Performance of multi-soil-layering system (MSL) treating leachate from rural unsanitary landfills

The widely spread rural unsanitary landfills in South China pose an environmental threat to water bodies and soil. Although various processing technologies have been utilized for treatment of landfill leachate, their application to the landfills in rural areas is restricted by the availability of skilled professionals and high operation costs. In this experiment, four MSLs with altered soil mixed block (SMB) and different hydraulic load rate (HLR) were applied in the experiment to investigate the treatment of the landfill leachate without aeration or under low aeration supply. The experiment results showed that the improved MSL could effectively treat the chemical oxygen demand (COD), NH4–N and P. COD and NH4–N removal efficiencies of MSL were 97.4%, 82.4% and 72.0%, 62.0%, respectively under HLRs of 200 and 400 L/(m2·d) without aeration; COD and NH4–N removal efficiencies of M800 and M1600 were 62.3%, 53.4% and 45.3%, 35.3% respectively under intermittent aeration. N removal efficiency was low due to a strong nitrification effect, and the nitrogen removal capacity of the MSL was greatly reduced at the end of the experiment. P removal efficiency of MSL was 75.6 to 91.9% under HLR 200 and 400 L/(m2·d). The intermittent aeration was helpful to remove the clogging of MSLs, after they were clogged under HLRs of 800 and 1600 L/(m2·d). MSL is promising as an appealing nitrifying biofilm reactor.

► Modified MSL could treat leachate from rural unsanitary landfills in South China.
► Intermittent aeration was helpful to remove the clogging of MSLs.
► MSL is a promising nitrifying biofilter.