Treatment Of Nickle-containing Wastewater By Two-stage Advanced Oxidation Process

The electroplating wastewater containing complex nickel is usually treated by “coagulation-sedimentation” craft,the breakage of complex is the key of the wastewater treatment.At present,Fenton method is commonly used in the project to break the complex.This method is simple in operation,but also has the problems that the hydraulic retention time is long,the treatment cost is high,an d the sludge production is large.The ozone-based advanced oxidation process takes more and more attention.In the previous research,the research group found that the treatment of the wastewater containing hypophosphite by O 3/H₂O₂+Fe²⁺ has good effect,and has the advantages of short hydraulic time,low treatment cost and small amount of mud.The removal mechanism of hypophosphite is close to that of complex nickel,so O₃/H₂O₂+Fe²⁺ process has the potential to effectively treat nickel-containing wastewater.This study investigated the characteristics of Fenton and O₃/H₂O₂+Fe²⁺ treatment of nickel-containing wastewater,and determined the appropriate treatment process of nickel-containing wastewater.The process was systematically optimized by treating the actual wastewater.The effect of Fenton and O₃/H₂O₂+Fe²⁺ process on the treatment of complex nickel wastewater was compared by a small scale test.The experimental results showed that under the best parameters,the nickel content in the effluent was 0.7 mg/L.O₃/H₂O₂+Fe²⁺ process could treat the effluent nickel concentration under 0.1 mg/L,but the cost of ozone addition was too high.By comparing two processes,the combined process of the two processes showed that the combined process of “Fenton+O₃/H₂O₂+Fe²⁺” was suitable for wastewater with high complex nickel content,and the concentration between was 15 mg/L.For the simulated wastewater,the “Fenton+O₃/H₂O₂+Fe²⁺” combination process was optimized.When the effluent of Fenton section below 15 mg/L,the subsequent process could treat the nickel concentration to 0.1 mg/L.The experimental results showed that the concentration of Fenton section effluent nickel could be maintained at about 15 mg/ L by reducing the dosage of reagent in Fenton section.The effluent of Fenton without precipitation could enhance the subsequent process.The residual hydrogen peroxide in the water could ensure the efficient operation of the subsequent ozone process,so the process of adding hydrogen peroxide in the O₃/H₂O₂+Fe²⁺ process could be simplified.Through the process comparison,O₃ and Fe²⁺ were added at the same time,the treatment effect was certain enhance the role.Therefore,for the complex nickel-containing wastewater,the appropriate process was “Fenton+O₃/Fe²⁺” two-stage advanced oxidation process,and the process parameters optimization.Based on the above research results,the effect of “Fenton+O₃/Fe²⁺” two stage advanced oxidation process on the actual wastewater treatment was investigated.The experimental results showed that the process had a stable and efficient treatment effect,the effluent nickel could reach the standard stability,and simultaneously could effectively remove Cu,COD and TP.The remove of them were 93%?76% and 99%.Compared with the traditional two-stage Fenton process,the process could save 30% to 50% of the cost,and could realize the economic and economical treatment of nickel-containing wastewater.