Hydrolysis anaerobic digestion

Liquid ion exchange Flotation Hydrolysis Anaerobic digestion... 

Fig. 4. Microbial phases in anaerobic digestion A, hydrolysis B, acidification C, methane fermentation.

R. L. Wentworth, "Anaerobic Digestion in North America," paper presented at Symposium Anaerobic Digestion and Carbohydrate Hydrolysis of Waste, sponsored by Commission of the European Communities, Luxembourg, May 8—10,1984. 

Pretreatments of the polymeric feedstocks to enhance the hydrolysis of the major components such as cellulose include size reduction, thermal-chemical treatments, and specific enzyme pretreatments (52,57). Although many of the pretreatment processes increase the rate and extent of potymer hydrolysis, the cost for treatment is prohibitive based upon the revenues generated for energy production alone in anaerobic digestion (32). 

Most often, the rates for feedstock destruction in anaerobic digestion systems are based upon biogas production or reduction of total solids (TS) or volatile solids (VS) added to the system. Available data for analyses conducted on the specific polymers in the anaerobic digester feed are summarized in Table II. The information indicates a rapid rate of hydrolysis for hemicellulose and lipids. The rates and extent of cellulose degradation vary dramatically and are different with respect to the MSW feedstock based on the source and processing of the paper and cardboard products (42). Rates for protein hydrolysis are particularly difficult to accurately determine due the biotransformation of feed protein into microbial biomass, which is representative of protein in the effluent of the anaerobic digestion system. 

The anaerobic biological conversion of the major polymeric components of MSW identified require appropriate microorganisms and hydrolytic enzyme systems. Extracellular hydrolytic enzymes, such as cellulases and lipases, have been shown to be effective in the post hydrolysis of anaerobic digester efQuent solids 34) or pretreatment of complex organic polymers before the digestion process 48),... 

Table II. Average Rates of Hydrolysis of Feedstock Polymers in Mesophilic Laboratory Anaerobic Digestion Systems (43)...

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 ... 

The microbial transformations and stages in anaerobic digestion are supported by experimental data accumulated over many years. The overall schematic of the process shown in Fig. 12.3 is perhaps the simplest chemical representation of the hydrolysis, acid-formation, and methane-formation stages. As discussed in Section IV, this information led to the development of... 

Typical anaerobic digestion facilities can contain hydrolysis units, digesters, gas cleanup and dehydration units, and liquid effluent treatment units, as illustrated in Fig. 12.7. Many improvements have been incorporated into the ancillary unit operations as well as the methane fermentation process itself. 

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