Study On Pretreatment Of Silicon Slicing Wastewater In Photovoltaic Industry

The industry of photovoltaic power generation has developed rapidly in recent years andthe complete industry chain has been formed in the domestic. The development of relevantindustries of photovoltaic power generation has huge social and economic benefits, however,the production of materials like battery pack et al. are supposed to be "high energyconsumption and high pollution". The environmental control for this kind pollution shouldarouse the high concern of the society.The wastewater generated by silicon slicing production in photovoltaic industry mainlycontains high concentration of organic matter in the wafer cutting part and large amount of H⁺and F^-in the silicon cleaning process. After the treatment of "lime+PAC+PAM" processing,the concentration of F-can be decrease to below10mg L^-1, but the organic matter is difficultto achieve treatment standards through the conventional hydrolysis acidification+oxygencontact oxidation technology. This article aims to reduce the concentration of organic matterand improve its biochemical performance by pretreating the high concentration organicslicing wastewater. Fenton,iron-carbon micro-electrolysis and their combined process hasbeen used to remove the organic matter in the slicing wastewater with COD10000mg·L^-1;Simulation studies confirm the effect factors of the important degree through the orthogonalexperiments and identify the best reaction conditions using single factor experiments.The results of Fenton tests display, the importance of effect were in the order of pH>dose of FeSO₄> effect time> dose of H₂O₂. The optimum parameters of those effects werefound to be2.5,23.3mL·L^-1,6.67g·L^-1,60min for pH, dose of FeSO4, effect time, dose ofH₂O₂respectively, and the removal of COD45.3%, B/C=0.34. The results ofH₂O_2-iron-carbon micro-electrolysis tests display, the importance of effect were in the orderof pH> effect time> iron-carbon ratio> dose of H₂O₂. The optimum parameters of thoseeffects were found to be2.6,60min,6.67g·L^-1,23.3mL·L^-1for pH, effect time, iron-carbonratio, dose of H₂O₂, respectively, and the removal of COD34.0%, B/C=0.26. The results ofH₂O_2-iron-carbon micro-electrolysis and Fenton combined tests display, the optimum parameters of those effects were found to be2.6,90min,1:1.25,6.7mL·L^-1for pH, effect time,iron-carbon ratio, dose of H₂O₂respectively for the H₂O_2-iron-carbon micro-electrolysis partand2.5,60min,23.3mL·L^-1,6.67g·L^-1for pH, effect time, dose of H₂O₂, dose of FeSO4respectively for Fenton part.The removal of COD is71.2%, B/C=0.51.The combined process of Fenton and H₂O_2-iron-carbon micro-electrolysis is optimalrelatively, but since the large dose of H₂O₂, its cost remains high.