Study On Pretreatment Of Dye Intermediates Wastewater By Ozonated Internal Electrolysis

Dye intermediates are crucial chemical raw materials.The wastewater from production process of dye intermediates is characterized by high salinity,poor biodegradability,and great changes in water quality and quantity,which make its treatment rather difficult.Herein,wastewater generated from the desalting treatment in a factory of dye intermediates in Hebei Province was taken as the research object,aiming to improve the existing internal electrolysis?IE?sewage treatment section.To improve the efficiency of sewage treatment,the existing IE treatment section was upgraded and modified into Ozonated Internal Electrolysis?OIE?treatment using new IE filler and ozone?O3?.The efficiency of wastewater treatment by IE,ozone and OIE was studied respectively with COD removal rate as evaluation indexes.The single factor experiment were carried out to find the optimal conditions;Specifically the law of changes in the pH value and iron ion concentration of wastewater after flocculation was explored;the passivation phenomenon of IE filler in IE treatment and OIE treatment was investigated;and the composition changes before and after treatment also studied.IE and O₃ treatment proeesses were adopted to treat the simulated wastewater of dye intermediates.In wastewater treatment of dye intermediates using IE,the optimal conditions is obtained as:pH=3,HRT=2,volume of:filler 30%,aeration time 15 min,air aeration volume 1.0 L/min;and the influence of various factors are ranked as:HRT>packing volume>pH>aeration time.In ozone treatment of dye intermediates wastewater,the optimum pH value of ozone oxidation is 9,it is found that the treatment effect under alkaline conditions is better than that under the acidic conditions.The higher the ozone concentration in the reaction,the lower the pH value after the reaction.In the experiment of OIE,the comparison of the treatment effect of different treatment shows that OIE outperforms other treatment measures in wastewater.When the dosage of ozone is 47.46 mg/?L·h?,under the optimal conditions,after 90 min of reaction,the COD removal rate of the real wastewater reach about 38%,and the TOC removal rate is about 13%,while that of the chroma is above 80%,and the B/C?BOD/COD?of wastewater increase from 0.12 to 0.34.In the analysis of component changes before and after treatment,the differences of benzene ring absorptions after different treatments were compared.Compared with IE treatment and ozone treatment,OIE treatment showed an obvious synergistic effect,which can effectively improve the B/C ratio of wastewater,break the benzene ring,and more extensively adapt to pH.The comprehensive consideration of the findings demonstrates the strong oPerability regarding OIE wastewater treatment of dye intermediates.This study provides a reference for the pretreatment of dye intermediates wastewater.