Anaerobic digestion process types

The performance of anaerobic digestion processes varies according to the type of unit, throughput, and feed concentration, but such processes are typically capable of removing between 75 and 85 percent of COD. ... 

The formation of hydrogen is accompanied with VFAs or solvent production during an anaerobic digestion process. Therefore, the distribution of VFA concentrations and their finctions is a usefiil indicator for monitoring hydrogen production. Fig. 3 shows the variations in alcohol and VFAs. Most of the VFAs were analyzed as acetate and butyrate, and most of the alcohols were analyzed as ethanol. The propionate concentration was below the analytical limit. It indicates that the anaerobic pathway in the reactor is not propionic-type fermentation but but5nrate-type fermentation. Clostridium butyricum is considered to be the dominant... 

Complete Mix Digester - A type of anaerobic digester that has a mechanical mixing system and where temperature and volume are controlled to maximize the anaerobic digestion process for biological waste treatment, methane production, and odor control. 

Another vital parameter in effective digestion is the availability of trace elements, or micronutrients, notably iron, cobalt, nickel and zinc, in the feedstock. These elements, when available in relatively small amonnts, can stimnlate methanogenic activities. The exact amount needed can vary for different types of wastewater, and prior trials are needed before they are added. More information on the importance of micronutrients on the anaerobic digestion process can be found in the literature (Banks, Zhang, Jiang, Haven, 2012 Demirel Scherer, 2011 Facchin et al., 2013). 

Hartmann, H., Angelidaki, L, Ahring, B. K. (2003). Co-digestion of the organic fraction of municipal waste with other waste types. Fundamentals of the anaerobic digestion process. In J. Mata-Alvarez (Ed.), Biomethanization of organic fraction of municipal solid waste (pp. 181-197). Cornwall IWA Pubhshing. 

Anaerobic digestion, like pyrolysis, occurs in the absence of air. But, the decomposition is caused by bacterial action rather than high temperatures. This process takes place in most biological materials, but it is accelerated by warm, wet and airless conditions. It occurs naturally in decaying vegetation in ponds, producing the type of marsh gas that can catch fire. 

Biomass can also be used to create biopower through a process called anaerobic digestion. Basically a digester is a tank in which decomposing biomass produces a gas (not gasoline, but a vapor) (Figure 20-2). With a special type of engine, this gas can produce renewable electricity. 

Type and efficiency of sludge stabilisation process (e.g. anaerobic digestion). Sludge age. 

Several bioreactor designs are used to produce bioproducts, and include, but are not limited to batch reactors, fed-batch reactors, continuous cultivation reactors, plug flow reactors, recycle bioreactor systems, immobilized cell reactors, biofilm reactors, packed bed reactors, fluidized-bed reactors, and dialysis cultivation reactors (Williams 2002). These reactor types can contain either mixed or pure cultures, and can stimulate heterotrophic and/or phototrophic cellular functions depending on the specific reactor design. Additionally, these reactor schemes can be used to produce products directly, or to harvest biomass or other products for downstream processes. Due to the complex nature of bioreactors, particularly anaerobic digesters, the use of metagenomics is helpful to understand the physiology of such systems. 

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