Open Dump Simulation for Estimation of Pollution Levels in Wet Tropical Climates

Abstract

Leachate management is one of the major issues in rehabilitation of present dumpsites. A field scale 'lysimeter' study for open dump simulation of municipal solid waste with 940 kg/m 3 placement density was carried out to determine decomposition pattern of waste, namely the quality and quantity of leachate generations in wet tropical climates for 4 years. The study entailed the development of an analytical model to determine mass and water balances. The percentage dry weight reduction of organic matter was 83 % in the 4 year period. The prediction from the mass balance model gave an evapotranspiration coefficient of 0.826. The classical 'logistic growth' kinetics used in the analysis by considering the cumulative solid content (CSC) in leachate as the microbial substrate complex discharged and it was the key factor used to determine the pollution levels. CSC in leachate showed four distinct phases considered as three growth curves and a straight-line relationship with time. Three growth curves separated and simulated the solid content discharges in each of the phases. The times for the maximum solid discharge rate for each phase were 17, 150, and 349 days, respectively from waste placement. In applying to actual dumpsite conditions, all of the CSC values of the three phases (727 days) become a day's event. In an 'effective rainfall event', the minimum CSC discharge should be 24,859.5 g. The maximum CSC is 49,684 g. The Biological Oxygen Demand (BOD 5) values at the maximum substrate utilization rate for first and second phases were 18937 mg/L and 1775 mg/L. Therefore, maximum aggregated BOD 5 value should be 9781.5 mg/L. Further studies are required towards modeling deep dumpsites.