Thin-film composite nano-filtration (NF) and reverse osmosis (RO) membranes based NF followed by ROpilot plant at a feed pressure of 20 atm.and flow rate of 10 L/min. was used to remove colour, total dissolved solid (TDS) and chemical oxygen demand (COD) of distillery spent wash. NF was found to be effective for high rejection of TDS, colour and COD by 85%, 99% and 95%, respectively. Furthermore, significant reduction of TDS (97%), colour (99.8%) and COD (99.90%) was achieved from RO runs. 1.

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... TRODUCTION Distilleries areto be scheduled as one of the most polluting industriesby the Central Pollution Control Board (CPCB) due to generation of huge quantities of high toxic effluents, e.g. spent wash.1 The spent wash is characterized by extremely high chemical oxygen demand (COD) (85,000-1,20,000 mg/l) and biochemical oxygen demand (BOD) (35,000-60,000 mg/l), apart from low pH, strong odor and dark brown color.2Most of the treated spent wash with the best available process technology (conventional effluent treatment plant (ETP), screening and equalisation followed by biomethanation)yields very high levels of COD and total dissolved solids (TDS), with black-colored effluent with odors. Moreover, ferti-irrigation and biocomposting with sugarcane press mud are highly energy intensive and hence quite expensive.3These disadvantages limit the use of existing technology and needed further research in the field of novel separation methods. Pertaining to this, membrane-based separation techniques such as RO and NF would yield excellent results when applied. 4-6 The effectiveness of NF membrane processes in water and wastewater treatment is generally acknowledged and has now become the most reliable standard technique. Hybrid techniques are also quite popular. The main objective of this study was to purify the spent wash by removing colour, TDS and COD by the combined use of NF and RO hybrid process.