Leachate Quality Monitoring from Conventional, Retrofit, and Bio-Reactor Landfill Cells

Abstract

The recirculation of leachate is a common strategy to accelerate the decomposition of municipal solid waste in landfills. In this study, leachates from a conventional landfill cell without supplemental liquid addition (Control cell), a new landfill area that had a piping network installed as waste was being placed (As-Built cell), and a conventional landfill that was modified to allow for the recirculation of liquids (Retrofit cell) were monitored at the outer loop landfill bioreactor (OLLB) in Louisville, Kentucky. In general, leachates from the Retrofit cells were statistically different from leachates from the As-Built and Control cells. This is likely because the waste in Retrofit cells was about 6 years old when liquids were first introduced and the waste had already reached a more mature state prior to supplemental liquids addition. Based on time series data, the Retrofit cells, which received nitrified leachate, did not show signs of accelerated waste decomposition based on the leachate chemistry. In contrast, there were significant differences in parameters affected by waste biodegradation [temperature, pH, biological oxygen demand (BOD), chemical oxygen demand (COD), volatile organic acid (VOA), total organic carbon (TOC)] between the As-Built and Control cells, suggesting that the introduction of liquids accelerated waste decomposition in the As-Built cells. Trends were generally similar in the As-Built cells compared to the Control cells, even though concentrations of some parameters were higher in the As-Built cells. The elevated temperature in the As-Built cells suggests more active decomposition.