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Methane Yield (methane + yield)
Selected AbstractsUtilization of semi-natural grassland through integrated generation of solid fuel and biogas from biomass.GRASS & FORAGE SCIENCE, Issue 4 2009Abstract A procedure (Integrated Generation of Solid Fuel and Biogas from Biomass, IFBB) was developed which uses a screw press to separate the readily digestible constituents of mature grassland biomass into a press fluid for conversion into biogas and a fibrous press cake for processing into a solid fuel. Effects of mechanical dehydration and prior hydrothermal conditioning at different temperatures (5, 60 and 80°C) on concentrations of organic compounds in the press fluid and on methane production in batch experiments were evaluated for five semi-natural grasslands typical of mountain areas of Germany. Results show that the crude protein concentration of the press fluids was higher and crude fibre concentration was lower than that of the parent material (herbage conserved as silage). Digestion tests in batch fermenters showed that the methane yield of the press fluids was double [397,426 normal litre (NL) kg,1 volatile solids (VS) after 13 d] that of the whole-crop grassland silage (218 NL kg,1 VS after 27 d) but no consistent effect of higher temperature during conditioning was observed. Within 13 d of fermentation the decomposition of the organic matter (OM) that occurred in the press fluids was 0·90, whereas after 27 d of fermentation more than 0·40 of the OM remained undigested in the whole-crop silage, pointing at a marked reduction in retention time for anaerobic digestion of press fluids in continuous systems. Press fluids produced 0·90 of the maximum methane yield after 4 to 7 d compared with 19 days for the whole-crop silage. [source] Effect of Drought Stress on Yield and Quality of Maize/Sunflower and Maize/Sorghum Intercrops for Biogas ProductionJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2010S. SchittenhelmArticle first published online: 16 FEB 2010 Abstract Intercropping represents an alternative to maize (Zea mays L.) monoculture to provide substrate for agricultural biogas production. Maize was intercropped with either sunflower (Helianthus annuus L.) or forage sorghum [Sorghum bicolor (L.) Moench] to determine the effect of seasonal water supply on yield and quality of the above-ground biomass as a fermentation substrate. The two intercrop partners were grown in alternating double rows at plant available soil water levels of 60,80 %, 40,50 % and 15,30 % under a foil tunnel during the years 2006 and 2007 at Braunschweig, Germany. Although the intercrop dry matter yields in each year increased with increasing soil moisture, the partner crops responded quite differently. While maize produced significantly greater biomass under high rather than low water supply in each year, forage sorghum exhibited a significant yield response only in 2006, and sunflower in none of the 2 years. Despite greatly different soil moisture contents, the contribution of sorghum to the intercrop dry matter yield was similar, averaging 43 % in 2006 and 40 % in 2007. Under conditions of moderate and no drought stress, sunflower had a dry matter yield proportion of roughly one-third in both years. In the severe drought treatment, however, sunflower contributed 37 % in 2006 and 54 % in 2007 to the total intercrop dry matter yield. The comparatively good performance of sunflower under conditions of low water supply is attributable to a fast early growth, which allows this crop to exploit the residual winter soil moisture. While the calculated methane-producing potential of the maize/sorghum intercrop was not affected by the level of water supply, the maize/sunflower intercrop in 2006 had a higher theoretically attainable specific methane yield under low and medium than under high water supply. Nevertheless, the effect of water regime on substrate composition within the intercrops was small in comparison with the large differences between the intercrops. [source] Straw bed priming enhances the methane yield and speeds up the start-up of single-stage, high-solids anaerobic reactors treating plant biomassJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2006L Mattias Svensson Abstract A simple and potentially inexpensive implementation of a high-solids reactor is a single-stage, stratified bed reactor, in which the bed is made up of the plant biomass fed into the system. In the present study, the stratified bed was started up for a period of four weeks by either direct feeding of sugar beet leaves at four different feeding rates, or by introducing a straw bed primer which was batch digested without feeding. During weeks five to six both systems were fed with sugar beet leaves at such a rate that the total amount of beet leaves added at the end of week six was the same in each of the four corresponding pairs of straw and ,no-straw' reactors. Straw bed priming enhanced the methane yield of the sugar beet leaves, with 0.33,0.37 m3 kg,1 VSadded (volatile solids) accumulated at average solid retention times as short as 11,25 days, while the ,no-straw' reactors had lower yields at longer average solid retention times. The levels and speciation of the organic acids suggested that both the rate and extent of the anaerobic digestion of the sugar beet leaves added in the straw reactors were improved. At the highest loading rate, the straw reactor failed, while the ,no-straw' reactor did not. It is hypothesised that the microbial biomass was better established in the straw reactors than in the ,no-straw' reactors. Copyright © 2006 Society of Chemical Industry [source] Effect of a chemical synthesis-based pharmaceutical wastewater on performance, acetoclastic methanogenic activity and microbial population in an upflow anaerobic filterJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2002B Kasapgil Ince Abstract The performance of an upflow anaerobic filter (UAF) treating a chemical synthesis-based pharmaceutical wastewater was evaluated under various operating conditions. During start-up, the UAF was initially fed by glucose till an organic loading rate (OLR) of approximately 7.5,kg COD m,3 day,1 with a hydraulic retention time of 2.3 days. A soluble COD removal efficiency of 98% was achieved before the addition of the wastewater. Initially, the filter inertia was acclimatized to the wastewater by sequential feeding of 10% (w/v), 30% (w/v) and 70% (w/v) of the pre-aerated wastewater mixed with glucose followed by a 100% (w/v) pre-aerated wastewater. During the operation, the COD removal efficiency and methane yield decreased to 75% and 0.30,m3 CH4,kg,1 CODremoved respectively. As the UAF became accustomed to the pre-aerated wastewater, raw wastewater was fed in increasing ratios of 20% (w/v), 60% (w/v) and 80% (w/v) with the pre-aerated wastewater as the remaining part. During this stage of the operation, a COD removal efficiency in a range of 77,86% was achieved and the methane yield decreased to 0.24,m3 CH4,kg,1 CODremoved. Finally, 100% (w/v) raw wastewater was fed and a COD removal efficiency of 65% was achieved with a methane yield of 0.20,m3 CH4,kg,1 CODremoved. At the end of the operation, acetoclastic methanogenic activity was only measured in the bottom section of the UAF, this showed a 90% reduction in comparison with activity of inoculation sludge. Microscopic examinations revealed that rod-shaped methanogens remained as the dominant species whereas Methanosarcina -like species and filaments were present only in insignificant numbers along the UAF. © 2002 Society of Chemical Industry [source] Pilot-scale anaerobic thermophilic digester treating municipal sludgeAICHE JOURNAL, Issue 1 2006M. A. de la Rubia Abstract The work reported concerns anaerobic thermophilic municipal sludge digestion (55°C) in a completely mixed anaerobic digester on a pilot-plant scale (850 L). The experimental protocol was defined to examine the effect of increasing the organic loading rate (OLR) on the efficiency of this digester and to report on its steady-state performance. The reactor had previously been converted from mesophilic to thermophilic conditions following the protocol previously proposed by the authors: this was achieved by a modified method that combined systems investigated in Chicago and in Vancouver. The reactor was subsequently subjected to a program of steady-state operation over a range of sludge retention times (SRTs) of 27, 20, and 15 days. The digester was fed with raw sludge [containing approximately 34.8 g/L volatile solids (VS)] three times per day. Under thermophilic conditions and with a 27-day SRT, the reactor was operated with an OLR of 1.48 kg VS m,3 day,1. The solids removal efficiency of the reactor was 42.9%, whereas the volumetric methane production rate in the digester reached 0.35 m3 m,3 day,1. Over an operating period of 150 days, an OLR of 2.63 kg VS m,3 day,1 was achieved with 41.8% VS removal efficiency in the pilot sludge digester (SRT: 15 days). During this period the volumetric methane production rate in the digester reached 0.20 m3 m,3 day,1 and 0.20 m3/kg VSr (VS reduction). The greatest efficiency in terms of substrate removal was 54.3% for an OLR of 1.71 kg VS m,3 day,1 and SRT of 20 days. Under these conditions, the generation of biogas and methane was at levels of 0.86 and 0.58 m3 m,3 day,1, respectively, with a methane yield of 0.70 m3/kg VSr. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source] Biomethane production from starch and lignocellulosic crops: a comparative reviewBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 4 2010Jean-Claude Frigon Abstract The methane produced from the anaerobic digestion of organic wastes and energy crops represents an elegant and economical means of generating renewable biofuel. Anaerobic digestion is a mature technology and is already used for the conversion of the organic fraction of municipal solid wastes and excess primary and secondary sludge from waste-water treatment plants. High methane yield up to 0.45 m3 STP CH4/kg volatile solids (VS) or 12 390 m3 STP CH4/ ha can be achieved with sugar and starch crops, although these cultures are competing with food and feed crops for high-quality land. The cultivation of lignocellulosic crops on marginal and set-aside lands is a more environmentally sound and sustainable option for renewable energy production. The methane yield obtained from these crops is lower, 0.17,0.39 m3 STP CH4/kg VS or 5400 m3 STP CH4/ha, as its conversion into methane is facing the same initial barrier as for the production of ethanol, for example, hydrolysis of the crops. Intensive research and development on efficient pre-treatments is ongoing to optimize the net energy production, which is potentially greater than for liquid biofuels, since the whole substrate excepted lignin is convertible into methane. Copyright © 2010 Crown in the right of Canada [source] Anaerobic digestion as final step of a cellulosic ethanol biorefinery: Biogas production from fermentation effluent in a UASB reactor,pilot-scale resultsBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010H. Uellendahl Abstract In order to lower the costs for second generation bioethanol from lignocellulosic biomass anaerobic digestion of the effluent from ethanol fermentation was implemented using an upflow anaerobic sludge blanket (UASB) reactor system in a pilot-scale biorefinery plant. Both thermophilic (53°C) and mesophilic (38°C) operation of the UASB reactor was investigated. At an OLR of 3.5,kg-VS/(m3,day) a methane yield of 340,L/kg-VS was achieved for thermophilic operation (53°C) while 270,L/kg-VS was obtained under mesophilic conditions (38°C). For loading rates higher than 5,kg-VS/(m3,day) the methane yields were, however, higher under mesophilic conditions compared to thermophilic conditions. The conversion of dissolved organic matter (VSdiss) was between 68% and 91%. The effluent from the ethanol fermentation showed no signs of toxicity to the anaerobic microorganisms. However, a high content of suspended matter reduced the degradation efficiency. The retention time of the anaerobic system could be reduced from 70 to 7,h by additional removal of suspended matter by clarification. Implementation of the biogas production from the fermentation effluent accounted for about 30% higher carbon utilization in the biorefinery compared to a system with only bioethanol production. Biotechnol. Bioeng. 2010;107: 59,64. © 2010 Wiley Periodicals, Inc. 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