Novel industrial wastewater treatment integrated with recovery of water and salt under a zero liquid discharge concept.

Abstract

Conventional industrial effluent treatment systems are designed to reduce biochemical oxygen demand (BOD), chemical oxygen demand (COD) but not total dissolved solids (TDS), mainly contributed by chlorides. In addition to the removal of TDS, it is necessary to recover water for reuse to meet the challenges of shortage of quality water. To recover water, the wastewater needs to be further treated by adopting treatment systems including microfilters, low pressure membrane units such as ultrafiltration (UF), membrane bioreactors (MBR), etc., for the application of reverse osmosis (RO) systems. By adopting the RO system, 75%-80% of quality water with <500 mg/L of TDS is recovered from treated effluent. The management of 20%-25% of the saline water rejected from the RO system with high TDS concentration is being addressed by methods such as forced evaporation systems. The recovery of water from domestic and industrial waste for reuse has become a reality. The membrane system has been used for different applications. It has become mandatory to achieve zero liquid discharge (ZLD) in many states in India and other countries such as Spain, China, etc., and resulted in development of new treatment technologies to suit the local conditions.