Recycling of textile wastewater with a membrane bioreactor and reverse osmosis plant for sustainable and cleaner production

Abstract

Due to increasing industrial and human water consumption, as well as increasing water and wastewater disposal costs, recycling of industrial wastewater is of growing importance. The textile wet processing industry discharges a significant volume of wastewater with considerable organic contamination and residuals. In Yunus Textile Mills (YTM) in Pakistan, we successfully recycled textile wastewater using a membrane bioreactor (ultrafiltration) followed by reverse osmosis (RO). This textile wastewater recycling plant is the first of its kind in Pakistan and is an important benchmark for all future developments in textile wastewater treatment (WWT). In YTM, wastewater was treated with a series of environmentally friendly processes including heat recovery from hot wastewater using a custom-designed heat exchanger with an operating efficiency of 65.9% and reducing the wastewater temperature from 70 to 43 degrees C. Neutralization of wastewater was achieved by mixing power plant exhaust emissions, thereby reducing wastewater pH from 12.1 to 8.4. Membrane bioreactor and RO plants reduced chemical oxygen demand, biological oxygen demand, and total dissolved solids up to 96.2, 97.1, and 96.4%, respectively, and removed color from the wastewater. This treated wastewater was then reused in the textile processes such as fabric washing and rinsing. Thus, the combination of the membrane bioreactor and the RO plant is feasible for textile WWT and reuse.