Flocculation Process Optimization of a Novel Coagulant for Landfill Leachate Pretreatment

Sanitary landfill leachates are considered as heavily polluted industrial wastewaters, so special care is required for their efficient treatment and disposal. The most popular biological treatments are mostly the secondary stage in a combination with additional physical-chemical pre-process. A novel inorganic polymer flocculants, poly-ferric(III)-magnesium(II)-aluminum(III)-sulfate (PFMAS in brief) is used to pretreat landfill leachate. Jar-test experiments are employed to investigate the effect of flocculation conditions such as PFMAS dosage, leachate pH, leachate temperature, and sedimentation time to organics removal. It is demonstrated that the removals of COD, BOD5 and color by coagulation with PFAMS can reach 67%, 56% and 90% respectively under the optimum conditions (including PFMAS dosage at 3.3 g/L (Fe+Al+Mg), the leachate pH at 8.0, the leachate temperature at 20degC, and the sedimentation time at 50 min, respectively), which greatly weakens its pollution extent and improves its visual appeal. Flocculation with PFMAS may be used as a useful pretreatment step for landfill leachate.