Treatment of landfill leachate wastewater by chemical coagulation-flocculation, electro-membrane bioreactor, and anaerobic hybrid system.

Abstract

In this study, the treatment of landfill leachate wastewater by chemical coagulation, an electro-membrane bioreactor (e-MBR), and an anaerobic hybrid system was studied. First, chemical coagulation process was applied to landfill leachate wastewater, which is referred to their high organic pollutants. Aluminum sulfate (alum), poly aluminum chloride (PAC), ferric chloride (FeCl₃), and ferrous sulfate (FeSO₄) were used as coagulants. After determining the coagulant type, pH optimization (6-10) and the amount of coagulant (0.5-2.5 g/l) was optimized. In the chemical coagulation-flocculation experiments, optimum conditions were determined as 1.0 g/l alum at pH 9. At these conditions, chemical oxygen demand (COD), total phenolic contents (TPC), and color analyses were examined and 31.16%, 35.32%, and 24.42% removal efficiencies were obtained, respectively. After coagulation-flocculation pretreatment, the e-MBR system was applied to the wastewater to obtain further treatment. Iron (Fe) electrode and ultrafiltration membrane (UP150) were used in the e-MBR system. 5, 10, and 20 V electric current was applied to the system and time-dependent flux measurements were carried out. COD, TPC, and color analyses were performed in both mixed liquor and membrane permeate. The results indicated that over ˃90% removal efficiency for COD, TPC, and color was achieved when the electric current increased from 5 to 20 V. In addition, it was also observed that the membrane fouling decreased and the flux increased. Since it still did not meet the discharge criteria, the wastewater obtained from e-MBR treatment was subjected to the anaerobic system. After 10 days of incubation, COD, TPC, and color removal were found to be 99.25%, 100%, and 99.57%, respectively. PRACTIONER POINTS: The treatment of leachate wastewater by chemical coagulation, electro-membrane bioreactor, and anaerobic hybrid system was studied. Optimum conditions were determined as 1 g/l alum at pH 9 for chemical coagulation. It was observed that the membrane fouling decreased and the flux increased. COD, color, and TPC removal efficiency were found to be 99.5%, 100%, and 99.6%, respectively.