Managing Ginnery Trash through Composting

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Cotton ginneries in the Northern, Upper East and West regions generate a lot of trash (waste). One of the problems they face is how to dispose of the trash generated during the ginning process. Disposal methods used are considered environmentally inappropriate. Composting is considered as one possible method of disposal. The goal of the study was to study the feasibility of managing cotton gin trash through windrow composting with dewatered sewage sludge. The study took place at the Kwame Nkrumah University of Science and Technology sewage treatment site. Mixes of dewatered sewage sludge and trash in the ratios 1:1 and 1:2 and a third ratio 1:1 for trash and sandy soil as inoculum were subjected to the windrow (pile) composting method over a 120 day period. pH of the finished compost was between 6.04 and 6.74, organic matter 6.93 % for 1:1 Soil/T and 49.30 % for 1:2 S/T, nitrogen 0.24 % for 1:1 Soil/T and 1.4% for 1:2 S/T, phosphorous 0.05 % for 1:1 Soil/T to 0.17 % for 1:2 S/T, potassium 0.17 % for 1:1 S/T to 0.53 % for 1:1 Soil/T, Nitrogen 0.24 % for1:1 Soil/T to 1.4 % for 1:1S/T. C/N ratio reduced to 16.36 for Soil/T and to 18.13 for 1:2 S/T ratio. Heap volume reduction of 50 % and above was observed. The highest reduction in heap volume took place in the 1:2 S/T ratio which was 60 %. Nutrient concentrations also declined due to their use by the composting organisms for various metabolic and physiological processes. Coliforms and Salmonella concentration showed a decline. By the end of the first thirty (30) days faecal colifom concentrations were mean log10 3.31 for 1:1 S/T, log10 3.07 for 1:2 S/T whereas for 1:1 Soil/T. Salmonella was totally eliminated by the end of the first month for 1:1 Soil/T but by the end of the second month for the other ratios. Faecal Coliform and Salmonella concentrations fell below the recommended standard concentrations set by vi the United States of America Environmental Protection Agency (USEPA). This was due to the high temperatures of between 45 to 57 oC attained during the composting as pathogen destruction was based on the time-temperature relationship which was typical for the composting of organic matter. Lettuce cultivated with compost from the different ratios including the use of non-composted dewatered sewage sludge produced dry weight of between 7.23-7.80 g and 5.43 g for the control (No treatment). Non-composted dewatered sewage sludge produced the highest mean wet weight of 103.4 g per five (5) plants due to its high nutrient content. The studies revealed that the ratio 1:2 S/T was the best mix ratio. The study also showed that soil could also be used as inoculum with dewatered sewage sludge for the composting of trash. Land application of compost with it’s non-detectable concentrations of faecal coliform and Salmonella should minimize environmental risk compared with raw non-composted sewage sludge. Windrow (pile) composting could be used to achieve quick, effective and environmentally safe disposal of gin trash.
A Thesis Submitted to the Department of Environmental Science, Kwame Nkrumah University of Science and Technology, in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE (ENVIRONMENTAL SCIENCE).
Compost, Sewage sludge, Gin trash, Coliform, Nutrient, Windrow