Biological conversion

The purpose of this subsection is to introduce the reader to the tech-niqiies and methods used to recover materials, conversion products, and energy from solid wastes. Topics to be considered include (I) processing techniques for solid waste, (2) processing techniques for hazardous wastes, (3) materials-recoveiy systems, (4) recovery of biological conversion products, (5) therm processes, and (6) waste-to-energy systems. 

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. 

Biological conversion to protein Protein, alcohol Shredding, air separation Technology on pilot scale only... 

Barik S, Corder RE, Clausen EC, et al. 1987. Biological conversion of coal synthesis gas to methane. 

This review limits itself to the treatment of high-temperature thermochemical biomass conversion technologies. There are very good overviews of biological conversion technologies for hydrogen production, for example, Ni et al.13 and Zaborsky.29... 

Biological conversion via anaerobic digestion is currently being practiced, resulting in methane that can be processed to hydrogen by conventional steam reforming processes. 

Chemical or biological conversion of pollutants to compounds which are less polluting than the original ones, and completely non-polluting if possible. 

Membrane processes can not only produce a water quality that satisfies set standards but can simultaneously concentrate the pollutants in a small volume. This strongly promotes the possibility for recovery of pollutants such as ammonia and phosphate for reuse. Also biological conversion of dissolved organic pollutants becomes easier. 

Integrate nutrient removal in SBR is successfully achieved similarly as in continuous flow systems. It requires multiple fill and react phases during one cycle, with successive periods of aeration and anaerobic or anoxic mixing. It is claimed (Artan et al. 2001), that no biological conversion is assumed to occur during settle, draw and idle phases. The processes take... 

In laboratory tests, several fungi and cultures of actinomycetes isolated from garden soil readily degraded disulfoton (Bhaskaran et al. 1973). In flooded soil under anaerobic conditions, the reduction of disulfoton sulfoxide to disulfoton was due to biological conversion (Tomizawa 1975). 

Kaars Sijpesteijn, A., Dekhuijzen, H.M., and Vonk, J.W. Biological conversion of fungicides in plants and microorganisms, in Antifungal Compounds (New York Marcel Dekker, 1977), pp. 91-147. 

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),... 

Nickel porphyrins are of interest because of their occurrance in coal, shale, and petroleum deposits (1) and because of their key role in biological conversion of COg to methane (2--5). The enzyme methylreductase is the nickel-tetrapyrrole-containing enzyme that catalyses the final step, and possibly other steps, in the 6-electron reduction of CO2 to methane (6). The active site of the methylreductase enzyme contains a nickel-sirochlorin derivative called F 3q (6-8). Understanding the involvement of in methane... 

The biochemical reactions cited above and the preliminary steps of removing heavy sediment comprise unit operations in a larger system. The designs, methods, and materials used in such operations define the quality of the results. The dewatering and sedimentation operations are discussed in engineering texts. Our interest is in the two general types of vessels in which biological conversion takes place. 

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