Study On Advanced Treatment And Reuse Of Printing And Dyeing Wastewater By The Combination Process Of Hydrid Hydrolization-Acidification+Hydrid MBR

Taking Suzhou Chengpeng printing and dyeing factory as research background, advanced treatment for the model wastewater of that factory was studied in the laboratory which by the combined process of hydrolization -acidification + MBR (process A) and the combined process of hybrid hydrolization-acidification + hybrid MBR(process B).On the basis of standardized emission,the better combined process was chose to provide financial and feasible technical method of advanced treatment and reuse for the printing and dyeing wastewater of that factory.First of all,bioflim culturing and acclimatization of biological treatment units of two processes was studied.When experimental temperature was at 13～17℃,the bioflim culturing and acclimatization was succeeded after 28 days in process A,and it was succeeded after 23 days in process B.Then,through changing different HRT and DO,analyzing the removal of CODcr,NH₃-N and color showed that the best HRT of system was 31.5h and best DO of aerobic MBR was 1.6～2.4mg/L in process A;the best HRT of system was 28h and best DO of hybrid aerobic MBR was 2.4～3.2mg/L in process B.After running on their best operation conditions,it was found that the removal ratios of CODcr,NH₃-N and color was 95%,88.6%,89.3%respectively by process A,the CODcr of effluent reached《Discharge standard of main water pollutants for municipal wastewater treatment plant and key industries in Taihu area》-discharge standard for dyeing and finishing,but the color of effluent was about 100～120 times and the NH₃-N of effluent maintained 5～10mg/L,these two indexes could't match the requirement;By process B,the removal ratios of CODcr,NH₃-N and color was very high which reached 95.1%,97.5%,92.5%respectively,the CODcr of effluent was always below 50mg/L,and NH₃-N,color could maintain 25～30 times and 3～5mg/L respectively,the indexes of all pollutants met the requirement of《Discharge standard of main water pollutants for municipal wastewater treatment plant and key industries in Taihu area》-discharge standard for dyeing and finishing.Comparing with process A,process B was more suitable for advanced treatment for this printing and dying wastewater.During stable running,removal of PVA and UV₂₅₄ by biological unit of each process was studied,it was found that the removal ratio of PVA and UV₂₅₄ by biological unit of process A was 13.9%and 22.69%respectively.The removal ratio of PVA and UV₂₅₄ by biological unit of process B was higher,which reached 22.76% and 33.23%respectively.Studying on ultrafiltration membrane of process B,which was more suitable for advanced treatment for the printing and dying wastewater,showed that the membrane flux attenuation coefficient declined with prolonging of HRT,and the amplitude became slowly.Relative membrane flux curve had different slope with different sludge concentration,the more the sludge concentration,the faster attenuation slope of relative membrane flux.Membrane flux increased with operating pressure increasing,and the increasing-rate trended to slow down.The experiment of membrane cleaning after fouling showed that membrane permeability only could be recovered to 38.5%after water cleaning,but it could be recovered to 89%after chemical cleaning.For recovery of membrane flux,chemical cleaning was better than water cleaning.Comparing the effluent quality which treat by process B with the《Discharge standard of main water pollutants for municipal wastewater treatment plant and key industries in Taihu area》-discharge standard for dyeing and finishing and《Water quality standard for urban miscelltaneous water consumption(GB/T 18920-2002)》,it was found that each index of pollutants reached the requirements.According to lab research in factory,the effluent water could reuse to former watching process. Reclaimed water reuse rate of Chengpeng printing and dyeing factory was analyzed,it showed that the reuse rate could reach 30%by process B which met the requirement of reuse rate of printing and dyeing enterprise in Kunshan area.Through designing monomer and analysising costs for advanced treating the wastewater of Chengpeng printing and dyeing factory by process B,it was found that pre-investment costs was higher because of membrane costs.But after budgeting,it showed that the final wastewater treatment costs was 2.62yuan/m³ which was not high for wastewater advanced treatment.The process B was entirely possible for wastewater advanced treatment of this factory because of its simple equipments and modest costs.