Assessment and Selection of Aerobic Biological Treatment Technology for Closed Landfill Leachate

Abstract

The post-closure phase of landfills poses ongoing challenges due to the continual production of leachate. Leachate is a complex liquid mixture of toxic pollutants that are characterized by the presence of complex inorganic and organic contaminants that can potentially impact human health and the natural environment. There is need for the selection and application of appropriate treatment technologies to minimize potential contamination risks in soil, surface water, groundwater and the environment at large.  A commonly applied treatment technology for landfill leachate is the aerobic biological treatment. This study conducted a comprehensive review of the most suitable aerobic biological treatment technologies for leachate from closed landfill sites. A Multi-criteria analysis (MCA) was employed to evaluate five aerobic biological leachate treatment technologies for closed landfill. The MCA used a structured approach that considers 16 criteria, grouped into environmental, technical, economical, and social categories to help breakdown the contribution of each category to the leachate treatment technologies and to select the most suitable treatment technology. The results of the MCA showed that Sequencing batch reactor (SBR) outperformed other treatment technologies, with an overall index score ranging from 6.84 to 8.25 out of a maximum of 10.00. The next ranked treatment technology was membrane bioreactor (MBR), with an overall index score ranging from 5.35 to 6.55. The lowest ranked treatment technology was activated sludge (AS), with an overall index score ranging from 4.18 to 5.34. A sensitivity analysis was conducted to evaluate the influence of variation in weighting factors under 7 scenarios and the results of the best performing treatment technology remain unchanged. Although, rotating biological contactors (RBC) had second best performance in 3 scenarios due to the reduction of the priority group weight for environmental category. In real world, emphasis is placed on the environmental performance of treatment technology due to the stringent environmental regulations that is applicable to a closed landfill leachate. This study is beneficial for selecting optimal treatment technology that improves treatment efficiency, supports long term leachate management and ensures regulatory compliance at closed landfills. Hence, MCA is a good decision-making tool that can assist waste management experts for selection of optimal treatment technology for long-term leachate management in closed landfills.