Assessment of Treatment Efficiency of Lysimeter Leachate using Leachate Pollution Index

Abstract

This study illustrates the leachate treatment efficiency based on leachate pollution index (LPI) of pre- treatment leachate as well as post-treatment leachate with chemical coagulants. Leachate samples were collected at regular intervals of time from the leachate collection chamber of the landfill lysimeter at KUET campus, Bangladesh to compute its pollution potential. The landfill lysimeter consists of one open dump lysimeter-A with leachate detection (A1) and collection system (A2) as well as two sanitary landfill lysimeters B and C having two different types of cap liner. The relevant parameters of leachate sample were measured in the laboratory to evaluate sub-pollution (sub-LPIs) in terms of LPI in organic pollutant (LPIor), inorganic pollutant (LPIin) and heavy metal (LPIhm) as well as the overall LPI. Moreover, the values of LPI in pre-treatment leachate were to be found 19.53, 25.33, 23.48 and 23.74 for the A1 and A2 systems of open lysimeter-A, as well as the collection systems of sanitary lysimeters- B and C, respectively. It reveals significantly the higher values than that of LPI of 5.77, 7.38 and 7.38 for the maximum leachate discharge standards of Bangladesh, India and Hong Kong, respectively. The leachate was then treated with ferric chloride (FeCl3), poly alluminum chloride (PAC), ferrus sulphate (FeSO4) and aluminum sulphate (Al2(SO4)3) in various dosages and pH values. The concentrations in post-treatment leachate by using FeCl3 at optimum dosage were to be found below the limit of maximum leachate discharge standards. Study also reveals the values of LPI of 5.32, 5.69, 5.32 and 5.24 in post-treatment leachate for the A1 and A2 systems of open lysimeter-A, as well as the collection systems of sanitary lysimeters-B and C, respectively belowthe values of LPI in leachate of maximum discharge standards. Finally, it can be concluded that differences in the level of contaminants of pre- treatment and post-treatment leachate indicated the role of leachate treatment system in minimizing the level of contaminants and lowering the risk of leachate contamination based on LPI.