Advanced treatment of sanitary landfill leachate by direct contact membrane distillation

Keywords: Direct contact membrane distillation, Ultrafiltration, Landfill Leachate treatment, Discharge Limits. In this study, it was aimed to treat municipal solid waste landfill leachate to the proper effluent quality to receiving body discharge standards by direct contact membrane distillation (DCMD) which is among innovative and developing membrane technologies. Treatment studies with İZAYDAŞ landfill leachate carried out in 2 different treatment options, a) only with DCMD process and b) DCMD process after UF process, according to the receiving body discharge standards. The best process conditions were determined according to each alternative. The best appropriate process conditions for UF are, UV150 membrane for filtered leachate bioreactor output, 900 rpm mixed velocity and 7,5 bar pressure. Water flow performance found as 28,9 L/m2.hr and TOC and COD removal efficiencies found as 73,8% and 71,4%. For the treatment of leachate bioreactor output in the DCMD process alone, membrane type should be PTFE, membrane mesh size should be 0,45 µm, traverse flow velocity 200 L/hr (leachate)-200 L/hr (distilled), and temperature difference should be as 600°C leachate – distilled 400°C. In accordance with those figures, water flow performance defined as 29.8 L/m2.hr, TOC and COD removal efficiencies found as 99,8% and 98,8%. After defining optimum process conditions for UF and DCMD, long-term performances were evaluated. In long term DCMD process, 10 days and every day 6hr processing resulted as, 24,9 L/m2.hr flow, 99,60% COD, 99,60% TOC removal efficiency. And DCMD after UF process resulted as 31,7 L/m2.hr flow, 99,69% COD, 99,47% TOC efficiency. When bioreactor output leachate water and filtered leachate bioreactor output water evaluated for DCMD and UF/ DCMD performances, in both alternatives, treated water quality is in accordance with the water pollution control regulations, Table 20.6. Within this study, the membrane distillation process DCMD, can be applied for the leachate water treatments.