Application of UF and RO for power plant's wastewater treatment and recycling for environmental sustainability

Abstract

Global indicators have warned of freshwater scarcity in Asia. However, the utilization of freshwater resources has skyrocketed for commercial and industrial purposes without any strategy for recycling and reuse. The power plant's wastewater/reject mainly consisted of cooling tower blowdown water and reverse osmosis (RO) plant reject water. Due to the high turbid nature of reject water, pretreatment was carried out to achieve SDI15 <3 by employing multimedia filters (MMF), activated carbon filters (ACF) and ultrafiltration (UF). Operational parameters of RO membranes were optimized (11.5 bar, 29 °C) to achieve maximum water recovery along with higher rejection rates of critical scale forming species such as 81% total dissolved solids (TDS), 73% calcium hardness and 72% silica (Si). After accounting for backwash water and other concentrate rejections, the membrane treatment plant has achieved an appreciable recovery rate of more than 44%. The RO membrane-treated water was then incorporated in the cooling tower and a 16% reduction in freshwater makeup was achieved. Reduction of microbial growth rate as well as corrosion and scaling in the cooling tower was observed due to the reuse of treated water. This is to confirm here that brackish water RO membranes can act as a strong contender for reject water reclamation and effective utilization. HIGHLIGHTS Lower TDS Brackish Water Reverse Osmosis (BWRO) membranes are found effective for recovery of high TDS wastewater of cooling tower.; Significant expulsion of turbidity and suspended particles was achieved through contemporary technologies, i.e., ultrafiltration (UF) and multimedia filters (MF).; Pretreatment plays an important role in the operational life span of RO membranes.; Membrane treatment of wastewater provided a recovery rate of more than 40%.; Wastewater recycling and reuse suppressed the utilization of freshwater and chemical consumption in the cooling tower.;

Keywords

• brackish water ro membrane
• environmental sustainability
• power plant
• wastewater treatment
• water reclamation