Study On The Treatment Of Printing And Dying Wastewater By Hybrid Dynamic Membrane Bioreactor

Dyeing and printing industry is a large water consumption in our country,and its wastewater and total pollutant in the industrial sector of the country’s second and fourth respectively.It is one of the key polluting industries.For large emissions and high treatment difficulty of dyeing and printing wastewater,it becomes the emphasis and difficulty in the study of wastewater treatment technology.With the rapid development of economy in our country,the shortage of water resources seriously restrict the further development of printing and dyeing industry.Therefore,resource recycling of printing and dyeing wastewater becomes the key to realize the sustainable development of dyeing and printing industry.Membrane separation technology is a new,efficient and environmental protection technology.With the development and progress of membrane separation technology,it has been widely applied successfully in the dyeing and printing industry and produced good economic and social benefits,which has brought new opportunity for technical innovation of dyeing and printing industry.The experiment on the treatment of printing and dying wastewater by combination of additive and hybrid dynamic membrane bioreactor（HDMBR）,pollutants removal efficiency and membrane fouling control mechanism were studied to seek a new and efficient treatment technology of printing and dyeing wastewater,and provide reliable method and theoretical basis for the delay and control membrane fouling.Referred to a large number researches of dynamic membrane bioreactor（DMBR）wastewater treatment and related references,the dissolved oxygen（DO）,sludge retention time（SRT）,hydraulic retention time（HRT）were determined as the factors of orthogonal test.Using orthogonal experiment,through range analysis and comprehensive balance method to determine the effects of DO,SRT and HRT on the pollutants removal of printing and dyeing wastewater treated by DMBR in order to find the optimal operation condition.The results showed that when DO was 2 3 mg/L,HRT was 12 h,SRT was45 d,the effect of pollutants removal on simulative printing and dyeing wastewater treated by DMBR was the best.Under the optimum operation condition,through the contrast experiment of HDMBR and DMBR to treat printing and dyeing wastewater,the enhancement of pollutants removal and membrane fouling control were studied with the addition of suspension packing.It was shown that the average removal rate of chromaticity,turbidity,ammonia nitrogen,total nitrogen,total phosphorus,COD and UV₂₅₄ in HDMBR were86.39%,96.00%,90.13%,85.84%,89.63%,95.75%,88.24%,and were higher than that in DMBR 6.15%,2.24%,8.33%,5.99%,5.56%,1.79%,6.39%,respectively.Fluorescence peak intensity of dissolved organic matter（DOM）of wastewater（the corresponding material content）in hydrolysis acidification and HDMBR（DMBR）process ware gradually decreased by three dimensional fluorescence spectrum analysis.The addition of suspension packing could enhance the DOM removal.The sludge mixed liquid of HDMBR and DMBR separated by denaturing gradient gel electrophoresis（DGGE）.The results of DGGE showed that there were both the same bands and specific bands in hydrolysis acidification pool and aerobic pool.The dominance of microbes in HDMBR is more obvious than DMBR.In the aspect of pollutant removal,microbial population and amount increase in HDMBR were the main reason for the enhancement of pollutant removal.In the aspect of membrane fouling control,HDMBR was lower than reactor DMBR in the EPS increase,the accumulation of LB-EPS,the percentage of particles less than 10 microns and the membrane flux decline.The variation of Zeta potential and viscosity of the sludge was mainly affected by LB-EPS accumulation amount.Fourier transform infrared（FTIR）spectrum and the three dimensional fluorescence（EEM）spectrum analysis of cake layer proved the major components of membrane fouling were protein and polysaccharide.On the one hand,the suspension packing provided carrier for microorganism,reduced the concentration of the mixture of activated sludge and decreased the viscosity of mixture;on the other hand,a large number of microbial adsorption in HDMBR absorbed EPS,reduced the content of EPS,and slowed the membrane fouling.Combined action of suspended and attached on the packing microorganisms in HDMBR,embodied the reinforcement of pollutant removal and good ability of membrane pollution control.Adding the particulate in HDMBR,its adsorption can not only strengthen the removal efficiency of pollutants,also improve mixture sludge characteristics,improve the filterability of active sludge,reduce the adsorption of gel layer,lower the viscosity of the mixture,inhibit sludge from depositing on the membrane surface,and extend the operation cycle of HDMBR.The contrast experiment by adding modified coal gasification residue and fly ash（reactor A and B）in HDMBR on the treatment of printing and dyeing wastewater,the effects of the pollutants removal efficiency reinforcement and the membrane fouling control on printing and dyeing wastewater by adding different particulate matter were studied.According to the effects on pollutant removal efficiency,SVI,viscosity of mixture and the impact of Zeta potential by different dosage,determined the optimal dosage of modified coal gasification residue and modified fly ash were 1200 mg/L,1000 mg/L,respectively.The results showed that under the optimal dosage condition,the reactor B was superior to reactor A on the removal efficiency of pollutants.The reason may be that particle size of modified fly ash was smaller than modified coal gasification residue,because the smaller particle size was,the larger specific surface area and surface free energy were,the greater the stronger adsorption ability was,and the higher the adsorption of the pollutants removal efficiency and the EPS were.Reactor A was higher than reactor B in EPS increase,the percentage of particles less than 10 microns,the Zeta potential decrease and viscosity increase,the membrane flux decline and membrane resistance increase,washing time of membrane.The membrane fouling process of reactor A was faster than reactor B.Scanning electron microscopy（SEM）of nylon fabric in two reactors showed the membrane surface with modified gasification residue deposited pollutants,the film hole were blocked.And less pollutants in the membrane surface added modified fly ash,pollution resistance was improved significantly.