For long term missions, composters may be an integral part of a life support system that provides edible food crops, extracts nutrients from plant biomass and removes contaminants from the recycling stream.
A study was initiated to develop the protocol for a land-based aquaculture solids management system that minimizes leaching of P to the surface water environment by storing and treating solids on land rather than in water in off-line settling basins. A layered mesophilic compost system was developed to provide fish farmers with an alternative to expensive solids management technology. Field plots were established with two carbon sources (wheat straw or oak sawdust) and three blocks. A six-inch layer of course wood chips was spread out to facilicate passive oxygen transfer. Arctic char manure was applied every ten days. After each application, carbon was added. At the completion of the study, samples were taken from layers that represented three stages of compost age. Analysis revealed that the layered mesophilic compost system greatly reduces the potential discharge of P to surface waters.
Presents results from a mulch production project in Pinellas County, Florida, introduced following waste composition studies indicating that municipal waste contains around 30% yard waste, consisting primarily of grass clippings, palm fronds, branches, tree trimmings, bush clippings, weeds, and plants. The authors highlight the savings available in landfill cost and capacity, and describe the integration of recycling programmes, the mulch grinding and stabilisation techniques, the development of markets, and the need for public education to achieve high levels of participation. -P.Hardiman
An analysis of materials recovery in Oregon's major urban center is discussed. The Metro region's 2001 recovery rate jumped to 48.8 percent, which includes recycling, composting and source-separated materials recovered for energy. It was found that almost half of the increase, or 1.8 percentage points was due to the Oregon Department of Environmental quality's (DEQ) effort to obtain more complete and accurate reporting from recycling businesses.
The less toxic methods of working the land through the use of cover crops, compost and integrated pest management by grape growers and wineries were discussed. The controlled microbial composting (CMC) method which is structured around feeding the soil and the microorganisms that are part of the composting process was described. This humus management system relied on forage and cover crop-based rotations, green manures, proper tillage operations, microbial inoculants and the finished compost to meet fertility and pest control needs.
A comprehensive waste diversion system is discussed. It uses a source seperation program that includes cart-based collection, centralized composting and energy generation. It was found that removal of organics from disposal sites shows a 90% reduction in leachate strength at the landfill facility which results in lower cost of treatment.
In the composting of garbage the authors found that adjusting the carbon to nitrogen ratio of the raw material was useful to make organic decomposition both rapid and thorough. The degradation of proteins in the garbage can be accelerated by the existence of easily biodegradable carbonaceous compounds when the C/N ratio is adjusted to the optimum value. By controlling the pH of composting solids to prevent pH decrease under seven, the organic degradation proceeded rapidly. In addition, nitrogen loss in association with pH control of composting materials did not seem to be a serious problem. It can be deduced that the pH control operation is effective for rapid composting of garbage.
The University of Ibadan has developed a simple design that can be easily employed by the smaller communities for managing their organic wastes. The model is consisting of three PVC digesters, which are connected in series with a slope for gravity flow of the slurry with uniform mixing. The capacity of the digesters is 226 liters and the top digester is the inlet tank and holds the slurry for seven days, which then allowed passing into the second digester. The feedstock is hydrolyzed by the microorganisms in the second digester, which is then suitable for methanogenesis phase. The digestion continues in the third digester and produces additional biogas, thus degrading any feedstock left untreated with the methanogenic organisms in the second digester. Vendors and processors are promoted to use the technology as 1 m3 of biogas derived from 13 kg of animal dung, which is equivalent to 3.47 kg of fire wood.
The City of Toronto's Dufferin Organics Processing Facility (DOPF) receives 25,000 metric tons/year of source separation organic (SSO) material from Toronto's residential Green Bin and the commercial Yellow Bag collection programs. The facility utilizes the patented BTA process that includes a wet pretreatment system and a single stage, mesophilic anaerobic digester. This paper describes the DOPF operations, material balances and composition of the SSO pulp and biogass.
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James D Metzger
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Nickolas J. Themelis
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Norman Arancon
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