Biological composting

Recovery of Riologieal Conversion Products Biological conversion produces that can be derived from solid wastes include compost, methane, various proteins and alcohols, and a variety of other intermediate organic compounds. The principal processes that have been used are reported in Table 25-64. Composting and anaerobic digestion, the two most highly developed processes, are considered further. The recovery of gas from landfills is discussed in the portion of this sec tion dealing with ultimate disposal. 

For best results temperature should he maintained hetween 322 and 327 K (130 and 140°F) for the first few days and hetween 327 and 333 K (130 and 140°F) for the remainder of the active composting period. If temperature goes beyond 339 K (150°F), biological activity is reduced significantly... 

Initial carbon-nitrogen ratios (by mass) hetween 35 and 50 are optimum for aerobic composting. At lower ratios ammonia is given off Biological activity is also impeded at lower ratios. At higher ratios nitrogen maybe a limiting nutrient. 

Composting is the process of aerobic thermophilic decomposition of organic wastes to a relatively stable humus. Decomposition results from the biological activity of microorganisms which exist in the waste. 

An alternative arrangement, as illustrated in Figure 25.20, replaces the packing with soil or compost in a bio-filter. One advantage of the bio-filter is that the compost usually used for such systems contains a reservoir of nutrients to sustain biological growth, and additional nutrients do not normally need to be added. However, biological activity eventually starts to decrease, and the bed will need to be replaced after typically five years. 

Composting is a biological process mediated by microbes belonging to the kingdom Protest, which includes bacteria, algae, fungi, protozoa, and virus particles (Table 12.2). Microbes can be classified into metabolic types based on the carbon and energy sources utilized by the cell. Autotrophs use carbon dioxide as a... 

The increase of the recent years in the biological waste treatment in Europe is reported by ECN (2008). The environmental and market requirements of the biologically treated waste are also reported. The selective biowaste collection the compost production is around 9 million Mg in the European Union. 

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