The Treatment Of High Concentration Laboratory Organic Wastewater By Fenton And Electrolytic Oxidation Technology

The wastewater discharged from university laboratories contained a large amount of contaminants. The phenomena that many laboratories discharged their wastewater into sewage pipes without any treatment had caused serious pollution. The treatment of organic wastewater(COD>15,000 mg/L) obtained from pharmaceutical manufacturing laboratory was investigated in this paper. The raw wastewater was treated by Fenton and Electrolytic oxidation technology separately. The optimal combined process of Fenton and Electrolytic oxidation technology was determined by the results of biotoxicity measurement and biodegradability assessment. Molecular distribution experiments, UV-vis scanning spectra and 3D-EEM spectra were applied to analyze the degradation pathway of the organic wastewater.The survey results suggested that university laboratories wastewater had high pH, SS, chroma and COD value. The wastewater produced by chemical laboratories had extremely high COD value, which could not be discharged into urban sewage pipes directly.Single factor experiments of Fenton process were used to investigate its optimal conditions. The experimental results showed that the TOC removal efficiency and COD removal efficiency could achieve 50.0% and 53.4%, respectively, under the conditions of pH=3-5, FeSO4=1.6 mmol/L, H2O2 =1.0 ml/L. The FeSO4 concentration was the main item which influenced initial the reaction rate of Fenton process.Box-bohnken Design(BBD) method was applied to optimize the conditions of Electrolytic oxidation technology. The results suggested the maximum value of COD reduction(38.6%) could be achieved at the following conditions: current density of 52.69 A/m2, electrolyte amount of 10.71 g/L and reaction time of 2.33 h. The analysis of variance(ANOVA) indicated the regression model was significant. The linear terms of the model and the interaction term of current density and electrolyte amount were significant factors.Three kinds of combined processes(Fenton-Electrolytic Oxidation, Electrolytic Oxidation-Fenton, Coupling process of Fenton and Electrolytic Oxidation) were tested for organic wastewater treatment. All the combined processes performed better than the standalone technology in organic wastewater COD reductionr. The biotoxicity of wastewater was proved to be reduced significantly after the Fenton-Electrolytic Oxidation treatment. The combined processes could improve the biodegradability significantly. The B/C values of the effluents by Fenton-Electrolytic Oxidation process, Electrolytic Oxidation-Fenton process and Coupling process had increased to be 0.41, 0.35 and 0.3 from 0.02, respectively, which suggested the wastewater could be further treated by biological technology.