Dynamics Of Methane Production Research Articles

Impact of dewatering inorganic coagulants on anaerobic digestion treating food waste leachate

Anaerobic digestion of food waste leachate (FWL) provides a viable solution for waste treatment and energy production. Returning solids from digested sludge to the reactor maintains a high microbial concentration and enhances digestion efficiency. However, this requires coagulants because the digestate has low dewaterability. This study analyzed methane production and microbial communities using biochemical methane potential tests for inorganic coagulants (AlCl3, Al2(SO4)3, FeCl3, and Fe2(SO4)3) in FWL treatment. Cumulative methane production was the highest in the control and decreased in the order of Fe2(SO4)3, AlCl3, FeCl3, and Al2(SO4)3. Iron ions inhibited H2S production while aluminum ions increased it compared to the control group. Despite the absence of significant changes in microbial communities following coagulant injection, a substantial increase in damaged cells was observed. These findings highlight the intricate repercussions of coagulant introduction in anaerobic digestion, emphasizing notable alterations in methane production dynamics and the integrity of microbial cells.

Promotion of methane production by magnetite via increasing acetogenesis revealed by metagenome-assembled genomes

Metal oxides are wildly studied to enhance anaerobic digestion and the methanogenic process, which is generally interpreted by increased direct interspecies electron transfer (DIET). Yet microbial mechanisms involved are under debate. Herein, methane production dynamics were analyzed, and acceleration on biogas accumulation was presented. Complementing previous findings, Fe3O4 nanoparticles stimulated bacterial fermentation rather than methanogenesis or syntropy between electro-microorganism and methanogen. More importantly, metagenome-assembled genomes proved that Fe3O4 nanoparticles increased acetogenesis by Parabacteroides chartae, which provided abundant substrates for acetoclastic methanogenesis. Interestingly, the weakly conductive V3O7·H2O nanowires increased potential hydrogen-producing bacteria, Brevundimonas, and electro-microorganisms, Clostridium and Rhodoferax, which is convenient for conducting DIET. Collectively, conductivity may not be a critical factor in mediating DIET and distinct strategies of metal oxides on methane production propose more possibilities, such as fermentation process.

Assessing the impact made by the geological features of a coalfield on producing well’s operation

Introduction. Coalbed methane extraction increases the economic efficiency of coal mining being a main measure mitigating coal mining risks. Research aim was to assess the impact made by host rocks with different reservoir properties on coalbed methane production dynamics before and after hydraulic fracturing. Methodology. A coal seam model has been constructed using software systems; the coal seam has been represented as an integrated deposit of two minerals, coal and gas. Gas production scenarios with and without impact on the seam have been calculated as well. A model of a coal bed with a hydraulic fracture was constructed in application program package Petrel (Shlumberger). Results. The calculation results showed the development of gas migration from the coal matrix to the surrounding rock through the fracture system during gas production. The use of hydraulic fracturing has positive impact on the dynamics of gas production from coal seams. Hydraulic fracturing revealed the growth of desorbed gas migration into the host interlayers. Analysis of coal methane migration to the surrounding rock has shown that the host rock can be considered as a transportation route for coalbed methane production.

Methane Production Dynamics of Co-Digestion of Cow Manure and Food Waste Under Mesophilic Condition

Methane Production Dynamics of Co-Digestion of Cow Manure and Food Waste Under Mesophilic Condition

Enhancement of Anaerobic Methane Production by Removal of Organic-bonding Metals from Sewage Sludge

To improve anaerobic digestion biogas yield, the removal of organic-bonding metals by EDTA pretreatment was investigated to strengthen the anaerobic biogas effect. The results showed that after EDTA pretreatment (experimental group), the organic-bonding metals were reduced from (5.09±0.57)% to (1.37±0.20)% (calculated with TS) and dissolved organic matter increased significantly (SCOD improved 627%), suggesting that this method could remove a large amount of organic-bonding metals and enhance the dissolution of organic sludge. According to the results for the apparent activation energy (AAE) of sludge organic matter dissolution, the AAE of the experiment group was 36% lower than the control group, showing that pretreatment could effectively reduce the reaction energy barrier for organic matter dissolution. In a test of anaerobic acid production lasting 16 days, the VFAs of the experiment group were higher than the control group, with the largest upgrade of 42%. In the anaerobic methane production test (BMP) that lasted for 22 days, compared with control group, the accumulated biogas production of the experiment group increased by 48%. Through further research on the dynamics of methane production, the rate-limiting step in the experiment group was methanogenesis, while that of the control group was hydrolysis, indicating that removal of organic-bonding metals by EDTA pretreatment could effectively accelerate the hydrolysis rate.

Mathematical modelling and simulation for biogas production from organic waste

This paper introduces the modelling, simulation of anaerobic digestion process for biogas production from organic waste. Insight on the relevant model parameters is obtained by performing a sensitivity analysis, followed by the estimation of the selected candidates using a sequential quadratic programming algorithm. Calibration and validation of the model are based on experimental data obtained from a pilot-scaled plant, showing that the proposed model is able to correctly predict the Methane production dynamics from few key measurements.

Dry anaerobic digestion in batch mode: Design and operation of a laboratory-scale, completely mixed reactor

A laboratory-scale (40 l) reactor was designed to investigate dry anaerobic digestion. The reactor is equipped with an intermittent paddle mixer, enabling complete mixing in the reactor. Three consecutive batch dry digestion tests of municipal solid waste were performed under mesophilic conditions and compared to operation results obtained on a pilot-scale (21 m 3) with the same feedstock. Biogas and methane production at the end of the tests were similar (around 200 m 3 CH 4STP/tVS), and 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 larger ones. Adaptation of micro-organisms to the waste and operating conditions was also pointed out along the consecutive batches.

Regulation of anaerobic methane oxidation in sediments of the Black Sea

Abstract. Anaerobic oxidation of methane (AOM) and sulfate reduction (SRR) were investigated in sediments of the western Black Sea, where upward methane transport is controlled by diffusion. To understand the regulation and dynamics of methane production and oxidation in the Black Sea, rates of methanogenesis, AOM, and SRR were determined using radiotracers in combination with pore water chemistry and stable isotopes. In the Danube Canyon and the Dnjepr palaeo-delta AOM did not consume methane effectively and upwards diffusing methane created an extended sulfate-methane transition zone (SMTZ) that spread over more than 2.5 m and was located in brackish and limnic sediment. Measurable AOM rates occurred mainly in the lower part of the SMTZ, sometimes even at depths where sulfate seemed to be unavailable. The inefficiency of methane oxidation appears to be linked to the paleoceanographic history of the sediment, since in all cores methane was completely oxidized at the transition from the formerly oxic brackish clays to marine anoxic sediments. The upward tailing of methane was less pronounced in a core from the deep sea in the area of the Dnjepr Canyon, the only station with a SMTZ close to the marine deposits. Sub-surface sulfate reduction rates were mostly extremely low, and in the SMTZ were even lower than AOM rates. Rates of bicarbonate-based methanogenesis were below detection limit in two of the cores, but δ13C values of methane indicate a biogenic origin. The most δ13C- depleted isotopic signal of methane was found in the SMTZ of the core from the deep sea, most likely as a result of carbon recycling between AOM and methanogenesis.

High-solids anaerobic digestion: comparison of three pilot scales

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.

Dynamics of Methane Production, Sulfate Reduction, and Denitrification in a Permanently Waterlogged Alder Swamp

The dynamics of sulfate reduction, methane production, and denitrification were investigated in a permanently waterlogged alder swamp. Molybdate, an inhibitor of sulfate reduction, stimulated methane production in soil slurries, thus suggesting competition for common substrates between sulfate-reducing and methane-producing bacteria. Acetate, hydrogen, and methanol were found to stimulate both sulfate reduction and methane production, while trimethylamine mainly stimulated methane production. Nitrate addition reduced both methane production and sulfate reduction, either as a consequence of competition or poisoning of the bacteria. Sulfate-reducing bacteria were only slightly limited by the availability of electron acceptors, while denitrifying bacteria were seriously limited by low nitrate concentrations. Arrhenius plots of the three processes revealed different responses to temperature changes in the slurries. Methane production was most sensitive to temperature changes, followed by denitrification and sulfate reduction. No significant differences between slope patterns were observed when comparing summer and winter measurements, indicating similar populations regarding temperature responses.