Treating High Salinity Organic Wastewater Via Membrane Bioreactor Integrated Technology Bioaugmented By Halotolerant Bacteria

High-salt organic wastewater refers to organic wastewater with total dissolved inorganic salt content greater than 1%.It should be derived from petroleum exploitation,food processing,printing,dyeing,pharmaceutical and chemical industries.This kind of wastewater contains a large amount of toxic pollutants which is difficult to degrade,having high salt content and the range of wastewater quality change is large.The existing physical and chemical treatment methods generally consume large operational energy and leave over serious secondary pollution problems.Therefore,the cost-effective treatment technology of high-salt organic wastewater is the point of current research.Membrane bioreactor(MBR)is a new type of high-efficiency sewage treatment technology.However,when dealing with high-salt organic wastewater,the high salinity of water will inhibit the degradation of organic pollutants by microorganisms and cause a large number of microorganisms to die who cannot tolerate high salt content,and then resulting the effluent quality getting worse.Therefore,this study takes the high-salt dye intermediate wastewater as the research object,and carries out research on adding salt-tolerant bacteria to activated sludge to strengthen MBR treating high-salt dye intermediate wastewater for solving the problem that conventional MBR is difficult to treat high-salt wastewater.Firstly,the actual dye intermediate wastewater needs to be pretreated,and then mixing the effluent with the anaerobic effluent water to reduce the salinity of the wastewater reaching the influent requirement of the MBR.Taking the mixed water quality index as a parameter for simulating high-salt organic wastewater,and adding the bacillus cereus which is high salt-tolerant to the activated sludge to strengthen the MBR treatment of high-salt organic wastewater.The results show that:Bacillus cereus can reduce the effluent COD value of MBR significantly.Specific contents and conclusions were as follows:(l)Pretreatment of actual dye intermediate wastewater:it is difficult to degrade dye intermediates by a single technology,so the integrated technology of iron-carbon microelectrolysis-Fenton-ozone oxidation treatment is studied.Firstly,the dye intermediate wastewater is degraded by iron-carbon microelectrolysis.The operating conditions optimized by orthogonal and single factor experiments are:pH=3,solid-liquid ratio=30%,reaction time(T)=1.5h,the wastewater COD is decreased from 47,200 ppm to 28,200 ppm.The Fenton oxidation is used to further treat the iron-carbon microelectrolysis effluent under the optimized operating conditions by orthogonal and single factor experiments(H2O2 addition amount is 8 ml/L,PH=4,T=40min),the effuent COD is decreased from 28200ppm to 24200ppm.Finally,the Fenton effluent is treated by the ozone.Under the optimized optimal operating conditions(03 concentration=110ppm,reaction time=40min,pH=8),the effluent COD is decreased from 24200ppm to 2600ppm,significantly reducing the COD and color of the wastewater.However,since the salinity of the wastewater is close to 200,000 ppm,it is difficult to carry out biochemical treatment.Therefore,it is mixed with the anaerobic effluent of the domestic sewage treatment plant in a ratio of 1:3 to reduce the wastewater salinity to 50,000 ppm.As a reference,the simulated wastewater is made up and carrying out MBR treatment to simulated high-salt organic wastewater.(2)Salt-tolerant bacteria enhance MBR to treat simulated high-salt organic wastewater:taking the activated sludge from domestic sewage treatment plant and continuously increasing its influent salinity to 11000ppm,so that the activated sludge can be domesticated to salt-tolerant microorganisms for subsequent exploration of higher influent salinity.Firstly,we will investigate the change of effluent water quality of domesticated activated sludge under different influent salinities(10,000 ppm to 50,000 ppm)and different influent COD compositions(100 ppm simulated pollutant(SP)+400 ppm glucose(Glu),200 ppm SP+800 ppm Glu,600 ppm SP+400 ppm Glu),and then comparing with the effluent water quality of the activated sludge inoculated with Bacillus cereus(BC)under the same influent conditions.The results show that under the condition of influent salinity=50,000 ppm and influent COD composition of 600 ppm SP+400 ppm Glu,the removal rate of COD by domesticated activated sludge is 65%,and the COD removal rate of the activated sludge inoculated with BC is reaching 77%,indicating that salt-tolerant bacteria has obvious strengthening effect on MBR when treating high-salt wastewater.Afterwards,operating parameters such as sludge concentration(MLSS)and hydraulic retention time(HRT)were optimized to increase the COD removal rate of salt-tolerant bacteria-enhanced MBR to 82%.This paper integrates the process of "iron-carbon micro-electrolysis-Fenton method-ozone method" with salt-tolerant bacteria-enhanced MBR effectively degrading COD in high-salt wastewater.The research result can be a reference when treating high-salt wastewater.