The reverse osmosis treatment preceded by ultrafiltration, conductivity was 50–200 μs/cm, total hardness was 2–10 mg/L and total alkalinity was 25–60 mg/L. The results showed that the membrane permeates
could be reused as dyeing process water. By these methods, COD value of 45.7–97.9 mg/L (within discharge standard) could be met and the concentrate water could be discharged directly without additional treatment (Qi et al. 2011).