Comparison of Membrane-Based Treatment Methods for the Removal of Micro-Pollutants from Reclaimed Water

Abstract

Dual membrane hybrid systems generally produce reclaimed water for non-potable uses by blending microfiltered biologically treated sewage effluent (BTSE) and reverse osmosis (RO) permeate. This reclaimed water is found to contain a significant amount of micro-pollutants, which possibly cause toxicity effects to aquatic organisms and plants when exposed to it. Therefore, removing such pollutants from the reclaimed water before reaching the community is highly emphasized nowadays. The currently used treatment of the RO treatment of microfiltered BTSE is energy intensive and not cost effective. This paper focuses on less costly and efficient membrane-based hybrid treatment systems such as the microfiltration-adsorption (MF-GAC) hybrid system, Nano filter (NF) and RO in the removal of micro-pollutants from the microfiltered BTSE. Both the MF-GAC hybrid system and NF (with NTR 729HF membrane) removed 70 to 95% of micropollutants from microfiltered BTSE. The removal depends on the hydrophobicity, charge, and size of the micropollutants. RO was excellent in removing more than 90% of pollutants, while MF was inefficient, as the latter primarily depends on the size exclusion mechanism. Based on the finding, it is suggested to treat only a portion of microfiltered BTSE through the MF-GAC or NF membrane before blending with RO permeate to enhance the removal of micro-pollutants from reclaimed water. The development of sustainable hybrid systems for the removal of all micropollutants of different chemical and physical properties is the key for the water reclamation.

Membranes in Water Reclamation: Treatment, Reuse and Concentrate Management

“…It consists of CMF and RO membrane filters, with a capacity of 7.5 ML/d. The permeate from the CMF and RO is mixed in an appropriate ration to produce reusable water and sold back to consumers [ 10 , 83 ].…”

“…In order to effectively eliminate the different types of micropollutants present in ROCs, it is crucial to establish sustainable hybrid systems. According to Devaisy et al [ 10 ], two effective methods for removing micropollutants from ROCs are an MF–GAC hybrid system or NF treatment. Both methods were found to be equally effective in removing these compounds.…”

“…It consists of CMF and RO membrane filters, with a capacity of 7.5 ML/d. The per-meate from the CMF and RO is mixed in an appropriate ration to produce reusable water and sold back to consumers [10,83]. (e) One of the largest wastewater treatment plants was established recently in Sulaibiya (Kuwait), where RO and UF-membrane-based membrane filtration is employed to reclaim municipal wastewater for nonpotable uses such as industry, irrigation, and aquifer recharge.…”

“…On the other hand, nanofiltration (NF) is commonly used to address water hardness due to its lower labor and operation costs in comparison to chemical methods [ 9 , 10 ]. NF membranes with a pore size of approximately 1 nm can effectively remove relatively smaller organic substances such as pharmaceuticals and personal care products (PPCPs), color, degradation products from BTSE, and dissolved organics, targeting dissolved compounds [ 11 ] with a molecular weight of about 300 Da.…”

“…NF membranes with a pore size of approximately 1 nm can effectively remove relatively smaller organic substances such as pharmaceuticals and personal care products (PPCPs), color, degradation products from BTSE, and dissolved organics, targeting dissolved compounds [ 11 ] with a molecular weight of about 300 Da. NF proves to be an efficient system capable of treating BTSE to produce water of desired quality for industrial, agricultural, and indirect potable reuse applications [ 8 , 10 ].…”