engleski

Removal of N-nitrosodipropylamine, mebendazole and clothianidin from drinking water by reverse osmosis

Excessive use of fertilizers and pesticides, as well as uncontrolled discharges of industrial effluents and domestic wastewater, has resulted in elevated concentrations of pollutants in source water. In addition, wastewater chemicals and chemicals added during drinking water treatment can produce numerous disinfection byproducts such as N-nitrosamines, which have been classified as "probable human carcinogens." In addition, pesticides and pharmaceuticals containing secondary or tertiary amines or carbamate moieties are also known precursors of N-nitrosamines [1, 2]. In this study, clothianidin (CLO), mebendazole (MEB) and N-nitrosodipropylamine (NDPA) were selected as representatives of pesticides, pharmaceuticals and N-nitrosamines, respectively. The removal of NDPA, MEB and CLO was investigated using four commercial nanofiltration membranes (NF, NF-DL, NF270, NF90) and one reverse osmosis membrane (XLE). All experiments were performed in a laboratory setup consisting of six stainless steel membrane units connected in series. Furthermore, the operating pressure in all experiments was 10 bar. The rejection of selected compounds was compared in single component, binary and ternary solutions. The concentration of the selected compounds in the permeate was determined by HPLC-DAD. The highest rejections were obtained with XLE and NF90 membranes, which showed rejection rates of >90 % and >89 %, respectively for all the compounds studied. The rejection values of NDPA and CLO increased in binary and ternary solutions compared to the single component solution i.e. the rejection increased up to 7 % and 20 % for NDPA and CLO, respectively. These significant variations in the rejection of NDPA and CLO suggest the existence of a synergistic effect of membrane rejection mainly due to size exclusion and adsorption of MEB on the membrane surface.

reverse osmosis ; N-nitrosodipropylamine ; mebendazole ; clothianidin

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