EFFECTS OF PH AND NATURAL ORGANIC MATTER ON REMOVAL OF CARBAMAZEPINE AND SULFAMETHOXAZOLE BY NANOFILTRATION AND REVERSE OSMOSIS MEMBRANES

Abstract

This study examined the efficiencies of nanofiltration and reverse osmosis membranes on the removals of carbamazepine (CBZ) and sulfamethoxazole (SMX). Reverse osmosis and nanofiltration membranes, namely, NF-1 and RO-1, respectively were investigated. Isoelectric points of NF-1 and RO-1 membranes were observed at pH 6.0. For NF-1 membrane, CBZ rejections at solution pH 5, 6, and 7 were 93%, 93%, and 92%, respectively. SMX rejections at solution pH 5, 6, and 7 were 87%, 91%, and 94%, respectively. For RO-1, CBZ rejections at solution pH 5, 6, and 7 were 93%, 94%, and 92%, respectively. SMX rejections at solution pH 5, 6, and 7 were 94%, 97%, and 98%, respectively. Solution pH had no effect on the CBZ rejection but it affected the SMX rejection. Hence, the removal of CBZ was controlled by size exclusion whereas the removal of SMX was controlled by size exclusion and electrostatic repulsion. Mixed pharmaceuticals showed an increasing in the rejection compared with that of single pharmaceutical. It could be due to a combination of pharmaceuticals during the membrane filtration. Effect of membrane fouling on the selected pharmaceutical removal, i.e. SMX was observed. It was found that when the membranes were fouled by tannic acid in the presence and absence of calcium chloride, tannic acid was accumulated and formed a dense layer on the membrane surface. This dense layer performed as another filtration layer and resulted in an increasing of SMX rejection. In case of membrane fouling by real wastewater from swine farm, the removal efficiencies of the two membranes were not affected. It could be due to the membrane fouling was not severe. The fouled layer was not formed noticeably on the membrane surface. Thus, the aforementioned results were carried out.