Study On Alkali-minimization Wastewater Treatment By Hydrolytic Acidification-hybrid MBR

Since 80 last century, printing and dyeing industry began implying alkali-minimization technique to deal with crude terylene in our country. Now, that technique has implied more and more, so it brings the new type wastewater- alkali-minimization wastewater.Alkali-minimization wastewater is made from polyester hydrolysis, its characteristic matter is Terephthalic Acid(TA) and little Ethylene Glycol(EG). Alkali-minimization wastewater of printing-dyeing industry is so little, which has much higher organic concentration and contaminated badly. The water quantity and COD of alkali-minimization wastewater account for 5%-10% and above 50% respectively in the whole printing-dyeing wastewater, whose COD is 2000-10000mg/L and pH is 12 upward. Alkali-minimization wastewater is hard treated directly by CAS bio-degraded.Experiment testify that bio-degraded probability and effect condition of a feature polluter-Terephthalic Acid(TA).Domestication microorganism can degraded TA better in pH=7 and 30-34℃.Study on removal TA as only carbon by hydrolytic acidification -PAC(sponge)MBR and effect factor. When system under HRT=24.9h, DO=4-5mg/L, SRT=50d, COD=784.15-982mg/L,TA =501-676 mg/L, PAC-MBR mean effluent quality COD 56.39mg/L, TA21.26 mg/L and sponge-MBR mean effluent quality COD 66.21mg/L, TA28.33 mg/L. Sludge particle diameter of PAC-MBR is bigger than sponge-MBR, degree of viscosity and membrane pollutant resistance of PAC-MBR is lower than sponge-MBR, PAC-MBR is better than sponge-MBR on treatment effect. In membrane, load of sludge obvious influence effluent quality at 0.1—0.37kgTA/kg.VSS.d.The result about the study of kinetics is that parameters are Yg= 0.1137kgVSS/kgCOD, Kd = 0.0792d~-1 in PAC-MBR and Yg = 0.1498kgVSS/kgCOD,Kd=0.0252d~-1 in sponge-MBR. By studying the kinetics parameters can direct the art design and management of the wastewater treatment, and make for improving the efficiency of wastewater treatment.The membrane fouling visualized by scanning electron microscope and the membrane cleaning ways were investigated. It was found that the membrane fouling was concentrated on the surface mainly, and the internal fouling was not obvious. After soaking by HCLO3the,the cake layer on the membrane surface was removed basically.