Study On UF-A/O-MBR Treating Polyester Chemical Fiber Wastewater

Polyester fiber factory wastewater of Liao Yang Petrochemical Co. Ltd include purified terephthalic acid (PTA) waste water, polyester waste water, aromatic oil-bearing wastewater, terylene wastewater as well as the local part of municipal wastewater.Firstly,PTA and polyester wastewater are pretreated with UASB and aerobic activated, and then the effluent of pretreatment mix with terylene waste water, municipal wastewater and aromatic oil-bearing wastewater (after gas floator, oil separator), for further process with aerobic activated sludge process.PTA wastewater contains large amounts of suspended solids, in which terephthalic acid (TA)concentrations is 1000～2500 mg/L. In the pretreatment unit,TA is recovered by gravity in the primary settling tank. But this traditional separation technology is less efficient for recycling of solid particulate matter, and there are a large part of the TA into the biochemical processing units, which increase the burden of follow-up treatment.Polyester fiber integrated wastewater is treated with two aerobic activated sludge process. the final effluent in which annual average COD concentration is 60 mg/L and the monthly average concentration is no more than 80 mg/L, TN concentration is 30～45 mg/L exceed the Integrated Wastewater Discharge Standard in Liaoning Province COD = 50 mg/L, TN=15 mg/L.Therefor, this paper study UF-A/O-MBR process to treat polyester fiber wastewater for upgrading the existing treatment process .It mainly consists of two aspects:(1) To recover valuable product and intermediates, PVDF ultrafiltration is used in treating purified terephthalic acid(PTA) production wastewater. PVDF Ultrafiltration performed well in recovering organic suspended particle.The organic component of PTA wastewater were analysed using with HPLC and LC-MS. The result showed that UF system can significantly reduce the concentration of organic component and recover terephthalic acid(TA) and p-toluic acid(p-TA) of the suspended solids.(2) Polyester wastewater was treated using A/O-MBR process with PP non-woven modified membrane. Simultaneously,PVDF commercial membrane were tested in the MBR.During 70days operation time, the process showed relatively stable in case of shock load and the effluent quality was relative stable.When COD increased from 200 to 500 mg/l,TN changed within 30-45 mg/l,NH₄⁺-N changed within 20-35 mg/L and turbidity changed within 15～36 NTU in the influent,the effluent quality(COD<40mg/L,NH₄⁺-N<0.5 mg/L,TN<10 mg/L, turbidity<0.2 NTU)of the A/O-MBR process could meet the recycling requirement and the new local discharge standard in Liaoning Province.