scispace - formally typeset
Search or ask a question

Showing papers on "Biogas published in 2007"


Journal ArticleDOI
TL;DR: The results of this study indicate that the food waste is a highly desirable substrate for anaerobic digesters with regards to its high biodegradability and methane yield.

927 citations


Journal ArticleDOI
TL;DR: Results suggested an optimum C/N ratio for co-digestion of algal sludge and waste paper was in the range of 20-25/1.

770 citations


Journal ArticleDOI
TL;DR: In this paper, anaerobic digestion of maize and dairy cattle manures was investigated for 60 days in 1-l eudiometer batch digesters at 38°C, and the authors derived a multiple linear regression equation, the Methane Energy Value Model, that estimates methane production from the composition of maize.

665 citations


Journal ArticleDOI
01 Aug 2007-Energy
TL;DR: In this paper, the composition and variation in three different biogas production plants were studied to provide information pertaining to its potential use as biofuel, and the results showed that the biogases in the different production plants varied, especially in trace compound content.

603 citations


Journal ArticleDOI
TL;DR: In this article, the potential for additional collection and utilization of landfill gas in the US and worldwide was estimated based on the landfill gas situation in the United States and worldwide, and a conservative estimate of methane generation of about 50 nm3 of methane per ton of municipal solid waste (MSW) landfilled was made.

541 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated suitability of different crop species and varieties, optimum time of harvesting, specific methane yield and methane yield per hectare for anaerobic digestion of energy crops.

497 citations


Journal ArticleDOI
TL;DR: Anaerobic co-digestion of grass silage, sugar beet tops and oat straw with cow manure was evaluated in semi-continuously fed laboratory continuously stirred tank reactors (CSTRs).
Abstract: Anaerobic co-digestion of grass silage, sugar beet tops and oat straw with cow manure was evaluated in semi-continuously fed laboratory continuously stirred tank reactors (CSTRs). Co-digestion of manure and crops was shown to be feasible with feedstock volatile solids (VS) containing up to 40% of crops. The highest specific methane yields of 268, 229 and 213 l CH4 kg−1 VSadded in co-digestion of cow manure with grass, sugar beet tops and straw, respectively, were obtained with 30% of crop in the feedstock, corresponding to 85–105% of the methane potential in the substrates as determined by batch assays. Including 30% of crop in the feedstock increased methane production per digester volume by 16–65% above that obtained from digestion of manure alone. Increasing the proportion of crops further to 40% decreased the specific methane yields by 4–12%, while doubling the loading rate from 2 to 4 kg VS m−3 day−1 decreased the specific methane yields by 16–26%. The post-methanation potential of the digestates corresponded to 0.9–2.5 m3 CH4 t−1 wet weight of digestate and up to 12–31% of total methane production in northern climatic conditions, being highest after co-digestion of manure with straw.

385 citations


Journal ArticleDOI
TL;DR: In this paper, the overall environmental impact when biogas systems are introduced and replace various reference systems for energy generation, waste management and agricultural production is analyzed using a life-cycle perspective.
Abstract: This paper analyses the overall environmental impact when biogas systems are introduced and replace various reference systems for energy generation, waste management and agricultural production. The analyses are based on Swedish conditions using a life-cycle perspective. The biogas systems included are based on different combinations of raw materials and final use of the biogas produced (heat, power and transportation fuel). A general conclusion is that biogas systems normally lead to environmental improvements, which in some cases are considerable. This is often due to indirect environmental benefits of changed land use and handling of organic waste products (e.g. reduced nitrogen leaching, emissions of ammonia and methane), which often exceed the direct environmental benefits achieved when fossil fuels are replaced by biogas (e.g. reduced emissions of carbon dioxide and air pollutants). Such indirect benefits are seldom considered when biogas is evaluated from an environmental point of view. The environmental impact from different biogas systems can, however, vary significantly due to factors such as the raw materials utilised, energy service provided and reference system replaced.

323 citations


Journal ArticleDOI
TL;DR: In this article, two predominant bacterial morphologies, namely spore-forming rod shape bacteria and micrococcus were screened, purified, and identified after enriched from a hydrogen-producing fermentor with cow dung composts.
Abstract: Biohydrogen production from the cornstalk wastes with acidification pretreatment was reported in this paper. Batch tests were carried out to analyze influences of several environmental factors on biohydrogen production from cornstalk wastes. Two predominant bacterial morphologies, namely spore-forming rod shape bacteria and micrococcus were screened, purified, and identified after enriched from a hydrogen-producing fermentor with cow dung composts. The maximum cumulative H2 yield of 149.69 ml H2 g−1 TVS was obtained at initial pH 7.0 and substrate concentration 15 g l−1, the value is about 46-fold as compared with that of raw cornstalk wastes. The maximum hydrogen production rate was 7.6 ml H2 h−1. The hydrogen concentration in biogas was 45–56% (v/v) and there was no significant methane observed in the biogas throughout this study. In addition, biodegradation characteristics of the substrate by microorganisms were also discussed. During the conversion of cornstalk wastes into hydrogen, the acetate, propionate, butyrate, and the ethanol were main by-products in the metabolism of hydrogen fermentation. The test results showed that the acidification pretreatment of the substrate plays a crucial role in conversion of the cornstalk wastes into biohydrogen gas by the cow dung composts generating hydrogen.

310 citations


Journal ArticleDOI
TL;DR: In this paper, different policies and policy instruments, as well as other factors, which influence a potential expansion of Swedish biogas systems, are identified and evaluated, and the existing incentives and barriers can be divided into those affecting the production of Biogas, and those affecting its utilisation.

296 citations


Journal ArticleDOI
TL;DR: In this paper, three lignocellulosic raw materials were studied, i.e. winter rye straw (Secale cereale L), oilseed rape straw (Brassica napus L.) and faba bean straw (Viciafaba L.).
Abstract: To meet the increasing need for bioenergy several raw materials have to be considered for the production of e.g. bioethanol and biogas. In this study, three lignocellulosic raw materials were studied, i.e. (1) winter rye straw (Secale cereale L), (2) oilseed rape straw (Brassica napus L.) and (3) faba bean straw (Viciafaba L.). Their composition with regard to cellulose, hemicellulose, lignin, extractives and ash was evaluated, as well as their potential as raw materials for ethanol and biogas production. The materials were pretreated by wet oxidation using parameters previously found to be optimal for pretreatment of corn stover (1951C, 15 min, 2 g l � 1 Na2CO3 and 12 bar oxygen). It was shown that pretreatment was necessary for ethanol production from all raw materials and gave increased biogas yield from winter rye straw. Neither biogas productivity nor yield from oilseed rape straw or faba bean straw was significantly affected by pretreatment. Ethanol was produced by the yeast Saccharomyces cerevisiae during simultaneous enzymatic hydrolysis of the solid material after wet oxidation with yields of 66%, 70% and 52% of theoretical for winter rye, oilseed rape and faba bean straw, respectively. Methane was produced with yields of 0.36, 0.42 and 0.44 l g � 1 volatile solids for winter rye, oilseed rape and faba bean straw, respectively, without pretreatment of the materials. However, biogas productivity was low and it took over 50 days to reach the final yield. It could be concluded that all three materials are possible raw materials for either biogas or ethanol production; however, improvement of biogas productivity or ethanol yield is necessary before an economical process can be achieved. r 2007 Elsevier Ltd. All rights reserved.

Journal ArticleDOI
TL;DR: In this paper, the experimental introduction of biogas plants in Denmark since the 1970s is reviewed, and the authors argue that three factors have been important for the current status of Biogas Plants in Denmark: the Danish government applied a bottom-up strategy and stimulated interaction and learning between various social groups.
Abstract: With 20 centralised plants and over 35 farmscale plants, the digestion of manure and organic waste is a well established technological practice in Denmark. These plants did not emerge without a struggle. Moreover, no new centralised plants have been established since 1998 and the development of farmscale plants has slowed down. This article reviews the experimental introduction of biogas plants in Denmark since the 1970s. We argue that three factors have been important for the current status of biogas plants in Denmark. First, the Danish government applied a bottom-up strategy and stimulated interaction and learning between various social groups. Second, a dedicated social network and a long-term stimulation enabled a continuous development of biogas plants without interruptions until the late 1990s. Third, specific Danish circumstances have been beneficial, including policies for decentralised CHP, the existence of district heating systems, the implementation of energy taxes in the late 1980s and the preference of Danish farmers to cooperate in small communities. The current setback in biogas plants is mainly caused by a shift in energy and environmental policies and limited availability of organic waste.

Journal ArticleDOI
TL;DR: In this article, the effects of thermal treatment on the semi-continuous anaerobic digestion of the main sludge compounds (proteins, carbohydrates and lipids) were studied.

Journal ArticleDOI
TL;DR: Inoculum acclimation not only accelerated the production of biogas, but also increased the extent of the ultimate mesophilic biodegradation of MW irradiated WAS (after 15-27 d).

Journal ArticleDOI
TL;DR: In this article, hydrogen was added in small amounts (5, 10% and 15% on the energy basis) to biogas and tested in a spark ignition engine at constant speed at different equivalence ratios to study the effects on performance, emissions and combustion.

BookDOI
01 Jan 2007
TL;DR: Waste Related to the Food Industry: A Challenge in Material Loops and to Food Waste Treament: The 14001 Standards as mentioned in this paper, Basic Unit Operations in Wastewater Treatment and Anaerobic Digestion of Organic Residues and Wastes.
Abstract: Waste Related to the Food Industry: A Challenge in Material Loops.- to Food Waste Treament: The 14001 Standards.- Basic Unit Operations in Wastewater Treatment.- Anaerobic Digestion of Organic Residues and Wastes.- Fundamentals and Applications of Anaerobic Digestion For Sustainable Treatment of Food Industry Wastewater.- Fermentation of Distiller's Wash in a Biogas Plant.- Brewery and Winery Wastewater Treatment: Some Focal Points of Design and Operation.- Olive Mill Wastewater Treatment.- Anaerobic Degradation of Animal By-Products.- Utilization of Whey.- Utilization of Plant By-Products for the Recovery of Proteins, Dietary Fibers, Antioxidants, and Colorants.- Utilization of By-Products in the Fish Industry.- Examples of Special Case Studies in Different Branches.- Incineration of Solid Food Waste: A Project About Spent Grain.- Composting of Food and Agricultural Wastes.

Journal ArticleDOI
TL;DR: A series of batch, slurry anaerobic digestion experiments were performed where the soluble and insoluble fractions, and unwashed MSW were separately digested in a 200l stirred stainless steel vessel and it was found that 7% of the total MSW COD was readily soluble, of which 80% was converted to biogas; 50% ofThe lag phase for the degradation of insoluble fraction of MSW can be overcome by acclimatising the culture with the soluble fraction

Journal ArticleDOI
TL;DR: In this paper, a series of laboratory experiments were performed in continuously stirred tank reactors at mesophilic conditions, fed semi-continuously with various mixtures of diluted poultry manure and whey.

Journal ArticleDOI
TL;DR: The application and modification of ADM1 is shown to simulate energy production of the digestion of cattle manure and renewable energy crops and an energy balance model is presented, which enables the dynamic calculation of the net energy production.

Journal ArticleDOI
TL;DR: The use of volatile fatty acids (VFA) as process indicators in biogas reactors treating manure together with industrial waste was studied in this paper, where an online VFA sensor was installed in order to study VFA dynamics during stable and unstable operation.
Abstract: The use of volatile fatty acids (VFA) as process indicators in biogas reactors treating manure together with industrial waste was studied. At a full-scale biogas plant, an online VFA sensor was installed in order to study VFA dynamics during stable and unstable operation. During stable operation acetate increased significantly during the feeding periods from a level of 2–4 to 12–17 mM, but the concentration generally dropped to about the same level as before feeding. The fluctuations in the propionate were more moderate than for acetate but the average level rose during 1 week of operation from 0.6 to 2.9 mM. A process disturbance caused by overloading with industrial waste was reflected by a significant increase in all VFA concentrations. During the recovery of the process, the return of propionate back to the steady-state level was 2–3 days slower than any other VFA and propionate could best describe the normalizing of the process. In a lab-scale continuously stirred tank reactor experiment, with manure as main substrate, the prospective of using either propionate concentration or methane production as single process indicators was studied. Propionate was found to be the best indicator. Thus, a process breakdown caused by organic overloading with meat and bone meal and lipids was indicated by changes in propionate concentration 12–18 days before a decrease in methane production was observed. Furthermore, a more efficient and stable utilization of the substrate was observed when propionate was used as process indicator.

Journal ArticleDOI
TL;DR: In this article, the use of electrochemical reduction of CO 2 at a copper electrode to a hydrocarbon mixture looks like a promising technology, especially when applied to upgrading biogases.

Journal ArticleDOI
TL;DR: This is the first report on fermentative production of hydrogen and methane from organic waste at an actual level and it is speculated that the operation at high temperature and the inoculation of thermophiles enabled the selective growth of the introduced microorganisms and gave hydrogen fermentation efficiencies comparable to laboratory experiments.
Abstract: A pilot-scale experimental plant for the production of hydrogen and methane by a two-stage fermentation process was constructed and operated using a mixture of pulverized garbage and shredded paper wastes. Thermophilic hydrogen fermentation was established at 60 degrees C in the first bioreactor by inoculating with seed microflora. Following the hydrogenogenic process, methanogenesis in the second bioreactor was conducted at 55 degrees C using an internal recirculation packed-bed reactor (IRPR). After conducting steady-state operations under a few selected conditions, the overall hydraulic retention time was optimized at 8 d (hydrogenogenesis, 1.2 d; methanogenesis, 6.8 d), producing 5.4 m3/m3/d of hydrogen and 6.1 m3/m3/d of methane with chemical oxygen demand and volatile suspended solid removal efficiencies of 79.3% and 87.8%, respectively. Maximum hydrogen production yield was calculated to be 2.4 mol/mol hexose and 56 L/kg COD loaded. The methanogenic performance of the IRPR was stable, although the organic loading rate and the composition of the effluent from the hydrogenogenic process fluctuated substantially. A clone library analysis of the microflora in the hydrogenogenic reactor indicated that hydrogen-producing Thermoanaerobacterium-related organisms in the inoculum were active in the hydrogen fermentation of garbage and paper wastes, although no aseptic operations were applied. We speculate that the operation at high temperature and the inoculation of thermophiles enabled the selective growth of the introduced microorganisms and gave hydrogen fermentation efficiencies comparable to laboratory experiments. This is the first report on fermentative production of hydrogen and methane from organic waste at an actual level.

Journal ArticleDOI
TL;DR: It was showed that using the capillary module with polyimide membranes it was possible to achieve the enrichment of CH(4) from the concentrations of 55-85% up to 91-94.4%.

Journal ArticleDOI
TL;DR: In this article, the principles of thermal plasma pyrolysis processes are outlined and a discussion of recent research activities about organic waste treatment using thermal plasminization technology is discussed.

Journal ArticleDOI
TL;DR: In this paper, a new approach to immobilize mixed culture of hydrogen-producing bacteria was examined by growing on granular activated carbon in an anaerobic fluidized bed reactor.

Journal ArticleDOI
TL;DR: Two-phase anaerobic digestion of cheese whey was investigated in a system consisting of a stirred acidogenic reactor followed by a stirred methanogenic reactor, the latter being coupled to a membrane filtration system to enable removal of soluble effluent whilst retaining solids.

Journal ArticleDOI
TL;DR: The results showed that an overdose of calcium hydroxide achieved higher ammonia, phosphorus, chemical oxygen demand, suspended solids, and turbidity removal efficiency in the anaerobic digestion effluent pretreated by ammonia stripping.

Journal ArticleDOI
TL;DR: Results indicated that SLUDGE is the best inoculum source for anaerobic thermophilic digestion of the treatment of organic fraction of municipal solid waste at dry conditions (30%TS) and also, SWINE/SLUDGE and SWINE were good inoculums at these experimental conditions.

Journal ArticleDOI
TL;DR: Progress that has been made in each of the aspects of wastes transformation, waste transformation, biofertilizers is addressed with emphasis on the advantages of biol and biosol fertilizers.
Abstract: Value addition of cassava and cassava wastes is necessitated by rapid post-harvest spoilage, deterioration, low protein content and environmental pollution caused by the effluent and the other associated wastes that poses aesthetic nuisance. Biogas plants of all sizes and varying levels of technical sophistication not only recover the energy contained in cassava wastes but also eliminate most of the animal and human health problems associated with contamination. Studies have shown the technical feasibility and nutritional desirability of converting carbohydrates and their residues into products containing a large amount of protein by means of microorganisms. Wastes transformation offers the possibility of creating marketable value-added products. There exists a great potential in the use of microorganisms such as fungi for the production of high quality feedstuffs from the abundantly available agro-industrial wastes, particularly carbohydrate residues. Cassava wastes can be processed and converted into value-added components such as methane (biogas), pig meat, ethanol, surfactant and fertilizer etc. Attention is now focused on the by-products of the anaerobic decomposition of the waste that takes place in a biodigester, which are the liquid fraction called biol and the solid fraction or biosol, which are excellent fertilizers for a variety of crops. The present review addresses the progress that has been made in each of these aspects with emphasis on the advantages of biol and biosol fertilizers. Key words: Carbohydrate residue, waste transformation, biofertilizers.

Journal ArticleDOI
TL;DR: Major advances have been made in elucidating the diversity of yet-to-be cultured microbes in anaerobic digestion processes, and the cultivation of uncultured organisms is of great interest with regard to gaining insights into the function of these organisms.