Anaerobic decomposition

The rate of decomposition in unmanaged landfills, as measured by gas production, reaches a peak within the first 2 years and then slowly tapers off, continuing in many cases for periods up to 25 years or more. The total volume of the gases released during anaerobic decomposition can be estimated in a number of ways. If all the organic constituents in the wastes (with the exception of plastics, rubber, and leather) are represented with a generahzed formula of the form QH O N, the total volume of gas can be estimated by using Eq. (25-27) with the assumption of completed conversion to carbon dioxide and methane. 

Potential Fire Hazard from Anaerobic Decomposition in Cooling Water System, Safety Note No. DOE/EH-0109, U.S. Dept, of Energy, Washington, D.C., Oct. 1989. 

Fig 1 Reacticm sequence for anaerobic decomposition of oiganic fatty adds consider Aa, Ba and Pa are yield coefSdents for respective decoiniosition reactiMis. 

The milk production stage is the largest source of GHG emissions over the entire life cycle of fluid milk production. CH4 is generafed primarily through enteric fermentation of dairy cows and also through the microbial, anaerobic decomposition of manure. Manure deposifed on soil or handled as a solid, an aerobic process, emits little CH4. However, manure generates CH4 when stored under the aerobic conditions of a lagoon. 

Degradation of solid waste materials in a landfill proceeds from aerobic to anaerobic decomposition very quickly, thereby generating gases that collect beneath the closure FML. Almost 98% of the gas produced is either carbon dioxide (CO2) or methane (CH4). Because C02 is heavier than air, it will move downward and be removed with the leachate. However, CH4, representing about 50% of the generated gas, is lighter than air and, therefore, will move upward and collect at the bottom of the facility s impermeable FML. If the gas is not removed, it will produce a buildup of pressure on the LML from beneath. 

Tsutsuki K, Ponnamperuma FN. Behavior of anaerobic decomposition products in submerged soils Effects of organic material amendment, soil properties, and temperature. Soil Sci. Plant Nutr. 1987 33 13-33. 

The anaerobic decomposition of organic matter by fermentation, methanogenesis (methane formation) and sulfate respiration is exemplified in Table 3.2. 

During decomposition, organic matter is broken down into smaller and smaller organic molecules until it is completely converted into carbon dioxide, water, and humus.2 The same is true for anaerobic decomposition except that one of the final decomposition products is methane. Thus, at any given time, intermediate decomposition products can be found in the soil solution. 

In settings that do not contain oxygen or alternative electron acceptors, methane production is favored. Methane production is the final step in anaerobic decomposition of organic matter. 

General formulations for anaerobic decomposition have been provided by Buswell for carbohydrates ... 

Evidently rates of decomposition are greater than expected for simple anaerobic decomposition. Figure 3.10 shows comparable rates of organic matter decomposition in soils that were kept continuously flooded or well-drained under otherwise similar, tropical conditions for 3-4years (Neue and Scharpenseel, 1987). Clearly,... 

The most striking difference between anaerobic and aerobic decomposition is in the nature of the end products. In aerobic decomposition the main prod-nets are CO2, NOs, 864 and resistant residues in anaerobic decomposition they are CO2, H2, CH4, N2, NH4+, H2S and various partially decomposed and humified residues. 

Figure 5.4 Calculated (a) electron balance (Equation 5.5), (b) production of acetate (Equation 5.6) and (c) production of H2 (Eqnation 5.7) as fnnctions of the ratio of CH4 to CO2 prodnced ( ) during anaerobic decomposition of soil organic matter. Numbers on curves are ratios of CH4 produced from H2 + CO2 to CH4 produced from acetate (V )...

Burge, W.D. Anaerobic Decomposition of DDT in soil. Acceleration by volatile components of alfalfa, J. Agrlc. Food Chem., 19(2) 375-378, 1971. 

The energy yield from glycolysis for the anaerobic decomposition of glucose to 2 mol of lactic acid may be calculated as follows ... 

Fermentation is the anaerobic decomposition of organic compounds, basically carbohydrate, into alcohols by the action of bacterial enzymes. Ethanol is the desired product of carbohydrate fermentation, but other alcohols, acids, ketones, and aldehydes can form as by-products. One common example of ethanol production from biomass is the fermentation of com. For illustration, this process will be summarized. 

Biogas or synthetic natural gas production can be accomplished by utilizing the process of anaerobic digestion to convert biomass into methane. This multistage process of anaerobic decomposition involves hydrolysis of complex organic compounds by multiple bacterial species. The bacteria are grouped into the following classes ... 

What are some of the main products of anaerobic decomposition ... 

The release of H2S from marsh sediments predominantly occurs across nonvegetated sediments and is controlled by anaerobic decomposition processes. Conversely, DMS is controlled more by the distribution of DMSP in plants and their associated physiology. 

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