Study On Forward Osmosis Membrane Separation Technology For Campus Life Wastewater Treatment

The current status of the urban wastewater treatment is that the nitrogen and phosphorus removal is not ideal,the energy consumption of the process is large and the cost of sewage treatment is high.The membrane separation technology has been studied widely and applicated practically because its sewage treatment effect is high efficient.In recent years,the FO membrane separation process as a new type of membrane separation technology has been attentioned and researched in-depth because of its low energy consumption,high rejection,reversible membrane fouling,etc.FO shows the potential used value in sewage treatment,food, pharmaceuticals,desalination,energy development and other sectors.To analyze the treatment effect and membrane fouling problems of FO membrane separation technology using for campus life wastewater treatment,and to provide experimental evidence for the actual operation,regulation,other aspects and the feasibility of seawater as driven solution,The paper uses the forward osmosis membrane separation equipment for the experimental device,TFC-ES forward osmosis membrane which from the HTI of United States as the membrane and the seawater as the draw solution.Firstly,the performance of TFC-ES forward osmosis membrane has been studied and evaluated in this paper.The forward osmosis membrane structures were characterized through the SEM image.When the experiment changed the membrane orientation and the cross-flow speed operation factors,the process of forward osmosis membrane such as water flux and the reverse solute diffusion phenomenon were studied. The experimental results shows:The initial water flux of FO mode is smaller to the PRO mode,the overall changing trend of water flux is smaller and the reverse solute diffusion phenomenon is also in a small amount. When the cross-flow speed from lL/min up to 1.5L/min and then increased to 2L/min,the initial water flux was more and more big,the driven solute reverse osmosis phenomenon was more and more serious.Then,the TFC-ES osmosis membrane was applied to the actual campus sewage treatment,the draw solution was used the seawater,the results showed that the water flux in FO mode was smaller than its under the PRO mode,but the downward trend was also smaller,the water flux was stable relatively,and the trapping effect of ammonia nitrogen, nitrite nitrogen, nitrate nitrogen were better,too.When the test used the FO mode and kept the other operating conditions remain unchanged,the cross-flow velocity from 1L/ min up to 1.5L/min and then increased to 2L/min,the water flux increased with the speed increasing,but the trapping effect of ammonia nitrogen, nitrite nitrogen,nitrate nitrogen of sewage were lower and lower.Finally,the test researched the membrane fouling and membrane cleaning of the forward osmosis membrane separation processes,The test did the membrane cleaning and observed the cleaning effect of the FO mode and PRO mode at the same time deal-ing with sewage,the we found that the water flux of contaminationed membrane in the FO mode was in low decline trend than the PRO mode,it shows that the low degree of pollution.The contaminationed membrane of the FO mode soaked in the distilled water and then cleaned through the system running,the cleaning efficiency reached 98.8%,while the cleaning efficiency of the contaminationed membrane in the PRO mode after cleaning reached 96.5%,the water flux are restored to the pre-contamination mostly,which indicates that the performance of forward osmosis membrane can be recovered,it also shows that the membrane fouling of FO mode is lighter,the cleaning effect is more obvious.The SEM results also proved that the pollution was lighter in FO infiltration process and the pollutants were simply attached to the surface of the membrane. Though the simple physical cleaning methods, the membrane surface can restore the original shape basically.