Solid waste separation at source: a case study of the Kumasi Metropolitan Area

Solid waste management is a very pertinent issue facing municipal and local authorities all over Ghana. Waste separation at source is often recommended for the collection of clean recyclables to support recycling as part of integrated waste management systems. Limited information exists on the quantities of various waste materials available for recycling and household’s potentials for separating waste at source to aid recycling in most developing countries like Ghana. The use of system analysis tools to support waste management decision in developing countries have been found to be low. The objective of this research work is to analyze the potential of implementing source separation (SS) of household solid waste in Kumasi and to discuss the implications of SS potential on the choice of waste treatment options. The study was conducted through a pilot SS of household solid waste in households of staff of KNUST and selected households in the Asokwa Sub-Metropolitan area in Kumasi. Household were asked to separate waste into three fractions; organic, plastics and others. The SS efficiency and level of compliance were evaluated from physically analysing waste collected from each household weekly. A questionnaire survey of selected household was undertaken before and during the pilot SS study. An optimization model was also set up to integrate different waste treatment options for Kumasi. Various economic costs associated with municipal solid waste management are taken into consideration in the development of the model. In staff residencies, on the average only 1.09% of households had contaminants above 50% in the organic waste bin, whilst 29.51% and 29.55% of households had contaminants above 50% in the plastic’s bag and ‘others’ waste bin respectively. The separation efficiency of 93.31%, 49.9% and 56.18% was achieved for organic, plastic and other wastes respectively. Waste separation efficiency and level of compliance weregenerally higher in the junior staff households than in the senior staff households. Organic wastes constitutes 69.2% of the total wastes analyzed with other wastes, plastics, paper, metals, textiles and glass constituting 13.4%, 7.3%, 4.4%, 2.6%, 1.8% and 1.3% respectively. In the Asokwa Sub-Metro, on the average 74.3%, 60.02% and 59.56% of organic wastes were placed in the bin designated for it from 1st, 2nd and 3rd class areas respectively. Likewise the separation efficiency for 1st, 2nd and 3rd class areas for plastic waste were 21.42%, 19.26% and 26.92% respectively. Furthermore, the separation efficiency for other waste for 1st, 2nd and 3rd class areas were 51.19%, 59.57% and 62.41% respectively. Per capita waste generation rate for the 1st, 2nd and 3rd class area was found to be 0.63, 0.52 and 0.27 (kg/person/day) respectively. The relationship between household’s socio-demographic characteristics and their SS efficiency was found to be generally weak. Suggestions for the design of appropriate SS schemes in Kumasi have been enumerated. It is inferred from the results of the optimization model solution that centralized composting, community composting and plastic waste recycling if included in the waste management system in Kumasi could reduce the annual system cost substantially within the limits of assumptions made in this study. The study demonstrates the usefulness of system analysis to the understanding of system performance in supporting decisions in the selection of waste treatment options. Further research directions are suggested to support the development of sustainable integrated solid waste management in Kumasi

Source: KNUST