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Enhancing composting and bioconversion of organic waste.


The problem of quantity, and disposal of waste streams from a myriad of industries, is becoming increasingly acute, the world over. Some of the measures that have been adopted to solve these problems have created more serious problems. The burning of such wastes in open dumps or in poorly designed incinerators is a major source of air pollution. Open dumps and sanitary landfills pollute surface and ground waters causing public health hazards. Meanwhile, the unavailability and rising cost of land near urban areas has made dumps and landfills increasingly expensive and impractical. The production of both livestock and grain has increasingly relied on enormous chemical and energy inputs, leaving soils depleted of indigenous nutrients and organic matter, and resulting in surface and groundwater contamination. The processing of organic wastes into organic fertilizers via traditional thermophillic composting is a technique that has been used to address the issues of: environmental pollution; non- reliance on chemical fertilizers; sustainable natural soil fertility; while minimizing the development of new dumps and landfills. The major problems associated with traditional thermophillic composting are: the long duration of the process, the labor requirements of turning the material, the material sometimes need to be reduced in size to provide the required surface area, loss of nutrients during the prolonged composting process, and the heterogeneous nature of the product. The high temperatures achieved however provide adequate pathogen kill, especially for highly susceptible materials. Vermicomposting (using earthworms in treatment/ bioconversion of such wastes) is also gaining popularity. Compared to conventional microbial composting, vermicomposting produces a product that is homogenous, with desirable aesthetics, with reduced levels of contaminants and tends to hold nutrients over a longer period, without impacting the environment. However, this is a low temperature process. The integrated approaches suggested in this study borrow pertinent attributes from each of these two processes and combine them to enhance the overall process, and improve the products' qualities. A supplementary alternative approach examined in this study was the use of a system's simulation model to enhance management and operation of a typical composting system.