Chemical pretreatment of landfill leachate discharged into municipal biological treatment systems

Landfill leachate produced in the Harmandali Landfill in Izmir in Turkey was characterized and chemically treated to examine chemical oxygen demand (COD) and color removal efficiencies. The leachate was coagulated adding various doses of an organic flocculant (DEC). Chemical oxidation was carried out using Fenton's reagent. Powdered activated carbon was used for adsorption to achieve improved COD and color removal in chemically treated leachate. The maximum removal efficiencies of 79% in COD and 98% in color were achieved by Fenton reagent and lime addition (at doses of 2,500 mg/L H2O2 + 2,500 mg/L FeSO(4)(.)7H(2)O(2)O(2)). The best DEC dose was found to be 4,600 mg/L, and COD and color removal efficiencies varied between 60-65% and 82-93%, respectively. A COD removal of 49% and a maximum color removal of 96% were obtained by lime slurry addition. Among the leachate samples, the highest COD and color removal was obtained using the Fenton's oxidation. Activated carbon adsorption tests indicated that the color parameter was best fitted to the Langmuir Isotherm (r(2) = 0.98). The isotherm constants were q(max) = 889 Mg Pt(.)Co(.)g(-1), K = 1,093. Oxygen uptake rate of the samples was also determined after lime and adsorption, Fenton and adsorption, DEC and adsorption, Fenton and lime, and DEC treatment. in raw landfill leachate and in its different dilutions with municipal wastewater. The oxygen uptake rate of municipal wastewater that is accepted as a reference value for biological treatability was found as 46 mg/L/h. In comparison to the OURS obtained from the different treatment alternatives, all alternatives were appropriate for biological treatment of leachate with the exception of discharging the raw leachate directly.