Conversion of municipal solid waste (MSW) into safe land filling material

Abstract

Generation of municipal solid waste is ominously increasing due to the rapid growth of population coupled with the increasing scale of economic activity, i.e. urbanization, industrialization, and improved living standards. Urban local bodies across the world are struggling with the tenacious problems of municipal waste management, particularly in disposal of waste. This research aims to induce an effective and simple technique for treating organic wastes as part of its waste management system with a view to minimizing the negative environmental impacts resulting from land filling. For sampling, fresh municipal solid waste was collected from twenty different sites of Dhaka City and the organic part of collected solid waste was separated and treated with soil, lime, and cement at different proportions. In this manner four samples were developed and separately preserved in open containers. Later, a series of laboratory tests was conducted to study the physical characteristics, prospective chemical reactions and the risks factors of the treated samples at field condition. More than 60 specimens were tested at predetermined intervals at Environmental Microbiology Laboratory of ICDDR’B, Soil Resource Development Institute of Ministry of Agriculture, and Department of Soil, Environment & Water of the University of Dhaka. The experiment results depicted that over time moisture content rates in each samples dropped to almost one third in an average in ambient conditions. The Hydraulic Conductivity rate of four developed samples ranged from 8.44×10-3 cm/s to 13.74×10-3 cm/s for a density of 0.625 gm/cm3 to 0.716 gm/cm3. Moreover, the number of colony forming units of Total Coliforms bacteria in per gram declined dramatically and were found almost zero at the end of the research. Throughout the study all samples were found very mild alkali (average pH value 7.15), which is suitable for land filling. Treatment costs of per m3 of waste were estimated in Taka for each developed samples. After technical evaluation and analysis of prospective treatment costs, the Sample comprised 77% of organic waste, 4% of lime and 19% of gravellier soil has been evolved as an appropriate technique of converting municipal solid waste into safe land filling material. A waste management system was proposed in context of the Dhaka city for the establishment of the developed technique by the city corporations. At the same time, a layout plan was also designed to accommodate the developed technique with existing landfill process.