Effect of fouling on removal of trace organic compounds by nanofiltration

Abstract

The fate of chemical of concern is not yet fully understood during treatment of impaired waters. The aim of this paper is to assess the impact of different organic-based fouling layers on the removal of a large range of trace organics. Both model and real water samples (mixed with trace organic contaminants at environmental concentration of 2 μg l<sup>−1</sup>) were used to simulate fouling in NF under controlled environment. The new and fouled membranes were systematically characterised for surface charge, hydrophobicity and roughness. It was observed that fouling generally reduced the membrane surface charge; however, the alterations of the membrane hydrophobicity and surface roughness were dependent on the foulants composition. The rejection of charged trace organics was observed to be improved due to the increased electrostatic repulsion by fouled membranes and the adsorption of the trace organic chemicals onto organic matters. On the other hand, the removal of nonionic compounds decreased when fouling occurred, due to the presence of cake enhanced concentration polarization. The fouling layer structure was found to play an important role in the rejection of the trace organic compounds

Nanofiltration as tertiary treatment method for removing trace pharmaceutically active compounds in wastewater from wastewater treatment plants

“…The high rejection index observed when trimethoprim existed as a neutral species was predominantly caused by hydrophobic interactions due to the effect of fouling on the membrane. In these conditions, the electrostatic forces ceased to exist and nonionic trimethoprim molecules with low sorption potential (log DOW < 2) were not easily adsorbed by both the hydrophobic membrane surface and the formed foulant layer (Hajibabania et al, 2011;Jewell et al, 2016). Ibuprofen, naproxen and sulfamethoxazole showed a more pH-dependent behaviour than the other studied PhACs, presenting higher rejection indexes with increasing pH, which was more visible for TFC-SR2 membranes (see Fig.…”

Carbamazepine Removal by Clay-Based Materials Using Adsorption and Photodegradation

“…Advanced oxidation processes [25,26] were an efficient option. Despite the high efficiency of those approaches, several problems limit their applicability, such as high costs, the toxicity of by-products in the oxidation process, biofouling, and the negative influence of natural organic matter during the removal by RO and NF [27][28][29][30].…”