Application of modified ADM1 to long-term experiments for methane/hydrogen production from model organic waste

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
S. Soda ◽  
K. Wada ◽  
M. Okuda ◽  
M. Ike
Keyword(s):  
Hydrogen Production ◽  
Methane Production ◽  
Organic Waste ◽  
Degradation Pathways ◽  
Bacterial Populations ◽  
Degrading Bacteria ◽  
Production Experiment ◽  
Methane Production Rate ◽  
Simulation Results

The modified ADM1 including lactate and ethanol was verified using experimental data for methane/hydrogen production processes from model organic waste. Monosaccharides were presumably degraded into acetate, lactate, butyrate, and ethanol; lactate is further degraded into propionate and acetate; ethanol is degraded into acetate. The methane production experiment was carried out using an 8-L reactor operated at 55°C, pH 6.8, and sludge retention time (SRT) of 7–20 days for 370 days. Concentrations of carbohydrates, monosaccharides, butyrate, propionate, valerate, acetate, and the methane production rate were simulated well by the modified ADM1. The ratio of degradation pathways from monosaccharides to acetate, lactate, butyrate, and ethanol were inferred, respectively, to be 0.4, 0.6, 0.0, and 0.0. The hydrogen production experiment was carried out using a 2-L (1.5L) reactor operated at 35°C, pH 6.0-6.5, and SRT of 0.5–2.0 days for 370 days. The simulation results suggested that all bacterial populations except the sugar-degrading bacteria were washed out from the reactor because of the short SRT. The respective ratios of degradation pathways from monosaccharides to acetate, lactate, propionate, and ethanol were inferred to be 0.55, 0.0, 0.4, and 0.05 at pH 6.5 and 0.7, 0.2, 0.05 and 0.05 at pH 6.0.

Microbial Ecology Studies of the Metula Spill in the Straits of Magellan

1978 ◽  
Vol 35 (5) ◽  
pp. 573-580 ◽  
Author(s):  
R. R. Colwell ◽  
A. L. Mills ◽  
J. D. Walker ◽  
P. Garcia-Tello ◽  
V. Campos-P.
Keyword(s):  
Oil Spills ◽  
Bacterial Populations ◽  
In Situ Conditions ◽  
Degrading Bacteria ◽  
Cold Tolerant ◽  
Term Basis ◽  
Spilled Oil ◽  
Straits Of Magellan

The grounding of the tanker V.L.C.C. Metula in the Straits of Magellan in August 1974 provided a unique opportunity to study a massive spill in a cold region on a long-term basis. Removal of spilled oil from the Metula was solely by in situ physiochemical and biological mechanisms. Microbiological studies undertaken in May 1976 showed increased heterotrophic bacterial populations at oil-impacted sites. A cold-tolerant population of petroleum degrading bacteria was observed. From biodegradation studies, we concluded that oil degradation under in situ conditions proceeds relatively slowly, with marked persistence of Metula oil in the Straits of Magellan 2 yr after the original spill. Key words: petroleum degradation, oil spills, Straits of Magellan, microbial degradation of oil, Metula

scholarly journals Διεργασίες ενεργειακής αξιοποίησης γλυκερόλης με παραγωγή βιοαερίου, βιοϋδρογόνου ή/και ηλεκτρικού ρεύματος με μικροβιακή κυψελίδα καυσίμου

2011 ◽  
Author(s):  
Θεόφιλος Βλάσσης
Keyword(s):  
Anaerobic Digestion ◽  
Hydrogen Production ◽  
Electric Current ◽  
Production Rate ◽  
Methane Production ◽  
Continuous Production ◽  
Maximum Yield ◽  
Glycerol Concentration ◽  
Production Of Hydrogen ◽  
Methane Production Rate

This study focused on the valorization of glycerol which is an important by-product of the biodiesel industry corresponding to 10 % of the produced biodiesel amount. This fact contributed to the increase of the global production of biodiesel, to a point at which the industries which traditionally consumed glycerol could not absorb. This situation should be overcome through new outlets on glycerol exploitation. Usually, glycerol is treated by chemical processes in order to form new chemical compounds.On the other side, biochemical processes like anaerobic digestion and fermentation or the technology of microbial fuel cells could potentially transform glycerol into methane, hydrogen and electric current respectively. These processes, which are the subject of this Ph.D, are preferable to their chemical counterparts due to the low energy demand and reduced environmental pollution.The anaerobic digestion process was conducted in a conventional CSTR reactor and in a high rate reactor, the PABR. The experiments dealt with the effect of glycerol concentration on the methane production rate. The obtained results showed that the CSTR could not withstand organic loadings above 0.25 g COD/L/d, however PABR operated at organic loading 10 times higher than CSTR such as 3 g COD/L/d and resulted to a methane production rate of 0.982 ± 0.089 L/L/d. A model was developed for both the CSTR and the PABR digesters. Fermentative hydrogen production was conducted successfully in batch reactors. The effect of the initial glycerol concentration and initial pH on hydrogen production was studied. A maximum yield, 27.3 mL H2/ g COD glycerol, was obtained when glycerol concentration was 8.3 g COD/L and the pH 6.5. Moreover, the fermentation of glycerol took place in a CSTR in order to investigate the continuous production of hydrogen. Hydrogen production was unstable, possibly due to the washout of proper biomass from the reactor.For electricity generation from glycerol, an H-type microbial fuel cell was used in batch mode. The effect of the initial glycerol on the electric current was studied. A maximum Coulombic efficiency (CE) 34.09% was obtained at a glycerol concentration of 3.2 g COD/L. A further increase of glycerol drove to a drop of the CE. Probably, this happened since the electrochemical microorganisms were inhibited by the high glycerol concentration.

Repeatability of methane emission measurements in Australian beef cattle

2016 ◽  
Vol 56 (3) ◽  
pp. 213 ◽  
Author(s):  
K. A. Donoghue ◽  
T. Bird-Gardiner ◽  
P. F. Arthur ◽  
R. M. Herd ◽  
R. S. Hegarty
Keyword(s):  
Methane Production ◽  
Life Time ◽  
Time Frame ◽  
Phenotypic Correlations ◽  
Methane Production Rate ◽  
Short And Long Term ◽  
Time Periods ◽  
Time Frames ◽  
Methane Measurement

Records on 175 young Angus heifer and bull progeny from 46 sires, measured for methane production in respiration chambers, were used to evaluate the repeatability of methane measurement over short- and long-term periods. The traits assessed were dry matter intake (DMI), methane production rate (MPR), methane yield (MPR per unit DMI), and four residual methane (RMP) traits. The RMP traits were computed as actual MPR minus expected MPR, where the expected MPR for the first three RMP traits were calculated from three different published and widely used equations. The expected MPR for the fourth was computed by regressing MPR on DMI, using the data from the study. Animals underwent an initial (first) methane measurement test for 48 h, and one repeat methane measurement test up to 450 days after the first test. Repeat tests were classified into four different time periods: tested across consecutive days; re-tested within 60 days of first test; re-tested 61–120 days after first test; and re-tested 121–450 days after first test. Repeatabilities were calculated for all traits across all time periods, and phenotypic correlations for the same trait measured over time were obtained from bivariate analyses. Methane traits from tests conducted over consecutive days were highly repeatable (0.75–0.94) and highly phenotypically correlated (0.85–0.95). Repeatabilities from tests conducted within 60 days of the first test were moderate to high (0.59–0.91), whereas phenotypic correlations were, in general, moderate (0.30–0.44), with the exception of MPR (0.78). Results for both longer-term time periods (61–120 days and 121–450 days after the first test) were very similar, with low estimates of repeatabilities (0.16–0.27) and phenotypic correlations (0.12–0.27). Correlations between sire progeny means from the first and repeat methane test were moderate (0.46–0.77) for all traits except RMPR (0.19). Results from this study indicate that methane traits from tests conducted either on consecutive days or within a short-term time frame afterward (~60 days) are highly repeatable and highly phenotypically correlated. However, methane tests conducted over longer-term time frames are substantially, but consistently, less repeatable and are lowly phenotypically correlated, which indicates that multiple measures may be required to accurately record methane traits over the life time of an animal.

scholarly journals Coproduction of hydrogen and methane in a CSTR-IC two-stage anaerobic digestion system from molasses wastewater

2019 ◽  
Vol 79 (2) ◽  
pp. 270-277 ◽  
Author(s):  
Qiaoyan Li ◽  
Yongfeng Li
Keyword(s):  
Hydrogen Production ◽  
Production Rate ◽  
Methane Production ◽  
Oxygen Demand ◽  
Organic Loading Rate ◽  
Continuous Stirred Tank Reactor ◽  
Two Stage ◽  
Molasses Wastewater ◽  
Methane Production Rate ◽  
Stage Process

Abstract A continuous hydrogen and methane production system in a two-stage process has been investigated to increase energy recovery rate from molasses wastewater in this study. This system consisted of a continuous stirred-tank reactor for hydrogen production and an internal circulation (IC) reactor for methane production, and was studied under the influent organic loading rate (OLR) of 18, 24, 30 and 36kg COD/(m3·d) (COD: chemical oxygen demand). The maximum volumetric hydrogen production rate of 2.41 L/(L·d) was obtained at the OLR of 30kg COD/(m3·d) with a hydrogen content of 42%, and the maximum volumetric methane production rate of 2.4 L/(L·d) with a methane content of 74.45% was obtained at the OLR of 36kg COD/(m3·d) using the effluents of hydrogen fermentation as substrate. The maximum of 71.06% of the molasses wastewater energy was converted to biogas (hydrogen and methane) at the OLR of 30kg COD/(m3·d).

Continuous hydrogen production from organic waste

2005 ◽  
Vol 52 (1-2) ◽  
pp. 145-151 ◽  
Author(s):  
T. Noike ◽  
I.B. Ko ◽  
S. Yokoyama ◽  
Y. Kohno ◽  
Y.Y. Li
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Hydrogen Production ◽  
Metabolic Pathway ◽  
Substrate Concentration ◽  
Acid Production ◽  
Organic Waste ◽  
Batch Experiments ◽  
Production Experiment ◽  
Propionic Acid Production

The antibiotic effects of lactic acid bacteria, Lactobacillus paracasei, on hydrogen production were investigated using glucose as the substrate for the batch experiments. The effects of lactic acid bacteria on hydrogen fermentation depended on pH and the inhibition of hydrogen-producing bacteria was prevented by keeping the pH over 5.0. Then, a continuous hydrogen production experiment was conducted by using bean curd manufacturing waste as an actual organic waste at pH 5.5 at 35 °C. The increase of the substrate concentration and the addition of nitrogen gave precedence to acetic and butyric acids production in the metabolic pathway and suppressed propionic acid production. As the result, continuous hydrogen production from municipal organic waste was enabled.

scholarly journals UV Stimulated Manganese Dioxide for the Persulfate Catalytic Degradation of Bisphenol A

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 502
Author(s):  
Guihua Dong ◽  
Bing Chen ◽  
Bo Liu ◽  
Stanislav R. Stoyanov ◽  
Yiqi Cao ◽  
...  
Keyword(s):  
Bisphenol A ◽  
Reaction Mechanisms ◽  
Reduction Rate ◽  
Catalytic Degradation ◽  
Gas Chromatography Mass Spectrometry ◽  
Degradation Pathways ◽  
Industrial Chemicals ◽  
Oh Groups ◽  
Long Term Adverse Effects

One of the most commonly produced industrial chemicals worldwide, bisphenol A (BPA), is used as a precursor in plastics, resins, paints, and many other materials. It has been proved that BPA can cause long-term adverse effects on ecosystems and human health due to its toxicity as an endocrine disruptor. In this study, we developed an integrated MnO2/UV/persulfate (PS) process for use in BPA photocatalytic degradation from water and examined the reaction mechanisms, degradation pathways, and toxicity reduction. Comparative tests using MnO2, PS, UV, UV/MnO2, MnO2/PS, and UV/PS processes were conducted under the same conditions to investigate the mechanism of BPA catalytic degradation by the proposed MnO2/UV/PS process. The best performance was observed in the MnO2/UV/PS process in which BPA was completely removed in 30 min with a reduction rate of over 90% for total organic carbon after 2 h. This process also showed a stable removal efficiency with a large variation of pH levels (3.6 to 10.0). Kinetic analysis suggested that 1O2 and SO4•− played more critical roles than •OH for BPA degradation. Infrared spectra showed that UV irradiation could stimulate the generation of –OH groups on the MnO2 photocatalyst surface, facilitating the PS catalytic degradation of BPA in this process. The degradation pathways were further proposed in five steps, and thirteen intermediates were identified by gas chromatography-mass spectrometry. The acute toxicity was analyzed during the treatment, showing a slight increase (by 3.3%) in the first 30 min and then a decrease by four-fold over 2 h. These findings help elucidate the mechanism and pathways of BPA degradation and provide an effective PS catalytic strategy.

scholarly journals Biochar promotes methane production during anaerobic digestion of organic waste

2021 ◽  
Author(s):  
Leilei Xiao ◽  
Eric Lichtfouse ◽  
P. Senthil Kumar ◽  
Quan Wang ◽  
Fanghua Liu
Keyword(s):  
Anaerobic Digestion ◽  
Methane Production ◽  
Organic Waste

scholarly journals Effects of Methanogenic Inhibitors on Methane Production and Abundances of Methanogens and Cellulolytic Bacteria inIn VitroRuminal Cultures

2011 ◽  
Vol 77 (8) ◽  
pp. 2634-2639 ◽  
Author(s):  
Zhenming Zhou ◽  
Qingxiang Meng ◽  
Zhongtang Yu
Keyword(s):  
Methane Production ◽  
Volatile Fatty Acids ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Cellulolytic Bacteria ◽  
Bacterial Populations ◽  
Content Type ◽  
Specific Pcr ◽  
Methanogen Population ◽  
Propynoic Acid

ABSTRACTThe objective of this study was to systematically evaluate and compare the effects of select antimethanogen compounds on methane production, feed digestion and fermentation, and populations of ruminal bacteria and methanogens usingin vitrocultures. Seven compounds, including 2-bromoethanesulphonate (BES), propynoic acid (PA), nitroethane (NE), ethyltrans-2-butenoate (ETB), 2-nitroethanol (2NEOH), sodium nitrate (SN), and ethyl-2-butynote (EB), were tested at a final concentration of 12 mM. Ground alfalfa hay was included as the only substrate to simulate daily forage intake. Compared to no-inhibitor controls, PA, 2NEOH, and SN greatly reduced the production of methane (70 to 99%), volatile fatty acids (VFAs; 46 to 66%), acetate (30 to 60%), and propionate (79 to 82%), with 2NEOH reducing the most. EB reduced methane production by 23% without a significant effect on total VFAs, acetate, or propionate. BES significantly reduced the propionate concentration but not the production of methane, total VFAs, or acetate. ETB or NE had no significant effect on any of the above-mentioned measurements. Specific quantitative-PCR (qPCR) assays showed that none of the inhibitors significantly affected total bacterial populations but that they did reduce theFibrobacter succinogenespopulation. SN reduced theRuminococcus albuspopulation, while PA and 2NEOH increased the populations of bothR. albusandRuminococcus flavefaciens. Archaeon-specific PCR-denaturing gradient gel electrophoresis (DGGE) showed that all the inhibitors affected the methanogen population structure, while archaeon-specific qPCR revealed a significant decrease in methanogen population in all treatments. These results showed that EB, ETB, NE, and BES can effectively reduce the total population of methanogens but that they reduce methane production to a lesser extent. The results may guide futureinvivostudies to develop effective mitigation of methane emission from ruminants.

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