EFFICACEOUS TOTAL DISSOLVED SOLIDS REMOVAL FROM SECONDARY TREATED TANNERY EFFLUENTS

Abstract

Forward osmosis (FO) is a cutting-edge technique that may be used to desalinate saltwater, treat wastewater, process food, and generate electricity. FO process performance depends on factors like the type of membrane, the draw solute and its concentration, the type of module configuration used, and its operating conditions. Several studies have been published on FO process performance, which uses cross-flow configuration, U-tube configuration, plate and frame configuration and the hybrid dead-end cross-flow configuration system. These configurations essentially use pumps to circulate the draw solution and carry out the FO process. This work proposes a novel bench-scale pump-less dead-end continuous flow compartment configuration experimental setup to evaluate FO process performance using aquaporin-based biomimetic forward osmosis flat sheet membranes. Firstly, deionised water as feed solution and sodium chloride as draw solution is used to optimize the FO configuration operating conditions. This study analyses the proposed configuration via an experimental approach to the effect of temperature, draw solution mixing rate and draw solution concentration effect on the performance of the FO process in terms of flux and reverse solute flux. Results showed that the proposed configuration could alleviate the internal concentration polarization (ICP) and enhance the FO process performance compared to the most widely used cross-flow setup. The obtained conclusions of this work lay a foundation for quantitatively understanding the performance of the proposed FO configuration and provide a guide for optimising the FO system. Secondly, due to high total dissolved solids (TDS) content in treated tannery wastewater, wastewater reuse in industry is only possible if a reverse osmosis process is implemented. It is evident from literature studies that RO can successfully be applied for TDS removal from secondary treated tannery wastewater, provided a suitable and effective pretreatment system prior to RO is employed. This work investigated the use of FO system to treat high TDS tannery effluents (4000-14000 mg/L). The FO system showed excellent pretreatment, due to stable water flux, high rejection to constituents presents in secondary treated synthetic and real tannery effluents.