Experimental Study On The Treatment Technology Of Photovoltaic Wastewater

Solar is inexhaustible. Though solar photovoltaic energy is green energy, but there is still some serious pollution in the production process of photovoltaic cell which cannot be ignored, such as the discharge of water pollutant. The treatment of this water can hardly meet the emission target. Further, the deep treatment and reuse of these water pollutants still lied in initial stage and much of technical problems need to be solved in the treatment of photovoltaic cell. Therefore, in view of characteristics and shortcomings of the current photovoltaic wastewater treatment process, this paper carried out the research of defluorination, decalcification, denitrifi cation, optimization of membrane filtration technology and reuse of concentrated water of reverse osmosis technology which based on the pretreatment/RO/triple-effect evaporation process.The membrane pre-treatment process was also studied by this paper. Impacts of physical and chemical precipitation of wastewater during solar cell production was analyzed. Concentration of calcium ion, pH and sedimentation time on the effects of fluoride removal were investigated. Removal rates of different Na2CO3 concentrations were studied, meantime. The calcium ion removal rate could arrived at 88.9% under the condition of 1.6 CO3/Ca molar ratio, while fluoride removal rate raised up to 99.38% at Ca/F molar ratio of 0.57, pH of 8.5 and sediment time of 2h.When treated by the biological technical, the ammonia and COD removal can arrive at more than 80% by designed system under steady temperature, pH and DO after adjusting.Reverse osmosis process was studied. The influence of RO’s working pressure, influent concentration, pH value, selection of RO membrane and modification of PAA laminating film on the nitrate removal performance were considered. Mechanism of optimum crystal form which can accelerate the crystallization of calcium sediment in the highly NOx-N content waste water, different pH valves and it’s usage on calcium ion removal were inspected. Compared with TFC and dow BW bitter brackish water reverse osmosis, dow SW desalination membrane revealed a best nitrate removal of 90% during the nitrate range of 400-3500 mg/L. The removal of nitrate in photovoltaic wastewater was raised by different degrees after the modification of RO. Removal rate of calcium in the concentrate was 83.3% at the CaCO3 addition of 10 g/L, pH of 9.5 and reacting time of 90 min.Multi membrane combined process integration technology was studied. In detail, a breakthrough was gained on the RO recovery. A better multi membrane integrated technology with higher concentrate times and lower operating costs was screen out by using secondary desalination membrane to further soften and treat the primary RO concentrated water.