Pretreatment Of The Fine Chemical Wastewater By The Combined Process Of Fe/C Micro-electrolysis, Electrocatalytic Oxidation And Electro-Fenton

Fine chemical wastewater is of complex organic components, toxic pollutant, high amount of organic content, high chroma and refractory, so it is always a challenge for us in the wastewater treatment. As one of many members of it, dyeing intermediate wastewater is getting more and more attention of the world and experts. The hybrid type dyeing intermediate wastewater is more difficultly treated than the dyeing intermediate wastewater in an enterprise, for its more complex organic components, stronger acid, higher salinity. As a result, the combined process of Fe/C micro-electrolysis, Electrocatalytic oxidation and Electro-Fenton was applied to pretreat the wastewater in the experiment, and evaluate the treatment effect through the analysis of decoloration and COD removal.Because the raw wastewater of hybrid type dyeing intermediate wastewater was of strong acid, high salinity and refractory and its acidity was much too strong as test wastewater, it was filtered with cinder and used as the intial test wastewater. Firstly, with the help of orthogonal test, the factors’impact on micro-electrolysis effluent was listed as the following order:iron carbon form>stirring intensity> reaction time. The orthogonal test and single-factor test results showed that the optimum condition in the test was that the iron carbon was a kind of mixed packing, the reaction time was6hours, the mass ratio of ferric to carbon was3:1, the stirring intensity was350r/min and the iron-carbon dosage was48g. Under the optimal conditions, the removal rate of chroma and COD was36.0%and22.9%, respectively.Secondly, based on the result of electrocatalytic oxidation orthogonal test, the factors’effect order on the effluent was that reaction time> electric current density> cathode material> plate space. The consequence of single-factor test indicates that the optimum conditions was that the cathode material was stainless steel, the reaction time was2.5h, the electric current density was60mA/cm2and the plate space was5.5cm. Under the optimal conditions, the removal rate of chroma and COD was45.60%and28.15%, respectively.Thirdly, according to the result’s range analysis of electro-Fenton, the factors’ influence order on the effluent was that catalyst dosing> the dosage of particle electrode> the aerobic means of cathode> the FeSO4dosage. The orthogonal test and single-factor test results showed that the optimum condition was that the FeSO4dosage was0.60g, the aerobic means of cathode was stirring and aeration, the catalyst dosing was La2O3and MnO2, the La2O3dosage was0.20g, the dosage of particle electrode was6.0g and the aeration rate of cathode was80L/h. Under the optimal conditions, the removal rate of chroma and COD was18.40%and19.12%, respectively.Finally, Adjusting the pH value to coagulate directly is moer effective, compared to the addition of PAC and PAM in the orthogonal test, and the best pH value was8. On the basis of adsorption test, its optimal conditions was that the mixed means was stirring, the kind of activated carbon was coaly activated carbon powder, the reaction time was20min and the activated carbon powder dosage was4.0g. Under the optimal conditions, the coagulation and adsorption test’s removal rate of chroma and COD was34.56%and24.38%, respectively.With the optimal operating parameter, the combined process’removal rate of chroma and COD was98.52%and64.40%, respectively. Meanwhile, according to the analysis of the volatile organic compound content in every process effluent, benzene series, methy benzene series, naphthaline and their ramification could be degraded to small molecule or be mineralized completely. The proposal was achievable in the result.