LIME COAGULATION-SUBMERGED EVAPORATION SYNERGISTIC TREATMENT FOR NANOFILTRATION MEMBRANE CONCENTRATE OF LANDFILL LEACHATE

In order to improve quantitative reduction of the landfill leachate membrane concentrate, the nanofiltration membrane concentrate was treated by lime coagulation-submerged evaporation, and the change rule of water quality was obtained. The results showed that in the lime-coagulation treatment alone, the softening effect of membrane concentration was best when the dosage of lime was 2 g/L; with the increase of lime dosage, the pH of the membrane concentrate, and the removal rate of COD, NH₃-N, and metal ions (Fe³⁺, Mg²⁺, Al³⁺, K⁺ and Na⁺) increased. In lime coagulation-immersion evaporation synergistic treatment, when the dosage of lime was 2 g/L and the concentration ratio was 10, compared to coagulation alone, the softening effect of evaporation residue liquid was further improved, with hardness removal rate increased from 29.1% to 65.9%, COD removal rate increased from 24.1% to 41.2%, NH₃-N removal rate increased from 39% to 81.4%, and K⁺ and Na⁺ concentration increased from 4300,5860 mg/L to 36210, 48300 mg/L, respectively. That provided conducive condition for the latter resource utilization. COD concentration in the condensate decreased from 26.3 mg/L to 16.3 mg/L, and NH₃-N decreased from 2.0 mg/L to 1.4 mg/L, complying with the relevant requirements of the Control Standard for Domestic Waste Landfill (GB 16889—2008).