Tertiary treatment of distillery wastewater by nanofiltration

Tertiary treatment of aerobically treated distillery wastewater by nanofiltration was carried out in a spiral wound nanofiltration membrane module under different operating conditions. The results show that the percentage separation of organic and inorganic compounds was quite high, as reflected by the reduction of chemical oxygen demand (COD) and total dissolved solids (TDS) in the range of 96–99.5%, and 85–95% respectively. The color removal was in the range of 98–99.5%. The results of the effect of variation of the inlet concentration, feed circulation rate and pH conform to the mechanism of gel layer formation. Gel layer formation and Concentration polarization was found to play a major role in the treatment of distillery waste using nanofiltration (NF) membrane. It was observed that as concentration of feed solution increases the permeate flux was reduced. This change was higher compared to the separation of COD and TDS. The result indicates that the NF membrane showed very high performance efficiency for organic components (96–99.5%), as indicated by COD removal. In comparison, the separation of inorganic compounds was found to be in the range of 25–90% as estimated from relative separation of COD and TDS. The present study shows that nanofiltration is a promising technique for recovery of water from distillery waste, which could be used to achieve zero discharge status and solve a major environmental problem.