Treatment of compost leachate by the combination of coagulation and membrane process

This study describes the treatment of composting leachate by the combination of coagulation and nanofiltration process. Poly ferric sulfate (PSF) was used as coagulant, and the effect of pH value and PSF dosage on the coagulation performance was investigated. The results indicated that the chemical oxidation demand (COD) and turbidity removal efficiency could reach to 62.8% and 75.3%, respectively at an optimum dosage of 1200 mg·L− 1 at pH 6.0. During the nanofiltration process, the operation conditions such as temperature and pressure were optimized, 89.7% of COD, 78.2% of TOC, 72.5% of TN, 83.2% of TP, and 78.6% of NH3-N were retained when tested at 0.6 MPa at 25 °C. The final leachate effluent concentration of COD, BOD5, NH3-N, TOC, SS was 92 mg·L− 1, 31 mg·L− 1, 21 mg·L− 1, 73 mg·L− 1 and 23 mg·L− 1, respectively, which reached the local discharge standard. The combination of coagulation-filtration is useful for composting leachate treatment.