting the proposed AD system? Disruptive conditions within these four dimensions are detected. Multi Criteria Decision Analysis is used to guide the process of translating the answers from six sustainability categories into scores, combining them with the relative importance (weights) attributed by the stakeholders. Risk assessment further evaluates the probability that certain aspects develop differently than originally planned and assesses the data reliability (uncertainty factors). The use of the tool is demonstrated with its application in a case study for Bahir Dar in Ethiopia. PMID:23722149

Lohri, Christian Riuji; Rodi?, Ljiljana; Zurbrügg, Christian

2013-09-15

161

Navigating wastewater energy recovery strategies: a life cycle comparison of anaerobic membrane bioreactor and conventional treatment systems with anaerobic digestion.  

PubMed

The objective of this study was to evaluate emerging anaerobic membrane bioreactor (AnMBR) technology in comparison with conventional wastewater energy recovery technologies. Wastewater treatment process modeling and systems analyses were combined to evaluate the conditions under which AnMBR may produce more net energy and have lower life cycle environmental emissions than high rate activated sludge with anaerobic digestion (HRAS+AD), conventional activated sludge with anaerobic digestion (CAS+AD), and an aerobic membrane bioreactor with anaerobic digestion (AeMBR+AD). For medium strength domestic wastewater treatment under baseline assumptions at 15 °C, AnMBR recovered 49% more energy as biogas than HRAS+AD, the most energy positive conventional technology considered, but had significantly higher energy demands and environmental emissions. Global warming impacts associated with AnMBR were largely due to emissions of effluent dissolved methane. For high strength domestic wastewater treatment, AnMBR recovered 15% more net energy than HRAS+AD, and the environmental emissions gap between the two systems was reduced. Future developments of AnMBR technology in low energy fouling control, increased flux, and management of effluent methane emissions would make AnMBR competitive with HRAS+AD. Rapid advancements in AnMBR technology must continue to achieve its full economic and environmental potential as an energy recovery strategy for domestic wastewater. PMID:24742289

Smith, Adam L; Stadler, Lauren B; Cao, Ling; Love, Nancy G; Raskin, Lutgarde; Skerlos, Steven J

2014-05-20

162

Growth of Chlorella vulgaris on sugarcane vinasse: the effect of anaerobic digestion pretreatment.  

PubMed

Microalgae farming has been identified as the most eco-sustainable solution for producing biodiesel. However, the operation of full-scale plants is still limited by costs and the utilization of industrial and/or domestic wastes can significantly improve economic profits. Several waste effluents are valuable sources of nutrients for the cultivation of microalgae. Ethanol production from sugarcane, for instance, generates significant amounts of organically rich effluent, the vinasse. After anaerobic digestion treatment, nutrient remaining in such an effluent can be used to grow microalgae. This research aimed to testing the potential of the anaerobic treated vinasse as an alternative source of nutrients for culturing microalgae with the goal of supplying the biodiesel industrial chain with algal biomass and oil. The anaerobic process treating vinasse reached a steady state at about 17 batch cycles of 24 h producing about 0.116 m(3)CH4 kgCODvinasse (-1). The highest productivity of Chlorella vulgaris biomass (70 mg l(-1) day(-1)) was observed when using medium prepared with the anaerobic digester effluent. Lipid productivity varied from 0.5 to 17 mg l(-1) day(-1). Thus, the results show that it is possible to integrate the culturing of microalgae with the sugarcane industry by means of anaerobic digestion of the vinasse. There is also the advantageous possibility of using by-products of the anaerobic digestion such as methane and CO2 for sustaining the system with energy and carbon source, respectively. PMID:24013860

Marques, Sheyla Santa Isabel; Nascimento, Iracema Andrade; de Almeida, Paulo Fernando; Chinalia, Fábio Alexandre

2013-12-01

163

The effect of iron and aluminium for phosphorus removal on anaerobic digestion and organic sulfur generation.  

PubMed

The addition of iron or aluminium into activated sludge basins for phosphorus removal is likely to impact both the efficiency of the anaerobic digestion process and the generation of odor-causing compounds following digestion and dewatering. In this study, the impact of iron and aluminium addition on digestion and odor-causing compounds was investigated by using batch digestion of combined primary and waste activated sludge. It was found that aluminium addition resulted in a decrease in volatile solids destruction by anaerobic digestion of approximately 2%. Of the 7 sludges tested, 5 showed a small increase in volatile solids destruction after iron addition. With regard to the generation of organic sulfur odors from the dewatered sludge cakes, both iron and aluminium reduced odor-causing gases except for one sludge that had already received iron for phosphorus control in the full-scale process. It appears that iron and aluminium addition will benefit odor control. PMID:20651448

Novak, John T; Park, Chang Min

2010-01-01

164

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

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Korean food waste was found to contain low level of trace elements. Black-Right-Pointing-Pointer Stable anaerobic digestion of food waste was achieved by adding trace elements. Black-Right-Pointing-Pointer Iron played an important role in anaerobic digestion of food waste. Black-Right-Pointing-Pointer 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{sub 4}/g VS{sub 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.

Zhang Lei, E-mail: wxzyfx@yahoo.com [Key Laboratory of Industrial Ecology and Environmental Engineering, School of Environmental Science and Technology, Dalian University of Technology, Linggong Road 2, Dalian 116024 (China); Jahng, Deokjin, E-mail: djahng@mju.ac.kr [Department of Environmental Engineering and Biotechnology, Myongji University, San 38-2, Namdong, Cheoin-Gu, Yongin, Gyeonggi-Do 449-728 (Korea, Republic of)

2012-08-15

165

Performance assessment of two-stage anaerobic digestion of kitchen wastes.  

PubMed

This study is aimed at investigating the performance of the two-phase anaerobic digestion of kitchen wastes in a lab-scale setup. The semi-continuous experiment showed that the two-phase anaerobic digestion of kitchen wastes had a bioconversion rate of 83%, biogas yield of 338 mL x (g chemical oxygen demand (COD))(-1) and total solid conversion of 63% when the entire two-phase anaerobic digestion process was subjected to an organic loading rate (OLR) of 10.7 g x (L d)(-1). In the hydrolysis-acidogenesis process, the efficiency of solubilization decreased from 72.6% to 41.1%, and the acidogenesis efficiency decreased from 31.8% to 17.8% with an increase in the COD loading rate. On the other hand, the performance of the subsequent methanogenic process was not susceptible to the increase in the feeding COD loading rate in the hydrolysis-acidogenesis stage. Lactic acid was one of the main fermentation products, accounting for over 40% of the total soluble COD in the fermentation liquid. The batch experiments indicated that the lactic acid was the earliest predominant fermentation product, and distributions of fermentation products were pH dependent. Results showed that increasing the feeding OLR of kitchen wastes made the two-stage anaerobic digestion process more effective. Moreover, there was a potential improvement in the performance of anaerobic digestion of kitchen wastes with a corresponding improvement in the hydrolysis process. PMID:24701925

Bo, Zhang; Pin-Jing, He

2014-01-01

166

Phosphorus release mechanisms during digestion of EBPR sludge under anaerobic, anoxic and aerobic conditions.  

PubMed

Three laboratory-scale digesters were operated in parallel under anaerobic, anoxic and aerobic conditions to reveal the release mechanisms of phosphorus when digesting enhanced biological phosphorus removal (EBPR) sludge. The variation rates of the parameters associated with phosphorus release were calculated and compared with that of a typical EBPR anaerobic process. The results show that both phosphorus-accumulating organisms (PAOs) and denitrifying phosphorus-accumulating organisms (DPAOs) played important roles in the phosphorus release during the digestion processes. Under anaerobic conditions, the PAOs hydrolyzed internal polyphosphorus (poly-P) into PO4(3-)-P concurrent with synthesis of polyhydroxyalkanoates (PHA). Under anoxic or aerobic conditions, PAOs and/or DPAOs assimilated part of the PO4(3-)-P from the digestive liquid using nitrate or oxygen as terminal electron acceptors. Nevertheless, the biological activities of PAOs under anaerobic conditions and DPAOs under anoxic conditions were limited. Moreover, it was the biomass hydrolysis degree that determined the phosphorus release capacity of the sludge, regardless of whether anaerobic, anoxic or aerobic conditions were adopted. Assuming that nitrate was the sole electron acceptor during anoxic digestion of EBPR biomass, the relationship between the consumption of nitrate and uptake of PO4(3-)-P associated with the denitrifying phosphorus removal (DPR) can be expressed as ?P = 0.11 × ?N. PMID:23656937

Bi, Dongsu; Guo, Xiaopin; Chen, Donghui

2013-01-01

167

Blending anaerobic co-digestates: synergism and economics.  

PubMed

Co-digestion is the process in which wastes from various sources are treated together. Therefore, more organic carbon is added to make efficient use of existing digesters. The objectives of this study were to compare potential co-digestates, determine synergistic and antagonistic co-digestion outcomes and estimate economic benefits for preliminary screening. Over 80 wastes were identified from 54 facilities within 160 km of an existing municipal digester. Synergistic, antagonistic and neutral co-digestion outcomes were observed for the various wastes. A simple economic comparison resulted in the greatest potential benefits for four co-digestates: yeast flavorings production waste, meat production dissolved air flotation float, acid whey from cheese production and thin stillage from corn ethanol production. Performance was investigated using bench-scale digesters receiving primary sludge with and without co-digestates. Methane production rates were 105 and 66% higher when co-digestates were present, but were anticipated to increase only 57 and 23% due to the additional chemical oxygen demand. Therefore, significant synergistic outcomes were observed during co-digestion. Co-digestion of the most promising wastes with primary sludge in full scale was estimated to generate enough electricity to power more than 2,500 houses. PMID:22049719

Navaneethan, N; Topczewski, P; Royer, S; Zitomer, D

2011-01-01

168

Comparison of sludge digestion under aerobic and anaerobic conditions with a focus on the degradation of proteins at mesophilic temperature.  

PubMed

Aerobic and anaerobic digestion are popular methods for the treatment of waste activated sludge. However, the differences in degradation of sludge during aerobic and anaerobic digestion remain unclear. In this study, the sludge degradation during aerobic and anaerobic digestion was investigated at mesophilic temperature, focused on protein based on the degradation efficiency and degree of humification. The duration of aerobic and anaerobic digestion was about 90 days. The final degradation efficiency of volatile solid was 66.1 ± 1.6% and 66.4 ± 2.4% under aerobic and anaerobic conditions, respectively. The final degradation efficiency of protein was 67.5 ± 1.4% and 65.1 ± 2.6% under aerobic and anaerobic conditions, respectively. The degradation models of volatile solids were consistent with those of protein under both aerobic and anaerobic conditions. The solubility of protein under aerobic digestion was greater than that under anaerobic digestion. Moreover, the humification index of dissolved organic matter of aerobic digestion was greater than that during anaerobic digestion. PMID:23685650

Shao, Liming; Wang, Tianfeng; Li, Tianshui; Lü, Fan; He, Pinjing

2013-07-01

169

Treatment of municipal landfill leachate using a combined anaerobic digester and activated sludge system  

SciTech Connect

The main objective of this study was to assess the feasibility of treating sanitary landfill leachate using a combined anaerobic and activated sludge system. A high-strength leachate from Shiraz municipal landfill site was treated using this system. A two-stage laboratory-scale anaerobic digester under mesophilic conditions and an activated sludge unit were used. Landfill leachate composition and characteristics varied considerably during 8 months experiment (COD concentrations of 48,552-62,150 mg/L). It was found that the system could reduce the COD of the leachate by 94% at a loading rate of 2.25 g COD/L/d and 93% at loading rate of 3.37 g COD/L/d. The anaerobic digester treatment was quite effective in removing Fe, Cu, Mn, and Ni. However, in the case of Zn, removal efficiency was about 50%. For the rest of the HMs the removal efficiencies were in the range 88.8-99.9%. Ammonia reduction did not occur in anaerobic digesters. Anaerobic reactors increased alkalinity about 3.2-4.8% in the 1st digester and 1.8-7.9% in the 2nd digester. In activated sludge unit, alkalinity and ammonia removal efficiency were 49-60% and 48.6-64.7%, respectively. Methane production rate was in the range of 0.02-0.04, 0.04-0.07, and 0.02-0.04 L/g COD{sub rem} for the 1st digester, the 2nd digester, and combination of both digesters, respectively; the methane content of the biogas varied between 60% and 63%.

Kheradmand, S. [Department of Civil and Environmental Engineering, University of Shiraz, Shiraz 7134851156 (Iran, Islamic Republic of); Karimi-Jashni, A., E-mail: akarimi@shirazu.ac.i [Department of Civil and Environmental Engineering, University of Shiraz, Shiraz 7134851156 (Iran, Islamic Republic of); Sartaj, M. [Department of Civil Engineering, Isfahan University of Technology, Isfahan 841568311 (Iran, Islamic Republic of)

2010-06-15

170

Economic and environmental analysis of four different configurations of anaerobic digestion for food waste to energy conversion using LCA for: a food service provider case study.  

PubMed

The US disposes of more than 34 million tons of food waste in landfills per year. As this food waste decomposes it generates methane gas and negatively contributes to global warming. Diverting theses organic food wastes from landfills and to emerging technologies will prevent these wastes and greenhouse gas emissions while at the same time generating a source renewable energy by collecting the emitted gases. From a waste prevention standpoint, instead of the food waste decomposing at local landfills, it is being converted into an energy source and the by-product may be used as a fertilizer (Fine and Hadas, 2012). The purpose of this study was to compare four different configurations of anaerobic digestion of organic waste to energy technologies from an economic, energy, and emissions standpoint using LCA via a case study at a large food services provider in Northwest Ohio, USA. The technologies studied included two-stage anaerobic digestion system using ultrasound pre-treating, two stage continuous combined thermophilic acidogenic hydrogenesis and mesophilic with recirculation of the digested sludge, long-term anaerobic digestion of food waste stabilized by trace elements, and single stage anaerobic digestion. Using LCA, these scenarios were compared to landfill disposal of the food waste. The findings from the case study indicated that implementing on-site waste to energy systems will result in lower operation costs and lower environmental impacts. In addition, a standardized environmental and economic comparison of competing food waste to energy technologies is provided. PMID:23583791

Franchetti, Matthew

2013-07-15

171

Effects of total ammonia nitrogen concentration on solid-state anaerobic digestion of corn stover.  

PubMed

The inhibitive effect of total ammonia nitrogen (TAN) (including NH3 and NH4(+)) on solid-state anaerobic digestion of corn stover was investigated in batch reactors at 37°C. The highest methane yield of 107.0 L/kg VS(feed) was obtained at a TAN concentration of 2.5 g/kg (based on total weight). TAN concentrations greater than 2.5 g/kg resulted in decreased methane yields, with a 50% reduction observed at a concentration of 6.0 g/kg. Reduced reaction rates and microbial activities for hydrolysis of cellulose and methanogenesis from acetate were observed at TAN concentrations higher than 4.3 g/kg. Strong ammonia stress was indicated at butyrate concentrations higher than 300 mg/kg. Result showed that the effluent of liquid anaerobic digestion can provide enough nitrogen for solid-state anaerobic digestion of corn stover. PMID:23880129

Wang, Zhongjiang; Xu, Fuqing; Li, Yebo

2013-09-01

172

Evaluating a model of anaerobic digestion of organic wastes through system identification  

SciTech Connect

Anaerobic digestion of the organic fraction of municipal solid waste (MSW), on its own or co-digested with primary sewage sludge (PSS), produces high quality biogas, suitable as renewable energy. Parameter estimation and evaluation of a two-stage mathematical model of the anaerobic co-digestion of the organic fraction of MSW and PSS are described. Measured data are from a bench scale laboratory experiment using a continuously stirred tank reactor and operated at 36 C for 115 days. The two-stage model simulates acidogenesis and methanogenesis, including ammonia inhibition. Model parameters are estimated using an output error, Levenberg-Marquardt (LM) algorithm. Sensitivity of the estimated parameter values and the model outputs to non-estimated model parameters and measurement errors are evaluated. The estimated mathematical model successfully predicts the performance of the anaerobic reactor. Sensitivity results provide guidance for improving the model structure and experimental procedures.

Anex, R.P.; Kiely, G.

1999-07-01

173

Rapid start-up of thermophilic anaerobic digestion with the turf fraction of MSW as inoculum.  

PubMed

This study aims to determine suitable start-up conditions and inoculum sources for thermophilic anaerobic digestion. Within days of incubation MSW at 55°C, methane was produced at a high rate. In an attempt to narrow down which components of typical MSW contained the thermophilic methanogens, vacuum cleaner dust, banana peel, kitchen waste, and garden waste were tested as inoculum for thermophilic methanogenesis with acetate as the substrate. Results singled out grass turf as the key source of thermophilic acetate degrading methanogenic consortia. Within 4 days of anaerobic incubation (55°C), anaerobically incubated grass turf samples produced methane accompanied by acetate degradation enabling successful start-up of thermophilic anaerobic digestion. Other essential start-up conditions are specified. Stirring of the culture was not conducive for successful start-up as it resulted specifically in propionate accumulation. PMID:21723117

Suwannoppadol, Suwat; Ho, Goen; Cord-Ruwisch, Ralf

2011-09-01

174

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

PubMed

Syngas is produced by thermal gasification of both nonrenewable and renewable sources including biomass and coal, and it consists mainly of CO, CO2, and H2. In this paper we aim to bioconvert CO in the syngas to CH4. A novel technology for simultaneous sewage sludge treatment and CO biomethanation in an anaerobic reactor was presented. Batch experiments showed that CO was inhibitory to methanogens, but not to bacteria, at CO partial pressure between 0.25 and 1 atm under thermophilic conditions. During anaerobic digestion of sewage sludge supplemented with CO added through a hollow fiber membrane (HFM) module in continuous thermophilic reactors, CO did not inhibit the process even at a pressure as high as 1.58 atm inside the HFM, due to the low dissolved CO concentration in the liquid. Complete consumption of CO was achieved with CO gas retention time of 0.2 d. Results from high-throughput sequencing analysis showed clear differences of the microbial community structures between the samples from liquid and biofilm on the HFM in the reactor with CO addition. Species close to Methanosarcina barkeri and Methanothermobacter thermautotrophicus were the two main archaeal species involved in CO biomethanation. However, the two species were distributed differently in the liquid phase and in the biofilm. Although the carboxidotrophic activities test showed that CO was converted by both archaea and bacteria, the bacterial species responsible for CO conversion are unknown. PMID:23952148

Luo, Gang; Wang, Wen; Angelidaki, Irini

2013-09-17

175

Kinetic analysis of anaerobic digestion of cattail by rumen microbes in a modified UASB reactor  

Microsoft Academic Search

The kinetics of anaerobic digestion of cattail by rumen microbes in a modified upflow anaerobic sludge blanket (UASB) reactor was systematically analyzed in this study. The Monod and first-order equations were combined to develop kinetic models to describe the substrate degradation, microbial growth and product formation. At an influent cattail concentration (volatile solids) of 12.1g\\/L, hydraulic retention time of 0.75

Zhen-Hu Hu; Han-Qing Yu; Zheng-Bo Yue; Hideki Harada; Yu-You Li

2007-01-01

176

Methanogenic population dynamics during start-up of anaerobic digesters treating municipal solid waste and biosolids  

Microsoft Academic Search

An aggressive start-up strategy was used to initiate codigestion in two anaerobic, continuously mixed bench-top reactors at mesophilic (37°C) and ther- mophilic (55°C) conditions. The digesters were inocu- lated with mesophilic anaerobic sewage sludge and cattle manure and were fed a mixture of simulated mu- nicipal solid waste and biosolids in proportions that re- flect U.S. production rates. The design

Matt E. Griffin; Katherine D. McMahon; Roderick I. Mackie; Lutgarde Raskin

1998-01-01

177

Treatment of municipal landfill leachate using a combined anaerobic digester and activated sludge system  

Microsoft Academic Search

The main objective of this study was to assess the feasibility of treating sanitary landfill leachate using a combined anaerobic and activated sludge system. A high-strength leachate from Shiraz municipal landfill site was treated using this system. A two-stage laboratory-scale anaerobic digester under mesophilic conditions and an activated sludge unit were used. Landfill leachate composition and characteristics varied considerably during

S. Kheradmand; A. Karimi-Jashni; M. Sartaj

2010-01-01

178

Anaerobic digestion of the liquid fraction of dairy manure in pilot plant for biogas production: residual methane yield of digestate.  

PubMed

The performance of the only dairy manure biogas plant in Cantabria (Northern coast of Spain) was evaluated in terms of liquid-solid separation and anaerobic digestion of the liquid fraction. Screened liquid fraction was satisfactorily treated in a CSTR digester at HRTs from 20 to 10 days with organic loading rates ranging from 2.0 to 4.5 kg VS/(m(3)d). Stable biogas productions from 0.66 to 1.47 m(3)/(m(3)d) were achieved. Four anaerobic effluents collected from the digester at different HRTs were analyzed to measure their residual methane potentials, which ranged from 12.7 to 102.4 L/gVS. These methane potentials were highly influenced by the feed quality and HRT of the previous CSTR anaerobic digestion process. Biomethanization of the screened liquid fraction of dairy manure from intensive farming has the potential to provide up to 2% of total electrical power in the region of Cantabria. PMID:21612905

Rico, Carlos; Rico, José Luis; Tejero, Iñaki; Muñoz, Noelia; Gómez, Beatriz

2011-01-01

179

Application of the IWA ADM1 model to simulate anaerobic digester dynamics using a concise set of practical measurements  

Microsoft Academic Search

This paper demonstrates how a complex model like the IWA Anaerobic Digestion Model no. 1 can be applied to gain more insight in the anaerobic process and particularly in the dynamics of the digester. The illustrated modelling approach avoids laborious measurements to characterise the influent according the extensive list of components defined in the model. It rather uses the model

U. Zaher; J. Rodríguez; A. Franco; P. A. Vanrolleghem

180

Potential for energy generation from anaerobic digestion of food waste in Australia.  

PubMed

Published national and state reports have revealed that Australia deposits an average of 16 million Mg of solid waste into landfills yearly, of which approximately 12.6% is comprised of food. Being highly biodegradable and possessing high energy content, anaerobic digestion offers an attractive treatment option alternative to landfilling. The present study attempted to identify the theoretical maximum benefit of food waste digestion in Australia with regard to energy recovery and waste diversion from landfills. The study also assessed the scope for anaerobic process to utilize waste for energy projects through various case study scenarios. Results indicated anaerobic digestion of total food waste generated across multiple sites in Australia could generate 558 453 dam(3) of methane which translated to 20.3 PJ of heating potential or 1915 GWe in electricity generation annually. This would contribute to 3.5% of total current energy supply from renewable sources. Energy contribution from anaerobic digestion of food waste to the total energy requirement in Australia remains low, partially due to the high energy consumption of the country. However its appropriateness in low density regions, which are prevalent in Australia, may allow digesters to have a niche application in the country. PMID:23381970

Lou, Xian Fang; Nair, Jaya; Ho, Goen

2013-03-01

181

Differences in volatile methyl siloxane (VMS) profiles in biogas from landfills and anaerobic digesters and energetics of VMS transformations.  

PubMed

The objectives of this study were to compare the types and levels of volatile methyl siloxanes (VMS) present in biogas generated in the anaerobic digesters and landfills, evaluate the energetics of siloxane transformations under anaerobic conditions, compare the conditions in anaerobic digesters and municipal solid waste (MSW) landfills which result in differences in siloxane compositions. Biogas samples were collected at the South District Wastewater Treatment Plant and South Dade Landfill in Miami, Florida. In the digester gas, D4 and D5 comprised the bulk of total siloxanes (62% and 27%, respectively) whereas in the landfill gas, the bulk of siloxanes were trimethylsilanol (TMSOH) (58%) followed by D4 (17%). Presence of high levels of TMSOH in the landfill gas indicates that methane utilization may be a possible reaction mechanism for TMSOH formation. The free energy change for transformation of D5 and D4 to TMSOH either by hydrogen or methane utilization are thermodynamically favorable. Either hydrogen or methane should be present at relatively high concentrations for TMSOH formation which explains the high levels present in the landfill gas. The high bond energy and bond distance of the Si-O bond, in view of the atomic sizes of Si and O atoms, indicate that Si atoms can provide a barrier, making it difficult to break the Si-O bonds especially for molecules with specific geometric configurations such as D4 and D5 where oxygen atoms are positioned inside the frame formed by the large Si atoms which are surrounded by the methyl groups. PMID:25160660

Tansel, Berrin; Surita, Sharon C

2014-11-01

182

Phase distribution and removal of pharmaceuticals and personal care products during anaerobic sludge digestion.  

PubMed

The fate and removal of 48 pharmaceuticals and personal care products (PPCPs) during anaerobic digestion of sewage sludge were investigated in four full-scale sewage treatment plants (STPs). We measured concentrations in both the liquid and solid phases of the sludge to compare the distribution ratios (Kd) between phases before and after digestion. The results showed changes in Kd values of PPCPs with carboxyl or amino functional groups, probably due to a shift of dissociation equilibrium with the increase in pH. Sulfamethoxazole and trimethoprim were almost completely degraded (>90%); triclosan, triclocarban, and ofloxacin were moderately degraded (around 30-50%); but carbamazepine was not eliminated. To our knowledge, this is the first report that shows (i) the occurrence and removal of several tens of PPCPs by anaerobic sludge digestion in full-scale municipal STPs and (ii) the change of distribution between the liquid and solid phases during digestion. PMID:23774781

Narumiya, Masanori; Nakada, Norihide; Yamashita, Naoyuki; Tanaka, Hiroaki

2013-09-15

183

Gas in the Digestive Tract  

MedlinePLUS

... and small intestine do not fully digest some carbohydrates—sugars, starches, and fiber found in many foods. ... intestine to the large intestine. Once there, undigested carbohydrates are broken down by bacteria in the large ...

184

Modeling of two-phase anaerobic process treating traditional Chinese medicine wastewater with the IWA Anaerobic Digestion Model No. 1.  

PubMed

The aim of the study was to implement a mathematical model to simulate two-phase anaerobic digestion (TPAD) process which consisted of an anaerobic continuous stirred tank reactor (CSTR) and an upflow anaerobic sludge blanket (UASB) reactor in series treating traditional Chinese medicine (TCM) wastewater. A model was built on the basis of Anaerobic Digestion Model No. 1 (ADM1) while considering complete mixing model for the CSTR, and axial direction discrete model and mixed series connection model for the UASB. The mathematical model was implemented with the simulation software package MATLABTM/Simulinks. System performance, in terms of COD removal, volatile fatty acids (VFA) accumulation and pH fluctuation, was simulated and compared with the measured values. The simulation results indicated that the model built was able to well predict the COD removal rate (-4.8-5.0%) and pH variation (-2.9-1.4%) of the UASB reactor, while failed to simulate the CSTR performance. Comparing to the measured results, the simulated acetic acid concentration of the CSTR effluent was underpredicted with a deviation ratios of 13.8-23.2%, resulting in an underprediction of total VFA and COD concentrations despite good estimation of propionic acid, butyric acid and valeric acid. It is presumed that ethanol present in the raw wastewater was converted into acetic acid during the acidification process, which was not considered by the model. Additionally, due to the underprediction of acetic acid the pH of CSTR effluent was overestimated. PMID:19477121

Chen, Zhaobo; Hu, Dongxue; Zhang, Zhenpeng; Ren, Nanqi; Zhu, Haibo

2009-10-01

185

Characterization of the methanogen community in a household anaerobic digester fed with swine manure in China.  

PubMed

Household anaerobic digesters have been installed across rural China for biogas production, but information on methanogen community structure in these small biogas units is sparsely available. By creating clone libraries for 16S rRNA and methyl coenzyme M reductase alpha subunit (mcrA) genes, we investigated the methanogenic consortia in a household biogas digester treating swine manure. Operational taxonomic units (OTUs) were defined by comparative sequence analysis, seven OTUs were identified in the 16S rRNA gene library, and ten OTUs were identified in the mcrA gene library. Both libraries were dominated by clones highly related to the type strain Methanocorpusculum labreanum Z, 64.0 % for 16S rRNA gene clones and 64.3 % for mcrA gene clones. Additionally, gas chromatography assays showed that formic acid was 84.54 % of the total volatile fatty acids and methane was 57.20 % of the biogas composition. Our results may help further isolation and characterization of methanogenic starter strains for industrial biogas production. PMID:23649353

Qin, Huibin; Lang, Huihua; Yang, Hongjiang

2013-09-01

186

Contribution of Anaerobic Digesters to Emissions Mitigation and Electricity Generation Under U.S. Climate Policy  

PubMed Central

Livestock husbandry in the U.S. significantly contributes to many environmental problems, including the release of methane, a potent greenhouse gas (GHG). Anaerobic digesters (ADs) break down organic wastes using bacteria that produce methane, which can be collected and combusted to generate electricity. ADs also reduce odors and pathogens that are common with manure storage and the digested manure can be used as a fertilizer. There are relatively few ADs in the U.S., mainly due to their high capital costs. We use the MIT Emissions Prediction and Policy Analysis (EPPA) model to test the effects of a representative U.S. climate stabilization policy on the adoption of ADs which sell electricity and generate methane mitigation credits. Under such policy, ADs become competitive at producing electricity in 2025, when they receive methane reduction credits and electricity from fossil fuels becomes more expensive. We find that ADs have the potential to generate 5.5% of U.S. electricity. PMID:21761880

2011-01-01

187

Impact of alkaline-hydrolyzed biosolids (Lystek) addition on the anaerobic digestibility of TWAS in lab - And full-scale anaerobic digesters.  

PubMed

The effect of different Lystek biosolids doses on the anaerobic digestability of thickened waste activated sludge (TWAS) was evaluated in a lab- and full-scale anaerobic digester. The overall findings of this study emphasize the beneficial impact of Lystek addition to the lab- and full-scale anaerobic digesters in terms of enhanced biogas production and increased volatile suspended solids reduction (VSSR) efficiency. Lystek added at 4% by volume to TWAS increased the methane yield from 0.22 to 0.26L CH4/g VSSadded at an solids retention time (SRT) of 10days, and from 0.27 to 0.29L CH4/g VSSadded at an SRT of 15days. Furthermore, the VSSRs of 37% and 47% were observed for the TWAS, and the TWAS with 4% Lystek, while at an SRT of 15days, the observed VSSR were 49% and 58%, respectively. The lab-scale study showed that the influence of Lystek addition on methane yield and solids destruction efficiencies was more pronounced at the shorter SRT, 20% enhancement (SRT of 10d) vs. 9% enhancement (SRT of 15d) for methane yield, and 27% (SRT of 10d) vs. 22% (SRT of 15d) for VSS destruction efficiency improvement. Furthermore, addition of 4% of Lystek to the feed of the full-scale anaerobic digester at St. Marys wastewater treatment plant (WWTP) resulted in a 50% increase in the average specific methanogenic activity and 23% increase in methane yield of the biochemical methane potential tests after eight months. The results showed that Lystek degradation kinetics were 40% faster than the TWAS, as reflected by first order kinetic coefficients of 0.053d(-1) and 0.073d(-1) for TWAS and Lystek at an SRT of 10days. PMID:25154917

Elbeshbishy, Elsayed; Aldin, Saad; Nakhla, George; Singh, Ajay; Mullin, Bill

2014-11-01

188

Continuous thermal hydrolysis and anaerobic digestion of sludge. Energy integration study.  

PubMed

Experimental data obtained from the operation in a pilot plant are used to perform mass and energy balances to a global process combining units of thermal hydrolysis (TH) of secondary sludge, anaerobic digestion (AD) of hydrolysed secondary sludge together with fresh primary sludge, and cogeneration from biogas by using a gas engine in which the biogas produces electricity and heat from the exhaust gases. Three scenarios were compared, corresponding to the three digesters operated: C (conventional AD, 17 days residence time), B (combined TH + AD, same time), and A (TH + AD at half residence time). The biogas production of digesters B and A was 33 and 24% better, respectively when compared with C. In the case of the combined TH + AD process (scenarios A and B), the key factors in the energy balance were the recovery of heat from hot streams, and the concentration of sludge. The results of the balances showed that for 8% DS concentration of the secondary sludge tested in the pilot plant, the process can be energetically self-sufficient, but a fraction of the biogas must by-pass the gas engine to be directly burned. From an economic point of view, scenario B is more profitable in terms of green energy and higher waste removal, while scenario A reduces the digester volume required by a half. Considering a population of 100,000 inhabitants, the economic benefit is 87,600 €/yr for scenario A and 132,373 €/yr for B. This value can be increased to 223,867 €/yr by increasing the sludge concentration of the feeding to the TH unit to a minimum value that allows use of all the biogas to produce green energy. This concentration is 13% DS, which is still possible from a practical point of view. Additional benefits gained with the combined TH + AD process are the enhancement of the digesters rheology and the possibility of getting Class A biosolids. The integration study presented here set the basis for the scale-up to a demonstration plant. PMID:22546800

Pérez-Elvira, S I; Fdz-Polanco, F

2012-01-01

189

INFLUENCE OF THERMAL PRETREATMENT ON MESOPHILIC ANAEROBIC DIGESTION OF SLUDGES  

Microsoft Academic Search

The anaerobic degradation of sludge is usually limited by the rate of hydrolysis of suspended matter and organic solids. Low temperature pre-treatment (below 80°C) results in incomplete destruction of micro-flora but many enzymes maintain their biocatalytic activity. Increasing hydrolysis through thermal and alkali pre-treatment was studied in an anaerobic thermophilic reactor operating between 70°C and 100°C with hydraulic retention times

Anne Menert; Tarmo Vaalu; Merje Michelis; Viktoria Blonskaja; Ergo Rikmann; Aita Mets; Raivo Vilu

2008-01-01

190

Biochar derived from anaerobically digested sugar beet tailings: Characterization and phosphate removal potential  

Microsoft Academic Search

Two biochars were produced from anaerobically digested and undigested sugar beet tailings through slow-pyrolysis at 600°C. The digested sugar beet tailing biochar (DSTC) and raw sugar beet tailing biochar (STC) yields were around 45.5% and 36.3% of initial dry weight, respectively. Compared to STC, DSTC had similar pH and surface functional groups, but higher surface area, and its surface was

Ying Yao; Bin Gao; Mandu Inyang; Andrew R. Zimmerman; Xinde Cao; Pratap Pullammanappallil; Liuyan Yang

2011-01-01

191

Upgrading of anaerobic digestion of thickened waste activated sludge by microwave-assisted alkali pretreatment  

Microsoft Academic Search

Pretreatment of thickened waste activated sludge (TWAS) can facilitate the hydrolysis step of mesophilic anaerobic digestion (MAD) and improves the digestibility. This study examined the effects of microwave\\/alkali pretreatment on TWAS disintegration and its subsequent batch and semi-continuous MAD. The maximum solubilization ratio of volatile suspended solids, 77%, achieved at 210°C with 0.15 g-NaOH\\/g-TSS and 10 min holding time. In

Yong-Zhi Chi; Xue-Ning Fei; Hong-Ying Yuan; Shao-Po Wang; Yu-You Li; Jian-Xing Li

2010-01-01

192

A comparison of analytical techniques for evaluating food waste degradation by anaerobic digestion  

Microsoft Academic Search

Organic matter contained in food waste was degraded by anaerobic digestion under mesophilic and thermophilic conditions at\\u000a two hydraulic retention times. Evolution of the digestion process was followed by thermogravimetry analysis, fluorescence\\u000a spectroscopy and 1H nuclear magnetic resonance. All analytical methods suggested that longer retention times might be required for food waste\\u000a stabilization under mesophilic conditions as compared to thermophilic

X. Gómez; M. J. Cuetos; B. Tartakovsky; M. F. Martínez-Núñez; A. Morán

2010-01-01

193

Monitoring methanogenic population dynamics in a full-scale anaerobic digester to facilitate operational management.  

PubMed

Microbial populations in a full-scale anaerobic digester fed on food waste were monitored over an 18-month period using qPCR. The digester exhibited a highly dynamic environment in which methanogenic populations changed constantly in response to availability of substrates and inhibitors. The methanogenic population in the digester was dominated by Methanosaetaceae, suggesting that aceticlastic methanogenesis was the main route for the production of methane. Sudden losses (69%) in Methanosaetaceae were followed by a build-up of VFAs which were subsequently consumed when populations recovered. A build up of ammonium inhibited Methanosaetaceae and resulted in shifts from acetate to hydrogen utilization. Addition of trace elements and alkalinity when propionate levels were high stimulated microbial growth. Routine monitoring of microbial populations and VFAs provided valuable insights into the complex processes occurring within the digester and could be used to predict digester stability and facilitate digester optimization. PMID:23707910

Williams, Julie; Williams, Haydn; Dinsdale, Richard; Guwy, Alan; Esteves, Sandra

2013-07-01

194

Laboratory-scale investigation of foaming in anaerobic digesters  

Microsoft Academic Search

A test was conducted to induce foaming by varying the waste activated sludge (WAS) content in the feed sludge at increasingly higher organic loading rates and shorter detention times. Foam was produced; however, it differed physically and chemically from foam observed in full-scale digesters. It was thickest in test digesters receiving feed sludge with a high primary sludge and low

R. D. Ross; L. A. M. Ellis

2009-01-01

195

The effects of digestion temperature and temperature shock on the biogas yields from the mesophilic anaerobic digestion of swine manure.  

PubMed

In order to obtain basic design criteria for anaerobic digesters of swine manure, the effects of different digesting temperatures, temperature shocks and feed loads, on the biogas yields and methane content were evaluated. The digester temperatures were set at 25, 30 and 35 degrees C, with four feed loads of 5%, 10%, 20% and 40% (feed volume/digester volume). At a temperature of 30 degrees C, the methane yield was reduced by only 3% compared to 35 degrees C, while a 17.4% reduction was observed when the digestion was performed at 25 degrees C. Ultimate methane yields of 327, 389 and 403 mL CH(4)/g VS(added) were obtained at 25, 30 and 35 degrees C, respectively; with moderate feed loads from 5% to 20% (V/V). From the elemental analysis of swine manure, the theoretical biogas and methane yields at standard temperature and pressure were 1.12L biogas/g VS(destroyed) and 0.724 L CH(4)/g VS(destroyed), respectively. Also, the methane content increased with increasing digestion temperatures, but only to a small degree. Temperature shocks from 35 to 30 degrees C and again from 30 to 32 degrees C led to a decrease in the biogas production rate, but it rapidly resumed the value of the control reactor. In addition, no lasting damage was observed for the digestion performance, once it had recovered. PMID:17306978

Chae, K J; Jang, Am; Yim, S K; Kim, In S

2008-01-01

196

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

Microsoft Academic Search

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°C. The effect on process performance was highly significant: Anaerobic digestion appeared feasible with a loading of up to 0.8kg volatile solids (VS)\\/m3d and an HRT of 50–100 days. The specific methane yield was high, from

Esa A Salminen; Jukka A Rintala

2002-01-01

197

Lignocellulolytic enzyme activity, substrate utilization, and mushroom yield by Pleurotus ostreatus cultivated on substrate containing anaerobic digester solids  

Microsoft Academic Search

Solid waste from anaerobic digestion of litter from the commercial production of broiler chickens has limited use as fertilizer.\\u000a Its disposal is a major problem for digester operators who are seeking alternative use for anaerobic digester solids, also\\u000a referred to as solid waste (SW). The use of SW as substrates for the cultivation of Pleurotus ostreatus strain MBFBL400 was investigated.

Omoanghe S. Isikhuemhen; Nona A. Mikiashvilli

2009-01-01

198

Test/QA Plan For Verification Of Anaerobic Digester For Energy Production And Pollution Prevention  

EPA Science Inventory

The ETV-ESTE Program conducts third-party verification testing of commercially available technologies that improve the environmental conditions in the U.S. A stakeholder committee of buyers and users of such technologies guided the development of this test on anaerobic digesters...

199

Enhanced Lead Sorption by Biochar Derived from Anaerobically Digested Sugarcane Bagasse  

Microsoft Academic Search

This study examined the ability of two sugarcane bagasse biochars to remove lead from water. The sorption of lead by biochars made from raw (BC) and anaerobically digested sugarcane bagasse (DBC) was compared with a commercial activated carbon (AC) using batch sorption experiments. DBC was a more effective sorbent of lead from water than AC, and far more effective than

Mandu Inyang; Bin Gao; Wenchuan Ding; Pratap Pullammanappallil; Andrew R. Zimmerman; Xinde Cao

2011-01-01

200

ANAEROBIC DIGESTION OF MICROALGAE: MODELING AND IDENTIFICATION FOR OPTIMIZATION AND CONTROL  

Microsoft Academic Search

Owing to the rise in fossil fuel prices, overall energy security concerns, and the current push towards green engineering; renewable and green fuels have seen an increase in interest in recent years. Two notable technologies in this green movement are the production of biodiesel from microalgae and the production of biogas from anaerobic digestion of waste biomass. Production of biodiesel

Elliot T Cameron

2012-01-01

201

Modelling anaerobic digestion of concentrated black water and faecal matter in accumulation system  

Microsoft Academic Search

A dynamic mathematical model based on anaerobic digestion model no. 1 (ADM1) was developed for accumulation (AC) system treating concentrated black water and faecal matter at different temperatures. The AC system was investigated for the treatment of waste(water) produced from the following systems: vacuum toilet for black water (VBW), vacuum toilet for faeces with urine separation (VF), dry toilet (DT),

T. Elmitwalli; G. Zeeman; R. Otterpohl

2011-01-01

202

Reducing the Anaerobic Digestion Model N1 for its application to an industrial wastewater treatment plant  

E-print Network

the Anaerobic Digestion Model N°1 for its application to an industrial wastewater treatment plant treating winery effluent wastewater Carlos García-Diéguez 1 , Olivier Bernard 2 , Enrique Roca 1, * 1 USC ­ PRODES for winery effluent wastewater. A new reduced stoichiometric matrix was identified and the kinetic parameters

Boyer, Edmond

203

Effect of temperature and temperature fluctuation on thermophilic anaerobic digestion of cattle manure  

Microsoft Academic Search

The influence of temperature, 50 and 60 °C, at hydraulic retention times (HRTs) of 20 and 10 days, on the performance of anaerobic digestion of cow manure has been investigated in completely stirred tank reactors (CSTRs). Furthermore, the effect of both daily downward and daily upward temperature fluctuations has been studied. In the daily downward temperature fluctuation regime the temperatures

Hamed M. El-Mashad; Grietje Zeeman; Wilko K. P. van Loon; Gerard P. A. Bot; Gatze Lettinga

2004-01-01

204

Video Article Continuously-Stirred Anaerobic Digester to Convert Organic Wastes into  

E-print Network

for a reliable testing methodology at the pilot- and laboratory-scale. Anaerobic digestion systems have a variety of Biological and Environmental Engineering, Cornell University Correspondence to: Largus T. Angenent at la249 for constructing, inoculating, operating, and monitoring a CSAD system for the purpose of testing the suitability

Angenent, Lars T.

205

Industrial landfill leachate characterization and treatment utilizing anaerobic digestion with methane production  

Microsoft Academic Search

Anaerobic digestion of organic compounds found in an industrial landfill leachate originating from a Superfund site was assessed using mixed methanogenic cultures. Leachate was found to contain a dissolved organic content (DOC) of about 16,000 mg\\/liter, of which 40% was in the form of acetic, propionic and butyric acids. The overall reduction of DOC and the fates of individual volatile

Corbo

1985-01-01

206

Department of Agricultural and Biological Engineering Fall 2011 Small Scale Anaerobic Digestion by PENERGY Solutions  

E-print Network

as a model for potential use on small farms to benefit food production, both on plants and animals. This would provide a means for owners of small-scale and hobby farms to produce valuable food products: A mechanical anaerobic digester to handle organic farm waste. A complete biogas collection system with hook

Demirel, Melik C.

207

Improvement of the kinetics of anaerobic digestion of molasses by the removal of phenolic compounds  

Microsoft Academic Search

Removal of most of the phenolic compounds (88.5%) present in molasses by an aerobic pretreatment with Geotrichum candidum considerably increased the kinetics of anaerobic digestion of this wastewater. Inhibition phenomena were not observed in the range of COD studied (2.3–12.9 g\\/l). The yield coefficient of methane was 51 % higher than for untreated molasses.

R. Borja; A. Martín; R. Maestro; M. Luque; M. M. Durán

1993-01-01

208

Anaerobic digestion of semi-solid organic waste: biogas production and its purification  

Microsoft Academic Search

The main objective of the present experimental investigation was to evaluate the effects of using different bacteria inoculums at identical technical settings on the anaerobic digestion process for the treatment of semi-solid organic waste available from the orthofruit market. As a possible means to improve the biogas production, as well as reduce their pollution potential, the idea of using recycled

G. Lastella; C. Testa; G. Cornacchia; M. Notornicola; F. Voltasio; Vinod Kumar Sharma

2002-01-01

209

Anaerobic Digestion. Selected Instructional Activities and References. Instructional Resources Monograph Series.  

ERIC Educational Resources Information Center

Focusing specifically on the wastewater treatment process of anaerobic digestion, this document identifies instructional and reference materials for use by professionals in the field in the development and implementation of new programs or in the updating of existing programs. It is designed to help trainers, plant operators, educators, engineers,…

Townsend, Robert D., Comp.

210

Effect of endogenous hydrolytic enzymes pretreatment on the anaerobic digestion of sludge.  

PubMed

In this study, the effects of endogenous amylase, endogenous protease and combined amylase/protease pretreatment of sludge were studied to enhance the efficiency of sludge anaerobic digestion. These enzymes were obtained from bacterial fermentation and bacteria were separated from the sludge. All treatments improved sludge solubilization and acidification but had little influence on the floc sizes. In terms of sludge solubilization and acidification amylase was better than protease or mixed enzyme. After 7 h endogenous amylase treatment, the supernatant soluble chemical oxygen demand and volatile fatty acids concentration increased by 78.2% and 129.6%, respectively. But, in terms of anaerobic biodegradability, the best result was obtained with combined enzyme treatment, biogas production increased by 23.1% compared to the control after 11 days of anaerobic digestion. Scanning electron micrographs observation and particle size analysis revealed that the most important mechanism for the enzyme treatment of sludge might be solubilization of extracellular polymeric substances. PMID:23948225

Yu, Shuyu; Zhang, Guangming; Li, Jianzheng; Zhao, Zhiwei; Kang, Xiaorong

2013-10-01

211

Anaerobic digestion of municipal solid waste: Utility of process residues as a soil amendment  

SciTech Connect

Tuna processing wastes (sludges high in fat, oil, and grease [FOG]) and municipal solid waste (MSW) generated on Tutuila Island, American Samoa, represent an ongoing disposal challenge. The biological conversion of the organic fraction of these wastes to useful products, including methane and fertilizer-grade residue, through anaerobic high-solids digestion is currently in scale-up development. The suitability of the anaerobic digestion residues as a soil amendment was evaluated through extensive chemical analysis and greenhouse studies using corn as an indicator crop. Additionally, native Samoan soil was used to evaluate the specific application rates for the compost. Experiments established that anaerobic residues increase crop yields in direct proportion to increases in the application rate. Additionally, nutrient saturation was not demonstrated within the range of application rates evaluated for the Samoan soil. Beyond nutrient supplementation, organic residue amendment to Samoan soil imparts enhanced water and nutrient-binding capacities.

Rivard, C.J.; Nagle, N.J.; Kay, B.D. [National Renewable Energy Labs., Golden, CO (United States)] [and others

1995-12-31

212

Anaerobic co-digestion of sewage sludge and primary clarifier skimmings for increased biogas production.  

PubMed

The objective of the study was to identify the impact of co-digesting clarifier skimmings on the overall methane generation from the treatment plant and additional energy value of the increased methane production. Biogas production from co-digesting clarifier skimmings and sewage sludge in pilot-scale fed-batch mesophilic anaerobic digesters has been evaluated. The digester was fed with increasing quantities of clarifier skimmings loads: 1.5, 2.6, 3.5 and 7.0 g COD equivalent/(L·d) (COD: chemical oxygen demand). Average volatile solids reduction of 65% was achieved in the scum-fed digester, compared with 51% in the control digester. Average 69% COD removal was achieved at highest scum loading (7 g COD eq/(L·d)) with approximate methane yield of 250 L CH(4)/kg COD fed (4 ft(3)/lb COD fed). The results show that scum as co-substrate in anaerobic digestion systems improves biogas yields while a 29% increase in specific CH(4) yield could be achieved when scum load is 7 g COD eq/(L·d). Based on the pilot-scale study results and full-scale data from South East Water Pollution Control Plant and Northeast Water Pollution Control Plant the expected annual energy recovery would be approximately 1.7 billion BTUs or nearly 0.5 million kWh. PMID:23128636

Alanya, S; Yilmazel, Y D; Park, C; Willis, J L; Keaney, J; Kohl, P M; Hunt, J A; Duran, M

2013-01-01

213

Anaerobic co-digestion of food waste and landfill leachate in single-phase batch reactors.  

PubMed

In order to investigate the effect of raw leachate on anaerobic digestion of food waste, co-digestions of food waste with raw leachate were carried out. A series of single-phase batch mesophilic (35±1°C) anaerobic digestions were performed at a food waste concentration of 41.8gVS/L. The results showed that inhibition of biogas production by volatile fatty acids (VFA) occurred without raw leachate addition. A certain amount of raw leachate in the reactors effectively relieved acidic inhibition caused by VFA accumulation, and the system maintained stable with methane yield of 369-466mL/gVS. Total ammonia nitrogen introduced into the digestion systems with initial 2000-3000 mgNH4-N/L not only replenished nitrogen for bacterial growth, but also formed a buffer system with VFA to maintain a delicate biochemical balance between the acidogenic and methanogenic microorganisms. UV spectroscopy and fluorescence excitation-emission matrix spectroscopy data showed that food waste was completely degraded. We concluded that using raw leachate for supplement water addition and pH modifier on anaerobic digestion of food waste was effective. An appropriate fraction of leachate could stimulate methanogenic activity and enhance biogas production. PMID:25062938

Liao, Xiaofeng; Zhu, Shuangyan; Zhong, Delai; Zhu, Jingping; Liao, Li

2014-11-01

214

Modeling anaerobic digestion of blue algae: stoichiometric coefficients of amino acids acidogenesis and thermodynamics analysis.  

PubMed

In order to facilitate the application of Anaerobic Digestion Model No. 1 (ADM1), an approach for a detailed calculation of stoichiometric coefficients for amino acids acidogenesis during the anaerobic digestion of blue algae is presented. The simulation results obtained support the approach by good predictions of the dynamic behavior of cumulative methane production, pH values as well as the concentrations of acetate, propionate, butyrate, valerate and inorganic nitrogen. The sensitivity analysis based on Monte Carlo simulation showed that the stoichiometric coefficients for amino acids acidogenesis had high sensitivities to the outputs of the model. The model further indicated that the Gibbs free energies from the uptake of long-chain fatty acids (LCFA), valerate and butyrate were positive through the digestion, while the free energies for other components were negative. During the digestion, the cumulative heat productions from microbial activities and methane were 77.69 kJ and 185.76 kJ, respectively. This result suggested that proper heat preservation of anaerobic digesters could minimize the external heating needs due to the heat produced from microbial activities. PMID:24326020

Yuan, Xian-Zheng; Shi, Xiao-Shuang; Yuan, Chun-Xin; Wang, Yu-Ping; Qiu, Yan-Ling; Guo, Rong-Bo; Wang, Li-Sheng

2014-02-01

215

Advanced dynamical risk analysis for monitoring anaerobic digestion process  

Microsoft Academic Search

Methanogenic fermentation involves a natural ecosystem that can be used for waste water treatment. This anaerobic process can have two locally stable steady-states and an unstable one making the process hard to handle. The aim of this work is to propose analytical criteria in order to detect hazardous working modes, namely situations where the system evolves towards the acidification of

Jonathan Hess; Olivier Bernard

2009-01-01

216

Microbial Ecology in Anaerobic Digestion at Agitated and Non-Agitated Conditions  

PubMed Central

To investigate the distribution and dynamics of microbial community in anaerobic digestion at agitated and non-agitated condition, 454 pyrosequencing of 16s rRNA was conducted. It revealed the distinct community compositions between the two digesters and their progressive shifting over time. Methanogens and syntrophic bacteria were found much less abundant in the agitated digester, which was mainly attributed to the presence of bacterial genera Acetanaerobacterium and Ruminococcus with relatively high abundance. The characterization of the microbial community corroborated the digestion performance affected at the agitated condition, where lower methane yield and delayed methane production rate were observed. This was further verified by the accumulation of propionic acid in the agitated digester. PMID:25313520

Tian, Zhuoli; Cabrol, Lea; Ruiz-Filippi, Gonzalo; Pullammanappallil, Pratap

2014-01-01

217

Nutrient and trace element supply in anaerobic digestion plants and effect of trace element application.  

PubMed

To investigate process behaviour and process disturbances in anaerobic digestion (AD) plants, samples of more than 1500 main digesters were taken and concentrations of macro- and micronutrients as well as volatile fatty acids were analyzed. Out of these samples, 600 digesters using energy crops only and 80 digesters using waste substrates were selected to compare the chemical composition as a result of different substrate feeding. High variations in element concentrations were found in both groups. In 60 plants with low micronutrient levels, trace elements were added and process changes were observed. A significant decrease of volatile fatty acids and an increase in digester performance were measured after trace element application. Furthermore, an increase of bacterial biomass could be detected. PMID:22925865

Lindorfer, H; Ramhold, D; Frauz, B

2012-01-01

218

Mesophilic and thermophilic anaerobic digestion of municipal sludge and fat, oil, and grease.  

PubMed

The anaerobic biodegradability of municipal primary sludge, thickened waste activated sludge (TWAS), and fat, oil, and grease (FOG) was assessed using semi-continuous-feed, laboratory-scale anaerobic digesters and compared with the ultimate degradability obtained from 120-day batch digestion at 35 degrees C. In run 1, combined primary sludge and TWAS (40/60%, volatile solids [VS] basis) were fed to digesters operated at mesophilic (35 degrees C) and thermophilic (52 degrees C) temperatures at loading rates of 0.99 and 1.46 g-VS/L x d for primary sludge and TWAS, respectively, and a hydraulic retention time (HRT) of 12 days. The volatile solids destruction values were 25.3 and 30.7% (69 and 83% biodegradable volatile solids destruction) at 35 degrees C and 52 degrees C, respectively. The methane (CH4) yields were 159 and 197 mL at the standard temperature and pressure (STP) conditions of 0 degree C and 1 atm/g-VS added or 632 and 642 mL @ STP/g-VS destroyed at 35 degrees C and 52 degrees C, respectively. In run 2, a mix of primary sludge, TWAS, and FOG (21/31/48%, volatile solids basis) was fed to an acid digester operated at a 1-day HRT, at 35 degrees C, and a loading rate of 52.5 g-VS/L x d. The acid-reactor effluent was fed to two parallel methane-phase reactors operated at an HRT of 12 days and maintained at 35 degrees C and 52 degrees C, respectively. After an initial period of 20 days with near-zero gas production in the acid reactor, biogas production increased and stabilized to approximately 2 mL CH4 @ STP/g-VS added, corresponding to a volatile solids destruction of 0.4%. The acid-phase reactor achieved a 43% decrease in nonsaturated fat and a 16, 26, and 20% increase of soluble COD, volatile fatty acids, and ammonia, respectively. The methane-phase volatile solids destruction values in run 2 were 45 and 51% (85 and 97% biodegradable volatile solids destruction) at 35 degrees C and 52 degrees C, respectively. The methane yields for the methane-phase reactors were 473 and 551 mL @ STP/g-VS added, which is approximately 3 times larger compared with run 1, or 1040 and 1083 mL @ STP/g-VS destroyed, at 35 degrees C and 52 degrees C, respectively. The results indicate that, when co-digesting municipal sludge and FOG, a large FOG organic load fraction could have a profound effect on the methane gas yield. PMID:19472939

Kabouris, John C; Tezel, Ulas; Pavlostathis, Spyros G; Engelmann, Michael; Dulaney, James A; Todd, Allen C; Gillette, Robert A

2009-05-01

219

Methanogenic population dynamics during start-up of anaerobic digesters treating municipal solid waste and biosolids  

SciTech Connect

An aggressive start-up strategy was used to initiate codigestion in two anaerobic, continuously mixed bench-top reactors at mesophilic (37 C) and thermophilic (55 C) conditions. The digesters were inoculated with mesophilic anaerobic sewage sludge and cattle manure and were fed a mixture of simulated municipal solid waste and biosolids in proportions that reflect US production rates. The design organic loading rate was 3.1 kg volatile solids/m{sup 3}/day and the retention time was 20 days. Ribosomal RNA-targeted oligonucleotide probes were used to determine the methanogenic community structure in the inocula and the digesters. Chemical analyses were performed to evaluate digester performance. The aggressive start-up strategy was successful for the thermophilic reactor, despite the use of a mesophilic inoculum.

Griffin, M.E.; McMahon, K.D.; Mackie, R.I.; Raskin, L. [Univ. of Illinois at Urbana, IL (United States)] [Univ. of Illinois at Urbana, IL (United States)

1998-02-05

220

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

PubMed

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

Ruiz, B; Flotats, X

2014-11-01

221

Nonlinear Autoregressive Exogenous modeling of a large anaerobic digester producing biogas from cattle waste.  

PubMed

In waste-to-energy plants, there is every likelihood of variations in the quantity and characteristics of the feed. Although intermediate storage tanks are used, but many times these are of inadequate capacity to dampen the variations. In such situations an anaerobic digester treating waste slurry operates under dynamic conditions. In this work a special type of dynamic Artificial Neural Network model, called Nonlinear Autoregressive Exogenous model, is used to model the dynamics of anaerobic digesters by using about one year data collected on the operating digesters. The developed model consists of two hidden layers each having 10 neurons, and uses 18days delay. There are five neurons in input layer and one neuron in output layer for a day. Model predictions of biogas production rate are close to plant performance within ±8% deviation. PMID:25151079

Dhussa, Anil K; Sambi, Surinder S; Kumar, Shashi; Kumar, Sandeep; Kumar, Surendra

2014-10-01

222

Studies on the use of an anaerobic baffled reactor for the continuous anaerobic digestion of pulp and paper mill black liquors  

Microsoft Academic Search

This paper reports the use of an anaerobic baffled reactor (ABR) and effect of different pH, temperatures, hydraulic retention times and organic loading rates on continuous anaerobic digestion of black liquor from pulp and paper mills. A maximum COD reduction of about 60% at an organic loading rate (OLR) of 5 kg m?3 d?1 at hydraulic retention time of 2

R Grover; S. S Marwaha; J. F Kennedy

1999-01-01

223

Anaerobic digester foaming in full-scale cylindrical digesters--effects of organic loading rate, feed characteristics, and mixing.  

PubMed

Cylindrical anaerobic digesters (AD) were investigated to determine the causes and contributors of AD foaming due to the following: organic loading rate (OLR) and mixing effects, waste activated sludge (WAS) storage effects and foam suppression mixing at the surface of AD, and the effects of primary sludge (PS) solids fraction in the feed sludge. No foaming was observed over the duration of the study, indicating absence of a primary foaming cause even though the suspected contributors to AD foaming were present. Total solids and temperature profiles showed that reducing mixing frequency did not significantly impact digester performance or the homogeneity of the digester contents. The results showed that high organic loading rates, reduced mixing, and feed sludge storage by themselves do not cause foaming in most ADs when the primary foaming cause is absent. Reduced mixing and surface sludge sprays are practical strategies to control AD foaming. PMID:24650532

Subramanian, Bhargavi; Pagilla, Krishna R

2014-05-01

224

Controlling the pH of acid cheese whey in a two-stage anaerobic digester with sodium hydroxide  

SciTech Connect

Anaerobic digestion of cheese whey offers a two-fold benefit: pollution potential reduction and biogas production. The biogas, as an energy source, could be used to reduce the consumption of traditional fuels in the cheese plant. However, as a result of little or no buffering capacity of whey, the pH of the anaerobic digester drops drastically and the process is inhibited. In this study, the effect of controlling the pH of the second chamber of a two-stage, 150 L anaerobic digester operating on cheese whey on the quality and quantity of biogas and the pollution potential reduction, was investigated using sodium hydroxide. The digester was operated at a temperature of 35 C and a hydraulic retention time of 15 days for three runs (no pH control, pH control with no reseeding, and ph control with reseeding) each lasting 50 days. The results indicated that operating the digester without pH control resulted in a low pH (3.3) which inhibited the methanogenic bacteria. The inhibition was irreversible and the digester did not recover (no methane production) when the pH was restored to 7.0 without reseeding, as the observed increased gas production was a false indication of recovery because the gas was mainly carbon dioxide. The addition of base resulted in a total alkalinity of 12,000 mg/L as CaCO{sub 3}. When the system was reseeded and the pH controlled, the total volatile acid concentration was 15,100 mg/L (as acetic acid), with acetic (28%), propionic (21%), butyric (25%), valeric (8%), and caproic (15%) acids as the major constituents. The biogas production was 62.6 L/d (0.84 m{sup 3}/m{sup 3}/d) and the methane content was 60.7%. Reductions of 27.3, 30.4 and 23.3% in the total solids, chemical oxygen demand and total kjeldahl nitrogen were obtained, respectively. The ammonium nitrogen content increased significantly (140%).

Ghaly, A.E.; Ramkumar, D.R. [Dalhousie Univ., Halifax, Nova Scotia (Canada). Biological Engineering Dept.

1999-07-01

225

Multi-objective cascade controller for an anaerobic digester  

Microsoft Academic Search

In this work, a new multi-objective control strategy based on the concentration of volatile fatty acids (VFAs) in the effluent and the methane flow rate (Qch4) has been proposed for an upflow sludge bed-filter (USBF) reactor, which is used in the anaerobic treatment of winery wastewater. The approach presented here is novel due to the following reasons: (i) it considers

Carlos García-Diéguez; Francisco Molina; Enrique Roca

2011-01-01

226

Application of acidic thermal treatment for one- and two-stage anaerobic digestion of sewage sludge.  

PubMed

The effectiveness of acidic thermal treatment (ATT) was examined in a 106-day continuous experiment, when applied to one- or two-stage anaerobic digestion of sewage sludge (4.3% TS). The ATT was performed at 170 °C and pH 5 for 1 hour (sulfuric acid for lowering pH). The one-stage process was mesophilic at 20 days hydraulic retention time (HRT), and incorporated the ATT as pre-treatment. The two-stage process consisted of a thermophilic digester at 5 days HRT and a mesophilic digester at 15 days HRT, and incorporated the ATT as interstage-treatment. On average, VSS reduction was 48.7% for the one-stage control, 65.8% for the one-stage ATT, 52.7% for the two-stage control and 67.6% for the two-stage ATT. Therefore, VSS reduction was increased by 15-17%, when the ATT was combined in both one- and two-stage processes. In addition, the dewaterability of digested sludge was remarkably improved, and phosphate release was enhanced. On the other hand, total methane production did not differ significantly, and color generation was noted in the digested sludge solutions with the ATT. In conclusion, the anaerobic digestion with ATT can be an attractive alternative for sludge reduction, handling, and phosphorus recovery. PMID:21099053

Takashima, M; Tanaka, Y

2010-01-01

227

Relationship between microbial activity and microbial community structure in six full-scale anaerobic digesters.  

PubMed

High activity levels and balanced anaerobic microbial communities are necessary to attain proper anaerobic digestion performance. Therefore, this work was focused on the kinetic performance and the microbial community structure of six full-scale anaerobic digesters and one lab-scale co-digester. Hydrolytic (0.6-3.5 g COD g(-1) VSS d(-1)) and methanogenic (0.01-0.84 g COD g(-1) VSS d(-1)) activities depended on the type of biomass, whereas no significant differences were observed among the acidogenic activities (1.5-2.2 g COD g(-1) VSS d(-1)). In most cases, the higher the hydrolytic and the methanogenic activity, the higher the Bacteroidetes and Archaea percentages, respectively, in the biomasses. Hydrogenotrophic methanogenic activity was always higher than acetoclastic methanogenic activity, and the highest values were achieved in those biomasses with lower percentages of Methanosaeta. In sum, the combination of molecular tools with activity tests seems to be essential for a better characterization of anaerobic biomasses. PMID:22770715

Regueiro, Leticia; Veiga, Patricia; Figueroa, Mónica; Alonso-Gutierrez, Jorge; Stams, Alfons J M; Lema, Juan M; Carballa, Marta

2012-12-20

228

Operating problems in anaerobic digestion plants resulting from nitrogen in MSW.  

PubMed

Organic waste and municipal solid waste usually contain considerable amounts of different nitrogen compounds, which may inhibit anaerobic degradation processes and cause problems in the downstream and peripheral devices. This refers particularly to the different process stages of anaerobic digestion, to wastewater treatment, and to exhaust air treatment. Neither the knowledge about nitrogen problems nor the technologies for elimination of nitrogen compounds from the wastewater or the exhaust air of anaerobic digestion can be regarded as state-of-the-art. Most of the technologies in question have already been applied in other areas, but are barely tested for application in anaerobic digestion plants. The few performance data and experiences at hand were mainly derived from pilot and demonstration facilities. In this paper, the problem of nitrogen will be discussed in detail according to the separate problem fields based on the authors' experience, as well as on the basis of a review of the relevant literature. Furthermore, possible solutions will be proposed and the need for further research and development will be formulated. PMID:16860554

Fricke, Klaus; Santen, Heike; Wallmann, Rainer; Hüttner, Axel; Dichtl, Norbert

2007-01-01

229

TIME-SETTLEMENT BEHAVIOR OF PROCESSED REFUSE. PART III: ANAEROBIC DIGESTION OF MILLED REFUSE  

EPA Science Inventory

The objectives of this laboratory investigation were to gain an understanding of the decomposition of milled refuse under anaerobic conditions, the rates of decomposition, and the gas production and composition. The rates of decomposition of cellulose and cellulosic materials, ga...

230

Anaerobic digestion of brewery primary sludge to enhance bioenergy generation: A comparison between low- and high-rate solids treatment and different temperatures  

Microsoft Academic Search

Anaerobic digestion of brewery wastewater solids in the form of primary sludge was investigated for its potential as a source of energy (methane). We operated a low-rate (hydraulic retention time (HRT)=solids retention time (SRT)) continuously stirred anaerobic digester (CSAD) and a high-rate (SRT>HRT) anaerobic sequencing batch reactor (ASBR) in parallel for 250days. We found that high-rate anaerobic digestion was beneficial

Matthew T. Agler; Zeynep Aydinkaya; Theresa A. Cummings; Allen R. Beers; Largus T. Angenent

2010-01-01

231

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

PubMed

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. PMID:24794850

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

232

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

NASA Astrophysics Data System (ADS)

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

Serranti, Silvia; Fabbri, Andrea; Bonifazi, Giuseppe

2012-11-01

233

Evaluation of Integrated Anaerobic Digestion and Hydrothermal Carbonization for Bioenergy Production  

PubMed Central

Lignocellulosic biomass is one of the most abundant yet underutilized renewable energy resources. Both anaerobic digestion (AD) and hydrothermal carbonization (HTC) are promising technologies for bioenergy production from biomass in terms of biogas and HTC biochar, respectively. In this study, the combination of AD and HTC is proposed to increase overall bioenergy production. Wheat straw was anaerobically digested in a novel upflow anaerobic solid state reactor (UASS) in both mesophilic (37 °C) and thermophilic (55 °C) conditions. Wet digested from thermophilic AD was hydrothermally carbonized at 230 °C for 6 hr for HTC biochar production. At thermophilic temperature, the UASS system yields an average of 165 LCH4/kgVS (VS: volatile solids) and 121 L CH4/kgVS at mesophilic AD over the continuous operation of 200 days. Meanwhile, 43.4 g of HTC biochar with 29.6 MJ/kgdry_biochar was obtained from HTC of 1 kg digestate (dry basis) from mesophilic AD. The combination of AD and HTC, in this particular set of experiment yield 13.2 MJ of energy per 1 kg of dry wheat straw, which is at least 20% higher than HTC alone and 60.2% higher than AD only. PMID:24962786

Reza, M. Toufiq; Werner, Maja; Pohl, Marcel; Mumme, Jan

2014-01-01

234

Microbial community structure and dynamics during anaerobic digestion of various agricultural waste materials.  

PubMed

The influence of the feedstock type on the microbial communities involved in anaerobic digestion was investigated in laboratory-scale biogas reactors fed with different agricultural waste materials. Community composition and dynamics over 2 months of reactors' operation were investigated by amplicon sequencing and profiling terminal restriction fragment length polymorphisms of 16S rRNA genes. Major bacterial taxa belonged to the Clostridia and Bacteroidetes, whereas the archaeal community was dominated by methanogenic archaea of the orders Methanomicrobiales and Methanosarcinales. Correlation analysis revealed that the community composition was mainly influenced by the feedstock type with the exception of a temperature shift from 38 to 55 °C which caused the most pronounced community shifts. Bacterial communities involved in the anaerobic digestion of conventional substrates such as maize silage combined with cattle manure were relatively stable and similar to each other. In contrast, special waste materials such as chicken manure or Jatropha press cake were digested by very distinct and less diverse communities, indicating partial ammonia inhibition or the influence of other inhibiting factors. Anaerobic digestion of chicken manure relied on syntrophic acetate oxidation as the dominant acetate-consuming process due to the inhibition of aceticlastic methanogenesis. Jatropha as substrate led to the enrichment of fiber-degrading specialists belonging to the genera Actinomyces and Fibrobacter. PMID:23624683

Ziganshin, Ayrat M; Liebetrau, Jan; Pröter, Jürgen; Kleinsteuber, Sabine

2013-06-01

235

Methane and nitrous oxide emissions following anaerobic digestion of sludge in Japanese sewage treatment facilities.  

PubMed

Methane (CH4) and nitrous oxide (N2O) are potent greenhouse gases with global warming potentials (expressed in terms of CO2-equivalents) of 28 and 265, respectively. When emitted to the atmosphere, they significantly contribute to climate change. It was previously suggested that in wastewater treatment facilities that apply anaerobic sludge digestion, CH4 continues to be emitted from digested sludge after leaving the anaerobic digester. This paper studies the CH4 and N2O emissions from anaerobically digested sludge in the subsequent sludge treatment steps. Two full-scale treatment plants were monitored over a 1-year period. Average emissions of CH4 and N2O were 509±72mg/m(3)-influent (wastewater) and 7.1±2.6mg/m(3)-influent, respectively. These values accounted for 22.4±3.8% of the indirect reduction in CO2-emissions when electricity was generated using biogas. They are considered to be significant. PMID:25194911

Oshita, Kazuyuki; Okumura, Takuya; Takaoka, Masaki; Fujimori, Takashi; Appels, Lise; Dewil, Raf

2014-11-01

236

Effect of the chlortetracycline addition method on methane production from the anaerobic digestion of swine wastewater.  

PubMed

Effects of antibiotic residues on methane production in anaerobic digestion are commonly studied using the following two antibiotic addition methods: (1) adding manure from animals that consume a diet containing antibiotics, and (2) adding antibiotic-free animal manure spiked with antibiotics. This study used chlortetracycline (CTC) as a model antibiotic to examine the effects of the antibiotic addition method on methane production in anaerobic digestion under two different swine wastewater concentrations (0.55 and 0.22mg CTC/g dry manure). The results showed that CTC degradation rate in which manure was directly added at 0.55mg CTC/g (HSPIKE treatment) was lower than the control values and the rest of the treatment groups. Methane production from the HSPIKE treatment was reduced (p<0.05) by 12% during the whole experimental period and 15% during the first 7days. The treatments had no significant effect on the pH and chemical oxygen demand value of the digesters, and the total nitrogen of the 0.55mg CTC/kg manure collected from mediated swine was significantly higher than the other values. Therefore, different methane production under different antibiotic addition methods might be explained by the microbial activity and the concentrations of antibiotic intermediate products and metabolites. Because the primary entry route of veterinary antibiotics into an anaerobic digester is by contaminated animal manure, the most appropriate method for studying antibiotic residue effects on methane production may be using manure from animals that are given a particular antibiotic, rather than adding the antibiotic directly to the anaerobic digester. PMID:25288543

Huang, Lu; Wen, Xin; Wang, Yan; Zou, Yongde; Ma, Baohua; Liao, Xindi; Liang, Juanboo; Wu, Yinbao

2014-10-01

237

Co-digestion of kitchen waste and fruit-vegetable waste by two-phase anaerobic digestion.  

PubMed

The high salinity and fat contents of kitchen waste (KW) inhibits the effect of two-phase anaerobic digestion system. This research introduces fruit-vegetable waste (FVW) to alleviate the inhibition effect caused by salinity and fat concentrations, and tries to achieve an optimal addition ratio of FVW, an optimal hydraulic remain time (HRT) of acidogenic-phase reactor and methanogenic-phase reactor. A two-phase anaerobic digestion (AD) system was developed to co-dispose KW and FVW. Four sets of experiments were run with different mass proportions between KW and FVW (25-75, 50-50, 75-25, and 100-0% m/m). Considering the biodegradation rate and the acidification degree, the system with 25% KW had the best performance during the acidogenic phase. When the system was run with 50% KW, it not only had the best stability performance but also had a bigger capacity to treat KW than the system with 25% KW. The system with 50% KW was the best ratio in this two-phase AD system. Co-digestion of KW and FVW by two-phase AD is feasible. The addition of FVW can reduce the inhibition effect caused by salinity and fat concentrations, reduce the HRT, and lead to a higher degree of acidification. PMID:23288673

Yang, Yu-Qiang; Shen, Dong-Sheng; Li, Na; Xu, Dong; Long, Yu-Yang; Lu, Xuan-Yu

2013-04-01

238

Anaerobic digestion of livestock manures in the US: A current opportunities casebook  

SciTech Connect

Growth and concentration of the livestock industry creates new opportunities for proper disposal of the large quantities of manures generated at dairy, swine, and poultry farms. One manure management system provides not only pollution prevention but also converts a problem into a new profit center. Economic evaluations and case studies of operating systems indicate that the anaerobic digestion of livestock manures is a commercially-available bioconversion technology with considerable potential for providing profitable co-products, including a renewable fuel. An introduction to the engineering economies of these technologies is provided, based on estimates of digesters that generate electricity from the recovered methane. Regression models used to estimate digester cost and internal rate of return are developed from the evaluations. Case studies of operating digesters, including project and maintenance histories, and the operator`s ``lessons learned``, are provided as a reality check.

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

1995-10-01

239

Pilot-scale anaerobic digestion of screenings from wastewater treatment plants.  

PubMed

The anaerobic digestion of screenings from a municipal wastewater treatment plant was studied in a 90 L pilot-scale digester operated at 35 degrees C under semi-continuous conditions. In the first 4 weeks, a dry solids residence time of 28 days was applied, but the installation of inhibitory conditions was observed. Feeding was therefore suspended for 4 weeks to allow the digester to recover from inhibition, and then progressively increased up to a constant load of 6 kg of raw waste per week, corresponding to an average residence time of about 35 days of dry solids. At this stage, biogas production stabilized between 513 and 618 Nl/kg VS(added) per week, with methane contents around 61% v/v. The results of this work thereby supported the feasibility of (co-)digestion as a potential alternative treatment of screenings from municipal wastewater treatment plants. PMID:20655208

Le Hyaric, Ronan; Canler, Jean-Pierre; Barillon, Bruno; Naquin, Pascale; Gourdon, Rémy

2010-12-01

240

Comparison of mechanical pretreatment methods for the enhancement of anaerobic digestion of pulp and paper waste activated sludge.  

PubMed

The conventional anaerobic digestion process, requiring long solids retention times (SRTs) to digest solids, is currently viewed as impractical for the pulp and paper industry because of high capital costs associated with the construction of new digesters. Recent developments in sludge solubilization technology could be promising in reducing digester size, which also allows for the potential use of decommissioned tanks, both of which can reduce the capital cost. Three pretreatment technologies for use with anaerobic digestion were tested on laboratory-scale to investigate their feasibility. The SRTs in all three digesters systematically decreased from 20 to 3 days. The reference digester was fed waste activated sludge (WAS) to serve as the control at the same SRTs. The other digesters were fed WAS that had been preconditioned using mechanical shearing, sonication, or high-pressure homogenization technology. Anaerobic digestion with high-pressure homogenization produced as much methane at 3-day mean SRT as that from the reference digester operated at 20-day SRT. Therefore, a new digester can theoretically be 85% smaller than a conventional digester. An added benefit of WAS to methane conversion is the recovery of nutrients nitrogen and phosphorus. PMID:22866390

Elliott, Allan; Mahmood, Talat

2012-06-01

241

Preliminary experimental results of Sewage Sludge (SS) Co-digestion with Palm Oil Mill Effluent (POME) for Enhanced Biogas Production in Laboratory Scale Anaerobic Digester  

NASA Astrophysics Data System (ADS)

An investigation on the feasibility of co-digesting Sewage Sludge with Palm Oil Mill Effluent for enhancing the biogas production and the corresponding effect of the co-digestion substrate ratio on the biogas production has been evaluated. Anaerobic co-digestion of POME with SS was performed at ratios of 100:0, 70:30, 60:40 and 0:100 to find the optimum blend required for enhanced waste digestion and biogas production. Single stage batch digestion was carried out for 12 days in a laboratory scale anaerobic digester. Co-digestion of sludge's at the 70:30 proportion resulted in optimal COD and C: N ratio which subsequently recorded the highest performance with regards to biogas production at 28.1 L's compared to the 1.98 L's of biogas produced from digestion of SS alone. From the results obtained, it is evident that co-digestion of POME and SS is an attractive option to be explored for enhancement of biogas production in anaerobic digesters.

Sivasankari, R.; Kumaran, P.; Normanbhay, Saifuddin; Halim Shamsuddin, Abd

2013-06-01

242

Anaerobic biodegradation of phenolic compounds in digested sludge  

SciTech Connect

The authors examined the anaerobic degradation of phenol and the ortho, meta, and para isomers of chlorophenol, methoxyphenol, methylphenol (cresol),and nitrophenol in anaerobic sewage sludge diluted to 10% in a mineral salts medium. Of the 12 monosubstituted phenols studied, only p-chlorophenol and o-cresol were not significantly degraded during an 8-week incubation period. The phenol compounds degraded and the time required for complete substrate disappearance (in weeks) were: phenol (2), o-chlorophenol (3), m-chlorophenol (7), o-methoxyphenol (2), m- and p-methoxyphenol (1), m-cresol (7), p-cresol (3), and o-, m-, and p-nitrophenol (1). Complete mineralization of phenol, o-chlorophenol, m-cresol, p-cresol, o-nitrophenol, p-nitrophenol, and o-, m-, and p-methoxyphenol was observed. In general, the presence of Cl and NO/sub 2/ groups on phenols inhibited methane production. Elimination or transformation of these substituents was accompanied by increased methane production. o-Chlorophenol was metabolized to phenol, which indicated that dechlorination was the initial degradation step. The methoxyphenols were transformed to the corresponding dihydroxybenzene compounds, which were subsequently mineralized. (Refs. 14).

Boyd, S.A.; Shelton, D.R.; Berry, D.; Tiedje, J.M.

1983-07-01

243

REACTIVATION AND REGROWTH OF INDICATOR ORGANISMS ASSOCIATED WITH ANAEROBICALLY DIGESTED AND DEWATERED BIOSOLIDS: EPA’S PERSPECTIVE  

EPA Science Inventory

The Water Environment Research Foundation (WERF) recently published a report titled Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bacte...

244

Detailed study of anaerobic digestion of Spirulina maxima algae biomass  

SciTech Connect

Biomass of the blue-green alga Spirulina maxima was converted to methane using continuous stirred tank digesters with an energy conversion efficiency of 59%. Digesters were operated using once-a-day feeding with a retention time (theta) between 5 and 40 days, volatile solid concentrations (Sto) between 20 and 100 kg VS/cubic m, and temperatures between 15 and 52/sup 0/C. The results indicated a maximum methane yield of 0.35 cubic m (STP)/kg VS added at theta = 30 days and Sto = 20 kg VS/cubic m. Under such conditions, the energy conversion of the algal biomass to methane was 59%. The maximum methane production rate of 0.80 cubic m (STP)/cubic m day was obtained with theta = 20 days and Sto = 100 kg VS/cubic m. The mesophilic condition at 35/sup 0/C produced the maximum methane yield and production rate. The process was stable and characterized by a high production of volatile acids (up to 23,200 mg/l), alkalinity (up to 20,000 mg/l), and ammonia (up to 7000 mg/l), and the high protein content of the biomass produced a well-buffered environment which reduced inhibitory effects. At higher loading rates, the inhibition of methanogenic bacteria was observed, but there was no clear-cut evidence that such a phenomenon was due to nonionized volatile acids or gaseous ammonia. The kinetic analysis using the model proposed by Chen and Hashimoto indicated that the minimum retention time was seven days. The optimum retention time increased gradually from 11 to 16 days with an increase in the initial volatile solid concentration. The kinetic constant K decreased with the improvement in the digester performance and increased in parallel with the ammonia concentration in the culture media. 32 references.

Samson, R.; LeDuy, A.

1986-07-01

245

Anaerobic digestion of starch-polyvinyl alcohol biopolymer packaging: biodegradability and environmental impact assessment.  

PubMed

The digestibility of a starch-polyvinyl alcohol (PVOH) biopolymer insulated cardboard coolbox was investigated under a defined anaerobic digestion (AD) system with key parameters characterized. Laboratory results were combined with industrial operational data to develop a site-specific life cycle assessment (LCA) model. Inoculated with active bacterial trophic groups, the anaerobic biodegradability of three starch-PVOH biopolymers achieved 58-62%. The LCA modeling showed that the environmental burdens of the starch-PVOH biopolymer packaging under AD conditions on acidification, eutrophication, global warming and photochemical oxidation potential were dominated by atmospheric emissions released from substrate degradation and fuel combustion, whereas energy consumption and infrastructure requirements were the causes of abiotic depletion, ozone depletion and toxic impacts. Nevertheless, for this bio-packaging, AD of the starch-PVOH biopolymer combined with recycling of the cardboard emerged as the environmentally superior option and optimization of the energy utilization system could bring further environmental benefits to the AD process. PMID:22001054

Guo, M; Trzcinski, A P; Stuckey, D C; Murphy, R J

2011-12-01

246

Anaerobic co-digestion of swine and poultry manure with municipal sewage sludge.  

PubMed

The anaerobic digestion of municipal sewage sludge (SS) with swine manure (SM) and poultry manure (PM) was undertaken. It was found that a mixture of sewage sludge with a 30% addition of swine manure gave around 400 dm(3)/kg VS of biogas, whereas the maximal biogas yield from ternary mixture (SS:SM:PM=70:20:10 by weight) was only 336 dm(3)/kg VS. An inhibition of methanogenesis by free ammonia was observed in poultry manure experiments. The anaerobic digestion was inefficient in pathogen inactivation as the reduction in the number of E. coli an Enterobacteriaceae was only by one logarithmic unit. A substantial portion of pathogens was also released into the supernatant. PMID:24280622

Borowski, Sebastian; Doma?ski, Jaros?aw; Weatherley, Laurence

2014-02-01

247

Dry anaerobic digestion of food waste under mesophilic conditions: performance and methanogenic community analysis.  

PubMed

The performance of dry anaerobic digestion (AD) of food waste was investigated under mesophilic conditions and the methanogenic community was investigated using 454 pyrosequencing. Stable dry AD was achieved by hydraulic retention time (HRT) control without the addition of alkali agents. The average CH4 production rate, CH4 content, and volatile solid reduction rate were 2.51±0.17m(3)/m(3)/d, 66±2.1%, and 65.8±1.22%, respectively, at an HRT of 40d. The methanogenic community of the seed sludge experienced a significant reduction in genus diversity from 18 to 4 and a dominant methanogenic shift from hydrogenotrophic to acetoclastic groups after the acclimation under dry condition. Almost all sequences of the dry anaerobic digester were closely related with those of Methanosarcina thermophila with similarity of 96.4-99.1%. The experimental results would serve as useful information to understand the dry AD system. PMID:23347929

Cho, Si-Kyung; Im, Wan-Taek; Kim, Dong-Hoon; Kim, Moon-Hwan; Shin, Hang-Sik; Oh, Sae-Eun

2013-03-01

248

Experimental and modeling study of a two-stage pilot scale high solid anaerobic digester system.  

PubMed

This study established a comprehensive model to configure a new two-stage high solid anaerobic digester (HSAD) system designed for highly degradable organic fraction of municipal solid wastes (OFMSW). The HSAD reactor as the first stage was naturally separated into two zones due to biogas floatation and low specific gravity of solid waste. The solid waste was retained in the upper zone while only the liquid leachate resided in the lower zone of the HSAD reactor. Continuous stirred-tank reactor (CSTR) and advective-diffusive reactor (ADR) models were constructed in series to describe the whole system. Anaerobic digestion model No. 1 (ADM1) was used as reaction kinetics and incorporated into each reactor module. Compared with the experimental data, the simulation results indicated that the model was able to well predict the pH, volatile fatty acid (VFA) and biogas production. PMID:22989632

Yu, Liang; Zhao, Quanbao; Ma, Jingwei; Frear, Craig; Chen, Shulin

2012-11-01

249

Should we pretreat solid waste prior to anaerobic digestion? An assessment of its environmental cost.  

PubMed

Many studies have shown the effectiveness of pretreatments prior to anaerobic digestion of solid wastes, but to our knowledge, none analyzes their environmental consequences/costs. In this work, seven different pretreatments applied to two types of waste (kitchen waste and sewage sludge) have been environmentally evaluated by using life cycle assessment (LCA) methodology. The results show that the environmental burdens associated to the application of pretreatments prior to anaerobic digestion cannot be excluded. Among the options tested, the pressurize-depressurize and chemical (acid or alkaline) pretreatments could be recommended on the basis of their beneficial net environmental performance, while thermal and ozonation alternatives require energy efficiency optimization to reduce their environmental burdens. Reconciling operational, economic and environmental aspects in a holistic approach for the selection of the most sustainable option, mechanical (e.g., pressurize-depressurize) and chemical methods appear to be the most appropriate alternatives at this stage. PMID:22040018

Carballa, Marta; Duran, Cecilia; Hospido, Almudena

2011-12-15

250

Start-up of an anaerobic dynamic membrane digester for waste activated sludge digestion: temporal variations in microbial communities.  

PubMed

An anaerobic dynamic membrane digester (ADMD) was developed to digest waste sludge, and pyrosequencing was used to analyze the variations of the bacterial and archaeal communities during the start-up. Results showed that bacterial community richness decreased and then increased over time, while bacterial diversity remained almost the same during the start-up. Proteobacteria and Bacteroidetes were the major phyla. At the class level, Betaproteobacteria was the most abundant at the end of start-up, followed by Sphingobacteria. In the archaeal community, richness and diversity peaked at the end of the start-up stage. Principle component and cluster analyses demonstrated that archaeal consortia experienced a distinct shift and became stable after day 38. Methanomicrobiales and Methanosarcinales were the two predominant orders. Further investigations indicated that Methanolinea and Methanosaeta were responsible for methane production in the ADMD system. Hydrogenotrophic pathways might prevail over acetoclastic means for methanogenesis during the start-up, supported by specific methanogenic activity tests. PMID:24695488

Yu, Hongguang; Wang, Qiaoying; Wang, Zhiwei; Sahinkaya, Erkan; Li, Yongli; Ma, Jinxing; Wu, Zhichao

2014-01-01

251

Zinc and copper distribution in swine wastewater treated by anaerobic digestion.  

PubMed

Swine wastewater contain high levels of metals, such as copper and zinc, which can cause a negative impact on the environment. Anaerobic digestion is a process commonly used to remove carbon, and can act on metal availability (e.g., solubility or oxidation state). The present study aimed to evaluate the influence of anaerobic digestion on total Zn and Cu contents, and their chemical fractioning due to the biodegradation of the effluent over different hydraulic retention times (HRTs). The sequential extraction protocol proposed by the Community Bureau of Reference (BCR), plus two additional fractions, was the method chosen for this study of Cu and Zn distribution evaluation in swine wastewater. The Zn and Cu concentrations in raw swine manure were 63.58 ± 27.72 mg L(-1) and 8.98 ± 3.99 mg L(-1), respectively. The metal retention capacity of the bioreactor decreased when the HRT was reduced from 17.86 d to 5.32 d. Anaerobic digestion had a direct influence on zinc and copper distribution when raw manure (RM) and digested manure (DM) were compared. The reducible fraction showed a reduction of between 3.17% and 7.84% for Zn and between 2.52% and 11.92% for Cu when DM was compared with RM. However, the metal concentration increased in the oxidizable fraction of DM, viz. from 3.01% to 10.64% for Zn and from 4.49% to 16.71% for Cu, thus demonstrating the effect of anaerobic conditions on metal availability. PMID:24794386

Cestonaro do Amaral, André; Kunz, Airton; Radis Steinmetz, Ricardo Luís; Justi, Karin Cristiane

2014-08-01

252

Nutrient removal by floating aquatic macrophytes cultured in anaerobically digested flushed dairy manure wastewater  

Microsoft Academic Search

The potential of three floating aquatic macrophytes to improve the water quality of anaerobically digested flushed dairy manure wastewater (ADFDMW) was evaluated. In undiluted ADFDMW (total chemical oxygen demand 2010mg\\/l), growth of water hyacinth (Eichhornia crassipes) was inhibited and both pennywort (Hydrocotyle umbellata) and water lettuce (Pistia stratiotes) failed to grow. In a 1:1 dilution of ADFDMW, all three plants

Reeta D. Sooknah; Ann C. Wilkie

2004-01-01

253

Anaerobic batch digestion of solid potato waste alone and in combination with sugar beet leaves  

Microsoft Academic Search

The objective of this study was to characterise anaerobic batch biodegradation of potato waste alone and when co-digested with sugar beet leaves. The effects of increasing concentration of potato waste expressed as percentage of total solids (TS) and the initial inoculum-to-substrate ratio (ISR) on methane yield and productivity were investigated. The ISRs studied were in the range 9.0–0.25 and increasing

W Parawira; M Murto; R Zvauya; B Mattiasson

2004-01-01

254

Effects of free long-chain fatty acids on thermophilic anaerobic digestion  

Microsoft Academic Search

Summary Low concentrations of the long-chain fatty acids oleate and stearate inhibited all steps of the anaerobic thermophilic biogas process during digestion of cattle manure. The lag phase increased when the concentrations of oleate and stearate were 0.2 g\\/l and 0.5 g\\/l, respectively, and no growth was found at concentrations of 0.5 g\\/l for oleate and 1.0 g\\/l for stearate.

I. Angelidaki; B. K. Ahring

1992-01-01

255

Effects of lipids on thermophilic anaerobic digestion and reduction of lipid inhibition upon addition of bentonite  

Microsoft Academic Search

The effect of bentonite-bound oil on thermophilic anaerobic digestion of cattle manure was investigated. In digestor experiments, addition of oil was found to be inhibitory during start-up and the inhibitory effect was less pronounced when the oil was added in the form of bentonite-bound oil compared to when the oil was added alone. After adaption of the digestors, very rapid

I. Angelidaki; S. P. Petersen; B. K. Ahring

1990-01-01

256

Agricultural potential of anaerobically digested industrial orange waste with and without aerobic post-treatment  

Microsoft Academic Search

The potential of anaerobically digested orange waste with (AAD) and without (AD) aerobic post-treatment for use in agriculture was evaluated through chemical analyses, short-term phytotoxicity and long-term plant assays. Chemical analyses showed that AD contained ammonia and organic acids, and aerobic post-treatment did not significantly remove these phytotoxins. The N:P2O5:K2O ratio in AD was 1:0.26:0.96 and aerobic post-treatment did not

Prasad Kaparaju; Jukka Rintala; Aimo Oikari

2012-01-01

257

Behavior of cellulose-degrading bacteria in thermophilic anaerobic digestion process.  

PubMed

Previously, we found that the newly isolated Clostridium sp. strain JC3 became the dominant cellulose-degrading bacterium in thermophilic methanogenic sludge. In the present study, the behavior of strain JC3 in the thermophilic anaerobic digestion process was investigated quantitatively by molecular biological techniques. A cellulose-degrading experiment was conducted at 55 degrees C with a 9.5 L of anaerobic baffled reactor having three compartments (Nos. 1, 2, 3). Over 80% of the COD input was converted into methane when 2.5 kgCOD m(-3) d(-1) was loaded for an HRT of 27 days. A FISH probe specific for strain JC3 was applied to sludge samples harvested from the baffled reactor. Consequently, the ratio of JC3 cells to DAPI-stained cells increased from below 0.5% (undetectable) to 9.4% (compartment 1), 13.1% (compartment 2) and 21.6% (compartment 3) at day 84 (2.5 kgCOD m(-3)d(-1)). The strain JC3 cell numbers determined by FISH correlated closely with the cellulose-degrading methanogenic activities of retained sludge. A specific primer set targeting the cellulase gene (cellobiohydrolaseA: cbhA) of strain JC3 was designed and applied to digested sludge for treating solid waste such as coffee grounds, wastepaper, garbage, cellulose and so on. The strain JC3 cell numbers determined by quantitative PCR correlated closely with the cellulose-sludge loading of the thermophilic digester. Strain JC3 is thus important in the anaerobic hydrolysis of cellulose in thermophilic anaerobic digestion processes. PMID:16180412

Syutsubo, K; Nagaya, Y; Sakai, S; Miya, A

2005-01-01

258

Designs of anaerobic digesters for producing biogas from municipal solid-waste  

Microsoft Academic Search

The production of biogas is of growing interest as fossil-fuel reserves decline. However, there exists a dearth of literature on the design considerations that would lead to process optimization in the development of anaerobic digesters aimed at creating useful commodities from the ever-abundant municipal solid-waste. Consequently, this paper provides a synthesis of the key issues and analyses concerning the design

A. Hilkiah Igoni; M. J. Ayotamuno; C. L. Eze; S. O. T. Ogaji; S. D. Probert

2008-01-01

259

Inactivation of virus during anaerobic digestion of manure in laboratory scale biogas reactors  

Microsoft Academic Search

Reduction of porcine parvovirus, bovine enterovirus and faecal enterococci were measured in biogas reactors continuously run\\u000a on manure and manure supplemented with household waste at 35°C and 55°C and in batch test run at 70°C. The aim of the experiments\\u000a was to study the sanitation effect of anaerobic digestion and to evaluate the use of faecal enterococci as an indicator

Bente Lund; Vibeke Frøkjær Jensen; Per Have; Birgitte Ahring

1996-01-01

260

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

PubMed

The analysis of seven aliphatic carboxylic acids (formic, acetic, propionic, iso-butyric, n-butyric, iso-valeric and n-valeric acid) in anaerobic digestion process waters for biogas production was examined by ion-exclusion chromatography with dilute acidic eluents (benzoic acid, perfluorobutyric acid (PFBA) and sulfuric acid) and non-suppressed conductivity/ultraviolet (UV) detection. The columns used were a styrene/divinylbenzene-based strongly acidic cation-exchange resin column (TSKgel SCX) and a polymethacrylate-based weakly acidic cation-exchange resin column (TSKgel Super IC-A/C). Good separation was performed on the TSKgel SCX in shorter retention times. For the TSKgel Super IC-A/C, peak shape of the acids was sharp and symmetrical in spite of longer retention times. In addition, the mutual separation of the acids was good except for iso- and n-butyric acids. The better separation and good detection was achieved by using the two columns (TSKgel SCX and TSKgel Super IC-A/C connected in series), lower concentrations of PFBA and sulfuric acid as eluents, non-suppressed conductivity detection and UV detection at 210 nm. This analysis was applied to anaerobic digestion process waters. The chromatograms with conductivity detection were relatively simpler compared with those of UV detection. The use of two columns with different selectivities for the aliphatic carboxylic acids and the two detection modes was effective for the determination and identification of the analytes in anaerobic digestion process waters containing complex matrices. PMID:22799193

Ito, Kazuaki; Sakamoto, Jun; Nagaoka, Kazuya; Takayama, Yohichi; Kanahori, Takashi; Sunahara, Hiroshi; Hayashi, Tsuneo; Sato, Shinji; Hirokawa, Takeshi; Tanaka, Kazuhiko

2012-04-01

261

Life cycle assessment of energy from waste via anaerobic digestion: a UK case study.  

PubMed

Particularly in the UK, there is potential for use of large-scale anaerobic digestion (AD) plants to treat food waste, possibly along with other organic wastes, to produce biogas. This paper presents the results of a life cycle assessment to compare the environmental impacts of AD with energy and organic fertiliser production against two alternative approaches: incineration with energy production by CHP and landfill with electricity production. In particular the paper investigates the dependency of the results on some specific assumptions and key process parameters. The input Life Cycle Inventory data are specific to the Greater London area, UK. Anaerobic digestion emerges as the best treatment option in terms of total CO2 and total SO2 saved, when energy and organic fertiliser substitute non-renewable electricity, heat and inorganic fertiliser. For photochemical ozone and nutrient enrichment potentials, AD is the second option while incineration is shown to be the most environmentally friendly solution. The robustness of the model is investigated with a sensitivity analysis. The most critical assumption concerns the quantity and quality of the energy substituted by the biogas production. Two key issues affect the development and deployment of future anaerobic digestion plants: maximising the electricity produced by the CHP unit fuelled by biogas and to defining the future energy scenario in which the plant will be embedded. PMID:24112851

Evangelisti, Sara; Lettieri, Paola; Borello, Domenico; Clift, Roland

2014-01-01

262

Anaerobic co-digestion of aquatic flora and quinoa with manures from Bolivian Altiplano  

SciTech Connect

Quinoa stalk (Chenopodium quinoa Willd.) from agricultural crop residue, totora (Schoenoplectus tatora) and o-macrophytes (aquatic flora) from Lake Titicaca (on the Bolivian Altiplano) were studied in a wet anaerobic co-digestion process together with manure from llama, cow and sheep. Anaerobic semi-continuous experiments were performed in (10) 2-l reactors at a temperature of 25 deg. C with 30 days of hydraulic retention time (HRT) and an organic loading rate (OLR) of 1.8 kg VS m{sup -3} d{sup -1}. Totora was found to be the best co-substrate. In mixture ratios of 1:1 (VS basis), it increased the biogas productivity by 130% for llama manure, 60% for cow manure, and 40% for sheep manure. It was possible to use up to 58% (VS basis) of totora in the substrate. Higher concentrations (including pure totora) could not be digested, as that caused acidification problems similar to those caused by other lignocellulosic materials. When quinoa and o-macrophytes were used as co-substrates, the increase in biogas productivity was slightly less. However, these co-substrates did not cause any operational problems. An additional advantage of quinoa and o-macrophytes was that they could be used in any proportion (even in pure form) without causing any destabilization problems in the anaerobic digestion process.

Alvarez, Rene [IIDEPROQ, UMSA, Plaza del Obelisco 1175, La Paz (Bolivia)], E-mail: Rene.alvarez@iideproq.org; Liden, Gunnar [Department of Chemical Engineering, Lund University, P.O. Box 124, 221 00 Lund (Sweden)

2008-07-01

263

Anaerobic co-digestion of aquatic flora and quinoa with manures from Bolivian Altiplano.  

PubMed

Quinoa stalk (Chenopodium quinoa Willd.) from agricultural crop residue, totora (Schoenoplectus tatora) and o-macrophytes (aquatic flora) from Lake Titicaca (on the Bolivian Altiplano) were studied in a wet anaerobic co-digestion process together with manure from llama, cow and sheep. Anaerobic semi-continuous experiments were performed in (10) 2-l reactors at a temperature of 25 degrees C with 30 days of hydraulic retention time (HRT) and an organic loading rate (OLR) of 1.8 kg VS m(-3) d(-1). Totora was found to be the best co-substrate. In mixture ratios of 1:1 (VS basis), it increased the biogas productivity by 130% for llama manure, 60% for cow manure, and 40% for sheep manure. It was possible to use up to 58% (VS basis) of totora in the substrate. Higher concentrations (including pure totora) could not be digested, as that caused acidification problems similar to those caused by other lignocellulosic materials. When quinoa and o-macrophytes were used as co-substrates, the increase in biogas productivity was slightly less. However, these co-substrates did not cause any operational problems. An additional advantage of quinoa and o-macrophytes was that they could be used in any proportion (even in pure form) without causing any destabilization problems in the anaerobic digestion process. PMID:18155895

Alvarez, René; Lidén, Gunnar

2008-01-01

264

Changes of heavy metal speciation during high-solid anaerobic digestion of sewage sludge.  

PubMed

The sequential extraction procedure developed by Tessier et al. was used in sludge anaerobic digestion to determine the heavy metal speciation. Sludge samples were taken every three days to investigate humic substances, VS/TS, pH, VFA, alkalinity, ammonia, the total content of Zn, Pb, Cu, Ni, and Cr, and also their distribution into EXCH, CARB, FeMnOx, OMB and RESI fractions. Results showed that, (1) Heavy metals were concentrated during the anaerobic digestion process. The concentration of all five kinds of heavy metals increased by about 50%. (2) The distribution of these heavy metals differed. (3) High-solid anaerobic digestion much or less increased the bioavailability of Cu, Zn, Ni and Cr while decreased the bioavailability of Pb. (4) There were significant degrees of correlation between heavy metal fractions and changes of some selected parameters (for example, pH, VS/TS, and VFA content). Except for Pb, the contents of total mobile fractions for Cu, Zn, Ni, Cr could be predictable from its total content. PMID:23347922

Dong, Bin; Liu, Xiaoguang; Dai, Lingling; Dai, Xiaohu

2013-03-01

265

Treatment of high-ammonium anaerobic digester supernatant by aerobic granular sludge and ultrafiltration processes.  

PubMed

Anaerobic sludge digester supernatant characterized by 569 mg TKN L(-1), high color and a COD/N ratio of 1.4 was treated in granular sequencing batch reactors (GSBRs) followed by post-denitrification (P-D) and ultrafiltration (UF) steps. The use of granular sludge allowed for the oxidation of ammonium in anaerobic digester supernatant at all investigated GSBR cycle lengths of 6, 8 and 12 h. The highest ammonium removal rate (15 mg N g(-1) VSS h(-1)) with removal efficiency of 99% was noted at 8 h. Since the GSBR effluent was characterized by a high concentration of nitrites, slowly-degradable substances and biomass, additional purification steps were applied. In P-D stage, the microbial activity of granular biomass in the GSBR effluent was implemented. The P-D was supported by external carbon source addition and the most advantageous variant comprised dosing of half of the theoretical acetate dose for nitrite reduction in the 3-h intervals. The use of the system consisting of the GSBR with 8 h, an optimal P-D variant and a UF for the treatment of anaerobic digester supernatant allowed for the 99%, 71% and 97% reductions of TKN, COD and color, respectively. PMID:23089393

Cydzik-Kwiatkowska, Agnieszka; Zieli?ska, Magdalena; Bernat, Katarzyna; Wojnowska-Bary?a, Irena; Truchan, Tomasz

2013-02-01

266

Digest Your Food!  

NSDL National Science Digital Library

In a multi-week experiment, student teams gather biogas data from the mini-anaerobic digesters that they build to break down different types of food waste with microbes. Using plastic soda bottles for the mini-anaerobic digesters and gas measurement devices, they compare methane gas production from decomposing hot dogs, diced vs. whole. They monitor and measure the gas production, then graph and analyze the collected data. Students learn how anaerobic digestion can be used to biorecycle waste (food, poop or yard waste) into valuable resources (nutrients, biogas, energy).

Membrane Biotechnology Laboratory

267

Elucidation of the thermophilic phenol biodegradation pathway via benzoate during the anaerobic digestion of municipal solid waste.  

PubMed

Anaerobic digestion makes it possible to valorize municipal solid waste (MSW) into biogas and digestate which are, respectively, a renewable energy source and an organic amendment for soil. Phenols are persistent pollutants present in MSW that can inhibit the anaerobic digestion process and have a toxic effect on microbiota if they are applied to soil together with digestate. It is then important to define the operational conditions of anaerobic digestion which allow the complete degradation of phenol. In this context, the fate of phenol during the anaerobic digestion of MSW at 55°C was followed using an isotopic tracing approach ((13)C6-phenol) in experimental microcosms with inoculum from an industrial thermophilic anaerobic digester. With this approach, it was possible to demonstrate the complete phenol biodegradation into methane and carbon dioxide via benzoate. Benzoate is known to be a phenol metabolite under mesophilic conditions, but in this study it was found for the first time to be a phenol degradation product at thermophilic temperature. PMID:24238916

Hoyos-Hernandez, Carolina; Hoffmann, Marieke; Guenne, Angeline; Mazeas, Laurent

2014-02-01

268

Anaerobic digestibility of marine microalgae Phaeodactylum tricornutum in a lab-scale anaerobic membrane bioreactor  

Microsoft Academic Search

The biomass of industrially grown Phaeodactylum tricornutum was subjected in a novel way to bio-methanation at 33A degrees C, i.e., in an anaerobic membrane bioreactor (AnMBR) at a hydraulic retention time of 2.5 days, at solid retention times of 20 to 10 days and at loading rates in the range of 2.6-5.9 g biomass-COD L(-1) day(-1) with membrane fluxes ranging

C. Zamalloa; J. De Vrieze; N. Boon; W. Verstraete

2012-01-01

269

Feasibility of anaerobic co-digestion of poultry blood with maize residues.  

PubMed

The potential of anaerobic digestion for the treatment of poultry blood was evaluated in batch assays at laboratory scale and in a mesophilic semi-continuously fed digester. The biodegradability test performed on poultry blood waste showed a strong inhibition. Maize residues were used as co-substrate to overcome inhibition thanks to nitrogen dilution. Under batch operation, increasing the maize concentration from 15% to 70% (volatile solids (VS) basis) provided an increase of biogas from 130±31 to 188±21 L CH4/kg VS. In the semi-continuous mesophilic anaerobic digester, the biogas yield was 165±17 L CH4/kg VS fed, as a result of strong volatile fatty acid (VFA) accumulation. Although physical modifications of maize particles were observed by Scanning Electron Microscopy (SEM), an incomplete degradation was confirmed from analysis of digestates. Furthermore, Fourier Transform Infrared (FTIR) spectroscopy analysis demonstrated that along with VFA build-up, an accumulation of non-degraded materials took place. PMID:23899572

Cuetos, M J; Gómez, X; Martínez, E J; Fierro, J; Otero, M

2013-09-01

270

Development of a pilot scale anaerobic digester for biogas production from cow manure and whey mix.  

PubMed

This paper presents results from anaerobic digestion of cow manure and whey mix. A pilot scale anaerobic digester, 128 l in volume, has been developed, to operate under batch and fed-batch conditions. The versatile and unique characteristics of the instrument allowed testing the methane production directly in the farm. The digester performance was evaluated with two calibration tests, the main for a period of 56 days. The study test was divided into three phases, one for each type of feeding operation (batch, fed-batch, batch). The initial phase of digestion resulted in 57 l-CH(4)/kg-VS, the second phase had a yield of 86.6 l-CH(4)/kg-VS and the third one had a production of 67 l-CH(4)/kg-VS. The total methane yield was equal to 211.4 l-CH(4)/kg-VS. Using the obtained pilot plant results to a real scale diary production cycle, it was possible to evaluate an electricity production equal to 8.86 kwh per 1 t/d. The conducted tests did show that there is a good potential to the use of a cow manure and whey biomass mix for biogas production. PMID:19559606

Comino, Elena; Rosso, Maurizio; Riggio, Vincenzo

2009-11-01

271

Performance of methanogenic reactors in temperature phased two-stage anaerobic digestion of swine wastewater.  

PubMed

The present study investigated the shifts in the chemical profiles of a two-phase anaerobic digestion system in methanogenic and acidogenic reactors for the treatment of swine wastewater. Acidogenic and methanogenic digesters were used with overall HRTs ranging from 27 to 6 d. In the optimized thermophilic/acidogenic phase throughout the entire experimental period, VS was reduced by 13.8% (1.6%); however, COD hardly decreased because of the thermophilic hydrolysis of organic materials, such as carbohydrates, proteins, and lipids, without any significant consumption of volatile fatty acids. In the methanogenic/mesophilic phase, COD was reduced by 65.8 (1.1)% compared to a 47.4 (2.9)% reduction in VS reduction efficiency with the gradual increase in methane production during a methanogenic HRT between 25 and 10 d. A high protein degradation rate was observed in the optimized acidogenic phase, which is assumed to be due to the low content of carbohydrates in raw swine wastewater as well as the readily thermophilic hydrolysis of proteins. Two-phase systems of anaerobic digestion consisting of optimized thermophilic and mesophilic methanogenic digesters showed a stable performance with respect to VS reduction efficiency with OLRs less than 3 g VS/L·d, in other words, more than 10 days of methanogenic HRT in this study. PMID:23041140

Kim, Woong; Shin, Seung Gu; Cho, Kyungjin; Lee, Changsoo; Hwang, Seokhwan

2012-12-01

272

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

PubMed

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 methodology for constructing, inoculating, operating, and monitoring a CSAD system for the purpose of testing the suitability of a given organic substrate for long-term anaerobic digestion. The construction section of this article will cover building the lab-scale reactor system. The inoculation section will explain how to create an anaerobic environment suitable for seeding with an active methanogenic inoculum. The operating section will cover operation, maintenance, and troubleshooting. The monitoring section will introduce testing protocols using standard analyses. The use of these measures is necessary for reliable experimental assessments of substrate suitability for AD. This protocol should provide greater protection against a common mistake made in AD studies, which is to conclude that reactor failure was caused by the substrate in use, when really it was improper user operation. PMID:22824993

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

2012-01-01

273

Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation  

PubMed Central

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 1-3. Increasingly, AD is being used in industrial, agricultural, and municipal waste(water) treatment applications 4,5. 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 6,7. As the application of AD technology broadens for the treatment of new substrates and co-substrate mixtures 8, 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 9. 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 methodology for constructing, inoculating, operating, and monitoring a CSAD system for the purpose of testing the suitability of a given organic substrate for long-term anaerobic digestion. The construction section of this article will cover building the lab-scale reactor system. The inoculation section will explain how to create an anaerobic environment suitable for seeding with an active methanogenic inoculum. The operating section will cover operation, maintenance, and troubleshooting. The monitoring section will introduce testing protocols using standard analyses. The use of these measures is necessary for reliable experimental assessments of substrate suitability for AD. This protocol should provide greater protection against a common mistake made in AD studies, which is to conclude that reactor failure was caused by the substrate in use, when really it was improper user operation 10. PMID:22824993

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

2012-01-01

274

Effect of microwave hydrolysis on transformation of steroidal hormones during anaerobic digestion of municipal sludge cake.  

PubMed

Fate and removal of 16 steroidal (estrogenic, androgenic and progestogenic) hormones were studied during advanced anaerobic digestion of sludge cake using microwave (MW) pretreatment. Effect of pretreatment temperature (80, 120, 160 °C), operating temperature (mesophilic at 35 ± 2 °C, thermophilic at 55 ± 2 °C) and sludge retention time (SRT: 20, 10, 5 days) were studied employing eight lab-scale semi-continuously fed digesters. To determine the potential effect of MW hydrolysis, hormones were quantified in total (sorbed + soluble) and supernatant (soluble) phases of the digester influent and effluent streams. Seven of 16 hormones were above the method reporting limit (RL) in one or more of the samples. Hormone concentrations in total phase of un-pretreated (control) and pretreated digester feeds ranged in <157-2491 ng/L and <157-749 ng/L, respectively. The three studied factors were found to be statistically significant (95% confidence level) in removal of one or more hormones from soluble and/or total phase. MW hydrolysis of the influent resulted in both release (from sludge matrix) and attenuation of hormones in the soluble phase. Accumulation of estrone (E1) as well as progesterone (Pr) and androstenedione (Ad) in most of the digesters indicated possible microbial transformations among the hormones. Compared to controls, all pretreated digesters had lower total hormone concentrations in their influent streams. At 20 days SRT, highest total removal (E1+E2+Ad +Pr) was observed for the thermophilic control digester (56%), followed by pretreated mesophilic digesters at 120 °C and 160 °C with around 48% efficiency. In terms of conventional performance parameters, relative (to control) improvements of MW pretreated digesters at a 5-d SRT ranged in 98-163% and 57-121%, for volatile solids removal and methane production, respectively. PMID:23866136

Hamid, Hanna; Eskicioglu, Cigdem

2013-09-15

275

Influence of anaerobic co-digestion of sewage and brewery sludges on biogas production and sludge quality  

Microsoft Academic Search

This research investigated operating parameters and treatment efficiency for the digestion of sewage and brewery sludge. The prime objective of this study was to enhance the quality of treated sludge for use as agriculture fertilizer and to enhance biogas production, a by-product that can be used as an energy source. Three bench-scale completely stirred tank reactor (CSTR) anaerobic digesters were

Athapol Pecharaply; Preeda Parkpian; Ajit P. Annachhatre; Aroon Jugsujinda

2007-01-01

276

EVALUATION OF THE FULL-SCALE APPLICATION OF ANAEROBIC SLUDGE DIGESTION AT THE BLUE PLAINS WASTEWATER TREATMENT FACILITY, WASHINGTON, DC  

EPA Science Inventory

The mesophilic-thermophilic digestion process is a new two-step concept for treating municipal wasterwater sludges. The first step operates under mesophilic process conditions (digestion with anaerobic microorganisms that thrive at 90 to 100F). The second step operates under ther...

277

Rapid measurement of the yield stress of anaerobically-digested solid waste using slump tests.  

PubMed

The anaerobic digestion of solid waste is usually performed using dry or semi-dry technology. Incoming waste and fermenting digestate are pasty media and thus, at the industrial scale, their suitability for pumping and mixing is a prerequisite at the industrial scale. However, their rheology has been poorly characterised in the literature because there is no suitable experimental system for analysing heterogeneous media composed of coarse particles. We have developed a practical rheometrical test, a "slump test", for the analysis of actual digested solid waste. It makes it possible to estimate yield stress from the final slump height. From the slump behavior, we conclude that digestates behave as visco-elastic materials. The yield stress of different digested waste was measured between 200 and 800Pa. We show that the media containing smaller particles or with higher moisture content are characterised by smaller yield stresses. This study thus demonstrates the impact of the origin of the digestate on the yield stress. PMID:21251807

Garcia-Bernet, D; Loisel, D; Guizard, G; Buffière, P; Steyer, J P; Escudié, R

2011-04-01

278

Biokinetic and molecular studies of methanogens in phased anaerobic digestion systems.  

PubMed

The influence of differing operational conditions of two-stage digesters on biokinetic characteristics and communities of methanogenic archaea was evaluated. Operating temperature of each phase influenced the archaeal communities significantly. Also, a strong correlation was observed between community composition and temperature and pH. The maximum specific substrate utilization rates (k max) of acetoclastic methanogens in the mesophilic and thermophilic 1st phases were 11.4 and 22.0 mgCOD mgCOD(-1)d(-1), respectively, whereas significantly lower k max values were estimated for the mesophilic and thermophilic 2nd-phase digesters which were 7.6 and 16.6 mgCOD mgCOD(-1)d(-1), respectively. It appeared that the biokinetic characteristics of the acetoclastic methanogen communities were reliant on digester loading rates. Also, higher temperature dependency coefficients (?) were observed for the long retention time digesters when compared to the values computed for the 1st-phase digesters. Accordingly, the implementation of two sets of biokinetic parameters for acetoclastic methanogen will improve modeling of phased anaerobic digesters. PMID:24125797

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

2013-12-01

279

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

PubMed

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 phosphorus from the anaerobic supernatant of OFMSW is an interesting research topic that has not yet been explored. At the moment, standardization in the design of facilities that treat anaerobic supernatant produced from the treatment of OFMSW is still under development. To move toward this direction, it is first necessary to assess the performance of alternative treatment options. It study concentrates existing data regarding the characteristics of the anaerobic supernatant produced from the treatment of OFMSW and from their co-digestion with other BOW. This provides data documenting the effect of the anaerobic digestion operating conditions on the supernatant quality and critically evaluates alternative options for the post-treatment of the liquid fraction produced from the anaerobic digestion process. PMID:23808751

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

2014-09-01

280

Effect of sulfate on low-temperature anaerobic digestion.  

PubMed

The effect of sulfate addition on the stability of, and microbial community behavior in, low-temperature anaerobic expanded granular sludge bed-based bioreactors was investigated at 15°C. Efficient bioreactor performance was observed, with chemical oxygen demand (COD) removal efficiencies of >90%, and a mean SO(2-) 4 removal rate of 98.3%. In situ methanogensis appeared unaffected at a COD: SO(2-) 4 influent ratio of 8:1, and subsequently of 3:1, and was impacted marginally only when the COD: SO(2-) 4 ratio was 1:2. Specific methanogenic activity assays indicated a complex set of interactions between sulfate-reducing bacteria (SRB), methanogens and homoacetogenic bacteria. SO(2-) 4 addition resulted in predominantly acetoclastic, rather than hydrogenotrophic, methanogenesis until >600 days of SO(2-) 4-influenced bioreactor operation. Temporal microbial community development was monitored by denaturation gradient gel electrophoresis (DGGE) of 16S rRNA genes. Fluorescence in situ hybridizations (FISH), qPCR and microsensor analysis were combined to investigate the distribution of microbial groups, and particularly SRB and methanogens, along the structure of granular biofilms. qPCR data indicated that sulfidogenic genes were present in methanogenic and sulfidogenic biofilms, indicating the potential for sulfate reduction even in bioreactors not exposed to SO(2-) 4. Although the architecture of methanogenic and sulfidogenic granules was similar, indicating the presence of SRB even in methanogenic systems, FISH with rRNA targets found that the SRB were more abundant in the sulfidogenic biofilms. Methanosaeta species were the predominant, keystone members of the archaeal community, with the complete absence of the Methanosarcina species in the experimental bioreactor by trial conclusion. Microsensor data suggested the ordered distribution of sulfate reduction and sulfide accumulation, even in methanogenic granules. PMID:25120534

Madden, Pádhraig; Al-Raei, Abdul M; Enright, Anne M; Chinalia, Fabio A; de Beer, Dirk; O'Flaherty, Vincent; Collins, Gavin

2014-01-01

281

Effect of sulfate on low-temperature anaerobic digestion  

PubMed Central

The effect of sulfate addition on the stability of, and microbial community behavior in, low-temperature anaerobic expanded granular sludge bed-based bioreactors was investigated at 15°C. Efficient bioreactor performance was observed, with chemical oxygen demand (COD) removal efficiencies of >90%, and a mean SO2?4 removal rate of 98.3%. In situ methanogensis appeared unaffected at a COD: SO2?4 influent ratio of 8:1, and subsequently of 3:1, and was impacted marginally only when the COD: SO2?4 ratio was 1:2. Specific methanogenic activity assays indicated a complex set of interactions between sulfate-reducing bacteria (SRB), methanogens and homoacetogenic bacteria. SO2?4 addition resulted in predominantly acetoclastic, rather than hydrogenotrophic, methanogenesis until >600 days of SO2?4-influenced bioreactor operation. Temporal microbial community development was monitored by denaturation gradient gel electrophoresis (DGGE) of 16S rRNA genes. Fluorescence in situ hybridizations (FISH), qPCR and microsensor analysis were combined to investigate the distribution of microbial groups, and particularly SRB and methanogens, along the structure of granular biofilms. qPCR data indicated that sulfidogenic genes were present in methanogenic and sulfidogenic biofilms, indicating the potential for sulfate reduction even in bioreactors not exposed to SO2?4. Although the architecture of methanogenic and sulfidogenic granules was similar, indicating the presence of SRB even in methanogenic systems, FISH with rRNA targets found that the SRB were more abundant in the sulfidogenic biofilms. Methanosaeta species were the predominant, keystone members of the archaeal community, with the complete absence of the Methanosarcina species in the experimental bioreactor by trial conclusion. Microsensor data suggested the ordered distribution of sulfate reduction and sulfide accumulation, even in methanogenic granules. PMID:25120534

Madden, Padhraig; Al-Raei, Abdul M.; Enright, Anne M.; Chinalia, Fabio A.; de Beer, Dirk; O'Flaherty, Vincent; Collins, Gavin

2014-01-01

282

High-solids anaerobic digestion: comparison of three pilot scales.  

PubMed

Two experiments were undertaken in three different experimental set-ups in order to compare them: an industrial 21-m3 pilot reactor, a new 40-l laboratory pilot reactor and bmp type plasma bottles. Three consecutive batch dry digestion tests of municipal solid waste were performed under mesophilic conditions with the same feedstock in all vessels. Biogas and methane production at the end of the tests were similar (around 200 m3 CH4STP/tVS) for both pilot reactors and were different from the bottle tests. The dynamics of methane production and VFA accumulation concurred. However, the maximal levels of VFA transitory accumulation varied between reactors and between runs in a same reactor. Ammonia levels were similar in both reactors. These results show that the new reactor accurately imitates the conditions found in the larger one. Adaptation of microorganisms to the waste and operating conditions was also pointed out along the consecutive batches. Thermophilic semi-continuous tests were performed in both reactors with similar conditions. The methane production efficiencies were similar. PMID:19029716

Guendouz, J; Buffière, P; Cacho, J; Carrère, M; Delgenes, J-P

2008-01-01

283

Effects of thermal pre-treatment on anaerobic co-digestion of municipal biowastes at high organic loading rate.  

PubMed

Anaerobic co-digestion of thermal pre-treated municipal biowaste (MBW) is a field of research that has had limited contributions to date. In this study, laboratory-scale semi-continuously fed anaerobic digesters treating thermally treated and non-treated MBW were operated at high organic loading rates (OLR). The results show that the methanogenesis process was inhibited by the accumulated volatile fatty acids when 30% (w/w) of dewatered activated sludge (DAS) was co-digested with food waste (FW) and fruit/vegetable residue (FVR) at high OLR?10 kg volatile solid m(-3) d(-1). Co-digestion with thermal hydrolysed DAS can significantly improve digester performance. In contrast to DAS, some adverse effects of thermal pretreatment on the biodegradability of FW and FVR were observed. Therefore, co-digestion of FW, FVR with thermally treated DAS is suggested as an alternative to promote high methane production and process stability. PMID:24374189

Guo, Jianbin; Wang, Wei; Liu, Xiao; Lian, Songjian; Zheng, Lei

2014-04-01

284

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

SciTech Connect

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.

Stabnikova, O. [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)], E-mail: costab@ntu.edu.sg; Liu, X.Y.; Wang, J.Y. [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2008-07-01

285

Anaerobic co-digestion of cattle manure with rice straw: economic & energy feasibility.  

PubMed

Rice straw (RS) is one of the most abundant wastes generated in Valencia (Spain). Traditional waste disposal methods are harmful to the environment. The straw burning emits large amounts of toxic air pollutants and the straw burying produces uncontrolled anaerobic fermentation in the soil. The aim of this research was to evaluate the feasibility of cow manure anaerobic co-digestion with RS in a semi-continuous plug flow pilot-scale reactor. Three different periods of co-digestion were carried out as the RS dose was increased. When the addition of RS was 1, 2 and 5% (on weight basis) the biogas productivity increased by 4, 28 and 54% respectively. Furthermore, economic and energy feasibility were analysed considering the logistics cost of the RS (baling, collection, crushing and transportation). Two different scenarios were analysed. In scenario 1, the anaerobic co-digestion process was considered that take place in a new biogas installation, and in scenario 2 the process was considered that take place in a biogas plant already in operation. In scenario 1, the cow manure co-digestion with 2% of RS in a biogas installation of 500 kW showed the best economic analysis (net present value of 13.23%). In scenario 2, the results showed that the maximum distance between the rice field and the biogas plant that produces a positive economic balance was less than 95 km (2% RS) and 74 km (5% RS). In the case of the addition of 1% RS the economic balance is negative. Energy balance is positive in the three mixtures analysed. PMID:23306251

Silvestre, G; Gómez, M P; Pascual, A; Ruiz, B

2013-01-01

286

Kinetics and dynamic modelling of batch anaerobic digestion of municipal solid waste in a stirred reactor  

SciTech Connect

A series of batch, slurry anaerobic digestion experiments were performed where the soluble and insoluble fractions, and unwashed MSW were separately digested in a 200 l stirred stainless steel vessel at a pH of 7.2 and a temperature of 38 deg. C. It was found that 7% of the total MSW COD was readily soluble, of which 80% was converted to biogas; 50% of the insoluble fraction was solubilised, of this only 80% was converted to biogas. The rate of digesting the insoluble fraction was about four times slower than the rate of digesting the soluble fraction; 48% of the total COD was converted to biogas and 40% of the total nitrogen was converted to ammonia. Soluble and insoluble fractions were broken down simultaneously. The minimum time to convert 95% of the degradable fraction to biogas was 20 days. The lag phase for the degradation of insoluble fraction of MSW can be overcome by acclimatising the culture with the soluble fraction. The rate of digestion and the methane yield was not affected by particle size (within the range of 2-50 mm). A dynamic model was developed to describe batch digestion of MSW. The parameters of the model were estimated using data from the separate digestion of soluble and insoluble fractions and validated against data from the digestion of unwashed MSW. Trends in the specific aceticlastic and formate-utilising methanogenic activity were used to estimate initial methanogenic biomass concentration and bacterial death rate coefficient. The kinetics of hydrolysis of insoluble fraction could be adequately described by a Contois equation and the kinetics of acidogenesis, and aceticlastic and hydrogen utilising methanogenesis by Monod equations.

Nopharatana, Annop [Division of Environmental of Engineering, The University of Queensland, Brisbane, Qld. 4072 (Australia); Pilot Plant Development and Training Institute, King Mongkut's University of Technology, Thonburi, Bangkok 10150 (Thailand); Pullammanappallil, Pratap C. [Division of Environmental of Engineering, The University of Queensland, Brisbane, Qld. 4072 (Australia); Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611 (United States); Clarke, William P. [Division of Environmental of Engineering, The University of Queensland, Brisbane, Qld. 4072 (Australia)], E-mail: billc@cheque.uq.edu.au

2007-07-01

287

Anaerobic digestion technology in poultry and livestock waste treatment--a literature review.  

PubMed

A literature review has been undertaken to investigate the performance of the different anaerobic process configurations and operational conditions used in poultry and livestock waste treatment. The results of the extensive literature review showed that a wide range of different reactor volumes varying from 100 mL to 95 m3 were utilized in the investigation of anaerobic processing of poultry manure. Retention times studied were between 13.2 h and 91 days. Most of studies were carried out under mesophilic conditions maintained between 25 and 35 degrees C. Chemical oxygen demand (COD) removals and organic loading rate (OLR) ranged from 32 to 78%, and from 1.1 to 2.9 kg COD m(-3) day(-1), respectively. Biogas yields were achieved between 180 mL g(-1) COD added and 74 m3 day(-1) for a wide range of different reactor configurations. Up-flow anaerobic sludge blanket (UASB) seems to be a suitable process for the treatment of poultry manure wastewater and the liquid fraction of hen manure, due to its ability to maintain a sufficient amount of active biomass. The literature review showed that various reactor configurations such as fixed-film reactor, attached-film bioreactor, anaerobic rotating biological reactor, batch reactors, downflow anaerobic filter, fixed dome plant, UASB, continuously stirred tank reactor (CSTR), up-flow anaerobic filter (UAF), temperature-phased anaerobic digestion (TPAD), anaerobic hybrid reactor (AHR), and two-stage anaerobic systems are well suited to anaerobic processing of cattle manure. At both mesophilic and thermophilic conditions, high COD removals (87-95%) were achieved for treatment of cattle manure wastewaters. The COD and volatile solids (VS) reductions obtained were 37.9 to 94% and 9.6 to 92%, respectively. During the studies, OLR and retention times ranged between 0.117 and 7.3 g VS L(-1) day(-1) and between 0.5 and 140 days, respectively. In anaerobic processing of cattle manure, methane yields between 48 mmol CH4 L(-1) and 4681.3 m3 CH4 month(- 1) were found for the corresponding reactor volumes of 120 mL and 1300 m3, respectively. In anaerobic processing of swine manure, OLR ranged from 0.9 to 15.42 g VS L(-1) day(- 1) at mesophilic conditions (25-35 degrees C). The reactor volumes varied between 125 mL and 380 L. Temperature and retention times ranged from 25 to 60 degrees C, and 0.9 to 113 days, respectively. COD and VS reductions achieved were between 57 and 78% and between 34.5 and 61%, respectively. Moreover, methane yields were obtained between 22 and 360 mL CH4 g(-1) VS added. The results showed that UASB, anaerobic baffled reactors, CSTR, and anaerobic sequencing batch reactor (ASBR) were successfully utilized in anaerobic processing of swine manure at both mesophilic and thermophilic conditions. PMID:19220987

Sakar, Suleyman; Yetilmezsoy, Kaan; Kocak, Emel

2009-02-01

288

Archaeal community composition affects the function of anaerobic co-digesters in response to organic overload  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Two types of methanogens are necessary to respond successfully to perturbation. Black-Right-Pointing-Pointer Diversity of methanogens correlates with the VFA concentration and methane yield. Black-Right-Pointing-Pointer Aggregates indicate tight spatial relationship between minerals and microorganisms. - Abstract: Microbial community diversity in two thermophilic laboratory-scale and three full-scale anaerobic co-digesters was analysed by genetic profiling based on PCR-amplified partial 16S rRNA genes. In parallel operated laboratory reactors a stepwise increase of the organic loading rate (OLR) resulted in a decrease of methane production and an accumulation of volatile fatty acids (VFAs). However, almost threefold different OLRs were necessary to inhibit the gas production in the reactors. During stable reactor performance, no significant differences in the bacterial community structures were detected, except for in the archaeal communities. Sequencing of archaeal PCR products revealed a dominance of the acetoclastic methanogen Methanosarcina thermophila, while hydrogenotrophic methanogens were of minor importance and differed additionally in their abundance between reactors. As a consequence of the perturbation, changes in bacterial and archaeal populations were observed. After organic overload, hydrogenotrophic methanogens (Methanospirillum hungatei and Methanoculleus receptaculi) became more dominant, especially in the reactor attributed by a higher OLR capacity. In addition, aggregates composed of mineral and organic layers formed during organic overload and indicated tight spatial relationships between minerals and microbial processes that may support de-acidification processes in over-acidified sludge. Comparative analyses of mesophilic stationary phase full-scale reactors additionally indicated a correlation between the diversity of methanogens and the VFA concentration combined with the methane yield. This study demonstrates that the coexistence of two types of methanogens, i.e. hydrogenotrophic and acetoclastic methanogens is necessary to respond successfully to perturbation and leads to stable process performance.

Lerm, S.; Kleyboecker, A. [International Centre for Geothermal Research (ICGR), GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany); Miethling-Graff, R. [International Centre for Geothermal Research (ICGR), GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany); Johann Heinrich von Thuenen Institut, Bundesforschungsinstitut fuer Laendliche Raeume, Wald und Fischerei Institut fuer Biodiversitaet, 38116 Braunschweig (Germany); Alawi, M.; Kasina, M.; Liebrich, M. [International Centre for Geothermal Research (ICGR), GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany); Wuerdemann, H., E-mail: wuerdemann@gfz-potsdam.de [International Centre for Geothermal Research (ICGR), GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany)

2012-03-15

289

An evaluation of the USEPA calculations of greenhouse gas emissions from anaerobic lagoons.  

PubMed

On 10 Apr. 2009, USEPA proposed and on 30 Oct. 2009 USEPA finalized reporting thresholds for a wide range of human-derived sources of greenhouse gas (GHG) as a first step in establishing emission limits in the United States. The only on-farm source category that required monitoring under the proposed and final rule was methane (CH(4)) and nitrous oxide (NO(2)) emissions from manure storage facilities. Our objective was to assess, through a literature review, the methodology used by USEPA to estimate current CH(4) emissions from uncovered anaerobic lagoons and the proposed methodology for reporting those emissions under the proposed rule. A review of the performance of uncovered anaerobic lagoons indicates that they are more effective at degrading volatile solids (VS) than predicted using parameters provided by USEPA that had been developed for anaerobic digesters. We also documented errors in the USEPA- and International Panel on Climate Change-estimated methane conversion factors for uncovered anaerobic lagoons. We suggest estimating CH(4) emissions from anaerobic lagoons based on VS degraded in the lagoon and B' (m(3) CH(4) generated kg(-1) VS destroyed). Our estimate of CH(4) released from uncovered anaerobic lagoons indicated the regulatory operation size threshold could be at least 65% smaller than predicted by USEPA in the proposed rule. Our calculated estimate of CH(4) emissions was substantially greater than the few estimates of CH(4) loss based on direct measurements on uncovered anaerobic lagoons. More research is needed before it will be possible to provide definitive estimates of CH(4) loss from uncovered anaerobic lagoons. PMID:20400573

Lory, John A; Massey, R E; Zulovich, J M

2010-01-01

290

Modeling a solar-heated anaerobic digester for the developing world using system dynamics  

NASA Astrophysics Data System (ADS)

Much of the developing world lacks access to a dependable source of energy. Agricultural societies such as Mozambique and Papua New Guinea could sustain a reliable energy source through the microbacterial decomposition of animal and crop waste. Anaerobic digestion produces methane, which can be used directly for heating, cooking, and lighting. Adding a solar component to the digester provides a catalyst for bacteria activity, accelerating digestion and increasing biogas production. Using methane decreases the amount of energy expended by collecting and preparing firewood, eliminates hazardous health effects linked to inhalation of particles, and provides energy close to where it is needed. The purpose of this work is two fold: initial efforts focus on the development and validation of a computer-based system dynamics model that combines elements of the anaerobic digestion process in order to predict methane output; second, the model is flexed to explore how the addition of a solar component increases robustness of the design, examines predicted biogas generation as a function of varying input conditions, and determines how best to configure such systems for use in varying developing world environments. Therefore, the central components of the system: solar insolation, waste feedstock, bacteria population and consumption rates, and biogas production are related both conceptually and mathematically through a serious of equations, conversions, and a causal loop and feedback diagram. Given contextual constraints and initial assumptions for both locations, it was determined that solar insolation and subsequent digester temperature control, amount of waste, and extreme weather patterns had the most significant impact on the system as a whole. Model behavior was both reproducible and comparable to that demonstrated in existing experimental systems. This tool can thus be flexed to fit specific contexts within the developing world to improve the standard of living of many people, without significantly altering everyday activities.

Bentley, Johanna Lynn

291

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

PubMed

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 (0.40m(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 1000UFC/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 25g per kg dry solids) were added to sludge. PMID:25151445

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

2014-11-01

292

Effects of disintegration on anaerobic degradation of sewage excess sludge in downflow stationary fixed film digesters.  

PubMed

The effects of mechanical disintegration on anaerobic digestibility of sewage excess sludge in downflow stationary fixed film (DSFF) digesters were investigated on laboratory scale. Mechanical pretreatment using a high pressure homogenizer led to significantly enhanced concentrations of soluble proteins and carbohydrates in the feed sludge. Using DSFF digesters with two different tubular plastic media as support material it was shown that a stable digestion process could be achieved at hydraulic retention times (HRT) down to 5 days. Compared to conventional digesters at 10 d and 15 d HRT respectively, the degradation of volatile solids was enhanced up to 25%, also resulting in a higher specific biogas production. Further investigations on degradation of soluble proteins and carbohydrates showed that a slowly degradable fraction of carbohydrates was released via disintegration. Using the distribution of chain length and the concentrations of volatile fatty acids as process parameters, the dependability on the HRT and the degree of disintegration (the release of soluble COD) predominated the effects of specific surface area of the support media. PMID:11381989

Engelhart, M; Krüger, M; Kopp, J; Dichtl, N

2000-01-01

293

A modified anaerobic digestion process with chemical sludge pre-treatment and its modelling.  

PubMed

Activated Sludge Models (ASMs) assume an unbiodegradable organic particulate fraction in the activated sludge, which is derived from the decay of active microorganisms in the sludge and/or introduced from wastewater. In this study, a seasonal change of such activated sludge constituents in a municipal wastewater treatment plant was monitored for 1.5 years. The chemical oxygen demand ratio of the unbiodegradable particulates to the sludge showed a sinusoidal pattern ranging from 40 to 65% along with the change of water temperature in the plant that affected the decay rate. The biogas production in a laboratory-scale anaerobic digestion (AD) process was also affected by the unbiodegradable fraction in the activated sludge fed. Based on the results a chemical pre-treatment using H2O2 was conducted on the digestate to convert the unbiodegradable fraction to a biodegradable one. Once the pre-treated digestate was returned to the digester, the methane conversion increased up to 80% which was about 2.4 times as much as that of the conventional AD process, whilst 96% of volatile solids in the activated sludge was digested. From the experiment, the additional route of the organic conversion processes for the inert fraction at the pre-treatment stage was modelled on the ASM platform with reasonable simulation accuracy. PMID:24901631

Hai, N M; Sakamoto, S; Le, V C; Kim, H S; Goel, R; Terashima, M; Yasui, H

2014-01-01

294

Improvement of mesophilic anaerobic co-digestion of agri-food waste by addition of glycerol.  

PubMed

Anaerobic co-digestion is a promising alternative to manage agri-food waste rather than landfilling, composting or incineration. But improvement of methane yield and biodegradability is often required to optimize its economic viability. Biomethanization of agri-food solid waste presents the disadvantage of a slow hydrolytic phase, which might be enhanced by adding a readily digestible substrate such as glycerol. In this study, strawberry extrudate, fish waste and crude glycerol derived from biodiesel manufacturing are mixed at a proportion of 54:5:41, in VS (VS, total volatile solids), respectively. The mesophilic anaerobic co-digestion at lab-scale of the mixture was stable at loads lower than 1.85 g VS/L, reaching a methane yield coefficient of 308 L CH4/kg VS (0 °C, 1 atm) and a biodegradability of 96.7%, in VS. Moreover, the treatment capacity of strawberry and fish waste was increased 16% at adding the crude glycerol. An economic assessment was also carried out in order to evaluate the applicability of the proposed process. Even in a pessimistic scenario, the net balance was found to be positive. The glycerol adding implied a net saving in a range from 25.5 to 42.1 €/t if compared to landfill disposal. PMID:24726968

Serrano, Antonio; Siles, Jose A; Chica, Arturo F; Martin, M Angeles

2014-07-01

295

Biomass retention on electrodes rather than electrical current enhances stability in anaerobic digestion.  

PubMed

Anaerobic digestion (AD) is a well-established technology for energy recovery from organic waste streams. Several studies noted that inserting a bioelectrochemical system (BES) inside an anaerobic digester can increase biogas output, however the mechanism behind this was not explored and primary controls were not executed. Here, we evaluated whether a BES could stabilize AD of molasses. Lab-scale digesters were operated in the presence or absence of electrodes, in open (no applied potential) and closed circuit conditions. In the control reactors without electrodes methane production decreased to 50% of the initial rate, while it remained stable in the reactors with electrodes, indicating a stabilizing effect. After 91 days of operation, the now colonized electrodes were introduced in the failing AD reactors to evaluate their remediating capacity. This resulted in an immediate increase in CH4 production and VFA removal. Although a current was generated in the BES operated in closed circuit, no direct effect of applied potential nor current was observed. A high abundance of Methanosaeta was detected on the electrodes, however irrespective of the applied cell potential. This study demonstrated that, in addition to other studies reporting only an increase in methane production, a BES can also remediate AD systems that exhibited process failure. However, the lack of difference between current driven and open circuit systems indicates that the key impact is through biomass retention, rather than electrochemical interaction with the electrodes. PMID:24576697

De Vrieze, Jo; Gildemyn, Sylvia; Arends, Jan B A; Vanwonterghem, Inka; Verbeken, Kim; Boon, Nico; Verstraete, Willy; Tyson, Gene W; Hennebel, Tom; Rabaey, Korneel

2014-05-01

296

Biochar derived from anaerobically digested sugar beet tailings: characterization and phosphate removal potential.  

PubMed

Two biochars were produced from anaerobically digested and undigested sugar beet tailings through slow-pyrolysis at 600°C. The digested sugar beet tailing biochar (DSTC) and raw sugar beet tailing biochar (STC) yields were around 45.5% and 36.3% of initial dry weight, respectively. Compared to STC, DSTC had similar pH and surface functional groups, but higher surface area, and its surface was less negatively charged. SEM-EDS and XRD analyses showed that colloidal and nano-sized periclase (MgO) was presented on the surface of DSTC. Laboratory adsorption experiments were conducted to assess the phosphate removal ability of the two biochars, an activated carbon (AC), and three Fe-modified biochar/AC adsorbents. The DSTC showed the highest phosphate removal ability with a removal rate around 73%. Our results suggest that anaerobically digested sugar beet tailings can be used as feedstock materials to produce high quality biochars, which could be used as adsorbents to reclaim phosphate. PMID:21450461

Yao, Ying; Gao, Bin; Inyang, Mandu; Zimmerman, Andrew R; Cao, Xinde; Pullammanappallil, Pratap; Yang, Liuyan

2011-05-01

297

Biochar Produced from Anaerobically Digested Fiber Reduces Phosphorus in Dairy Lagoons  

SciTech Connect

This study evaluated the use of biochar produced from anaerobic digester dairy fiber (ADF) to sequester phosphorus (P) from dairy lagoons. The ADF was collected from a plugged flow digester, air-dried to <8% water content, and pelletized. Biochar was produced by slow pyrolysis in a barrel retort. The potential of biochar to reduce P in the anaerobic digester effluent (ADE) was assessed in small-scale filter systems through which the effluent was circulated. Biochar sequestered an average of 381 mg L?1 P from the ADE, and 4 g L?1 ADF was captured as a coating on the biochar. There was an increase of total (1.9 g kg?1), Olsen (763 mg kg?1), and water-extractable P (914 mg kg?1) bound to the biochar after 15 d of filtration. This accounted for a recovery of 32% of the P in the ADE. The recovered P on the biochar was analyzed using 31P nuclear magnetic resonance for P speciation, which confirmed the recovery of inorganic orthophosphate after liquid extraction of the biochar and the presence of inextractable Ca-P in the solid state. The inorganic phosphate was sequestered on the biochar through physical and weak chemical bonding. Results indicate that biochar could be a beneficial component to P reduction in the dairy system.

Streubel, Jason D.; Collins, Harold P.; Tarara, Julie M.; Cochran, Rebecca L.

2012-07-01

298

Anaerobic Digestion of Renewable Biomass: Thermophilic Temperature Governs Methanogen Population Dynamics ? †  

PubMed Central

Beet silage and beet juice were digested continuously as representative energy crops in a thermophilic biogas fermentor for more than 7 years. Fluorescence microscopy of 15 samples covering a period of 650 days revealed that a decrease in temperature from 60°C to 55°C converted a morphologically uniform archaeal population (rods) into a population of methanogens exhibiting different cellular morphologies (rods and coccoid cells). A subsequent temperature increase back to 60°C reestablished the uniform morphology of methanogens observed in the previous 60°C period. In order to verify these observations, representative samples were investigated by amplified rRNA gene restriction analysis (ARDRA) and fluorescence in situ hybridization (FISH). Both methods confirmed the temperature-dependent population shift observed by fluorescence microscopy. Moreover, all samples investigated demonstrated that hydrogenotrophic Methanobacteriales dominated in the fermentor, as 29 of 34 identified operational taxonomic units (OTUs) were assigned to this order. This apparent discrimination of acetoclastic methanogens contradicts common models for anaerobic digestion processes, such as anaerobic digestion model 1 (ADM1), which describes the acetotrophic Euryarchaeota as predominant organisms. PMID:20097828

Krakat, Niclas; Westphal, A.; Schmidt, S.; Scherer, P.

2010-01-01

299

Comparison of Seven Chemical Pretreatments of Corn Straw for Improving Methane Yield by Anaerobic Digestion  

PubMed Central

Agriculture straw is considered a renewable resource that has the potential to contribute greatly to bioenergy supplies. Chemical pretreatment prior to anaerobic digestion can increase the anaerobic digestibility of agriculture straw. The present study investigated the effects of seven chemical pretreatments on the composition and methane yield of corn straw to assess their effectiveness of digestibility. Four acid reagents (H2SO4, HCl, H2O2, and CH3COOH) at concentrations of 1%, 2%, 3%, and 4% (w/w) and three alkaline reagents (NaOH, Ca(OH)2, and NH3·H2O) at concentrations of 4%, 6%, 8%, and 10% (w/w) were used for the pretreatments. All pretreatments were effective in the biodegradation of the lignocellulosic straw structure. The straw, pretreated with 3% H2O2 and 8% Ca(OH)2, acquired the highest methane yield of 216.7 and 206.6 mL CH4 g VS ?1 in the acid and alkaline pretreatments, which are 115.4% and 105.3% greater than the untreated straw. H2O2 and Ca(OH)2 can be considered as the most favorable pretreatment methods for improving the methane yield of straw because of their effectiveness and low cost. PMID:24695485

Song, Zilin; GaiheYang; Liu, Xiaofeng; Yan, Zhiying; Yuan, Yuexiang; Liao, Yinzhang

2014-01-01

300

Liquid digestate from anaerobic treatment of source-separated household waste as fertilizer to barley.  

PubMed

This study examined the efficiency of different organic waste materials as NPK fertilizer, in addition to the risk for leaching losses related to shower precipitation in the first part of the growing season. The experiment was tested in a pot trial on a sandy soil in a greenhouse. Six organic fertilizers were evaluated: liquid anaerobic digestate (LAD) sourced from separated household waste, nitrified liquid anaerobic digestate (NLAD) of the same origin as LAD, meat and bone meal (MBM), hydrolysed salmon protein (HSP), reactor-composted catering waste (CW) and cattle manure (CM). An unfertilized control, calcium nitrate (CN) and Fullgjødsel® 21-4-10 were used as reference fertilizers. At equal amounts of mineral nitrogen both LAD and Fullgjødsel® gave equal yield of barley in addition to equal uptake of N, P, and K in barley grain. NLAD gave significantly lower barley yield than the original LAD due to leaching of nitrate-N after a simulated surplus of precipitation (28?mm) at Zadoks 14. There was significantly increased leaching of nitrate N from the treatments receiving 160?kg?N?ha(-1) of CN and NLAD in comparison with all the other organic fertilizers. In this study LAD performed to the same degree as Fullgjødsel® NPK fertilizer and it was concluded that LAD can be recommended as fertilizer for cereals. Nitrification of the ammonium N in the digestate caused significantly increased nitrate leaching, and cannot be recommended. PMID:21746761

Haraldsen, Trond Knapp; Andersen, Uno; Krogstad, Tore; Sørheim, Roald

2011-12-01

301

Ribosomal intergenic spacer analysis as a tool for monitoring methanogenic Archaea changes in an anaerobic digester.  

PubMed

The applicability of a newly-designed PCR primer pair in examination of methanogenic Archaea in a digester treating plant biomass was evaluated by Ribosmal Intergenic Spacer Analysis (RISA). To find a suitable approach, three variants of RISA were tested: (1) standard, polyacrylamide gel-based, (2) automated, utilized capillary electrophoresis (GA-ARISA), and (3) automated microfluidics-based (MF-ARISA). All three techniques yielded a consistent picture of archaeal community structure changes during anaerobic digestion monitored for more than 6 weeks. While automated variants were more practical for handling and rapid analysis of methanogenic Archaea, the gel-based technique was advantageous when micro-organism identification was required. A DNA-sequence analysis of dominant bands extracted from the gel revealed that the main role in methane synthesis was played by micro-organisms affiliated with Methanosarcina barkeri. The obtained results revealed that RISA is a robust method allowing for detailed analysis of archaeal community structure during organic biomass conversion into biogas. In addition, our results showed that GA-ARISA has a higher resolution and reproducibility than other variants of RISA and could be used as a technique for tracking changes in methanogenic Archaea in an anaerobic digester. PMID:23525724

Ciesielski, Slawomir; Bu?kowska, Katarzyna; Dabrowska, Dorota; Kaczmarczyk, Dariusz; Kowal, Przemyslaw; Mo?ejko, Justyna

2013-08-01

302

Hydrogen utilization rate: A crucial indicator for anaerobic digestion process evaluation and monitoring.  

PubMed

Hydrogenotrophic methanogens had been considered as key species for the anaerobic digestion (AD) of industrial wastewater and municipal sludge. However, how to evaluate the activity of the hydrogenotrophic methanogens was less studied. In this study, a volumetric device and a test procedure were developed for measuring the specific hydrogen utilization rate (HUR) of anaerobic sludge. Results showed that HUR values were highly influenced by sludge concentrations because of limitation on H2 mass transfer. The critical value of sludge concentration in the test bottle should not be higher than 1 gVSS/L. Under such condition, the kinetics of HUR would not be limited by H2 mass transfer and the maximal value of HUR could be obtained. Field survey confirmed that HUR exhibits a good relationship with specific methanogenic activity (SMA) and reactor performance. An anaerobic system with a relatively high HUR was found to be beneficial for maintaining H2 partial pressure in an appropriately low level. Moreover, such system was thermodynamically favourable for the syntrophic degradation of volatile fatty acids. As a crucial parameter of the anaerobic process, HUR could be used as a key indicator for evaluating and monitoring AD processes. PMID:24216460

Hou, Yin-ping; Peng, Dang-cong; Xue, Xu-dong; Wang, Hong-ye; Pei, Li-ying

2014-04-01

303

High pressure thermal hydrolysis as pre-treatment to increase the methane yield during anaerobic digestion of microalgae.  

PubMed

Anaerobic digestion of algal biomass will be an essential component of algal biofuel production systems, yet the methane yield from digestion of algae is typically much lower than the theoretical potential. In this work, high pressure thermal hydrolysis (HPTH) is shown to enhance methane yield during algae digestion. HPTH pre-treatment was applied to both raw algae and algal residue resulting from lipid extraction. HPTH and even the lipid extraction process itself increased methane yield, by 81% and 33% respectively; in combination they increased yield by 110% over that of the raw algae (18L CH4 gVS(-1) substrate). HPTH had little effect on the rate of anaerobic digestion, however lipid extraction enhanced it by 33% over that for raw algae (0.21day(-1)). Digestion resulted in solubilisation of nitrogen (and phosphorous to a lesser degree) in all cases, showing that there is potential for nutrient recycling for algal growth. PMID:23347920

Keymer, Philip; Ruffell, Ian; Pratt, Steven; Lant, Paul

2013-03-01

304

Start-up and operation strategies on the liquefied food waste anaerobic digestion and a full-scale case application.  

PubMed

Batch anaerobic digestion was employed to investigate the efficient start-up strategies for the liquefied food waste, and sequencing batch digestion was also performed to determine maximum influent organic loading rate (OLR) for efficient and stable operation. The results indicated that the start-up could be well improved using appropriate wastewater organic load and food-to-microorganism ratios (F/M). When digestion was initialized at low chemical oxygen demand (COD) concentration of 20.0 gCOD L(-1), the start-up would go well using lower F/M ratio of 0.5-0.7. The OLR 7.0 gCOD L(-1) day(-1) was recommended for operating the ASBR digestion, in which the COD conversion of 96.7 ± 0.53 % and biomethane yield of 3.5 ± 0.2 L gCOD(-1) were achieved, respectively. The instability would occur when OLR was higher than 7.0 gCOD L(-1) day(-1), and this instability was not recoverable. Lipid was suggested to be removed before anaerobic digestion. The anaerobic digestion process in engineering project ran well, and good performance was achieved when the start-up and operational strategies from laboratory study were applied. For case application, stable digestion performance was achieved in a digester (850 m(3) volume) with biogas production of 1.0-3.8 m(3) m(-3) day(-1). PMID:24861312

Meng, Ying; Shen, Fei; Yuan, Hairong; Zou, Dexun; Liu, Yanping; Zhu, Baoning; Chufo, Akiber; Jaffar, Muhammad; Li, Xiujin

2014-11-01

305

Enhancement of anaerobic digestion of shredded grass by co-digestion with sewage sludge and hyperthermophilic pretreatment.  

PubMed

Anaerobic co-digestion of shredded grass with sewage sludge was investigated under various temperature conditions. The conversion of grass to methane was difficult to achieve under mesophilic conditions, while its methane yield was 0.19NL/g VS-grass under thermophilic conditions. The mixture ratio of grass to sludge affected the methane yield, and the highest synergistic effect was obtained at a C/N ratio of around 10. In a continuous experiment, hyperthermophilic (80°C) pretreatment promoted a methane yield of 0.34NL/g VS-mixture, higher than that under mesophilic and thermophilic conditions (0.20 and 0.30NL/g VS-mixture, respectively). A batch experiment with hyperthermophilic pretreatment showed that 3days of treatment was sufficient for subsequent methane production, in which the highest dissolution of particulate COD, carbohydrate and protein was 25.6%, 33.6% and 25.0%, respectively. PMID:25062542

Wang, Feng; Hidaka, Taira; Tsumori, Jun

2014-10-01

306

Comparison of various microbial inocula for the efficient anaerobic digestion of Laminaria hyperborea  

PubMed Central

Background The hydrolysis of seaweed polysaccharides is the rate limiting step in anaerobic digestion (AD) of seaweeds. Seven different microbial inocula and a mixture of these (inoculum 8) were therefore compared in triplicate, each grown over four weeks in static culture for the ability to degrade Laminaria hyperborea seaweed and produce methane through AD. Results All the inocula could degrade L. hyperborea and produce methane to some extent. However, an inoculum of slurry from a human sewage anaerobic digester, one of rumen contents from seaweed-eating North Ronaldsay sheep and inoculum 8 used most seaweed volatile solids (VS) (means ranged between 59 and 68% used), suggesting that these each had efficient seaweed polysaccharide digesting bacteria. The human sewage inoculum, an inoculum of anaerobic marine mud mixed with rotting seaweed and inoculum 8 all developed to give higher volumes of methane (means between 41 and 62.5 ml g-1 of seaweed VS by week four) ,compared to other inocula (means between 3.5 and 27.5 ml g-1 VS). Inoculum 8 also gave the highest acetate production (6.5 mmol g-1 VS) in a single-stage fermenter AD system and produced most methane (8.4 mL mmol acetate-1) in phase II of a two-stage AD system. Conclusions Overall inoculum 8 was found to be the most efficient inoculum for AD of seaweed. The study therefore showed that selection and inclusion of efficient polysaccharide hydrolysing bacteria and methanogenic archaea in an inoculum offer increased methane productivity in AD of L. hyperborea. This inoculum will now being tested in larger scale (10L) continuously stirred reactors optimised for feed rate and retention time to determine maximum methane production under single-stage and two-stage AD systems. PMID:24456825

2014-01-01

307

Waste activated sludge treatment based on temperature staged and biologically phased anaerobic digestion system.  

PubMed

The concept of temperature staged and biological phased (TSBP) was proposed to enhance the performance of waste-activated sludge anaerobic digestion. Semi-continuous experiments were used to investigate the effect of temperature (35 to 70 degrees C) as well as the hydraulic retention time (HRT) (2, 4 and 6 days) on the acidogenic phase. The results showed that the solubilization degree of waste-activated sludge increased from 14.7% to 30.1% with temperature increasing from 35 to 70 degrees C, while the acidification degree was highest at 45 degrees C (17.6%), and this was quite different from the temperature impact on hydrolysis. Compared with HRT of 2 and 6 days, 4 days was chosen as the appropriate HRT because of its relatively high solubilization degree (24.6%) and acidification degree (20.1%) at 45 degrees C. The TSBP system combined the acidogenic reactor (45 degrees C, 4 days) with the methanogenic reactor (35 degrees C, 16 days) and the results showed 84.8% and 11.4% higher methane yield and volatile solid reduction, respectively, compared with that of the single-stage anaerobic digestion system with HRT of 20 days at 35 degrees C. Moreover, different microbial morphologies were observed in the acidogenic- and methanogenic-phase reactors, which resulted from the temperature control and HRT adjustment. All the above results indicated that 45 degrees C was the optimum temperature to inhibit the activity of methanogenic bacteria in the acidogenic phase, and temperature staging and phase separation was thus accomplished. The advantages of the TSBP process were also confirmed by a full-scale waste-activated sludge anaerobic digestion project which was an energy self-sufficient system. PMID:24494492

Yu, Jingwen; Zheng, Mingxia; Tao, Tao; Zuo, Jiane; Wang, Kaijun

2013-10-01

308

Anaerobic digestion of seven different sewage sludges: a biodegradability and modelling study.  

PubMed

Seven mixed sewage sludges from different wastewater treatment plants, which have an anaerobic digester in operation, were evaluated in order to clarify the literature uncertainty with regard to the sewage sludge characterisation and biodegradability. Moreover, a methodology is provided to determine the Anaerobic Digestion Model No. 1 parameters, coefficients and initial state variables as well as a discussion about the accuracy of the first order solubilisation constant, which was obtained through biomethane potential test. The results of the biomethane potential tests showed ultimate methane potentials from 188 to 214 mL CH4 g(-1) CODfed, COD removals between 58 and 65% and two homogeneous groups for the first order solubilisation constant: (i) the lowest rate group from 0.23 to 0.35 day(-1) and (ii) the highest rate group from 0.27 to 0.43 day(-1). However, no statistically significant relationship between the ultimate methane potential or the disintegration constant and the sewage sludge characterisation was found. Next, a methodology based on the sludge characterisation before and after the biomethane potential test was developed to calculate the biodegradable fraction, the composite concentration and stoichiometric coefficients and the soluble COD of the sewage sludge; required parameters for the implementation of the Anaerobic Digestion Model No. 1. The comparison of the experimental and the simulation results proved the consistency of the developed methodology. Nevertheless, an underestimation of the first order solubilisation constant was detected when the experimental results were simulated with the solubilisation constant obtained from the linear regression experimental data fitting. The latter phenomenon could be related to the accumulation of intermediary compounds during the biomethane potential assay. PMID:23938118

Astals, S; Esteban-Gutiérrez, M; Fernández-Arévalo, T; Aymerich, E; García-Heras, J L; Mata-Alvarez, J

2013-10-15

309

Comparative mesophilic and thermophilic anaerobic digestion of palm oil mill effluent using upflow anaerobic sludge blanket.  

PubMed

The effects of organic loading rate and operating temperature on the microbial diversity and performances of upflow anaerobic sludge blanket (UASB) reactors treating palm oil mill effluent (POME) were investigated. The following two UASB reactors were run in parallel for comparison: (1) under a mesophilic condition (37 degrees C) and (2) under a mesophilic condition in transition to a thermophilic condition (57 degrees C). A polymerase chain reaction (PCR)-based denaturing gradient gel electrophoresis (DGGE) analysis showed that the microbial population profiles significantly changed with the organic loading rate (OLR) and the temperature transition from the mesophilic to the thermophilic condition. Significant biomass washout was observed for the mesophilic UASB when operating at a high organic loading rate (OLR) of 9.5 g chemical oxygen demand (COD)/L.d. In contrast, the thermophilic UASB can be operated at this OLR and at a temperature of 57 degrees C with satisfactory COD removal and biogas production. The PCR-based DGGE analysis suggested that the thermophilic temperature of 57 degrees C was suitable for a number of hydrolytic, acidogenic, and acetogenic bacteria. PMID:22876480

Khemkhao, Maneerat; Nuntakumjorn, Boonyarit; Techkarnjanaruk, Somkiet; Phalakornkule, Chantaraporn

2012-07-01

310

The variability in nutrient composition of Anaerobic Digestate granules produced from high shear granulation.  

PubMed

This study investigates the production of organic fertilizer using Anaerobic Digestate (as a nutrient source) and limestone powder as the raw materials. A two-level factorial experimental design was used to determine the influence of process variables on the nutrient homogeneity within the granules. Increasing the liquid-to-solid ratio during granulation resulted in increased granule nutrient homogeneity. Increasing the processing time and the impeller speed were also found to increase the nutrient homogeneity. In terms of nutrients release into deionized water, the granules effectively released both potassium and phosphate into solution. PMID:23083974

Mangwandi, Chirangano; JiangTao, Liu; Albadarin, Ahmad B; Allen, Stephen J; Walker, Gavin M

2013-01-01

311

Anaerobic digestion of cattail with rumen culture in the presence of heavy metals  

Microsoft Academic Search

The anaerobic digestion of cattail by rumen cultures in the presence of Cu(II), Cd(II) or Cr(VI) was investigated in this study. Three cases were respectively observed for the different metal dosages: promoted cattail degradation and methane production at a low heavy metal concentration, e.g., Cu(II) 2.4mg\\/l, Cd(II) 1.6mg\\/l, Cr(VI) 4.0mg\\/l; reduced cattail degradation efficiency and methane production at a middle

Zheng-Bo Yue; Han-Qing Yu; Zhi-Liang Wang

2007-01-01

312

Purification of municipal wastewater by subsequent reverse osmosis and anaerobic digestion  

SciTech Connect

Experiments are described in which municipal wastewater is submitted to reverse osmosis. During a test period of two months a tubular apparatus, operated batchwise, maintained its original flux and rejection, the permeate being of good quality as a raw material for drinking water. The wastewater was concentrated 7.7 times. Continuous anaerobic digestion of the brine removed over 90% of the BOD evolving the expected amount of methane. The overall process is considered in its context of environmental and energetic aspects and is compared with a conventional treatment. This reveals clear perspectives for practical application in urban area. 10 refs.

Van Den Heuvel, J.C.; Zoetemeyer, R.J.; Boelhouwer, C.

1981-09-01

313

Prediction of trace compounds in biogas from anaerobic digestion using the MATLAB Neural Network Toolbox  

Microsoft Academic Search

Abstract The outlook,to apply the highly energetic biogas,from,anaerobic,digestion into fuel cells will result in a significantly higher electrical efficiency and,can contribute,to an increase of renewable,energy,production. The practical bottleneck is the fuel cell poisoning,caused,by several gaseous,trace compounds,like hydrogen,sulfide and,ammonia.,Hence artificial neural networks,were developed,to predict these trace compounds.,The experiments,concluded,that ammonia,in biogas,can indeed,be present up to 93 ppm. Hydrogen,sulfide and ammonia,concentrations,in biogas were

David P. B. T. B. Strik; Alexander M. Domnanovich; Loredana Zani; Rudolf Braun; Peter Holubar

2005-01-01

314

Characterization of three Chlorella sorokiniana strains in anaerobic digested effluent from cattle manure.  

PubMed

Chlorella sorokiniana CS-01, UTEX 1230 and UTEX 2714 were maintained in 10% anaerobic digester effluent (ADE) from cattle manure digestion and compared with algal cultivation in Bold's Basal Medium (BBM). Biomass of CS-01 and UTEX 1230 in ADE produced similar or greater than 280mg/L after 21days in BBM, however, UTEX 2714 growth in ADE was suppressed by more than 50% demonstrating a significant species bias to synthetic compared to organic waste-based media. The highest accumulation of protein and starch was exhibited in UTEX 1230 in ADE yielding 34% and 23% ash free dry weight (AFDW), respectively, though fatty acid methyl ester total lipid measured less than 12% AFDW. Results suggest that biomass from UTEX 1230 in ADE may serve as a candidate alga and growth system combination sustainable for animal feed production considering high yields of protein, starch and low lipid accumulation. PMID:24185420

Kobayashi, Naoko; Noel, Eric A; Barnes, Austin; Watson, Andrea; Rosenberg, Julian N; Erickson, Galen; Oyler, George A

2013-12-01

315

Anaerobic digestion of acidified slurry fractions derived from different solid-liquid separation methods.  

PubMed

Batch assays investigating the ultimate methane yields (B(0)) of acidified slurry fractions produced with different solid-liquid slurry separation techniques were done. The result showed that the anaerobic digestion (AD) process was inhibited when raw and liquid fractions of sow, pig and dairy cow acidified slurry are digested, but AD treating solid fractions (SF) acidified slurry showed no sulphide inhibition. The B(0) of SF acidified sow slurry increased significantly with increasing screen size in the screw press. No significant effect of acidification processes on B(0) of SF dairy cow slurry (DCS) was observed. The ultimate methane yields of SF acidified DCS and SF non acidified DCS were 278±13 and 289±1LkgVS(-1), while in term of fresh weigh substrate were 59±2.8 and 59±0.3Lkgsubstrate(-1), respectively. PMID:23313767

Sutaryo, Sutaryo; Ward, Alastair James; Møller, Henrik Bjarne

2013-02-01

316

Anaerobic model for high-solids or high-temperature digestion - additional pathway of acetate oxidation.  

PubMed

Current anaerobic digestion models cannot properly simulate processes that are operated under high solids concentrations or high temperatures. A modification to existing models has been implemented by adding important missing degradation pathways, to accommodate these systems without artificially recalibrating the model parameters. Specifically, we implemented the alternate acetate oxidizing mechanism that is more tolerant to ammonia than the standard aceticlastic pathway. Inhibition values were estimated and an empirical function has been used to apply ammonia inhibition. The model also relates metabolic activity to un-ionised species such as undissociated acetic acid as substrate (although not obligatory for all organisms) and unionised ammonia as inhibitor. The model relies on an equilibrium chemistry module (e.g. including the phosphate buffer), resulting in more accurate pH predictions, which is crucial for proper modeling of CO2 and NH3 stripping. Calibration results from three case-studies modeling thermal hydrolysis and subsequent digestion of sludge are presented. PMID:24759522

Wett, B; Takács, I; Batstone, D; Wilson, C; Murthy, S

2014-01-01

317

Continuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditions.  

PubMed

With increasing concerns over the limited capacity of landfills, conservation of resources, and reduction of CO(2) emissions, high-solids (dry) anaerobic digestion of organic solid waste (OSW) is attracting a great deal of attention these days. In the present work, two dry anaerobic co-digestion systems fed with different mixtures of OSW were continuously operated under mesophilic conditions. Dewatered sludge cake was used as a main seeding source. In reactor (I), which was fed with food waste (FW) and paper waste (PW), hydraulic retention time (HRT) and solid content were controlled to find the maximum treatability. At a fixed solid content of 30% total solids (TS), stable performance was maintained up to an HRT decrease to 40 d. However, the stable performance was not sustained at 30 d HRT, and hence, HRT was increased to 40 d again. In further operation, instead of decreasing HRT, solid content was increased to 40% TS, which was found to be a better option to increase the treatability. The biogas production rate (BPR), CH(4) production yield (MPY) and VS reduction achieved in this condition were 5.0m(3)/m(3)/d, 0.25 m(3) CH(4)/g COD(added), and 80%, respectively. Reactor (II) was fed with FW and livestock waste (LW), and LW content was increased during the operation. Until a 40% LW content increase, reactor (II) exhibited a stable performance. A BPR of 1.7 m(3)/m(3)/d, MPY of 0.26 m(3) CH(4)/g COD(added), and VS reduction of 72% was achieved at 40% LW content. However, when the LW content was increased to 60%, there was a significant performance drop, which was attributed to free ammonia inhibition. The performances in these two reactors were comparable to the ones achieved in the conventional wet digestion and thermophilic dry digestion processes. PMID:21684733

Kim, Dong-Hoon; Oh, Sae-Eun

2011-01-01

318

Can sludge dewatering reactivate microorganisms in mesophilically digested anaerobic sludge? Case of belt filter versus centrifuge.  

PubMed

The anaerobic digestion process that successfully reduces the organic content of sludge is one of the most common alternatives to meet pathogen reduction requirements for particular classes of biosolids. However, recently it was reported that, much higher densities of indicator bacteria were measured in dewatered cake samples compared to samples collected after anaerobic digestion. Additionally, this increase was commonly observed after centrifugation but not after belt filter dewatering. Several hypotheses were tested to explain this occurrence; however, much of the attention was given to the reactivation of the indicator bacteria which might enter a viable but non-culturable state (VBNC) during digestion. The objective of this research is to examine sludge samples from 5 different full-scale treatment plants in order to observe the effect of dewatering processes on the reactivation potential of indicator bacteria. The bacterial enumerations were performed by both Standard Culturing Methods (SCM) and quantitative polymerase chain (qPCR) on samples collected after digestion and dewatering. Results obtained by SCM indicated that in two investigated treatment plants operating belt filter dewatering, an average 0.6 log decrease was observed after the dewatering process. However, 0.7-1.4 log increases were observed immediately after centrifuge dewatering for the other three treatment plants. On the other hand, qPCR results gave 0.1-1.9 log higher numbers compared to SCM. Comparative evaluation of results obtained by two analytical methods for five treatment plants indicates that the differences observed might be originating from both reactivation of VBNC bacteria and amplification of DNA from dead cells found in the sludge. PMID:23141737

Erkan, M; Sanin, F D

2013-01-01

319

Anaerobic slurry co-digestion of poultry manure and straw: effect of organic loading and temperature  

PubMed Central

In order to obtain basic design criteria for anaerobic digestion of a mixture of poultry manure and wheat straw, the effects of different temperatures and organic loading rates on the biogas yield and methane contents were evaluated. Since poultry manure is a poor substrate, in term of the availability of the nutrients, external supplementation of carbon has to be regularly performed, in order to achieve a stable and efficient process. The complete-mix, pilot-scale digester with working volume of 70 L was used. The digestion operated at 25°C, 30°C and 35°C with organic loading rates of 1.0, 2.0, 2.5, 3.0, 3.5 and 4.0 kg Volatile solid/m3d and a HRT of 15 days. At a temperature of 35°C, the methane yield was increased by 43% compared to 25°C. Anaerobic co-digestion appeared feasible with a loading rate of 3.0 kg VS/m3d at 35°C. At this state, the specific methane yield was calculated about 0.12 m3/kg VS with a methane content of 53–70.2% in the biogas. The volatile solid (VS) removal was 72%. As a result of volatile fatty acid accumulation and decrease in pH, when the loading rate was less than 1 or greater than 4 kg VS/m3d, the process was inhibited or overloaded, respectively. Both the lower and higher loading rates resulted in a decline in the methane yield. PMID:24502409

2013-01-01

320

Continuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditions  

SciTech Connect

Highlights: > High-solids (dry) anaerobic digestion is attracting a lot of attention these days. > One reactor was fed with food waste (FW) and paper waste. > Maximum biogas production rate of 5.0 m{sup 3}/m{sup 3}/d was achieved at HRT 40 d and 40% TS. > The other reactor was fed with FW and livestock waste (LW). > Until a 40% LW content increase, the reactor exhibited a stable performance. - Abstract: With increasing concerns over the limited capacity of landfills, conservation of resources, and reduction of CO{sub 2} emissions, high-solids (dry) anaerobic digestion of organic solid waste (OSW) is attracting a great deal of attention these days. In the present work, two dry anaerobic co-digestion systems fed with different mixtures of OSW were continuously operated under mesophilic conditions. Dewatered sludge cake was used as a main seeding source. In reactor (I), which was fed with food waste (FW) and paper waste (PW), hydraulic retention time (HRT) and solid content were controlled to find the maximum treatability. At a fixed solid content of 30% total solids (TS), stable performance was maintained up to an HRT decrease to 40 d. However, the stable performance was not sustained at 30 d HRT, and hence, HRT was increased to 40 d again. In further operation, instead of decreasing HRT, solid content was increased to 40% TS, which was found to be a better option to increase the treatability. The biogas production rate (BPR), CH{sub 4} production yield (MPY) and VS reduction achieved in this condition were 5.0 m{sup 3}/m{sup 3}/d, 0.25 m{sup 3} CH{sub 4}/g COD{sub added}, and 80%, respectively. Reactor (II) was fed with FW and livestock waste (LW), and LW content was increased during the operation. Until a 40% LW content increase, reactor (II) exhibited a stable performance. A BPR of 1.7 m{sup 3}/m{sup 3}/d, MPY of 0.26 m{sup 3} CH{sub 4}/g COD{sub added}, and VS reduction of 72% was achieved at 40% LW content. However, when the LW content was increased to 60%, there was a significant performance drop, which was attributed to free ammonia inhibition. The performances in these two reactors were comparable to the ones achieved in the conventional wet digestion and thermophilic dry digestion processes.

Kim, Dong-Hoon [Wastes Energy Research Center, Korea Institute of Energy Research, 102, Gajeong-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Oh, Sae-Eun, E-mail: saeun@hanbat.ac.kr [Department of Environmental Engineering, Hanbat National University, San 16-1, Duckmyoung-dong, Yuseong-gu, Daejeon (Korea, Republic of)

2011-09-15

321

Anaerobic co-digestion of desugared molasses with cow manure; focusing on sodium and potassium inhibition.  

PubMed

Desugared molasses (DM), a syrup residue from beet-molasses, was investigated for biogas production in both batch and in continuously-stirred tank reactor (CSTR) experiments. DM contained 2-3 times higher concentration of ions than normal molasses, which could inhibit the biogas process. The effect of sodium and potassium concentration on biogas production from manure was also investigated. Fifty percent inhibition occurred at sodium and potassium concentration of 11 and 28 g/L, respectively. The reactor experiments were carried out to investigate the biogas production from DM under different dilutions with water and co-digestion with manure. Stable operation at maximum methane yield of 300 mL-CH4/gVS-added was obtained at a mixture of 5% DM in cow manure. The biogas process was inhibited at DM concentrations higher than 15%. Manure was a good base substrate for co-digestion, and a stable anaerobic digestion could be achieved by co-digesting DM with manure at the concentration below 15% DM. PMID:20951579

Fang, Cheng; Boe, Kanokwan; Angelidaki, Irini

2011-01-01

322

Anaerobic digestate as substrate for microalgae culture: the role of ammonium concentration on the microalgae productivity.  

PubMed

In spite of the increasing interest received by microalgae as potential alternatives for biofuel production, the technology is still not industrially viable. The utilization of digestate as carbon and nutrients source can enhance microalgal growth reducing costs and environmental impacts. This work assesses microalgal growth utilizing the liquid phase of anaerobic digestate effluent as substrate. The effect of inoculum/substrate ratio on microalgal growth was studied in a laboratory batch experiment conduced in 0.5L flasks. Results suggested that digestate may be an effective substrate for microalgal growth promoting biomass production up to 2.6 gTSS/L. Microalgal growth rate was negatively affected by a self-shading phenomenon, while biomass production was positively correlated with the inoculum and substrate concentrations. Thus, the increasing of both digestate and microalgal initial concentration may reduce the initial growth rate (? from 0.9 to 0.04 d(-1)) but significantly enhances biomass production (from 0.1 to 2.6 gTSS/L). PMID:24316486

Uggetti, Enrica; Sialve, Bruno; Latrille, Eric; Steyer, Jean-Philippe

2014-01-01

323

Dry anaerobic digestion of cow dung for methane production: effect of mixing.  

PubMed

The performance characteristics of a dry batch reactor with a blender treating cow dung has been evaluated for 35 days in a single-stage batch reactor of 3 L effective volume at 35 +/- 1 degree C to investigate the effect of continuous-mixing on biogas production and organic materials removal. The results showed that the performance of unmixed and mixed digesters was quite different and the dry digester with mixing system produced methane of 0.358 LCH4/gVS(r) which was 7.50% higher than that for unmixed digester. Moreover, the organic material removal efficiency was increased by 9.73% in term of VS. The wide diversity of prominent bacteria and methanogenic archaea affiliated with all steps along the anaerobic degradation pathway made the process stable. But the dry digester with mixing system during start up was not beneficial, as it resulted in relatively higher volatile fatty acids, higher volatile fatty acid to alkalinity ratio, lower pH and consequently prolonged start up time. PMID:24261113

Jha, Ajay Kumar; Li, Jianzheng; Ban, Qiaoying; Zhang, Liguo; Zhao, Bowei

2012-12-01

324

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

PubMed

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 without the use of additives was developed in which the pH-regulation is executed by the pH-dependent recycling of effluent from the anaerobic filter into the acidification reactor. During this investigation, the influence of the different target pH-values (5.5, 6.0, 7.0 and 7.5) on the degradation rate, the gas composition and the methane yield of the substrate maize silage was determined. With an increase in the target pH-value from 5.5 to 7.5, the acetic acid equivalent decreased by 88.1% and the chemical oxygen demand-concentration by 18.3% in the hydrolysate. In response, there was a 58% increase in the specific methane yield of the overall system. Contrary to earlier studies, a marked increase in biogas production and in substrate degradation was determined with increasing pH-values. However, these led to a successive approximation of a single-phase process. Based on these results, pH-values above 7.0 seem to be favourable for the digestion of fibre-rich substrates. PMID:25413114

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

2015-01-01

325

Removal of phosphate from aqueous solution by biochar derived from anaerobically digested sugar beet tailings.  

PubMed

Biochar converted from agricultural residues or other carbon-rich wastes may provide new methods and materials for environmental management, particularly with respect to carbon sequestration and contaminant remediation. In this study, laboratory experiments were conducted to investigate the removal of phosphate from aqueous solution by biochar derived from anaerobically digested sugar beet tailings (DSTC). Batch adsorption kinetic and equilibrium isotherm experiments and post-adsorption characterizations using SEM-EDS, XRD, and FTIR suggested that colloidal and nano-sized MgO (periclase) particles on the biochar surface were the main adsorption sites for aqueous phosphate. Batch adsorption experiments also showed that both initial solution pH and coexisting anions could affect the adsorption of phosphate onto the DSTC biochar. Of the mathematical models used to describe the adsorption kinetics of phosphate removal by the biochar, the Ritchie N_th-order (N=1.14) model showed the best fit. Two heterogeneous isotherm models (Freundlich and Langmuir-Freundlich) fitted the experimental isotherm of phosphate adsorption onto the biochar better than the Langmuir adsorption model. Our results suggest that biochar converted from anaerobically digested sugar beet tailings is a promising alternative adsorbent, which can be used to reclaim phosphate from water or reduce phosphate leaching from fertilized soils. In addition, there is no need to regenerate the exhausted biochar because the phosphate-laden biochar contains abundance of valuable nutrients, which may be used as a slow-release fertilizer to enhance soil fertility and to sequester carbon. PMID:21497441

Yao, Ying; Gao, Bin; Inyang, Mandu; Zimmerman, Andrew R; Cao, Xinde; Pullammanappallil, Pratap; Yang, Liuyan

2011-06-15

326

Effects of different SRT on anaerobic digestion of MSW dosed with various MSWI ashes.  

PubMed

This study investigated different solid retention time (SRT) on municipal solid waste (MSW) anaerobic digestion with various MSW incinerator fly ash (FA) and bottom ash (BA) addition. Results showed that biogas production rates (BPRs, ? 200 to ? 400 mL/gVS) with organic loading rate of ? 0.053 gVS/gVS(reactor) (Day 1-435, SRT 20 days, SRT20) at FA 1g/d (FA1), BA 12 g/d (BA12) and BA 24 g/d (BA24) dosed bioreactors increased after adaptation. BPRs with SRT10 and SRT5 decreased while BPRs with SRT40 showed to increase compared to initial BPRs (? 200 mL/gVS) with SRT20. SRT5 operation reduced the BPRs (? 10 - ? 90 mL/gVS) significantly and only BA12 and BA24 dosed bioreactors could recover the BPRs (? 100 - ? 200 mL/gVS) after SRT20 operation (Day 613-617) compared to FA1 and FA3 and control. Released levels of Co, Mo and W at BA12 and BA24 dosed bioreactors showed most potential to improve MSW anaerobic digestion. PMID:23026339

Lo, H M; Chiu, H Y; Lo, S W; Lo, F C

2012-12-01

327

Environmental assessment of anaerobically digested sludge reuse in agriculture: potential impacts of emerging micropollutants.  

PubMed

Agricultural application of sewage sludge has been emotionally discussed in the last decades, because the latter contains organic micropollutants with unknown fate and risk potential. In this work, the reuse of anaerobically digested sludge in agriculture is evaluated from an environmental point of view by using Life Cycle Assessment methodology. More specifically, the potential impacts of emerging micropollutants, such as pharmaceuticals and personal care products, present in the sludge have been quantified. Four scenarios were considered according to the temperature of the anaerobic digestion (mesophilic or thermophilic) and the sludge retention time (20 or 10d), and they have been compared with the non-treated sludge. From an environmental point of view, the disposal of undigested sludge is not the most suitable alternative, except for global warming due to the dominance (65-85%) of the indirect emissions associated to the electricity use. Nutrient-related direct emissions dominate the eutrophication category impact in all the scenarios (>71.4%), although a beneficial impact related to the avoidance of industrial fertilisers production is also quantified (up to 6.7%). In terms of human and terrestrial toxicity, the direct emissions of heavy metals to soil dominate these two impact categories (>70%), and the contribution of other micropollutants is minimal. Moreover, only six (Galaxolide, Tonalide, Diazepam, Ibuprofen, Sulfamethoxazole and 17alpha-ethinyloestradiol) out of the 13 substances considered are really significant since they account for more than 95% of the overall micropollutants impact. PMID:20347114

Hospido, Almudena; Carballa, Marta; Moreira, Maite; Omil, Francisco; Lema, Juan M; Feijoo, Gumersindo

2010-05-01

328

Utilisation of wastewater nutrients for microalgae growth for anaerobic co-digestion.  

PubMed

The feasibility of growing microalgae in natural light using wastewater high in nutrients (N & P) for the production of more bioenergy was examined. The main retrofitting unit would be a photobioreactor for wastewater treatment plants (wwtp) having anaerobic digesters in close proximity. Theoretical microalgae production rates from different wastewater sources (municipal wwtp, source separation of human and animal wastewaters) were estimated using mass balance. Mass and energy balances for a conventional wwtp using chemically enhanced primary treatment was investigated for microalgae growth for a situation limited by availability of carbon dioxide (CO2) generated onsite and where additional CO2 was imported from outside source. Reject water from dewatering of anaerobically digested sludge from four wwtp around Oslo region were pretreated for improved light penetration and examined for microalgae growth. Several pre-treatment methods were investigated. Pretreatment using flocculation + settling + anthracite filtration yielded high light transmittance. A maximum microalgae growth rate of 13 g TSS/m(2)-d was achieved using this pretreated reject water. The challenges of integrating photobioreactors with existing units have been highlighted. PMID:23570973

Sahu, Ashish K; Siljudalen, Jon; Trydal, Tina; Rusten, Bjørn

2013-06-15

329

Flux analysis of the human proximal colon using anaerobic digestion model 1.  

PubMed

The colon can be regarded as an anaerobic digestive compartment within the gastro intestinal tract (GIT). An in silico model simulating the fluxes in the human proximal colon was developed on basis of the anaerobic digestion model 1 (ADM1), which is traditionally used to model waste conversion to biogas. Model calibration was conducted using data from in vitro fermentation of the proximal colon (TIM-2), and, amongst others, supplemented with the bio kinetics of prebiotic galactooligosaccharides (GOS) fermentation. The impact of water and solutes absorption by the host was also included. Hydrolysis constants of carbohydrates and proteins were estimated based on total short chain fatty acids (SCFA) and ammonia production in vitro. Model validation was established using an independent dataset of a different in vitro model: an in vitro three-stage continuous culture system. The in silico model was shown to provide quantitative insight in the microbial community structure in terms of functional groups, and the substrate and product fluxes between these groups as well as the host, as a function of the substrate composition, pH and the solids residence time (SRT). The model confirms the experimental observation that methanogens are washed out at low pH or low SRT-values. The in silico model is proposed as useful tool in the design of experimental setups for in vitro experiments by giving insight in fermentation processes in the proximal human colon. PMID:24880006

Motelica-Wagenaar, Anne Marieke; Nauta, Arjen; van den Heuvel, Ellen G H M; Kleerebezem, Robbert

2014-08-01

330

Deterministic processes guide long-term synchronised population dynamics in replicate anaerobic digesters.  

PubMed

A replicate long-term experiment was conducted using anaerobic digestion (AD) as a model process to determine the relative role of niche and neutral theory on microbial community assembly, and to link community dynamics to system performance. AD is performed by a complex network of microorganisms and process stability relies entirely on the synergistic interactions between populations belonging to different functional guilds. In this study, three independent replicate anaerobic digesters were seeded with the same diverse inoculum, supplied with a model substrate, ?-cellulose, and operated for 362 days at a 10-day hydraulic residence time under mesophilic conditions. Selective pressure imposed by the operational conditions and model substrate caused large reproducible changes in community composition including an overall decrease in richness in the first month of operation, followed by synchronised population dynamics that correlated with changes in reactor performance. This included the synchronised emergence and decline of distinct Ruminococcus phylotypes at day 148, and emergence of a Clostridium and Methanosaeta phylotype at day 178, when performance became stable in all reactors. These data suggest that many dynamic functional niches are predictably filled by phylogenetically coherent populations over long time scales. Neutral theory would predict that a complex community with a high degree of recognised functional redundancy would lead to stochastic changes in populations and community divergence over time. We conclude that deterministic processes may play a larger role in microbial community dynamics than currently appreciated, and under controlled conditions it may be possible to reliably predict community structural and functional changes over time. PMID:24739627

Vanwonterghem, Inka; Jensen, Paul D; Dennis, Paul G; Hugenholtz, Philip; Rabaey, Korneel; Tyson, Gene W

2014-10-01

331

Advanced techniques for characterization of organic matter from anaerobically digested grapemarc distillery effluents and amended soils.  

PubMed

The effects of grapemarc distillery effluents on the quality of soil organic matter is extremely important to ensure the environmentally-safe and agronomically efficient use of these materials as organic amendment. In this work, the effects of the application of untreated (UG) and anaerobically digested grapemarc distillery effluents, either added with (AGM) or without mycorrhiza (AG), on soil humic acid (HA) were investigated in field plot experiments in comparison to HAs from a control soil and an inorganic fertilized soil. The humic acid-like fractions (HALs) isolated from UG, AG and soils were characterized for compositional, structural and functional properties by the use of elemental and functional group analysis, and ultraviolet/visible, Fourier transform infrared and fluorescence spectroscopies. Results obtained indicated that anaerobic digestion of effluents produced an extended mineralization with loss of organic C and stabilization of residual organic matter by increasing the content of HALs in the effluent. With respect to control soil HA, HALs isolated from UG and AG were characterized by smaller acidic functional group contents, a prevalent aliphatic character and smaller aromatic polycondensation and humification degrees. The chemical and spectroscopic characteristics of native soil HA were not substantially modified by application of UG, AG and AGM to soil, which suggests the occurred incorporation of the effluent HAL into native soil HA. In conclusion, these results showed the possibility of a beneficial and safe recycling of grapemarc distillery effluents as soil amendment. PMID:21573856

Brunetti, Gennaro; Farrag, Karam; Plaza, Cesar; Senesi, Nicola

2012-04-01

332

Start-up of thermophilic-dry anaerobic digestion of OFMSW using adapted modified SEBAC inoculum.  

PubMed

The work presented here concerns the start-up and stabilization stages of a Continuous Stirred Tank Reactor (CSTR) semicontinuously fed for the treatment of the Organic Fraction of Municipal Solid Waste (OFMSW) through anaerobic digestion at thermophilic temperature range (55 degrees C) and dry conditions (30% Total Solids). The procedure reported involves two novel aspects with respect to other start-up and stabilization protocols reported in the literature. The novel aspects concern the adaptation of the inoculum to both the operating conditions (thermophilic and dry) and to the type of waste by employing a modified SEBAC (Sequential Batch Anaerobic Composting) system and, secondly, the direct start-up of the process in a thermophilic temperature regime and feeding of the system from the first day of operation. In this way a significant reduction in the start-up time and stabilization is achieved i.e. 110 days in comparison to 250 days for the processes reported by other authors for the same type of waste and digester. The system presents suitable operational conditions to stabilize the reactor at SRT of 35 days, with a maximum biogas production of 1.944 LR/L.d with a CH(4) and CO(2) percentage of 25.27% and 68.15%, respectively. PMID:20659796

Fdéz-Güelfo, L A; Alvarez-Gallego, C; Sales Márquez, D; Romero García, L I

2010-12-01

333

Agar medium for gas-liquid chromatography of anaerobes.  

PubMed

This study evaluates a method of performing gas-liquid chromatography (GLC) by direct extraction of fatty acids from agar for identification of clinically significant anaerobic bacteria. The potential use of agar cultures for GLC was studied by comparing chromatograms of 117 clinically isolated anaerobes grown in peptone yeast glucose broth and chopped meat carbohydrate broth, and on enriched brucella blood agar. For 98 of 117 anaerobes, fatty acid patterns from agar cultures were similar to those in broth. Significant differences were only found with Streptococcus intermedius, Clostridium perfringens, Clostridium tertium, and Actinomyces species, which produced less of certain fatty acids on agar than in broth. Results of this study indicate that GLC of short chain fatty acids produced on agar medium by anaerobes, combined with simple tests such as Gram's stain and colonial morphology, may allow fir direct presumptive genus identification from an initial pure agar culture. PMID:3940426

Pankuch, G A; Appelbaum, P C

1986-01-01

334

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

PubMed

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. PMID:20176467

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

2010-10-01

335

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

PubMed Central

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 AD 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 AD, 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.

Alvarado, Alejandra; Montañez-Hernández, Lilia E.; Palacio-Molina, Sandra L.; Oropeza-Navarro, Ricardo; Luévanos-Escareño, Miriam P.; Balagurusamy, Nagamani

2014-01-01

336

Anaerobic digestion as a core technology in sustainable management of organic matter.  

PubMed

In the past decades, anaerobic digestion (AD) has steadily gained importance. However, the technology is not regarded as a top priority in science policy and in industrial development at present. In order for AD to further develop, it is crucial that AD profits from the current fuel issues emerging in the international arena. AD can provide low-cost treatment of sewage and solid domestic wastes, which represents a vast application potential that should be promoted in the developing world. Furthermore, the developments in the last decades in the domain of anaerobic microbiology and technology have generated some interesting niches for the application of AD, such as anaerobic nitrogen removal and the treatment of chlorinated organics. Recently, AD has also generated some serendipities, such as the use of AD in processes for sulphur and calcium removal and the coupling of AD with microbial fuel cells. The international developments in terms of bio-refineries and CO2-emission abatement are of crucial importance with respect to the impetus that AD will receive in the coming decade. There should be little doubt that by placing the focus of AD on the production of green energy and clean nutrients, the future of AD will be assured. PMID:16180409

Verstraete, W; Morgan-Sagastume, F; Aiyuk, S; Waweru, M; Rabaey, K; Lissens, G

2005-01-01

337

Application of ADM1 model to a full-scale anaerobic digester under dynamic organic loading conditions.  

PubMed

The IWA Anaerobic Digestion Model No. 1 (ADM1) was used to simulate the full-scale anaerobic sludge digester of Ankara Central Wastewater Treatment Plant. The digester is a completely mixed, once through continuous flow type which is being fed with a primary and secondary sludge mixture. The variability and unpredicted nature of the primary sludge composition was expected to challenge the model. A one-year dynamic data set from the digester was used for model calibration and validation in the study. The standard ADM1 model was corrected in the study with regard to nitrogen and carbon mass balances. A good correlation between the measured and simulated data was obtained for biogas yield, total volatile fatty acids and pH after heuristically calibrating stoichiometric and kinetic parameters of the ADM1 model. The simulation is sensitive to influent composition. PMID:20540425

Ozkan-Yucel, U G; Gökçay, C F

2010-05-01

338

Effect of natural zeolite on methane production for anaerobic digestion of ammonium rich organic sludge.  

PubMed

The effect of an inorganic additive on the methane production from NH(4+)-rich organic sludge during anaerobic digestion was investigated using different kinds of inorganic adsorbent zeolites (mordenite, clinoptilolite, zeolite 3A, zeolite 4A), clay mineral (vermiculite), and manganese oxides (hollandite, birnessite). The additions of inorganic materials resulted in significant NH4+ removals from the natural organic sludge ([NH4+]=1, 150 mg N/l), except for the H-type zeolite 3A and birnessite. However, an enhanced methane production was only achieved using natural mordenite. Natural mordenite also enhanced the methane production from the sludge with a markedly high NH4+ concentration (4500 mg N/l) during anaerobic digestion. Chemical analyses of the sludge after the digestion showed considerable increases in the Ca2+ and Mg2+ concentrations in the presence of natural mordenite, but not with synthetic zeolite 3A. The effect of Ca2+ or Mg2+ addition on the methane production was studied using Na(+)-exchanges mordenite and Ca2+ or Mg(2+)-enriched sludge. The simultaneous addition of Ca2+ ions and Na(+)-exchanged mordenite enhanced the methane production; the amount of produced methane was about three times greater than that using only the Na(+)-exchanged mordenite. In addition, comparing the methane production by the addition of natural mordenite or Ca2+ ions, the methane production with natural mordenite was about 1.7 times higher than that with only Ca2+ ions. The addition of 5% and 10% natural mordenite were suitable condition for obtaining a high methane production. These results indicated that the Ca2+ ions, which are released from natural mordenite by a Ca2+/NH4+ exchange, enhanced the methane production of the organic waste at a high NH4+ concentration. Natural mordenite has a synergistic effect on the Ca2+ supply as well on the NH4+ removal during anaerobic digestion, which is effective for the mitigation of NH4+ inhibition against methane production. PMID:15491827

Tada, Chika; Yang, Yingnan; Hanaoka, Toshiaki; Sonoda, Akinari; Ooi, Kenta; Sawayama, Shigeki

2005-03-01

339

Centralized anaerobic digestion bioprocess plant identification and direct I-term neural control using second order learning  

Microsoft Academic Search

The paper proposed to use a recurrent neural network model, and a real-time Levenberg-Marquardt algorithm of its learning for centralized modeling, identification and I-term control of an anaerobic digestion bioprocess, carried out in a fixed bed and a recirculation tank of a wastewater treatment system. The analytical model of the digestion bioprocess, used as process data generator, represented a distributed

I. S. Baruch; E. E. Saldierna; R. Galvan-Guerra

2011-01-01

340

Predicting anaerobic biogasification potential of ingestates and digestates of a full-scale biogas plant using chemical and biological parameters  

Microsoft Academic Search

The aim of this work was to develop simple and fast tests to predict anaerobic biogasification potential (ABP) of ingestates and digestates from a biogas plant. Forty-six samples of both ingestates and digestates were collected within an eight-month observation period and were analyzed in terms of biological and chemical parameters, namely, ABP test, oxygen demand in a 20-h respirometric test

Andrea Schievano; Michele Pognani; Giuliana D’Imporzano; Fabrizio Adani

2008-01-01

341

Conventional mesophilic vs. thermophilic anaerobic digestion: a trade-off between performance and stability?  

PubMed

A long-term comparative study using continuously-stirred anaerobic digesters (CSADs) operated at mesophilic and thermophilic temperatures was conducted to evaluate the influence of the organic loading rate (OLR) and chemical composition on process performance and stability. Cow manure was co-digested with dog food, a model substrate to simulate a generic, multi-component food-like waste and to produce non-substrate specific, composition-based results. Cow manure and dog food were mixed at a lower - and an upper co-digestion ratio to produce a low-fiber, high-strength substrate, and a more recalcitrant, lower-strength substrate, respectively. Three increasing OLRs were evaluated by decreasing the CSADs hydraulic retention time (HRT) from 20 to 10 days. At longer HRTs and lower manure-to-dog food ratio, the thermophilic CSAD was not stable and eventually failed as a result of long-chain fatty acid (LCFA) accumulation/degradation, which was triggered by the compounded effects of temperature on reaction rates, mixing intensity, and physical state of LCFAs. At shorter HRTs and upper manure-to-dog food ratio, the thermophilic CSAD marginally outperformed the biomethane production rates and substrate stabilization of the mesophilic CSAD. The increased fiber content relative to lipids at upper manure-to-dog food ratios improved the stability and performance of the thermophilic process by decreasing the concentration of LCFAs in solution, likely adsorbed onto the manure fibers. Overall, results of this study show that stability of the thermophilic co-digestion process is highly dependent on the influent substrate composition, and particularly for this study, on the proportion of manure to lipids in the influent stream. In contrast, mesophilic co-digestion provided a more robust and stable process regardless of the influent composition, only with marginally lower biomethane production rates (i.e., 7%) for HRTs as short as 10 days (OLR = 3 g VS/L-d). PMID:24530545

Labatut, Rodrigo A; Angenent, Largus T; Scott, Norman R

2014-04-15

342

Estudio de las condiciones de operación para la digestión anaerobia de residuos sólidos urbanos A study of operational conditions for anaerobic digestion of solid urban waste  

Microsoft Academic Search

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

Femando Castillo M; Diego Edison Cristancho

2003-01-01

343

Anaerobic digestion of pressed off leachate from the organic fraction of municipal solid waste  

SciTech Connect

A highly polluted liquid ('press water') was obtained from the pressing facility for the organic fraction of municipal solid waste in a composting plant. Methane productivity of the squeezed-off leachate was investigated in batch assays. To assess the technical feasibility of 'press water' as a substrate for anaerobic digestion, a laboratory-scale glass column reactor was operated semi-continuously at 37 {sup o}C. A high methane productivity of 270 m{sup -3} CH{sub 4} ton{sup -1} COD{sub added} or 490 m{sup -3} CH{sub 4} ton{sup -1} VS{sub added} was achieved in the batch experiment. The semi-continuously run laboratory-scale reactor was initially operated at an organic loading rate of 10.7 kg COD m{sup -3} d{sup -1}. The loading was increased to finally 27.7 kg COD m{sup -3} d{sup -1}, corresponding to a reduction of the hydraulic retention time from initially 20 to finally 7.7 days. During the digestion, a stable elimination of organic material (measured as COD elimination) of approximately 60% was achieved. Linearly with the increment of the OLR, the volumetric methane production of the reactor increased from 2.6 m{sup 3} m{sub reactor}{sup -3} d{sup -1} to 7.1 m{sup 3} m{sub reactor}{sup -3} d{sup -1}. The results indicated that 'press water' from the organic fraction of municipal solid waste was a suitable substrate for anaerobic digestion which gave a high biogas yield even at very high loading rates.

Nayono, Satoto E. [Department of Civil Engineering, Yogyakarta State University, Campus UNY Karangmalang Yogyakarta 55281 (Indonesia); Institute of Biology for Engineers and Biotechnology of Wastewater, University of Karlsruhe, Am Fasanengarten, 76131 Karlsruhe (Germany); Winter, Josef, E-mail: josef.winter@iba.uka.d [Institute of Biology for Engineers and Biotechnology of Wastewater, University of Karlsruhe, Am Fasanengarten, 76131 Karlsruhe (Germany); Gallert, Claudia [Institute of Biology for Engineers and Biotechnology of Wastewater, University of Karlsruhe, Am Fasanengarten, 76131 Karlsruhe (Germany)

2010-10-15

344

Identification and quantification of microbial populations in activated sludge and anaerobic digestion processes.  

PubMed

Eight different phenotypes were studied in an activated sludge process (AeR) and anaerobic digester (AnD) in a full-scale wastewater treatment plant by means of fluorescent in situ hybridization (FISH) and automated FISH quantification software. The phenotypes were ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, denitrifying bacteria, phosphate-accumulating organisms (PAO), glycogen-accumulating organisms (GAO), sulphate-reducing bacteria (SRB), methanotrophic bacteria and methanogenic archaea. Some findings were unexpected: (a) Presence of PAO, GAO and denitrifiers in the AeR possibly due to unexpected environmental conditions caused by oxygen deficiencies or its ability to survive aerobically; (b) presence of SRB in the AeR due to high sulphate content of wastewater intake and possibly also due to digested sludge being recycled back into the primary clarifier; (c) presence of methanogenic archaea in the AeR, which can be explained by the recirculation of digested sludge and its ability to survive periods of high oxygen levels; (d) presence of denitrifying bacteria in the AnD which cannot be fully explained because the nitrate level in the AnD was not measured. However, other authors reported the existence of denitrifiers in environments where nitrate or oxygen was not present suggesting that denitrifiers can survive in nitrate-free anaerobic environments by carrying out low-level fermentation; (e) the results of this paper are relevant because of the focus on the identification of nearly all the significant bacterial and archaeal groups of microorganisms with a known phenotype involved in the biological wastewater treatment. PMID:25409582

Reyes, M; Borrás, L; Seco, A; Ferrer, J

2015-01-01

345

Application of physico-chemical pretreatment methods to enhance the sludge disintegration and subsequent anaerobic digestion: an up to date review  

Microsoft Academic Search

Anaerobic digestion of waste activated sludge (WAS) is most commonly used at wastewater treatment facilities to stabilize\\u000a the sludge. However, poor biodegradation efficiency of sludge and longer retention times (20–30 days) are the major limitations\\u000a of anaerobic digestion method, which can be overcome by disintegrate the sludge and make intracellular material readily available\\u000a to anaerobic biodegradation. Several sludge disintegration techniques (Thermal,

Vinay Kumar Tyagi; Shang-Lien Lo

346

Treatment of anaerobically digested dairy manure in a two-stage biofiltration system.  

PubMed

High concentrations of ammonium and phosphate present a challenge to cost-effective treatment of anaerobically digested dairy manure. This study investigated the efficacy of a two-stage biofiltration system for passive treatment of digested dairy manure. The first stage pebble filters were batch loaded. When the slurry-like digested dairy manure was retained on pebble beds, soluble contaminants were removed before liquid infiltrated over 8-17 days. The pebble filters removed 70% of soluble chemical oxygen demand, 71% of soluble biochemical oxygen demand, 75% of ammonium, and 68% of orthophosphate. Nitrogen removal was attributed to the conventional nitrification - denitrification process and novel nitritation - anammox process. Aerobic ammonium oxidizing and anammox bacteria accounted for 25 and 23% of all bacteria, respectively, in the filtrate of the pebble filters. The longer it took for filtration, the greater the removal efficiency of soluble contaminants. The second stage sand filters had removal efficiencies of 17% for soluble chemical oxygen demand, 45% for soluble biochemical oxygen demand, 43% for ammonium, and 16% for orthophosphate during batch operations at a hydraulic retention time of 7 days. Aerobic ammonium oxidation and anammox were primarily responsible for nitrogen removal in the sand filters. Vegetation made an insignificant difference in treatment performance of the sand filters. PMID:22592467

Xia, Mengjing; Tao, Wendong; Wang, Ziyuan; Pei, Yuansheng

2012-01-01

347

The viscoelastic behaviour of raw and anaerobic digested sludge: strong similarities with soft-glassy materials.  

PubMed

Over the last few decades, municipal and industrial wastewater treatment activities have been confronted with a dramatically increasing flow of sewage sludge. To improve treatment efficiency, process and material parameters are needed but engineers are dealing with vast quantities of fundamentally poorly understood and unpredictable material Thus, accurate prediction of critically important, but analytically elusive process parameters is unattainable and is a matter of grave concern. Because engineers need reliable flow properties to simulate the process, this work is an attempt to approach sludge rheological behaviour with well-known materials which have similar characteristics. Sludge liquid-like behaviour is already well documented so, we have focused mainly on the solid-like behaviour of both raw and digested sludge by performing oscillatory measurements in the linear and non-linear regimes. We have shown that the viscoelastic behaviour of sludge presents strong similarities with soft-glassy materials but differences can be observed between raw and digested sludge. Finally, we confirm that colloidal glasses and emulsions may be used to model the rheological behaviour of raw and anaerobic digested sludge. PMID:23089360

Baudez, Jean-Christophe; Gupta, Rahul K; Eshtiaghi, Nicky; Slatter, Paul

2013-01-01

348

Quick Startup of EGSB Reactor Seeded with Anaerobic Digestion Sludge for the Treatment of Actual Domestic Sewage under Ambient Temperature  

Microsoft Academic Search

To obtain the rapid startup of EGSB reactor seeded with anaerobic digestion sludge for the treatment of actual domestic wastewater under ambient temperature, two startup methods i.e. A and B were tried out at 25°C. For method A, reactor A (RA) was fed with brewery wastewater to incubate granular sludge and then treated domestic sewage, for method B, reactor B

Dong Chunjuan; Li Qingwei; Geng Zhaoyu; Wang Haihui; Wang Zengzhang

2010-01-01

349

Review of composting and anaerobic digestion of municipal solid waste and a methodological proposal for a mid-size city  

E-print Network

Review of composting and anaerobic digestion of municipal solid waste and a methodological proposal decades, MSW management is one of the main public subjects under discussion. In the literature, researchers have been sharing case-studies about waste management practices in many different countries

Wisconsin-Milwaukee, University of

350

Changes in chemical and biological parameters during co-composting of anaerobically digested sewage sludges with lignocellulosic material  

Microsoft Academic Search

This study reports a pilot experiment of composting of anaerobically digested sewage sludges deriving from the production of biogas in a wastewater treatment plant. Two composting piles (about 15 m each) were prepared by mixing 50% and 30% (v\\/v) sludges with lignocellulosic material. The composting process was monitored through determination of the main physicochemical properties. The stability of the composts

Michele Negre; Chiara Mozzetti Monterumici; Daniela Vindrola; Giuseppe Piccone

2011-01-01

351

Semi-continuous anaerobic co-digestion of thickened waste activated sludge and fat, oil and grease  

SciTech Connect

Highlights: > Co-digestion of thickened waste activated sludge (TWAS) with fat, oil and grease (FOG). > Co-digestion of TWAS and FOG at 64% VS increased biogas production by 137%. > FOG addition ratio at 74% of total VS caused inhibition of the anaerobic digestion process. > Micronutrients addition did not significantly improve the biogas production and digestion stabilization. - Abstract: Co-digestion of thickened waste activated sludge (TWAS) and fat, oil and grease (FOG) was conducted semi-continuously under mesophilic conditions. The results showed that daily methane yield at the steady state was 598 L/kg VS{sub added} when TWAS and FOG (64% of total VS) were co-digested, which was 137% higher than that obtained from digestion of TWAS alone. The biogas composition was stabilized at a CH{sub 4} and CO{sub 2} content of 66.8% and 29.5%, respectively. Micronutrients added to co-digestion did not improve the biogas production and digestion stabilization. With a higher addition of FOG (74% of total VS), the digester initially failed but was slowly self-recovered; however, the methane yield was only about 50% of a healthy reactor with the same organic loading rate.

Wan Caixia; Zhou Quancheng; Fu Guiming [Department of Food, Agricultural, and Biological Engineering, Ohio State University/Ohio Agricultural Research and Development Center, 1680 Madison Ave., Wooster, OH 44691-4096 (United States); Li Yebo, E-mail: li.851@osu.edu [Department of Food, Agricultural, and Biological Engineering, Ohio State University/Ohio Agricultural Research and Development Center, 1680 Madison Ave., Wooster, OH 44691-4096 (United States)

2011-08-15

352

ASSESSMENT OF THE UTILIZATION AND CONTROL OF DIGESTER GAS USING FUEL CELL TECHNOLOGY  

EPA Science Inventory

To conduct a 2-year assessment of the use of fuel cells to recover energy from anaerobic digester as a wastewater treatment facility. Will determine the environmental and economic benefits/impacts for the use of fuel cells to utilize waste methane from anaerobic digesters. Due ...

353

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

PubMed

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. PMID:24715809

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

2014-01-01

354

Mesophilic anaerobic co-digestion of sewage sludge and orange peel waste.  

PubMed

Mesophilic anaerobic digestion is a treatment that is widely applied for sewage sludge management but has several disadvantages such as low methane yield, poor biodegradability and nutrient imbalance. In this paper, we propose orange peel waste as an easily biodegradable co-substrate to improve the viability of the process. Sewage sludge and orange peel waste were mixed at a proportion of 70:30 (wet weight), respectively. The stability was maintained within correct parameters throughout the process, while the methane yield coefficient and biodegradability were 165 L/kg volatile solids (VS) (0 degrees C, 1 atm) and 76% (VS), respectively. The organic loading rate (OLR) increased from 0.4 to 1.6kg VS/m3 d. Nevertheless, the OLR and methane production rate decreased at the highest loads, suggesting the occurrence of an inhibition phenomenon. PMID:24645472

Serrano, Antonio; Siles López, José Angel; Chica, Arturo Francisco; Martín, M Angeles; Karouach, Fadoua; Mesfioui, Abdelaziz; El Bari, Hassan

2014-01-01

355

Nitrogen mineralization from anaerobically digested centrifuge cake and aged air-dried biosolids.  

PubMed

This study was conducted to estimate nitrogen (N) mineralization of anaerobically digested centrifuge cake from the Stickney Water Reclamation Plant (SWRP) and Calumet Water Reclamation Plant (CWRP), lagoon-aged air-dried biosolids from the CWRP, and Milorganite at three rates of application (0, 12.5 and 25 Mg ha(-1)). The N mineralized varied among biosolids as follows: Milorganite (44%) > SWRP centrifuge cake (35%) > CWRP centrifuge cake (31%) > aged air-dried (13%). The N mineralized in the SWRP cake (32%) and CWRP aged air-dried biosolids (12%) determined from the 15N study were in agreement with the first study. The N mineralization value for centrifuge cake biosolids observed in our study is higher than the value given in the Part 503 rule and Illinois Part 391 guidelines. These results will be used to fine-tune biosolids application rate to match crop N demand without compromising yield while minimizing any adverse effect on the environment. PMID:25327023

Kumar, Kuldip; Hundal, Lakhwinder S; Cox, Albert E; Granato, Thomas

2014-09-01

356

CFD simulation of vertical linear motion mixing in anaerobic digester tanks.  

PubMed

Computational fluid dynamics (CFD) was used to simulate the mixing characteristics of a small circular anaerobic digester tank (diameter 6 m) equipped sequentially with 13 different plunger type vertical linear motion mixers and two different type internal draft-tube mixers. Rates of mixing of step injection of tracers were calculated from which active volume (AV) and hydraulic retention time (HRT) could be calculated. Washout characteristics were compared to analytic formulae to estimate any presence of partial mixing, dead volume, short-circuiting, or piston flow. Active volumes were also estimated based on tank regions that exceeded minimum velocity criteria. The mixers were ranked based on an ad hoc criteria related to the ratio of AV to unit power (UP) or AV/UP. The best plunger mixers were found to behave about the same as the conventional draft-tube mixers of similar UP. PMID:25327022

Meroney, Robert N; Sheker, Robert E

2014-09-01

357

Ionic liquid pretreatment to enhance the anaerobic digestion of lignocellulosic biomass.  

PubMed

Four lignocellulosic biomasses, water hyacinth, rice straw, mango leaves and spruce were pretreated by ionic liquid (IL) to enhance anaerobic digestion. The effect of pretreatment conditions, such as alkyl chain length of IL, temperature, time and operation cycle on lignocellulosic composition, structure and biogas production was evaluated. The enhancement of biogas production by [C4mim]Cl pretreatment at 120°C for 2 h decreases in the order of water hyacinth>spruce>rice straw>mango leaves. Higher methane production of regenerated rice straw and mango leaves could reach 233 and 125 mL/g carbohydrates under 140°C or 2 h and 140°C for 8, respectively. Furthermore, the technology of aqueous biphasic systems was developed to recovery IL, and the recovery rate of ILs was in the range of 54.3-94.6%. PMID:24185036

Gao, Jing; Chen, Li; Yuan, Ke; Huang, Hemao; Yan, Zongcheng

2013-12-01

358

Anaerobic co-digestion of winery waste and waste activated sludge: assessment of process feasibility.  

PubMed

In this study the anaerobic co-digestion of wine lees together with waste activated sludge in mesophilic and thermophilic conditions was tested at pilot scale. Three organic loading rates (OLRs 2.8, 3.3 and 4.5 kgCOD/m(3)d) and hydraulic retention times (HRTs 21, 19 and 16 days) were applied to the reactors, in order to evaluate the best operational conditions for the maximization of the biogas yields. The addition of lee to sludge determined a higher biogas production: the best yield obtained was 0.40 Nm(3)biogas/kgCODfed. Because of the high presence of soluble chemical oxygen demand (COD) and polyphenols in wine lees, the best results in terms of yields and process stability were obtained when applying the lowest of the three organic loading rates tested together with mesophilic conditions. PMID:24473294

Da Ros, C; Cavinato, C; Cecchi, F; Bolzonella, D

2014-01-01

359

Chemical and spectroscopic characterization of organic matter during the anaerobic digestion and successive composting of pig slurry.  

PubMed

In this work, anaerobic digestion of pig slurry and successive composting of the digestate after centrifugation were studied by means of chemical analysis, FTIR and fluorescence spectroscopy as excitation-emission matrix (EEM). Chemical analysis highlighted the organic matter transformation occurring during the processes. A decrease of volatile solids and total organic carbon were observed in the digestate with respect to the fresh pig slurry as a consequence of the consumption of sugars, proteins, amino acids and fatty acids used by microorganisms as a C source. Water Extractable Organic Matter (WEOM) was obtained for all samples and fractionated into a hydrophilic and a hydrophobic fraction. The highest WEOM value was found in the pig slurry indicating a high content of labile organic C. The digestate centrifuged and the digestate composted showed lower hydrophilic and higher hydrophobic contents because of the decrease of labile C. Total phenolic content was lower in the digestate with respect to fresh pig slurry sample (36.7%) as a consequence of phenolic compounds degradation. The strong decrease of total reducing sugars in the digestate (76.6%) as compared to pig slurry confirmed that anaerobic process proceed mainly through consumption of sugars which represent a readily available energy source for microbial activity. FTIR spectra of pig slurry showed bands indicative of proteins and carbohydrates. A drop of aliphatic structures and a decrease of polysaccharides was observed after the anaerobic process along with the increase of the peak in the aromatic region. The composted substrate showed an increase of aromatic and a relative decrease of polysaccharides. EEM spectra provided tryptophan:fulvic-like fluorescence ratios which increased from fresh substrate to digestate because of the OM decompostion. Composted substrate presented the lowest ratio due to the humification process. PMID:24411986

Provenzano, Maria Rosaria; Malerba, Anna D; Pezzolla, Daniela; Gigliotti, Giovanni

2014-03-01

360

Potentials for food waste minimization and effects on potential biogas production through anaerobic digestion.  

PubMed

Several treatment alternatives for food waste can result in both energy and nutrient recovery, and thereby potential environmental benefits. However, according to the European Union waste management hierarchy, waste prevention should be the prioritized strategy to decrease the environmental burdens from all solid waste management. The aim of the present study was therefore to investigate the potential for food waste minimization among Swedish households through an investigation of the amount of avoidable food waste currently disposed of. A further aim was to investigate the effect on the national biogas production potential through anaerobic digestion of food waste, considering minimization potentials. A method for waste composition analyses of household food waste, where a differentiation between avoidable and unavoidable food waste is made, was used in a total of 24 waste composition analyses of household waste from Swedish residential areas. The total household food waste generation reached 3.4 kg (household and week)(-1), on average, of which 34% is avoidable. The theoretical methane (CH4) potential in unavoidable food waste reached 442 Ndm(3) (kg VS)(-1) or 128 Nm(3) tonne(-1) wet waste, while the measured (mesophilic CH4 batch tests) CH4 production reached 399 Ndm(3) (kg VS)(-1), which is lower than several previous assessments of CH4 production from household food waste. According to this study the combination of a decrease in food waste generation-in case of successful minimization-and decreased CH4 production from unavoidable food waste will thus result in lower total potential energy recovery from household food waste through anaerobic digestion CH4 potential than previously stated. PMID:23681829

Schott, Anna Bernstad Saraiva; Vukicevic, Sanita; Bohn, Irene; Andersson, Tova

2013-08-01

361

Enhanced methane production in a two-phase anaerobic digestion plant, after CO2 capture and addition to organic wastes.  

PubMed

Cost-effective technologies are needed to reach the international greenhouse gas (GHG) reduction targets in many fields, including waste and biomass treatment. This work reports the effects of CO(2) capture from a combustion flue gas and its use in a newly-patented, two-phase anaerobic digestion (TPAD) process, to improve energy recovery and to reduce CO(2) emissions. A TPAD process, fed with urban wastewater sludge, was successfully established and maintained for several months at pilot scale. The TPAD process with injection of CO(2) exhibits efficient biomass degradation (58% VSS reduction), increased VFA production during the acidogenic phase (leading to VFA concentration of 8.4 g/L) and high biomethane production (0.350 S m(3)/kg(SSV); 0.363 S m(3)/m(3)(react) · d). Moreover, CO(2) intake in the acid phase has a positive impact on the overall GHG balance associated to biomethane production, and suggests an improved solution for both emission reduction and biomass conversion into biomethane. PMID:21498069

Salomoni, C; Caputo, A; Bonoli, M; Francioso, O; Rodriguez-Estrada, M T; Palenzona, D

2011-06-01

362

An integrated anaerobic digestion and UV photocatalytic treatment of distillery wastewater.  

PubMed

Anaerobic up-flow fixed bed reactor and annular photocatalytic reactor were used to study the efficiency of integrated anaerobic digestion (AD) and ultraviolet (UV) photodegradation of real distillery effluent and raw molasses wastewater (MWW). It was found that UV photodegradation as a stand-alone technique achieved colour removal of 54% and 69% for the distillery and MWW, respectively, with a COD reduction of <20% and a negligible BOD reduction. On the other hand, AD as a single treatment technique was found to be effective in COD and BOD reduction with efficiencies of above 75% and 85%, respectively, for both wastewater samples. However, the AD achieved low colour removal efficiency, with an increase in colour intensity of 13% recorded when treating MWW while a colour removal of 51% was achieved for the distillery effluent. The application of UV photodegradation as a pre-treatment method to the AD process reduced the COD removal and biogas production efficiency. However, an integration in which UV photodegradation was employed as a post-treatment to the AD process achieved high COD removal of above 85% for both wastewater samples, and colour removal of 88% for the distillery effluent. Thus, photodegradation can be employed as a post-treatment technique to an AD system treating distillery effluent for complete removal of the biorecalcitrant and colour imparting compounds. PMID:23974530

Apollo, Seth; Onyango, Maurice S; Ochieng, Aoyi

2013-10-15

363

Activated zeolite--suitable carriers for microorganisms in anaerobic digestion processes?  

PubMed

Plant cell wall structures represent a barrier in the biodegradation process to produce biogas for combustion and energy production. Consequently, approaches concerning a more efficient de-polymerisation of cellulose and hemicellulose to monomeric sugars are required. Here, we show that natural activated zeolites (i.e. trace metal activated zeolites) represent eminently suitable mineral microhabitats and potential carriers for immobilisation of microorganisms responsible for anaerobic hydrolysis of biopolymers stabilising related bacterial and methanogenic communities. A strategy for comprehensive analysis of immobilised anaerobic populations was developed that includes the visualisation of biofilm formation via scanning electron microscopy and confocal laser scanning microscopy, community and fingerprint analysis as well as enzyme activity and identification analyses. Using SDS polyacrylamide gel electrophoresis, hydrolytical active protein bands were traced by congo red staining. Liquid chromatography/mass spectroscopy revealed cellulolytical endo- and exoglucanase (exocellobiohydrolase) as well as hemicellulolytical xylanase/mannase after proteolytic digestion. Relations to hydrolytic/fermentative zeolite colonisers were obtained by using single-strand conformation polymorphism analysis (SSCP) based on amplification of bacterial and archaeal 16S rRNA fragments. Thereby, dominant colonisers were affiliated to the genera Clostridium, Pseudomonas and Methanoculleus. The specific immobilisation on natural zeolites with functional microbes already colonising naturally during the fermentation offers a strategy to systematically supply the biogas formation process responsive to population dynamics and process requirements. PMID:23435898

Weiß, S; Lebuhn, M; Andrade, D; Zankel, A; Cardinale, M; Birner-Gruenberger, R; Somitsch, W; Ueberbacher, B J; Guebitz, G M

2013-04-01

364

Psychrophilic and mesophilic anaerobic digestion of brewery effluent: a comparative study.  

PubMed

Two expanded granular sludge bed-anaerobic filter (EGSB-AF) bioreactors (3.38 l active volume) were used to directly compare psychrophilic (15 degrees C), anaerobic digestion (PAD) to mesophilic (37 degrees C) anaerobic digestion (MAD) for the treatment of a brewery wastewater (chemical oxygen demand (COD) concentration of 3,136+/-891 mg l(-1)). Bioreactor performance was evaluated by COD removal efficiency and biogas yields at a range of hydraulic and organic loading rates. Specific methanogenic activity (SMA) assays were also employed to investigate the activity of the biomass in the bioreactors. No significant difference in the COD removal efficiencies (which ranged from 85-93%) were recorded between PAD and MAD during the 194-d trial at maximum organic and hydraulic loading rates of 4.47 kg m(-3) day(-1) and 1.33 m(3) m(-3) day(-1), respectively. In addition, the methane content (%) of the biogas was very similar. The volumetric biogas yield from the PAD bioreactor was approximately 50% of that from the MAD bioreactor at an organic loading rate of 4.47 kg COD m(-3) day(-3) and an applied liquid up-flow velocity (V(up)) of 2.5 m h(-1). Increasing the V(up) in the PAD bioreactor to 5 m h(-1) resulted in a volumetric biogas production rate of approximately 4.1 l d(-1) and a methane yield of 0.28 l CH(4) g(-1) COD d(-1), which were very similar to the MAD bioreactor. Significant and negligible biomass washout was observed in the mesophilic and psychrophilic systems, respectively, thus increasing the sludge loading rate applied to the former and underlining the robustness of the latter, which appeared underloaded. A psychrotolerant mesophilic, but not truly psychrophilic, biomass developed in the PAD bioreactor biomass, with comparable maximum SMA values to the MAD bioreactor biomass. PAD, therefore, was shown to be favourably comparable to MAD for brewery wastewater treatment and biogas generation. PMID:16814840

Connaughton, Sean; Collins, Gavin; O'Flaherty, Vincent

2006-07-01

365

Batchwise mesophilic anaerobic co-digestion of secondary sludge from pulp and paper industry and municipal sewage sludge.  

PubMed

Residues from forest-industry wastewater-treatment systems are treated as waste at many pulp and paper mills. These organic substances have previously been shown to have potential for production of large quantities of biogas. There is concern, however, that the process would require expensive equipment because of the slow degradation of these substances. Pure non-fibrous sludge from forest industry showed lower specific methane production during mesophilic digestion for 19days, 53±26 Nml/g of volatile solids as compared to municipal sewage sludge, 84±24 Nml/g of volatile solids. This paper explores the possibility of using anaerobic co-digestion with municipal sewage sludge to enhance the potential of methane production from secondary sludge from a pulp and paper mill. It was seen in a batch anaerobic-digestion operation of 19 days that the specific methane production remained largely the same for municipal sewage sludge when up to 50% of the volatile solids were replaced with forest-industry secondary sludge. It was also shown that the solid residue from anaerobic digestion of the forest-industry sludge should be of suitable quality to use for improving soil quality on lands that are not used for food production. PMID:23294534

Hagelqvist, Alina

2013-04-01

366

Effect of thermal hydrolysis pre-treatment on anaerobic digestion of municipal biowaste: a pilot scale study in China.  

PubMed

Co-digestion of wasted sewage sludge, restaurant kitchen waste, and fruit-vegetable waste was carried out in a pilot plant with thermal hydrolysis pre-treatment. Steam was used as heat source for thermal hydrolysis. It was found 38.3% of volatile suspended solids were dissolved after thermal hydrolysis, with digestibility increased by 115%. These results were more significant than those from lab studies using electricity as heat source due to more uniform heating. Anaerobic digesters were then operated under organic loading rates of about 1.5 and 3 kg VS/(m³ d). Little difference was found for digesters with and without thermal pre-treatment in biogas production and volatile solids removal. However, when looking into the digestion process, it was found digestion rate was almost doubled after thermal hydrolysis. Digester was also more stable with thermal hydrolysis pre-treatment. Less volatile fatty acids (VFAs) were accumulated and the VFAs/alkalinity ratio was also lower. Batch experiments showed the lag phase can be eliminated by thermal pre-treatment, implying the advantage could be more significant under a shorter hydraulic retention time. Moreover, it was estimated energy cost for thermal hydrolysis can be partly balanced by decreasing viscosity and improving dewaterability of the digestate. PMID:23419457

Zhou, Yingjun; Takaoka, Masaki; Wang, Wei; Liu, Xiao; Oshita, Kazuyuki

2013-07-01

367

Microbial community structure in a thermophilic aerobic digester used as a sludge pretreatment process for the mesophilic anaerobic digestion and the enhancement of methane production.  

PubMed

An effective two-stage sewage sludge digestion process, consisting of thermophilic aerobic digestion (TAD) followed by mesophilic anaerobic digestion (MAD), was developed for efficient sludge reduction and methane production. Using TAD as a biological pretreatment, the total volatile suspended solid reduction (VSSR) and methane production rate (MPR) in the MAD reactor were significantly improved. According to denaturing gradient gel electrophoresis (DGGE) analysis, the results indicated that the dominant bacteria species such as Ureibacillus thermophiles and Bacterium thermus in TAD were major routes for enhancing soluble organic matter. TAD pretreatment using a relatively short SRT of 1 day showed highly increased soluble organic products and positively affected an increment of bacteria populations which performed interrelated microbial metabolisms with methanogenic species in the MAD; consequently, a quantitative real-time PCR indicated greatly increased Methanosarcinales (acetate-utilizing methanogens) in the MAD, resulting in enhanced methane production. PMID:23419990

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

2013-10-01

368

Effect of Solids Retention Time on the Denitrification Potential of Anaerobically Digested Swine Waste  

NASA Astrophysics Data System (ADS)

Three continuously stirred tank reactors (CSTR) were operated in semi continuous mode treating swine waste using anaerobic digestion. The reactors were used to test the effect of solid retention time (SRT) on CH4 yield, total ammonia nitrogen (TAN) concentrations, % volatile solids (VS), chemical oxygen demand (COD) and volatile fatty acids (VFA) removal, readily biodegradable COD concentration and the denitrification potential for the effluent in a biological nutrient removal (BNR) system. During Phase I of the study, the three reactors were operated at the same 28 day SRT for 16 weeks. SRTs were then changed during the 12 week Phase II period. The SRTs studied were 14, 21 and 28 days, with the same organic loading rate (OLR) of 1.88 ± 0.2 kg VS/ m3-day. The reactor with the lowest SRT (14 days) had the highest VS and VFA removal at 73.6 and 67.6% and lowest TAN concentration at 0.78 g NH4+-N/L, followed by the 21 day and 28 day reactors. This was likely due to the fast microbial growth rates and substrate utilization rates in this reactor compared with the other two. The 14 day reactor had the highest CH4 yield at 0.33 m3CH 4/kg VS added and readily biodegradable COD concentration at 0.93 COD/L. The variations in CH4 yield and readily biodegradable COD concentrations between the three reactors were not statistically significant. Denitrification potential for the reactors was 1.20, 0.73 and 0.56 g COD/g N for 14, 21 and 28 day reactors, respectively, and the differences were statistically significant. None of the reactors achieved a denitrification potential of 5 g COD/g N, the amount required to use effluent of anaerobically digested swine waste as an internal carbon source in a BNR. This was attributed to operating conditions such as freezing and thawing of the raw swine waste that maximized CH4 yield and lowered the readily biodegradable COD concentration. In addition the 14 day reactor had low TAN concentrations thus increasing the denitrification potential of the centrate from that reactor.

Kinyua, Maureen Njoki

369

Microbial community structure and methanogenic activity during start-up of psychrophilic anaerobic digesters treating synthetic industrial wastewaters  

Microsoft Academic Search

Culture-independent, molecular techniques were applied to the characterization of microbial communities of an anaerobic granular sludge obtained from a full-scale digester. Procedures were optimised for total DNA recovery and polymerase chain reaction (PCR) amplification of 16S rDNA using archaea- and eubacteria-specific oligonucleotide primers. Cloned PCR products were subsequently screened by amplified rDNA restriction analysis to identify operational taxonomic units (OTUs).

Gavin Collins; Adele Woods; Sharon McHugh; Micheal W. Carton; Vincent O’Flaherty

2003-01-01

370

Membrane Fouling Control in an Anaerobic Membrane Bioreactor Coupled with Online Ultrasound Equipment for Digestion of Waste Activated Sludge  

Microsoft Academic Search

In this study, an online ultrasonic equipment was employed to control membrane fouling in an anaerobic membrane bioreactor for waste activated sludge digestion. Four groups of ultrasound parameters were tested for the performance of membrane fouling control. The ultrasound power intensity of 0.18 W\\/cm and timing of 3 min\\/h were considered to be optimal since that membrane fouling could be effectively controlled

Meilan Xu; Xianghua Wen; Xia Huang; Yushan Li

2010-01-01

371

Anaerobic co-digestion of source segregated brown water (feces-without-urine) and food waste: for Singapore context.  

PubMed

The objective of this study was to evaluate the feasibility of anaerobic co-digestion of brown water (BW) [feces-without-urine] and food waste (FW) in decentralized, source-separation-based sanitation concept. An effort has been made to separate the yellow water (urine) and brown water from the source (using no-mix toilet) primarily to facilitate further treatment, resource recovery and utilization. Batch assay analytical results indicated that anaerobic co-digestion [BW+FW] showed higher methane yield (0.54-0.59 L CH(4)/gVS(added)) than BW or FW as a sole substrate. Anaerobic co-digestion was performed in the semi-continuously fed laboratory scale reactors viz. two-phase continuous stirred-tank reactor (CSTR) and single-stage sequencing-batch operational mode reactor (SeqBR). Initial 120 d of operation shows that SeqBR performed better in terms of organic matter removal and maximum methane production. At steady-state, CODs, CODt, VS removals of 92.0±3.0, 76.7±5.1 and 75.7±6.6% were achieved for SeqBR at 16d HRT, respectively. This corresponds to an OLR of 2-3 gCOD/L d and methane yield of about 0.41 L CH(4)/gVS(added). Good buffering capacity did not lead to accumulation of VFA, showing better process stability of SeqBR at higher loading rates. The positive findings show the great potential of applying anaerobic co-digestion of BW+FW for energy production and waste management. In addition, daily flush water consumption is reduced up to 80%. Decentralized, source-separation-based sanitation concept is expected to provide a practical solution for those countries experiencing rapid urbanization and water shortage issues, for instance Singapore. PMID:23247290

Rajagopal, Rajinikanth; Lim, Jun Wei; Mao, Yu; Chen, Chia-Lung; Wang, Jing-Yuan

2013-01-15

372

Mathematical Modeling of Batch, Single Stage, Leach Bed Anaerobic Digestion of Organic Fraction of Municipal Solid Waste  

Microsoft Academic Search

Energy recovery can play an important role in municipal solid waste (MSW) management strategies by providing a saleable by-product\\u000a and mitigating the environmental effects of the residue that requires disposal. Incineration, in-vessel anaerobic digestion\\u000a processes and bioreactor landfills can all produce energy and can be used for pretreatment of MSW prior to eventual disposal.\\u000a Organic fraction of municipal solid waste

Takwai E. Lai; Abhay K. Koppar; Pratap C. Pullammanappallil; William P. Clarke

373

In situ identification of the synthrophic protein fermentative Coprothermobacter spp. involved in the thermophilic anaerobic digestion process.  

PubMed

Thermophilic bacteria have recently attracted great attention because of their potential application in improving different biochemical processes such as anaerobic digestion of various substrates, wastewater treatment or hydrogen production. In this study we report on the design of a specific 16S rRNA-targeted oligonucleotide probe for detecting members of Coprothermobacter genus characterized by a strong protease activity to degrade proteins and peptides. The newly designed CTH485 probe and helper probes hCTH429 and hCTH439 were optimized for use in fluorescence in situ hybridization (FISH) on thermophilic anaerobic sludge samples. In situ probing revealed that thermo-adaptive mechanisms shaping the 16S rRNA gene may affect the identification of thermophilic microorganisms. The novel developed FISH probe extends the possibility to study the widespread thermophilic syntrophic interaction of Coprothermobacter spp. with hydrogenotrophic methanogenic archaea, whose establishment is a great benefit for the whole anaerobic system. PMID:25041640

Gagliano, Maria Cristina; Braguglia, Camilla Maria; Rossetti, Simona

2014-09-01

374

Microbial community structure reveals how microaeration improves fermentation during anaerobic co-digestion of brown water and food waste.  

PubMed

The purpose of this study was to investigate the impact of microaeration on the fermentation process during anaerobic co-digestion of brown water (BW) and food waste (FW). This was achieved by daily monitoring of reactor performance and the determination of its bacterial consortium towards the end of the study. Molecular cloning and sequencing results revealed that bacteria within phyla Firmicutes and Bacteriodetes represented the dominant phylogenetic group. As compared to anaerobic conditions, the fermentation of BW and FW under microaeration conditions gave rise to a significantly more diverse bacterial population and higher proportion of bacterial clones affiliated to the phylum Firmicutes. The acidogenic reactor was therefore able to metabolize a greater variety of substrates leading to higher hydrolysis rates as compared to the anaerobic reactor. Other than enhanced fermentation, microaeration also led to a shift in fermentation production pattern where acetic acid was metabolized for the synthesis of butyric acid. PMID:25194261

Lim, Jun Wei; Chiam, Jun An; Wang, Jing-Yuan

2014-11-01

375

Modeling biogas production from organic fraction of MSW co-digested with MSWI ashes in anaerobic bioreactors.  

PubMed

This study aims at investigating the effects of MSW incinerator fly ash (FA) and bottom ash (BA) on the anaerobic co-digestion of OFMSW with FA or BA. It also simulates the biogas production from various dosed and control bioreactors. Results showed that suitable ashes addition (FA/MSW 10 and 20 g L(-1) and BA/MSW 100 g L(-1)) could improve the MSW anaerobic digestion and enhance the biogas production rates. FA/MSW 20 g L(-1) bioreactor had the higher biogas production and rate implying the potential option for MSW anaerobic co-digestion. Modeling studies showed that exponential plot simulated better for FA/MSW 10 g L(-1) and control bioreactors while Gaussian plot was applicable for FA/MSW 20 g L(-1) one. Linear and exponential plot of descending limb both simulated better for BA/MSW 100 g L(-1) bioreactor. Modified Gompertz plot showed higher correlation of biogas accumulation than exponential rise to maximum plot for all bioreactors. PMID:20400299

Lo, H M; Kurniawan, T A; Sillanpää, M E T; Pai, T Y; Chiang, C F; Chao, K P; Liu, M H; Chuang, S H; Banks, C J; Wang, S C; Lin, K C; Lin, C Y; Liu, W F; Cheng, P H; Chen, C K; Chiu, H Y; Wu, H Y

2010-08-01

376

Enhancement of waste activated sludge anaerobic digestion by a novel chemical free acid/alkaline pretreatment using electrolysis.  

PubMed

Anaerobic digestion of waste activated sludge (WAS) is relatively poor due to hydrolysis limitations. Acid and alkaline pretreatments are effective in enhancing hydrolysis leading to higher methane yields. However, chemical costs often prohibit full-scale application. In this study, 12 V two-chamber electrolysis using an anion exchange membrane alters sludge pH without chemical dosing. pH dropped from 6.9 to 2.5 in the anode chamber and increased to 10.1 in the cathode chamber within 15 h. The volatile suspended solids solubilisation of WAS was 31.1% in the anode chamber and 34.0% in the cathode chamber. As a result, dissolved chemical oxygen demand increased from 164 to 1,787 mg/L and 1,256 mg/L in the anode and cathode chambers, respectively. Remixing of sludge from the two chambers brought the pH back to 6.5, hence no chemical neutralisation was required prior to anaerobic digestion. Methane yield during anaerobic digestion at 20 d retention time was 31% higher than that of untreated sludge. An energy balance assessment indicated that the non-optimised process could approximately recover the energy (electricity) expended in the electrolysis process. With suitable optimisation of treatment time and voltages, significant energy savings would be expected in addition to the benefit of decreased sludge volume. PMID:23787324

Charles, W; Ng, B; Cord-Ruwisch, R; Cheng, L; Ho, G; Kayaalp, A

2013-01-01

377

Quantitative and qualitative transitions of methanogen community structure during the batch anaerobic digestion of cheese-processing wastewater.  

PubMed

Qualitative and quantitative shifts in methanogen community structure, associated with process performance data, were investigated during the batch anaerobic digestion of a cheese-processing wastewater, whey permeate. Denaturing gradient gel electrophoresis (DGGE) and real-time PCR techniques were applied to obtain qualitative and quantitative microbial data sets, respectively, based on methanogen 16S rRNA genes. Throughout the operation, dynamic variations in both qualitative and quantitative community structures were observed, with repeated shifts in dominance between the aceticlastic Methanosarcinaceae (suggested mainly by the detection of a Methanosarcina-like population) and the hydrogenotrophic Methanomicrobiales (suggested mainly by the detection of a Methanofollis-like population). This trend corresponded well to the diauxic utilization of acetate and longer-chain fatty acids (C(3)-C(6)), mainly propionate. Joint-plot non-metric multidimensional scaling (NMS) analysis demonstrated that the qualitative and quantitative community shifts had significant correlations with the composition of residual organic acids and the methane production rate, respectively. This suggests the potential use of microbial community shift analysis as an indicative tool for diagnosing anaerobic digestion processes. The results suggest that more attention should be directed to quantitative, as well as qualitative, approaches for a better understanding of anaerobic digestion, particularly in terms of biogas production efficiency, under dynamic and transitional conditions. PMID:20512323

Lee, Changsoo; Kim, Jaai; Shin, Seung Gu; O'Flaherty, Vincent; Hwang, Seokhwan

2010-08-01

378

Enhancing the anaerobic digestion potential of dairy waste activated sludge by two step sono-alkalization pretreatment.  

PubMed

High efficiency resource recovery from dairy waste activated sludge (WAS) has been a focus of attention. An investigation into the influence of two step sono-alkalization pretreatment (using different alkaline agents, pH and sonic reaction times) on sludge reduction potential in a semi-continuous anaerobic reactor was performed for the first time in literature. Firstly, effect of sludge pretreatment was evaluated by COD solubilization, suspended solids reduction and biogas production. At optimized condition (4172 kJ/kg TS of supplied energy for NaOH - pH 10), COD solubilization, suspended solids reduction and biogas production was 59%, 46% and 80% higher than control. In order to clearly describe the hydrolysis of waste activated sludge during sono-alkalization pretreatment by a two step process, concentrations of ribonucleic acid (RNA) and bound extracellular polymeric substance (EPS) were also measured. Secondly, semi-continuous process performance was studied in a lab-scale semi-continuous anaerobic reactor (5L), with 4 L working volume. With three operated SRTs, the SRT of 15 d was found to be most appropriate for economic operation of the reactor. Combining pretreatment with anaerobic digestion led to 58% and 62% of suspended solids and volatile solids reduction, respectively, with an improvement of 83% in biogas production. Thus, two step sono-alkalization pretreatment laid the basis in enhancing the anaerobic digestion potential of dairy WAS. PMID:24309086

Rani, R Uma; Kumar, S Adish; Kaliappan, S; Yeom, Ick-Tae; Banu, J Rajesh

2014-05-01

379

Physicothermochemical pretreatments of food processing waste for enchancing anaerobic digestion and biogas generation  

SciTech Connect

This paper was conducted to evaluate the effect of milling and alkali lime cooking pretreatments on the rate and extent of methane generation from sugar Cane bagasse. The effect of pretreatment process variables (Particle size 8.0.003 mm, temperature between 100 and 250[degree]C and alkaline dosage between 0 and 8g CaO/kg VS) on the biogas generation from Sugar Cane bagasse has been investigated. Methane generation from the pretreated cane bagasse was studied using serum bottle technique and an upflow anaerobic filter bioreactor. The optimum condition involves alkali-cooking of cane bagasse (0.5 mm) with 4% CaO at 200[degree]C, dissolving most of the cellulose and converting it in a mixture of organic acids, including formic, acetic, lactic, and succinic acids. About 80% of the COD content of the cellulose was retained in the cooked liquor. A very rapid biogas were observed in the first three days of 70% methane content from the pretreated cane bagasse and the digestion was completed within 8 days. It has been concluded, that the lime-cooking of CB could produce methane as much as 70% of that from glucose. Inhibition did not seems to be serious problem in the biogas generation from the alkali-cooking cane bagasse. 29 refs., 3 figs., 5 tabs.

Azzam, A.M. (National Research Centre, Cairo (Egypt) Menoufia Univ., Sadat City (Egypt)); Nasr, M.I. (Menoufia Univ., Sadat City (Egypt))

1993-10-01

380

Application of optimized alkaline pretreatment for enhancing the anaerobic digestion of different sunflower stalks varieties.  

PubMed

The use of lignocellulosic residues such as sunflower stalks (SS) for the production of bioenergy such as methane is a promising alternative to fossil fuels. However, their recalcitrant structure justifies the use of pretreatment to enhance the accessibility of holocelluloses and their further conversion into methane. First, different conditions of alkaline pretreatment (i.e. duration and NaOH concentration (g/100 g TS) at a fixed temperature of 55 degrees C) were tested to enhance the methane potential of the stalks of the Serin sunflower (193 mL of methane per gram of volatile solids (VS)). The greatest improvement to the methane potential (262 mL CH4 g(-1) VS) was observed at 55 degrees C, 24 h, 4 g NaOH/100 g TS. Fourier Transform Infrared spectra highlighted an accumulation of lignin in the digestate and the degradation of holocelluloses during the anaerobic process, both for pretreated and untreated SS. In a second stage, this optimum condition for alkaline pretreatment (55 degrees C, 24 h, 4 g NaOH/100 g TS) was applied to the stalks of three other varieties of sunflower. Alkaline pretreatment was effective in the delignification of the stalks of the different sunflower varieties, with lignin reduction varying from 23.3% to 36.3% VS. This reduction of lignin was concomitant with the enhancement of methane potential as compared to that of raw SS, with an increase ranging from 29% to 44% for the different SS. PMID:24350469

Monlau, Florian; Aemig, Quentin; Barakat, Abdellatif; Steyer, Jean-Philippe; Carrère, Hélène

2013-01-01

381

Reducing agitation energy-consumption by improving rheological properties of corn stover substrate in anaerobic digestion.  

PubMed

Rheological properties of corn stover substrate were investigated to explore agitation energy reduction potential for different total solid (TS) in anaerobic digestion. The effects of particle size and temperature on rheological properties and corresponding energy reduction were studied. The results indicated that corn stover slurry exhibited pseudo-plastic flow behavior at TS of 4.23-7.32%, and was well described by Power-law model. At TS of 4.23%, rheological properties were not obviously affected by particle size and temperature. However, when TS was increased to 7.32%, there was 10.37% shear stress reduction by size-reduction from 20 to 80-mesh, and 11.73% shear stress reduction by temperature-increase from 25 to 55 °C. PTS was advanced as variations of power consumption by TS-increase from 4.23% to 7.32%. There was 9.2% PTS-reduction by size-reduction from 20 to 80-mesh at 35 °C. Moreover, PTS-reduction of 10.3%/10 °C was achieved at 20-mesh compared with 9.0%/10 °C at 80-mesh. PMID:24690465

Tian, Libin; Shen, Fei; Yuan, Hairong; Zou, Dexun; Liu, Yanping; Zhu, Baoning; Li, Xiujin

2014-09-01

382

Biomethane production and dynamics of microflora in response to copper treatments during mesophilic anaerobic digestion.  

PubMed

This study discussed the effects of different concentrations (0.625, 1.875 and 3.125 mM) of copper (Cu) in the form of CuSO4 on biomethane production and on the dynamics of microbial communities during the mesophilic anaerobic digestion (AD) of cow manure. The effects on biomethane production were found to depend on CuSO4 concentrations. After 50 days of AD, treatment A3 (3.125 mM) had lower cumulative biomethane production than the no-Cu control. The maximum value of cumulative biomethane production was detected under treatment A2 (1.875 mM). These results suggested that the stimulation or inhibition to biomethane production might be related to the concentration and chemical forms of Cu. Moreover, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to discuss the dynamics of microbial communities. Results revealed that different concentrations of CuSO4 had effects on the richness and diversity of bacterial and archaeal communities. The predominance of Bacteroidetes bacterium (GU339485.1) was verified through the sequencing of the dominant DGGE bands. Furthermore, Bacteroidetes bacterium could be detected during the whole AD process and is adaptable to a certain concentration range of CuSO4. PMID:25092381

Ke, Xin; Wang, Chunyong; Li, Rundong; Zhang, Yun; Zhang, Haijun; Gui, Shaofeng

2014-08-01

383

Total solids content: a key parameter of metabolic pathways in dry anaerobic digestion  

PubMed Central

Background In solid-state anaerobic digestion (AD) bioprocesses, hydrolytic and acidogenic microbial metabolisms have not yet been clarified. Since these stages are particularly important for the establishment of the biological reaction, better knowledge could optimize the process performances by process parameters adjustment. Results This study demonstrated the effect of total solids (TS) content on microbial fermentation of wheat straw with six different TS contents ranging from wet to dry conditions (10 to 33% TS). Three groups of metabolic behaviors were distinguished based on wheat straw conversion rates with 2,200, 1,600, and 1,400 mmol.kgVS-1 of fermentative products under wet (10 and 14% TS), dry (19 to 28% TS), and highly dry (28 to 33% TS) conditions, respectively. Furthermore, both wet and dry fermentations showed acetic and butyric acid metabolisms, whereas a mainly butyric acid metabolism occurred in highly dry fermentation. Conclusion Substrate conversion was reduced with no changes of the metabolic pathways until a clear limit at 28% TS content, which corresponded to the threshold value of free water content of wheat straw. This study suggested that metabolic pathways present a limit of TS content for high-solid AD. PMID:24261971

2013-01-01

384

Optimization of anaerobic co-digestion of strawberry and fish waste.  

PubMed

Anaerobic co-digestion of agri-food waste is a promising management alternative. Its implementation, however, requires evaluating the proportion in which waste should be mixed to optimize their centralized treatment. The combined treatment of strawberry extrudate and fish waste, which are widely generated in Mediterranean areas, was optimized. Strawberry extrudate and fish waste were mixed and treated at different proportions (88:12, 94:6, and 97:3, respectively; wet basis). The proportions selected for the mixture allow the different flows to be absorbed simultaneously. The highest methane production was observed for the ratio 94:6 (0.205 m(3) STP CH4/kg volatile solid) (VS) (STP; 0 °C, 1 atm), with a methane production rate in the range of 5?·?10(-3)-9?·?10(-3) m(3) STP/kg VS?·?d, while the highest organic loading rate was observed for the mixture at a proportion 88:12 (1.9?±?0.1 kg VS/m(3)?·?d). Biodegradability was found to be similar for the 88:12 and 94:6 proportions, with values around 90 % in VS. Nevertheless, the 97:3 ratio was not viable due to a low methane production. An inhibition phenomenon occurred at increasing loads due to the effect of some compounds contained in the fish waste such as chloride or nitrogen. PMID:24801408

Serrano, Antonio; Siles, José A; Gutiérrez, M Carmen; Martín, M Angeles

2014-07-01

385

Start-up of a biological sequencing batch reactor to treat supernatant from anaerobic sludge digester.  

PubMed

Treating the supernatant (reject water) from an anaerobic sludge digestion (800-1200 mg NH4(+)-N l(-1)) may be a good solution for meeting local requirements. As reject water represents 0.6% of the total wastewater influent flow and contains 10-30% of the total N it is recirculated to the head plant. In this study, a lab-scale start-up of biological nitrification/denitrification process to treat reject water was developed in a sequencing batch reactor. Sludge acclimation to the denitrification process was quite fast (6-7 days) for both NO2(-)-N and NO3(-)-N, whereas in nitrification it was slower (20 days). The use of a sequencing batch reactor to treat reject water produced a complete biological reduction of the NH4(+)-N via nitrite, working with sludge age of 15 days, hydraulic retention time of 1.3 days, temperature of 28 degrees C, pH between 7-8.5 and biomass concentration around 3500 mg VSS l(-1). Specific efficiencies were 14 mg NH4(+)-N (g VSS h(-1)) and 30 mg NO2(-)-N (g VSS h)(-1). PMID:16972385

Galí, A; Dosta, J; Macé, S; Mata-Alvarez, J

2006-08-01

386

Enhancing methane production during the anaerobic digestion of crude glycerol using Japanese cedar charcoal.  

PubMed

The use of Japanese cedar charcoal as a support material for microbial attachment could enhance methane production during anaerobic digestion of crude glycerol and wastewater sludge. Methane yield from a charcoal-containing reactor was approximately 1.6 times higher than that from a reactor without charcoal, and methane production was stable over 50 days when the loading rate was 2.17 g chemical oxygen demand (COD) L(-1) d(-1). Examination of microbial communities on the charcoal revealed the presence of Uncultured Desulfovibrio sp. clone V29 and Pelobacter seleniigenes, known as 1,3-propandiol degraders. Hydrogenotrophic methanogens were also detected in the archaeal community on the charcoal. Methanosaeta, Methanoregula, and Methanocellus were present in the charcoal-containing reactor. The concentration of propionate in the charcoal-containing reactor was also lower than that in the control reactor. These results suggest that propionate degradation was enhanced by the consumption of hydrogen by hydrogenotrophic methanogens on the charcoal. PMID:24189339

Watanabe, Ryoya; Tada, Chika; Baba, Yasunori; Fukuda, Yasuhiro; Nakai, Yutaka

2013-12-01

387

Two-phase anaerobic digestion within a solid waste/wastewater integrated management system  

SciTech Connect

A two-phase, wet anaerobic digestion process was tested at laboratory scale using mechanically pre-treated municipal solid waste (MSW) as the substrate. The proposed process scheme differs from others due to the integration of the MSW and wastewater treatment cycles, which makes it possible to avoid the recirculation of process effluent. The results obtained show that the supplying of facultative biomass, drawn from the wastewater aeration tank, to the solid waste acidogenic reactor allows an improvement of the performance of the first phase of the process which is positively reflected on the second one. The proposed process performed successfully, adopting mesophilic conditions and a relatively short hydraulic retention time in the methanogenic reactor, as well as high values of organic loading rate. Significant VS removal efficiency and biogas production were achieved. Moreover, the methanogenic reactor quickly reached optimal conditions for a stable methanogenic phase. Studies conducted elsewhere also confirm the feasibility of integrating the treatment of the organic fraction of MSW with that of wastewater.

De Gioannis, G. [DIGITA, Department of Geoengineering and Environmental Technologies, University of Cagliari, Piazza D'Armi 09123 Cagliari (Italy); Diaz, L.F. [CalRecovery, Inc., 2454 Stanwell Drive, Concord, California 94520 (United States); Muntoni, A. [DIGITA, Department of Geoengineering and Environmental Technologies, University of Cagliari, Piazza D'Armi 09123 Cagliari (Italy)], E-mail: amuntoni@unica.it; Pisanu, A. [DIGITA, Department of Geoengineering and Environmental Technologies, University of Cagliari, Piazza D'Armi 09123 Cagliari (Italy)

2008-07-01

388

Two-phase anaerobic digestion within a solid waste/wastewater integrated management system.  

PubMed

A two-phase, wet anaerobic digestion process was tested at laboratory scale using mechanically pre-treated municipal solid waste (MSW) as the substrate. The proposed process scheme differs from others due to the integration of the MSW and wastewater treatment cycles, which makes it possible to avoid the recirculation of process effluent. The results obtained show that the supplying of facultative biomass, drawn from the wastewater aeration tank, to the solid waste acidogenic reactor allows an improvement of the performance of the first phase of the process which is positively reflected on the second one. The proposed process performed successfully, adopting mesophilic conditions and a relatively short hydraulic retention time in the methanogenic reactor, as well as high values of organic loading rate. Significant VS removal efficiency and biogas production were achieved. Moreover, the methanogenic reactor quickly reached optimal conditions for a stable methanogenic phase. Studies conducted elsewhere also confirm the feasibility of integrating the treatment of the organic fraction of MSW with that of wastewater. PMID:18191559

De Gioannis, G; Diaz, L F; Muntoni, A; Pisanu, A

2008-01-01

389

Copper-binding ability of dissolved organic matter derived from anaerobically digested biosolids  

SciTech Connect

The fate of metals in soils where soluble organic compound are present may be strongly influenced by the degree to which they are complexed by organic ligands. The authors undertook this study to determine the combined effect of molecular weight (MW) and hydrophobicity on the Cu-binding ability of dissolved organic compounds in biosolids (i.e., sewage sludge). Dissolved organic matter (DOM) from anaerobically digested sewage biosolids was fractionated by using a combination of MW fractionation and XAD-8 resin chromatography. The Cu-binding abilities of the DOM fractions were obtained by using a Cu{sup 2+}-ion-selective electrode (Cu-ISE) technique. The Cu-binding ability of fractionated DOM decreased significantly with increasing molecular weight, indicating that low-MW DOM had more metal-binding sites than high-MW DOM. Within each MW fraction, the hydrophilic and the hydrophobic components also exhibited differences in Cu-binding ability. For the DOM with MW 500--3,500 Da, the hydrophilic fraction showed a greater Cu-binding capacity than did the hydrophobic fraction, whereas the hydrophobic acid components were most important in binding Cu for DOM with MW > 3,500 Da. The maximum Cu-binding capacities of different biosolids-derived DOM fractions, estimated by employing a Langmuir model, ranged from 1.85 to 14.3 mmol Cu mol{sup {minus}1} dissolved organic C (DOC), which is the same order of magnitude as similar measurements of DOM from other sources.

Han, N.; Thompson, M.L. [Iowa State Univ., Ames, IA (United States). Agronomy Dept.

1999-05-01

390

Cellulose digestion and metabolism induced biocatalytic transitions in anaerobic microbial ecosystems.  

PubMed

Anaerobic digestion of highly polymerized biomass by microbial communities present in diverse microbial ecosystems is an indispensable metabolic process for biogeochemical cycling in nature and for industrial activities required to maintain a sustainable society. Therefore, the evaluation of the complicated microbial metabolomics presents a significant challenge. We here describe a comprehensive strategy for characterizing the degradation of highly crystallized bacterial cellulose (BC) that is accompanied by metabolite production for identifying the responsible biocatalysts, including microorganisms and their metabolic functions. To this end, we employed two-dimensional solid- and one-dimensional solution-state nuclear magnetic resonance (NMR) profiling combined with a metagenomic approach using stable isotope labeling. The key components of biocatalytic reactions determined using a metagenomic approach were correlated with cellulose degradation and metabolic products. The results indicate that BC degradation was mediated by cellulases that contain carbohydrate-binding modules and that belong to structural type A. The degradation reactions induced the metabolic dynamics of the microbial community and produced organic compounds, such as acetic acid and propionic acid, mainly metabolized by clostridial species. This combinatorial, functional and structural metagenomic approach is useful for the comprehensive characterization of biomass degradation, metabolic dynamics and their key components in diverse ecosystems. PMID:24958386

Yamazawa, Akira; Iikura, Tomohiro; Morioka, Yusuke; Shino, Amiu; Ogata, Yoshiyuki; Date, Yasuhiro; Kikuchi, Jun

2013-01-01

391

Struvite formation from the supernatants of an anaerobic digestion pilot plant.  

PubMed

This work studied the influence of the characteristics of the supernatants on the struvite precipitation process. Eighteen experiments with the supernatants generated in an anaerobic digestion pilot plant were performed in a stirred reactor. In order to obtain the pH control during the crystallization process, a Fuzzy Logic based controller was used. High phosphorus precipitation and recovery efficiencies were obtained. The composition of the supernatants was analyzed in order to study its influence on the solids formed from those solutions. The presence of calcium reduced the percentage of phosphorus precipitated as struvite leading to the formation of amorphous calcium phosphate (ACP), which tended to be lost with the effluent of the reactor. Calcite was also formed when supernatants with high magnesium:phosphorus (Mg/P) and calcium:phosphorus (Ca/P) molar ratios were employed. Some ammonium volatilization by conversion to NH(3) occurred in all the experiments. The use of air to increase the pH to an adequate value showed to be feasible. Aeration cleaned struvite crystals from suspended solids, which makes aeration interesting for struvite separation. However, aeration slightly increased the loss of phosphorus with the effluent of the reactor and promoted ammonium volatilization. PMID:19733058

Pastor, L; Mangin, D; Ferrer, J; Seco, A

2010-01-01

392

Prediction of hydrogen sulphide production during anaerobic digestion of organic substrates.  

PubMed

The main objective of this study was to develop a methodology to predict the hydrogen sulphide content of raw biogas produced during anaerobic mono-digestion of a bioenergy feedstock. Detailed chemical and biological analyses were made on 37 different feedstocks originating from urban wastewater treatment plants, farms, agri-food facilities and municipal wastes. Total sulphur content ranged from 1 to 29.6 mg S/kg of total solids, and 66% of the feedstocks analysed contained less than 5 mg S/kg of total solids. The biochemical methanogenic potential and biochemical biogas potential of each feedstock combined with its S content were used to predict appearance of H(2)S in the raw biogas. A model to link H(2)S in biogas with the carbon:sulphur ratio was established. Based on this model, a minimum carbon:sulphur ratio of 40 is required in feedstock to limit the concentration of hydrogen sulphide in raw biogas to less than 2% (volume/volume). PMID:22864178

Peu, Pascal; Picard, Sylvie; Diara, Arnaud; Girault, Romain; Béline, Fabrice; Bridoux, Gilbert; Dabert, Patrick

2012-10-01

393

Effects of Psychrophilic Storage on Manures as Substrate for Anaerobic Digestion  

PubMed Central

The idea that storage can enhance manure quality as substrate for anaerobic digestion (AD) to recover more methane is evaluated by studying storage time and temperature effects on manure composition. Volatile fatty acids (VFA) and total dissolved organics (CODs) were measured in full scale pig manure storage for a year and in multiple flasks at fixed temperatures, mainly relevant for colder climates. The CODs generation, influenced by the source of the pig manure, was highest initially (0.3?g?COD?L?1d?1) gradually dropping for 3 months towards a level of COD loss by methane production at 15°C. Methane emission was low (<0.01?g?COD?L?1d?1) after a brief initial peak. Significant CODs generation was obtained during the warmer season (T > 10°C) in the full scale storage and almost no generation at lower temperatures (4–6°C). CODs consisted mainly of VFA, especially acetate. All VFAs were present at almost constant ratios. The naturally separated manure middle layer without sediment and coarser particles is suitable for sludge bed AD and improved further during an optimal storage time of 1–3 month(s). This implies that high rate AD can be integrated with regular manure slurry handling systems to obtain efficient biogas generation. PMID:25165712

Bergland, Wenche; Dinamarca, Carlos

2014-01-01

394

Anaerobic digestate from biogas production as a resource for improving soil fertility: effects on crop yield and soil properties  

NASA Astrophysics Data System (ADS)

Soil fertility is fundamental in determining crops productivity in all farming systems. Production of biogas through anaerobic digestion of energy crops generates residues that can represent a valuable resource to sustain and improve soil fertility and to increase soil organic matter content. Residues from anaerobic digestion contain organic fractions and available nutrients, that can thus be returned to the cultivation soil as fertilizer and soil conditioner. However, some unknown aspects of digested residues utilization remain to explore: i) the nutrient supply and the real potential for mineral fertilization substitution, ii) the impact on the structure and functioning of soil microbial communities, iii) the direct and indirect effects on soil structure, organic matter and C mineralization. The aim of the present research was to gain a better understanding of these aspects, evaluating the effects of anaerobic digestate application on soil properties and maize yield. With the main focus of comparing mineral fertilization (250 Kg N ha-1) with digested residues addition (at the dose of 25 % and 50 % of mineral fertilizer), a triplicate sets of plots were designed in a field experiment on a silty-clay loam soil in the southern Po Valley (Italy). The amount of applied residues was calculated according to its N content in order to fertilizer each plots with the same amount of total nitrogen. Residues from digestion showed a N content of 0.4 % (60 % as N-NH4) and a C/N ratio of 3. Changes in soil quality after residues application were studied with a holistic approach, involving microbiological, physical and chemical aspects of soil fertility. In particular, we determined: the abundance and diversity of bacterial and fungal soil communities; the soil organic matter content, its distribution within soil aggregates and the C mineralization potential; cation exchange capacity; the main macro and micro nutrients; bulk density; aggregate stability. No significant differences among treatments were registered in the above ground maize biomass. Molecular analysis conducted on microbial soil communities suggested that the application of digested residues to soil contributes to substantial modifications of both bacterial and fungal community structure. Soil organic C and total N increased in soils treated with digested residues addition, with no significant differences between the two doses of digestate. Cation exchange capacity did not show significant differences among treatments, remaining stable during the maize vegetative cycle. Differently, some variations occurred in the exchangeable cation pool. In particular, K content increased under digestate treatments, while Na and Mg contents increased with time irrespective of the fertilization treatment. No significant variations were observed in soil microelement levels, except for an increase in Zn content at the highest digestate dose. Moreover, digested residue addition had a positive impact on aggregates stability. From the first results, the absence of negative effects in plant productivity and soil fertility after residues application, at both doses, is a promising indication for the potential use of anaerobic digestate as substitute of mineral fertilizers.

Pastorelli, Roberta; Lagomarsino, Alessandra; Vignozzi, Nadia; Valboa, Giuseppe; Papini, Rossella; Fabiani, Arturo; Simoncini, Stefania; Mocali, Stefano; Piccolo, Raimondo

2013-04-01

395

Energy and economic assessment of anaerobic digester and biofuels for waste management  

SciTech Connect

A history of biogas production in the USA is presented. Recent systems approaches to biogas are considered. Technological problems that have interfered with the routine operation of biogas digesters are the barriers to feed-material handling, inadequate feed material preparation, irregular gas production of current designs of small-scale systems, and the capital- and maintenance-intensive nature of the conversion of biogas to electricity. Finally, it was noted that so far no work has been carried out to study alternative uses for biogas, as for example the production of methanol or ammonia.

Not Available

1981-08-01

396

Investigation into the effect of high concentrations of volatile fatty acids in anaerobic digestion on methanogenic communities.  

PubMed

A study was conducted to determine whether differences in the levels of volatile fatty acids (VFAs) in anaerobic digester plants could result in variations in the indigenous methanogenic communities. Two digesters (one operated under mesophilic conditions, the other under thermophilic conditions) were monitored, and sampled at points where VFA levels were high, as well as when VFA levels were low. Physical and chemical parameters were measured, and the methanogenic diversity was screened using the phylogenetic microarray ANAEROCHIP. In addition, real-time PCR was used to quantify the presence of the different methanogenic genera in the sludge samples. Array results indicated that the archaeal communities in the different reactors were stable, and that changes in the VFA levels of the anaerobic digesters did not greatly alter the dominating methanogenic organisms. In contrast, the two digesters were found to harbour different dominating methanogenic communities, which appeared to remain stable over time. Real-time PCR results were inline with those of microarray analysis indicating only minimal changes in methanogen numbers during periods of high VFAs, however, revealed a greater diversity in methanogens than found with the array. PMID:25164858

Franke-Whittle, Ingrid H; Walter, Andreas; Ebner, Christian; Insam, Heribert

2014-11-01

397

Investigation into the effect of high concentrations of volatile fatty acids in anaerobic digestion on methanogenic communities  

PubMed Central

A study was conducted to determine whether differences in the levels of volatile fatty acids (VFAs) in anaerobic digester plants could result in variations in the indigenous methanogenic communities. Two digesters (one operated under mesophilic conditions, the other under thermophilic conditions) were monitored, and sampled at points where VFA levels were high, as well as when VFA levels were low. Physical and chemical parameters were measured, and the methanogenic diversity was screened using the phylogenetic microarray ANAEROCHIP. In addition, real-time PCR was used to quantify the presence of the different methanogenic genera in the sludge samples. Array results indicated that the archaeal communities in the different reactors were stable, and that changes in the VFA levels of the anaerobic digesters did not greatly alter the dominating methanogenic organisms. In contrast, the two digesters were found to harbour different dominating methanogenic communities, which appeared to remain stable over time. Real-time PCR results were inline with those of microarray analysis indicating only minimal changes in methanogen numbers during periods of high VFAs, however, revealed a greater diversity in methanogens than found with the array. PMID:25164858

Franke-Whittle, Ingrid H.; Walter, Andreas; Ebner, Christian; Insam, Heribert

2014-01-01

398

Sulphur fate and anaerobic biodegradation potential during co-digestion of seaweed biomass (Ulva sp.) with pig slurry.  

PubMed

Seaweed (Ulva sp.) stranded on beaches were utilized as co-substrate for anaerobic digestion of pig slurry in three-month co-digestion tests in pilot scale anaerobic digesters in the laboratory. The methanogenic potential of Ulva sp. was low compared to that of other potential co-substrates available for use by farmers: 148 N m3CH4/t of volatile solids or 19 N m3CH4/t of crude product. When used as a co-substrate with pig manure (48%/52% w/w), Ulva sp. seaweed did not notably disrupt the process of digestion; however, after pilot stabilisation, biogas produced contained 3.5% H2S, making it unsuitable for energy recovery without treatment. Sequentially addition of the sulphate reduction inhibitor, potassium molybdate, to a final concentration of 3mM, temporarily reduced H2S emissions, but was unable to sustain this reduction over the three-month period. According to these pilot tests, the use of seaweed stranded on beaches as co-substrate in farm-based biogas plants shows some limitations. PMID:21982451

Peu, P; Sassi, J-F; Girault, R; Picard, S; Saint-Cast, Patricia; Béline, F; Dabert, P

2011-12-01

399

USE OF SOLAR ENERGY TO HEAT ANAEROBIC DIGESTERS. PART I. TECHNICAL AND ECONOMIC FEASIBILITY STUDY. PART II. ECONOMIC FEASIBILITY THROUGHOUT THE UNITED STATES  

EPA Science Inventory

Two distinct, yet related studies were conducted to determine the technical and economic feasibility of using solar energy as the source of heat for the anaerobic digestion process. Retrofitting a solar energy collection and heat transfer system to a digester at Annapolis, Maryla...

400

Heterotrophic denitrification plays an important role in N?O production from nitritation reactors treating anaerobic sludge digestion liquor.  

PubMed

Nitrous oxide (N2O) emissions from nitritation reactors receiving real anaerobic sludge digestion liquor have been reported to be substantially higher than those from reactors receiving synthetic digestion liquor. This study aims to identify the causes for the difference, and to develop strategies to reduce N2O emissions from reactors treating real digestion liquor. Two sequencing batch reactors (SBRs) performing nitritation, fed with real (SBR-R) and synthetic (SBR-S) digestion liquors, respectively, were employed. The N2O emission factors for SBR-R and SBR-S were determined to be 3.12% and 0.80% of the NH4(+)-N oxidized, respectively. Heterotrophic denitrification supported by the organic carbon present in the real digestion liquor was found to be the key contributor to the higher N2O emission from SBR-R. Heterotrophic nitrite reduction likely stopped at N2O (rather than N2), with a hypothesised cause being free nitrous acid inhibition. This implies that all nitrite reduced by heterotrophic bacteria was converted to and emitted as N2O. Increasing dissolved oxygen (DO) concentration from 0.5 to 1.0 mg/L, or above, decreased aerobic N2O production from 2.0% to 0.5% in SBR-R, whereas aerobic N2O production in SBR-S remained almost unchanged (at approximately 0.5%). We hypothesised that DO at 1 mg/L or above suppressed heterotrophic nitrite reduction thus reduced aerobic heterotrophic N2O production. We recommend that DO in a nitritation system receiving anaerobic sludge digestion liquor should be maintained at approximately 1 mg/L to minimise N2O emission. PMID:24956602

Wang, Qilin; Jiang, Guangming; Ye, Liu; Pijuan, Maite; Yuan, Zhiguo

2014-10-01

401

Evaluation of batch anaerobic co-digestion of palm pressed fiber and cattle manure under mesophilic conditions.  

PubMed

Palm pressed fiber (PPF) and cattle manure (CM) are the waste which can be managed properly by anaerobic co-digestion. The biogas production in co-digested PPF and CM at three volatile solids (VS) ratios of 3:1, 1:1, and 1:3 was investigated in a series of batch experiments at an organic loading rate of 30.0g VS/L under mesophilic (37±1°C) conditions. The highest daily biogas yield of PPF and CM only, was 90.0mL/g VSadded at day 12 and 23.4mL/g VSadded at day 7. For co-digestion of PPF/CM at mixing ratios of 3:1, 1:1 and 1:3, there were 93.6mL/g VSadded at day 11, 86.8 and 26.4mL/g VSadded at day 8. VS removal rate for PPF, CM, and co-digestion at mixing ratio of 3:1, 1:1, and 1:3 were 91.1%, 86.0% and 71.0%, respectively. The anaerobic digestion of PPF and CM and their co-digestion systems were stable in operation with low range of volatile fatty acids (VFA)/TIC (total inorganic carbon) of (0.035-0.091). The main volatile fatty acids were propionic, and iso-butyric acids for PPF, iso-butyric and n-butyric acids for CM. The VFAs and ammonium inhibition were not occurred. The modified Gompertz model can be used to perform a better prediction with a lower difference between the measured and predicted biogas yields. A VS ratio of 3:1 is recommended for practice. PMID:25148926

Bah, Hamidou; Zhang, Wanqin; Wu, Shubiao; Qi, Dandan; Kizito, Simon; Dong, Renjie

2014-11-01