Temporal Variation in Leachate Composition of A Newly Constructed Landfill Site in Lahore in Context To Human and Environmental Risks

Abstract

The present study was aimed to explore the seasonal and temporal variation in the extent and sources of physiochemical and trace elements in the Lakhodair solid waste Landfill site in Lahore, Pakistan. For the seasonal and temporal study of leachates, systematic composite samples were collected monthly (for one year) and analyzed for physiochemical and trace elements. The concentration of TDS, TSS, COD, NH3-N, BOD5, sulfate, sulfides, phenolic compounds, oil and grease were higher than the National Environmental Quality standard (NEQs). The trace elements, namely Mn (1.7 mg/L), and Cd (0.05 mg/L), while in a few samples Fe (14 mg/L), Ni (1.6 mg/L), and Zn (6.7 mg/L) were higher than the NEQs. In Lakhodair leachates, TDS, COD, NH3-N, BOD5, sulfides, and Cl have a high concentration coefficient (i.e., CC 3 to > 6), which may cause considerable to high contamination, while remaining parameters may cause low to moderate contamination (CC 1 to ≤ 3). The lower BOD5/COD ratio (< 0.1) in the Spring and Autumn seasons, represents the active methanogenesis and anaerobic activities in the Lakhodair landfill site. The anaerobic and methanogenesis enhance the redox reaction as a result CO2 is emitted and alternatively increases pH, TDS, COD, Cl, BOD5, NH3-N, sulfides, phenolic compounds in leachates. However, the lower concentration of some trace elements may be because of an anaerobic process that may immobilize the trace elements. It is presumed that the trace elements in the Lakhodair landfill may be in a metastable state, which is not easy to leach out. It’s hereby recommended that Leachate produced in the Lakhodair landfill site need to handle carefully so as to limit the environmental and health implication.