Fabrication Of Continuous Flow Photocatalytic Sterilizer And Study Of Its Water Treatment Performance

The two major types of the water pollution are the biological and chemical pollution.Biological pollution mainly refers to pathogenic microorganism,including bacterials,virus and protozoa which can make human get infectious diseases.To control the biological pollution in water effectively,disinfection processes must be set in all kinds of water treatment process.At present,UV disinfection is widely used in water disinfection field.But the cell structure of bacterial won't be destroyed in UV process.So the phenomenon of photoreactivation may occur.In recent years,lots of reports revealed that trace amounts of antibiotics and other kinds of toxic organic pollutants had been detected in natural water.These organic pollutants can not be removed through the simple process of waterworks.Photocatalysis technology is expected to solve the aboved two problems simultaneously.Photocatalysis process can produce hydroxyl radicals to oxide the cell wall of bacterial to kill it thoroughly.Besides that,photocatalysis technology is also an effecient way to degrade trace organic pollutants.Based on those,we designed and fabricated a continuous flow photocatalytic supported reactor which disposal capacity is 150 L/h.We measured its ability of disinfection and degrading organic pollutants.The main experiment contents and achievements are as follow:?1?Fabrication of continuous flow photocatalytic reactor.The device totally consists of UV reactor,photocatalyst support component,influent pump,flow control valve,turbine flowmeter,UV sensor,temperature sensor,control system and digital screen.Raw water pipeline connects to the pump suction,outlet of influent pump connects to flow control valve.Flow control valve connects to turbine flowmeter,and turbine flowmeter connects to UV reactor.Photocatalyst support component can be made into different shapes but its size must adapt to the size of UV reactor to be put into.It should be also convenient to be installed and detachable.If so we can replace it at any moment.Double-helical catalyst supporters were designed and manufactured.With the UV irradiation dose of 10.5 mJ/cm2,its removal rate of E.coli was 3.33 log10,which was higher than 3.00 log10 of parallel plate and 3.06 log10 of corrugated palte.So double helix was chosen as the supporter configuration.?2?Catalyst immobilization and research of device's performance of removing bacterial and organic pollutants.TiO₂ was doped on double helical supporters by sol-gel method and anode oxidation method,respectively.SEM images show that TiO₂ film and TiO₂ nanotube were loaded on the surface of Ti successfully.UV-VIS DRS shows that two types of TiO₂ have good absorption in ultraviolet ray.XRD shows that the main crystal form of TiO₂ made by two methods are both anatase 004.Ultrasonic concussion experiment demonstrated that the mechanic strength between catalyst and supporter was strong enough.Supporter was put in the UV reactor and then the performance of sterilization and removing organic pollutants were checked.With the UV irradiation dose of 42 mJ/cm2,the removal rate of E.coli of photocatalytic sterilization process is as high as 5.45 log10,which is dramatically higher than that of UV sterilization process.Meanwhile,we also investigate the sterilization effect under different influent concentration and different UV radiation dose.The device showed excellent stability.Besides that,the device showed good removal efficiency of phenol and sulfamethoxazole.After the treatment that includes three circles,the removal rate of phenol and sulfamethoxazole achieved 32.1% and 99.4%.?3?The preparation of TiO₂/GR photocatalyst and the composite material's performance research of removing of E.coli and organic pollutants.Static experiment of photocatalytic degradation of phenol demonstrated that TiO₂/GR?1 wt%?showed highest photocatalytic activity.Its first-order photodegradation rate constant was 4.02 mg/L·h,which was higher than that of other composite materials.TiO₂/GR?1 wt%?was then loaded on double helical supporter and used to remove E.coli and phenol in continuous flow photocatalytic reactor.The results indicated that the concentration of E.coli in effluent was 29.9% lower than that of TiO₂,and the removal rate of phenol was improved by 12.7%.That testified TiO₂/GR?1 wt%?with stronger absorption ability and better photocatalytic efficiency contributed to better water treatement capacity of continuous flow photocatalytic reactor.