Kinetics of biomethanation of solid tannery waste and the concept of interactive metabolic control.
01 Apr 1994-Applied Biochemistry and Biotechnology (Appl Biochem Biotechnol)-Vol. 47, Iss: 1, pp 73-87
TL;DR: The concept of interactive metabolic control earlier proposed has been validated based on the levels of various metabolites detected and the overall decrease in volatile solid level was 65%, whereas the collagen level declined by 85%.
Abstract: Anaerobic digestion of calf skin collagenous waste was optimized for a batch process based on accelerated maximal methane yield per gram of input volatile solid. A kinetic analysis with respect to changes in the levels of volatile solid, collagen, amino sugars, amino acids, hydroxyproline, ammonium ions, and volatile fatty acid were followed for a period of 80 d. Distinct metabolic phases included an initial high rate collagenolysis for 4d, with 50% degradation and was followed by an acidogenic phase between 4-12 d with volatile fatty acids levels increasing to 215 mmol/L. Subsequently methanogenesis ensued and was maximal between 12-24 d when volatile fatty acids attained steady state levels. During the period of 80 d, the overall decrease in volatile solid level was 65%, whereas the collagen level declined by 85% with 0.45 L of methane yield/g of volatile solid degraded. Based on the levels of various metabolites detected, the concept of interactive metabolic control earlier proposed has been validated.
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01 Jan 1988
TL;DR: In this paper, the dynamics of a bicarbonate-formate electron shuttle mechanism for control of carbon and more electron flow during syntrophic methanogenesis was described and provided a novel mechanism for energy conservation by syntrophic acetogens.
Abstract: Microbial formate production and consumption during syntrophic conversion of ethanol or lactate to methane was examined in purified flocs and digestor contents obtained from a whey-processing digestor. Formate production by digestor contents or purified digestor flocs was dependent on CO/sub 2/ and either ethanol or lactate but not H/sub 2/ gas as an electron donor. Floc preparations accumulated fourfold-higher levels of formate (40 ..mu..M) than digestor contents, and the free flora was the primary site for formate cleavage to CO/sub 2/ and H/sub 2/ (90 ..mu..M formate per h). Inhibition of methanogenesis by CHCl/sub 3/ resulted in formate accumulation and suppression of syntrophic ethanol oxidation. H/sub 2/ gas was an insignificant intermediary metabolite of syntrophic ethanol conversion by flocs, and it exogenous addition neither stimulated methanogenes nor inhibited the initial rate of ethanol oxidation. These results demonstrated that >90% of the syntrophic ethanol conversion to methane by mixed cultures containing primarily Desulfovibrio vulgaris and Methanobacterium formicicum was mediated via interspecies formate transfer and the <10% was mediated via interspecies H/sub 2/ transfer. The results are discussed in relation to biochemical thermodynamics. A model is presented which describes the dynamics of a bicarbonate-formate electron shuttle mechanism for control of carbon andmore » electron flow during syntrophic methanogenesis and provides a novel mechanism for energy conservation by syntrophic acetogens.« less
275 citations
TL;DR: The start-up procedure of a tannery waste thermophilic anaerobic digestion in 100 days using seed from mesophilic digester processing municipal sludge is presented and Chromium content and salinity showed no adverse effects, however a reactor temperature reduction led to a drop in biogas production of 25%, indicating a requirement to keep the temperature constant at 55 degrees C.
96 citations
TL;DR: In this article, the co-digestion of cow dung with rice husk for biogas production at laboratory scale was investigated, and the results showed that the codigestions achieved a cumulative production of 161.5 ml at the end of the 38th day of the experiment after which there was no further production.
Abstract: The co-digestion of cow dung with rice husk for biogas production at laboratory scale was the subject of this investigation. The study was carried out at room temperature that is, 26 - 29°C for a period of 52 days with a total solid concentration of 8% in each sample (fermentation slurry). The biogas produced was collected by water displacement method which was subsequently measured. Sample A (50 wt % cow dung, 50 wt % rice husk) showed a cumulative biogas production of 161.5 ml at the end of the 38th day of the experiment after which there was no further production. The production from sample B (25 wt % cow dung, 75 wt % rice husk) was not significant, while there was no production from sample C(0 wt % cow dung, 100 wt % rice husk).
Key words: Biogas, cow dung, rice husk, co-digestion.
93 citations
Cites background from "Kinetics of biomethanation of solid..."
...This inactivity is probably due to the methanogens undergoing a methamorphic growth process by consuming methane precursors produced from the initial activity as suggested by Lalitha et al. (1994), Bal and Dhaghat (2001)....
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...days, respectively is followed by 31 days of inactivity before a sudden burst of production of 78 ml. This inactivity is probably due to the methanogens undergoing a methamorphic growth process by consuming methane precursors produced from the initial activity as suggested by Lalitha et al. (1994) , Bal and Dhaghat (2001)....
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TL;DR: The results indicated a considerable gain in biogas production, if the leather substrate is treated or mixed with readily degradable materials prior to its use as substrate for anaerobic digestion (destabilizing the chrome–collagen complexes, increasing of the water dispersion and lowering the stability of chrome– Collagen complexes).
69 citations
TL;DR: In this paper, a co-digestion of morning glory (MG, Ipomoea aquatica) with water hyacinth (WH, Eichhornia crassipes) with cow dung slurry was added to each treatment as inoculum to seed the digesters.
27 citations
References
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TL;DR: In this article, the enzyme activity of all enzyme preparations was determined by measurement of leucyldiglycine hydrolysis, and the peptidase unit employed, which was identical with the unit used in previous papers, may be defined as the amount of enzyme which will bring about 50 per cent hydrolyisation of I-peptide in 30 minutes.
544 citations
TL;DR: Fermentation of cellobiose was more rapid than that of cellulose, and agents of fermentation stoppage were found to be low pH and high concentrations of ethanol in the monoculture and low pH in the coculture.
Abstract: The fermentation of cellulose and cellobiose by Clostridium thermocellum monocultures and C. thermocellum/Methanobacterium thermoautotrophicum cocultures was studied. All cultures were grown under anaerobic conditions in batch culture at 60 degrees C. When grown on cellulose, the coculture exhibited a shorter lag before initiation and growth and celluloysis than did the monoculture. Cellulase activity appeared earlier in the coculture than in the monoculture; however, after growth had ceased, cellulase activity was greater in the monoculture. Monocultures produced primarily ethanol, acetic acid, H2 and CO2. Cocultures produced more H2 and acetic acid and less ethanol than did the monoculture. In the coculture, conversion of H2 to methane was usually complete, and most of the methane produced was derived from CO2 reduction rather than from acetate conversion. Agents of fermentation stoppage were found to be low pH and high concentrations of ethanol in the monoculture and low pH in the coculture. Fermentation of cellobiose was more rapid than that of cellulose. In cellobiose medium, the methanogen caused only slight changes in the fermentation balance of the Clostridium, and free H2 was produced.
352 citations
01 Jan 1988
TL;DR: In this paper, the dynamics of a bicarbonate-formate electron shuttle mechanism for control of carbon and more electron flow during syntrophic methanogenesis was described and provided a novel mechanism for energy conservation by syntrophic acetogens.
Abstract: Microbial formate production and consumption during syntrophic conversion of ethanol or lactate to methane was examined in purified flocs and digestor contents obtained from a whey-processing digestor. Formate production by digestor contents or purified digestor flocs was dependent on CO/sub 2/ and either ethanol or lactate but not H/sub 2/ gas as an electron donor. Floc preparations accumulated fourfold-higher levels of formate (40 ..mu..M) than digestor contents, and the free flora was the primary site for formate cleavage to CO/sub 2/ and H/sub 2/ (90 ..mu..M formate per h). Inhibition of methanogenesis by CHCl/sub 3/ resulted in formate accumulation and suppression of syntrophic ethanol oxidation. H/sub 2/ gas was an insignificant intermediary metabolite of syntrophic ethanol conversion by flocs, and it exogenous addition neither stimulated methanogenes nor inhibited the initial rate of ethanol oxidation. These results demonstrated that >90% of the syntrophic ethanol conversion to methane by mixed cultures containing primarily Desulfovibrio vulgaris and Methanobacterium formicicum was mediated via interspecies formate transfer and the <10% was mediated via interspecies H/sub 2/ transfer. The results are discussed in relation to biochemical thermodynamics. A model is presented which describes the dynamics of a bicarbonate-formate electron shuttle mechanism for control of carbon andmore » electron flow during syntrophic methanogenesis and provides a novel mechanism for energy conservation by syntrophic acetogens.« less
275 citations
TL;DR: A model is presented which describes the dynamics of a bicarbonate-formate electron shuttle mechanism for control of carbon and electron flow during syntrophic methanogenesis and provides a novel mechanism for energy conservation by syntrophic acetogens.
Abstract: Microbial formate production and consumption during syntrophic conversion of ethanol or lactate to methane was examined in purified flocs and digestor contents obtained from a whey-processing digestor. Formate production by digestor contents or purified digestor flocs was dependent on CO(2) and either ethanol or lactate but not H(2) gas as an electron donor. During syntrophic methanogenesis, flocs were the primary site for formate production via ethanol-dependent CO(2) reduction, with a formate production rate and methanogenic turnover constant of 660 muM/h and 0.044/min, respectively. Floc preparations accumulated fourfold-higher levels of formate (40 muM) than digestor contents, and the free flora was the primary site for formate cleavage to CO(2) and H(2) (90 muM formate per h). Inhibition of methanogenesis by CHCl(3) resulted in formate accumulation and suppression of syntrophic ethanol oxidation. H(2) gas was an insignificant intermediary metabolite of syntrophic ethanol conversion by flocs, and its exogenous addition neither stimulated methanogenesis nor inhibited the initial rate of ethanol oxidation. These results demonstrated that >90% of the syntrophic ethanol conversion to methane by mixed cultures containing primarily Desulfovibrio vulgaris and Methanobacterium formicicum was mediated via interspecies formate transfer and that <10% was mediated via interspecies H(2) transfer. The results are discussed in relation to biochemical thermodynamics. A model is presented which describes the dynamics of a bicarbonate-formate electron shuttle mechanism for control of carbon and electron flow during syntrophic methanogenesis and provides a novel mechanism for energy conservation by syntrophic acetogens.
270 citations
TL;DR: This study confirms previous reports that the effluent quality of biological treatment systems for organic wastes depends on influent organic waste concentration and shows that the kinetic parameters vary with temperature, while the refractory coefficient remains fairly constant.
Abstract: The applicability of Contois' kinetic equation to aerobic and anaerobic treatments of organic wastes is investigated. A refractory coefficient to account for the nonbiodegradable portion of the organic substrates in the digester is incorporated into the kinetic equation. The kinetic equation is applied to the data for aerobic digestions of organic substrates and for anaerobic treatment of dairy wastes. They all show a very good fit of the kinetic equation to the data. Furthermore, the kinetic parameters and the refractory coefficients are shown to be independent of influent organic substrate concentration. This study confirms previous reports that the effluent quality of biological treatment systems for organic wastes depends on influent organic waste concentration. The effect of temperature on the kinetic parameters and the refractory coefficient for anaerobic treatment of sewage sludge are studied. It shows that the kinetic parameters vary with temperature, while the refractory coefficient remains fairly constant. Equations to predict biodegradable treatment efficiency and volumetric substrate utilization rate are also briefly discussed.
188 citations