Application of integrated ozone biological aerated filters and membrane filtration in water reuse of textile effluents

摘要

A combined process including integrated ozone-BAFs (ozone biological aerated filters) and membrane filtration was first applied for recycling textile effluents in a cotton textile mill with capacity of 5000m~3/d. Influent COD (chemical oxygen demand) in the range of 82-120mg/L, BOD_5 (5-day biochemical oxygen demand) of 12.6-23.1mg/L, suspended solids (SSs) of 38-52mg/L and color of 32-64° were observed during operation. Outflows with COD≤45mg/L, BOD_5≤7.6mg/L, SS≤15mg/L, color≤8° were obtained after being decontaminated by ozone-BAF with ozone dosage of 20-25mg/L. Besides, the average removal rates of PVA (polyvinyl alcohol) and UV_(254) were 100% and 73.4% respectively. Permeate water produced by RO (reverse osmosis) could be reused in dyeing and finishing processes, while the RO concentrates could be discharged directly under local regulations with COD≤100mg/L, BOD_5≤21mg/L, SS≤52mg/L, color≤32°. Results showed that the combined process could guarantee water reuse with high quality, and solve the problem of RO concentrate disposal.