Study On The Treatment Of Mustard Wastewater With Super-Hydrophobic Membrane Device In Series With A/O Technology

With the continuous development of pickle industry,pickle wastewater and a large amount of wastewater produced in mustard production are increasingly.The concentration of organic matter,nitrogen,phosphorus,salt and other substances in mustard wastewater is high.Improper treatment will lead to surface water pollution and deterioration of environment.The treatment method of mustard wastewater is mainly biological method,but the salt in mustard wastewater inhibits the microbial metabolism of biological method and affects the pollutant removal efficiency.After the treatment facilities operate for a period of time,the pollutant removal efficiency decreases,resulting in the effluent quality not meeting the standard.Therefore,it is a hot issue in the field of high salt wastewater treatment to find a cost-effective and salt free wastewater treatment technology.Membrane distillation（MD）is a widely used technology in the field of seawater and brackish water desalination.It has good desalination efficiency and has great application prospects in the resource utilization of high salt wastewater and the concentration of brine.In this study,a technical route of using super hydrophobic membrane device in series Anaerobic-Oxic（Anaerobic-Oxic）technology to treat mustard wastewater is proposed and relevant research is carried out,in order to develop a process technology that can effectively remove salt,organic matter,nitrogen and phosphorus and other pollutants in mustard wastewater.The main contents and conclusions of this study are as follows:（1）The effect of influent temperature on the treatment of mustard wastewater by super-hydrophobic membrane device was studied.The results show that at the influent temperature of 50℃～70℃,the concentrations of COD,NH₄⁺-N,TN,TP and Cl^-in the effluent of mustard wastewater treated by super-hydrophobic membrane device decrease with the increase of influent temperature,while the membrane flux and contact angle are opposite.The removal rates of COD,NH₄⁺-N,TN,TP and Cl^-reached more than 95%,99%,99%,99%and 99%,respectively.The membrane flux gradually increased from 7.45 L·m^-2·h^-1 at 50℃to 14.29 L·m^-2·h^-1 at 70℃.The contact angle increased from 140.95°at 50℃to 144.9°at 70℃.When the temperature reached 70℃,the decrease of membrane flux was the smallest under the same membrane distillation time.Considering the pollutant removal and membrane flux,the super-hydrophobic membrane device treat mustard wastewater is better when the inlet water temperature is not lower than 60℃.（2）The effect of influent salinity on the treatment of mustard wastewater by super-hydrophobic membrane device was studied.The results show that in the range of influent salinity of 1%～15%,the concentration of COD,NH₄⁺-N,TN,TP and Cl^-of effluent for super-hydrophobic membrane device increase with the increase of salinity,the membrane flux is on the contrary,and the pollutant removal rate is relatively stable.The removal rates of COD,NH₄⁺-N,TN,TP and Cl^-were more than 85%,98%,96.5%,99.5%and 99.9%,respectively.The membrane flux gradually decreased from 14.9 L·m^-2·h^-1 at 1%salinity to 11.6 L·m^-2·h^-1at15%salinity.Considering the pollutant removal and membrane flux,the super-hydrophobic membrane device treat mustard wastewater is better when the inlet salinity is not more than 9%.（3）The effect of influent flow rate on the treatment of mustard wastewater by super-hydrophobic membrane device was studied.The results show that in the range of influent flow rate of 72 m L/min～470 m L/min,the concentrations of COD,NH4⁺-N,TN,TP and Cl^-in the effluent of mustard wastewater treated by super-hydrophobic membrane device decrease with the increase of influent flow rate,and the membrane flux increases with the increase of influent flow rate.When the influent flow rate is not lower than 289 m L/min,the removal rates of COD,NH4⁺-N,TN,TP and Cl^-are more than 85%,97%,95%,94%and 99.9%,respectively.The membrane flux gradually increased from 8.78 L·m^-2·h^-1 at 72 m L/min to 13.3 L·m^-2·h^-1 at 470m L/min.Considering the pollutant removal and membrane flux,the super-hydrophobic membrane device treat mustard wastewater is better when the influent flow rate is not less than289 m L/min.（4）The effect of vacuum degree on the treatment of mustard wastewater by super-hydrophobic membrane device was studied.The results show that the concentration of COD,NH₄⁺-N,TN,TP and Cl^-and membrane flux of mustard wastewater treated by super-hydrophobic membrane device with vacuum degree of-0.080mpa～-0.095mpa increase with the increase of vacuum degree,and the pollutant removal rate is relatively stable.The removal rates of COD,NH₄⁺-N,TN,TP and Cl^-reached more than 86%,98%,95%,97%and 99%,respectively.The membrane flux increased from 6.94 L·m^-2·h^-1 at-0.080MPa to 16.44 L·m^-2·h^-1 at-0.095MPa.Considering the pollutant removal and membrane flux,when the vacuum degree is not less than-0.090mpa,the super hydrophobic membrane device has a better effect on the treatment of mustard wastewater.（5）The influence degree of operation parameters of super hydrophobic membrane device was studied.The results showed that salinity had the most significant effect on membrane flux,COD removal rate and chloride ion removal rate;temperature had the most significant effect on ammonia nitrogen and total phosphorus removal rate;and flow rate had the most significant effect on total nitrogen removal rate.（6）The three-dimensional model of the super-hydrophobic membrane device is simulated by fluent.The effects of the inlet temperature and inlet flow of cold and hot liquid on the flux are simulated respectively,and the simulation results are verified by the experimental results.The results show that the trend of the simulation curve is basically consistent with the experimental trend.（7）The start-up of UASB and SBR reactors was studied.The results show that UASB and SBR reactors can be successfully started in about 2 months and 30 days,respectively.The removal rate of COD by UASB reactor can stably reach more than 90%,and the removal rates of COD,ammonia nitrogen,total nitrogen and phosphate by SBR reactor can reach more than90%,95%,80%and 60%,respectively.（8）The UASB and SBR reactors were acclimated under salinity of 0.5%,1.0%,1.5%and 1.5%,2%,2.5%,3%,3.5%,4%,4.5%and 5.5%,respectively.The results show that when the salinity is less than 1.5%,the UASB reactor still has a COD removal rate of more than 90%and has good salt tolerance;When the influent salinity of SBR reactor is lower than 4.0%,the removal rates of COD,ammonia nitrogen,total nitrogen and phosphate of SBR reactor can reach more than 80%,90%,80%and 50%respectively,which has good salt resistance.（9）The mixed liquid of super hydrophobic membrane device effluent and mustard comprehensive wastewater was treated by UASB+SBR device.The pollutant removal performance of the mixed liquid treated by UASB+SBR device was studied when the mixing ratio was 1:1,1:4 and 1:10,respectively.The results show that the mixed wastewater for the effluent from super hydrophobic membrane device and mustard comprehensive wastewater was treated by UASB+SBR device at the mixing ratio of 1:1～1:10,the COD、NH₄⁺-N、TN、PO₄^3--P removal efficiency are high.