EVALUATION OF BEHAVIOR OF WASTE DISPOSAL SITES IN KARACHI, PAKISTAN AND EFFECTS OF ENHANCED LEACHING ON THEIR EMISSION POTENTIAL

Abstract

This study aims to assess the efficiency of enhanced leaching on biodegradation of residual waste and gas emissions from waste disposal sites. The investigation simulated the waste disposal conditions in the landfill sites of Karachi, Pakistan in terms of waste composition, moisture content, and climatic conditions. For this purpose, a lysimetric analysis method was applied. Landfill sites in Karachi have typically no cover and the waste degrades in relatively dry conditions due to the lower moisture content of the waste as well as due to the low annual rainfall. Decomposition of organic waste with low moisture content and limited water introduction is causing prolonged emissions in the form of gas and leachate due to the slow biodegradation process. This paper focuses on the comparison of gaseous emissions from waste disposal sites in two different circumstances by applying two different experimental approaches. In the first approach, the actual dry conditions were simulated by means of limited water addition and without leachate recirculation. In the second approach, enhanced leaching conditions were provided with process water addition and leachate recirculation. The results from 100 days of experimental operation revealed that an enhanced leaching is able to increase gas formation in comparatively short periods and prolongs gaseous emissions from waste disposal sites can be controlled. This lab scale study can provide baseline data for further research and planning to transform waste dumpsites to sanitary landfills in the region.