ABSTRACT

This work evaluates the kinetic parameters of first order (exponential) models for methane generation in sanitary landfills in the subtropical region of São Paulo, SP. Specially for this purpose, a test cell was built. The temporal response function for the test cell’s methane generation was obtained over 600 days due to placement of municipal solid waste (MSW). The time required to start the methane generation was 190 days. Between the 400^th and 500^th day after the MSW placement there was a period of high methane generation rate, and after the 560^th day it began to decrease. The kinetic parameters methane generation potential (L) and biodegradation constant for methane generation (k) were inferred through fittings of the first order model to the experimental response function and using MSW composition information. The values obtained for L and k for fast biodegradation were respectively 1,481±1,072 mol t^-1 MSW and 0.18±0.13 year^-1. The values obtained for L and k considering fast and slow biodegradation were 3,835 mol t^-1 MSW and 0.069±0.002 year^-1 and 5,027 mol t^-1 RSU and 0.052±0.002 year^-1, respectively, depending on the methodology used for determining L. The results obtained in the test cell indicate that the biodegradation of municipal solid waste in Caieiras occurs rapidly, i.e., with higher values for k and lower values for L than those suggested in the literature. These results indicate a possible reduction in the longevity of energy generation projects through methane recovery in landfills located in tropical and subtropical regions. Finally, we present recommendations for choosing L and k for sizing energy recovery projects and for undertaking environmental assessments and remediation.

Keywords:
municipal solid waste; methane generation; sanitary landfills; test cell; kinetic parameters