Application Of Multiple Membrane Process In Textile Wastewater Reutilization

The textile industry produces a large amount of wastewater that is highly colored with high loading of inorganic salt, and is difficult to be treated. How to treat the textile wastewater and recycle water in a more effective way has been always an important item of investigation by domestic and overseas experts.In the present study the microfiltration(MF), ultrafiltration (UF) and reverse osmosis (RO) were used to treat the secondary effluent from the textile factory sewage treatment plant. Firstly, MF and UF were used to separate the possible organic and suspended matters as a pretreatment; then two kinds of RO membranes(BW30 and CPA2) were used for effective desalination and removing the residual dyestuff, and the effects of operating parameters (pressure, temperature and operating time) on separation performance of RO were investigated too. The results showed that the CTA was the best UF membrane as a pretreatment, it can remove 52% of COD, 90% of turbidity and some color. Two kinds of RO membranes can remove almost the total salinity and organic dyestuff, and had clarify permeates with less than 15mg/L COD, monovalent and bivalent ions, which can not only reach the legislative primary discharge standard, but also meet the standard for reusing. The CPA2 has a better permeability than BW30 in pure water filtration, but BW30 behaved better in anti-compacting and rejecting ability in wastewater treatment.The concentration polarization mass-transfer coefficient in the RO process was calculated, which showed that under a stable velocity of feed water, an increase of pressure or flux rate have no influence on mass-transfer coefficient; and the increase of temperature can raise it, and reduce the concentration polarization RO membranes were cleaned by pure water under low pressure to eliminate the membrane fouling. BW30 got 59% flux rate recovered, and CPA2 got 39% recovered.