Assessing the chlorine disinfection of landfill leachate and optimization by response surface methodology (RSM)

Total coliforms and Escherichia coli (E. coli) were quantified as representatives of fecal pollution in Ampang Jajar landfill site (AJLS) leachate. Leachate samples were monitored for six months and an average of total coliforms and geometric mean of E. coli was determined. The highest concentrations of total coliforms and E. coli were 0.66 × 104 and 0.15 × 104 colony forming units (CFU) per 100 mL, respectively. The inactivation of these organisms was studied by using sodium hypochlorite with 4% available chlorine. The indicator bacteria showed high susceptibility to chlorine and a 100% inactivation of total coliforms and E. coli was achieved at 1.5 and 0.5 mg/L Cl2 dosages when contact times of 50 and 90 s were applied, respectively. Optimum conditions of inactivation analysed by using response surface methodology (RSM) were 0.91 mg/L Cl2 and 43.5 s contact time whereby 99% E. coli and 50% total coliform inactivation was obtained.

Research Highlights
► The highest concentration of Total Coliforms was 0.66 × 104 per 100 mL.
► The highest concentration of E.coli was 0.15 × per 100 mL.
► A 100% inactivation of total coliforms and E.coli was achieved at 1.5 and 0.5 mg/L Cl2 dosages.
► Optimum conditions of inactivation analysed by using RSM were 0.91 mg/L Cl2 and 43.5 s.