Biodegradation of Chlorinated Solvents in Bioreactor Landfills

Abstract

The objective of this research is to investigate the intrinsic biodegradation potential of the municipal solid waste (MSW) landfill ecosystem for chlorinated aliphatic hydrocarbons (CAHs). The research was conducted in two complementary systems: simulated landfill bioreactors and batch degradation experiment in serum bottles. Refuse samples excavated from a MSW landfill were tested in laboratory bioreactors operated with leachate recirculation and gas collection. Tetrachloroethene (PCE) and trichloroethene (TCE) were added to reactors and maintained at 20 μM each in leachate to simulate the long-term exposure of refuse microorganisms to CAHs in landfills. Anaerobic microbial cultures were derived from reactors at two different stages of refuse decomposition: active refuse decomposition stage representing young landfills and maturation phase representing aged landfills. These cultures were tested in serum bottles for their abilities to biodegrade target CAHs. Results of this study show that MSW landfills have an intrinsic reductive dechlorination capacity for PCE and TCE. The decomposition of refuse also enhanced reductive dechlorination in this study. This research suggests the potential to develop engineering strategies to promote chlorinated solvent degradation concurrently with refuse decomposition in MSW landfills.