Grey water treatment with spiral wound UF and RO membranes

Abstract

A typical combination of spiral wound ultra-filtration and spiral wound reverse-osmosis membranes were used to treat grey water obtained from washing machine discharge in order to recover the surfactant solution as well as water both of which could be reused for another couple of washes. The process leads to the separation of dirt and dust particles from the grey water using the UF process and later the surfactant solution and water is separated from the mixture using the reverse osmosis membrane. Various backwash and backwash-backflush methods were used to increase the membrane performance by decreasing the fouling problems which generally occurs in such types of membranes. These backwashing procedures were found to have enhanced the life of the membrane by cleaning the membranes. The TDS and turbidity of the solution mixtures were analyzed by conductivity meter and turbidity meter respectively and the results obtained from these instruments provided a good idea regarding the separation processes. The UF membranes could decrease the turbidity of a dirty mixture solution but allows the surfactant solution to pass though it which is finally treated using the RO membranes which could decrease both the turbidity and TDS of the solution. The experiment provides a comprehensive idea related to the treatment of grey water which could help in better waste water reuse as well as economic ways of reusing detergents for subsequent washes.