Remediation of dumpsite leachate contaminants by coagulation and complexation

Leachate is a major threat to groundwater quality and ecosystem. The present study adopted four selected coagulants (inorganic: Al2(SO4)3 [Alum], FeCl3, FeSO4; biological: Moringa oleifera) and a complexing agent (ethylenediaminetetraacetic acid EDTA) to remediate leachates collected from two dumpsites in Abeokuta. The leachate samples were subjected to chemical and heavy metal analyses using the American Public Health Association (APHA) standard method. The data obtained were evaluated for simple descriptive statistics (mean and standard deviation) using SPSS for Windows. The results indicated that except for Fe and Ni, metal values in both raw and treated leachates were generally higher than the permissible standard of the National Environment Management Authority (NEMA). The study revealed that despite treatment, the values of metals in treated leachates were still issues of environmental concerns. The reduction data revealed substantial removal of EC and TDS (100%), Cl- (87-95 %) and SO42- (60-84%) in leachates. The present study also revealed that each coagulant has varied affinity for removal of different parameters in the leachate. Among the coagulants, Moringa oleifera showed the highest % removal efficiency for Cd (57-63%) and Ni (57-98%), while EDTA showed the lowest removing ability for Cd (2-6%). All the remediating agents effectively reduced the chemical contaminants in leachate samples to appreciate levels.