Study on Acceptable Composting Technology in Bangladesh

Abstract

Composting has several benefits including list conversion of the organic solid wastes to a biologically stable end product as compared to bio-chemical reactions occurring in landfills and recovery of waste material in the form of compost for utilization in agriculture, horticulture or other applications, as a soil conditioner, polling soil, organic fertilizer, landscaping material etc. Historically the composting is applied in the di different civilization including Europe, China and Bangladesh. Despite the huge potential to convert a significant portion of Municipal Solid Waste (MSW) of Bangladesh into compost due to its inherent Physical characteristics, the expected success is not seen, moreover, it suffers several setbacks. With the view to overcome existing setbacks, the technology (known elsewhere) suitable for l3angladesh should he evolved. To search in acceptable composting technology for the country, a Demo Compost Plant was built as a part of WasteSafe II research project in cooperation with a NGO named as Samadan, at Khalishpur. Khulna. This study mainly conducted in this plant through necessary field works to develop an acceptable composting technology for Bangladesh. In this study four types of processes - three are passively aerated and the rest one is forced aerated, used as the aeration system was constructed successfully and hence evaluated practically through constructing series of compost piles, in the first passively aerated compost pile, horizontal bamboo frame was used. In the Second one, perforated vertical PVC pipe was used instead of, bamboo frame. The Third compost pile is forced aerated, in which locally fabricated blower was used. While the fourth one is passively aerated as practiced in the Samadan Compost Plant. MSW was collected from the adjacent areas or the plant giving special initiative to minimize the existence of non-biodegradable wastes. As the solid waste comes directly from the kitchen. percentage of rapidly degradable waste is greater than others and toxic substance and metal type waste are less in the used waste for demo compost plant. Twelve compost piles at three set-up were studied. Physical properties or input MSW such as composition. hulk density, moisture content and particle size distribution were evaluated for all compost piles. Temperature was taken from nine different positions of individual compost piles of two set-up and twenty seven different position of last set-up. Twelve self heating tests were performed in this study. Most of' all stability index (SI) is found as IV. Density change during the composting process was measured also for all compost piles of first two set-ups. It is found that density has changed up to about 77% at loose state and about 50% at dense state. It is seen that the production or compost is varied from 25 to 39% of total input waste. The Physical parameters like volatile solids, moisture content, dry matter, p11. salinity. nutrients like total nitrogen. nitrate nitrogen. ammonia nitrogen potassium, magnesium. phosphorus and heavy metal contamination of the compost were measured taking the help from 13auhaus University Weimar. Germany. The values of' the relevant parameters of compost in most or the cases are found in the standard range. To overcome the disadvantage of practiced screening system. a newly designed and locally fabricated rotary screening system is developed and hence the performance was evaluated. The new system depicted better performance than the existing one in all aspects. From physical inspection and experimental findings, it is revealed that the passively aerated (horizontal aeration system) composting technique is suitable for Bangladesh. However, some easily affordable and sustainable mechanical device' should be incorporated to increase the efficiency and to reduce the health hazards of the compost plant.