Fate and inhibition of Bis (2-Ethylhexyl) phthalate in biophysical reactors for treating real landfill leachate

Abstract

In this study, the performance of combined Non-Thermal Plasma ( as a pre-treatment) and granular sludge sequencing batch reactor ( as a post-treatment) was evaluated for decontamination of real landfill leachate containing Bis (2-Ethylhexyl) phthalate. Special emphasis was placed on the biodegradability of leachate due to its high chemical stability and generation of intermediate species. A plasma reactor with a useful volume of 0.5 L, quartz material was utilized by this study for the pre-treatment process. The biological treatment efficiency was investigated using three granular sludge sequencing batch reactors, each containing 1.2 L with different apparatuses. The Hamadan landfill leachate sample was diluted with synthetic wastewater at 20%, 50%, and 100% v/v ratios. The applied influent Bis (2-Ethylhexyl) phthalate concentrations were 2, 4, 6, 8, 10, 15, and 20 mg/l. Organic loading rate in terms of COD and Bis (2-Ethylhexyl) phthalate concentrations, as well as reactor hydraulic retention time, were worked out to assess the processes performance (COD, nitrogen, phosphorus, and Bis (2-Ethylhexyl) phthalate removal efficiencies). Total Organic Carbon and 5-day Biochemical Oxygen Demand were also measured at the influent and effluent of the NTP reactor over a range of retention time (5, 10, 15, 20, 30, 45, and 60 min) to determine the degree of biodegradability enhancement. Cell protein concentration was also measured using a nanotherape device to assess the effect of DEHP inhibitor on bacterial growth. The main results arrived at from the overall assessment of the processes are that the BOD5/COD ratio of Non-Thermal Plasma reactor effluent at all leachate dilution, i.e., 20%, 50%, and 100% (v/v ratios) considerably increased, reaching 1.09 as compared to 0.33 in the raw influent. The findings indicated that the longer hydraulic retention time affected the granular sludge sequencing batch reactor efficiency. Further, cell protein concentration decreased by increasing the leachate contribution of inlet COD and increased Bis (2-Ethylhexyl) phthalate. It is concluded that Non-Thermal Plasma, as a highly competitive waste treatment technology coupled with aerobic granular sludge, could be considered for the biodegradation of landfill leachate containing chemically stable and recalcitrant organics not treatable by conventional techniques.