Application Of Advanced Oxidation Technology In Dye Wastewater Treatment

Disperse dye wastewater with high chroma,salinity and organic matter concentration,and with certain toxicity and difficult to biological degradation,is recognized one of the intraetable industrial wastewater.The crystallization waste mother liquors and the effluent which from regulation pool and biological treatment used in the experiment obtained from a dyestuff making plant.Fenton oxidation was applied to improve effect of wastewate treatment.Fenton reagent was used to treat five wastewaters including disperse orange,disperse blue and disperse violet waste mother liquors and the effluent from regulation pool and biological treatment.In order to confirm the optimum response condition,the main factors influencing color,COD and TOC removal efficiency were investigated one by one.For the first four wastewaters,when the concentration of hydrogen peroxide were 264.4mmol/L,352.9 mmol/L,441.2mmol/L,312.5mmol/L,n[H2O2]/n[Fe2+]value for10?20,initial pH value for 3,reaction two hours,the experimental results indicated that the removal rate of TOC were 43.1%,27.3%,39.5%and 55.6%.The biochemical effluent obtained a poor effect with the highest TOC removal rate was only reach 17.5%by Fenton reagent.The concentration of hydrogen peroxide is the most important factor to the cost of Fenton reagent.The TOC removal rate of five wastewaters treated by same conditions were compared,the results showed which obtain a higher utilization of H2O2 with higher initial concentration of TOC.Therefore,Fenton reagent suitable for application in preprocessing when use it treat wastewater.The organic molecular structure takes important influence to Fenton reagent oxidation effect.For the three kinds of disperse dyes waste mother liquors in same COD,the removal of COD and TOC were investigated by Fenton reagent in the same conditions.The results showed that the disperse violet waste mother liquor was the most difficult to degradation,canbon mineralization amount significantly lower than disperse orange waste mother liquor and disperse blue waste mother liquor.It was founded that in all processed solutions,acetic acid ions appeared and the amount of nitrate ions increased detected by ion chromatograph.And in the processed disperse orange waste mother liquor and disperse blue waste mother liquor,there were another small molecule organic acid(such as formic acid,acetic acid and propionic acid,etc.)and halogen ions which the dye molecular structure contains.Combined the results with the organic matter degradation mechanism researched,three dye molecules's degradated way by Fenton reagent were gussed.First,hydroxy radical attacked C-N bond where high electron density near the azo bond,and then turned another C-N bond,N became nitrate ions free in solution.Finally,hydroxy radical through a series of reaction such as electron transfer reaction,addition and benzene ring ring opening degradation completely mineralized organic matter into CO2 and H2O or degradated to small molecule organic acid.The disadvantage of Fenton reagent is the strict initial pH value and secondary pollution cause by ferrous ion.This paper researched TOC and color removal of the three waste mother liquors treated by saturated acticated carbon catalytic hydrogen peroxide oxidation(AC/H2O2)and AC/Feonton system,used saturated carbon instead of ferrous ion and added saturated saturated activated carbon in Fenton reagent.And recycling tested the saturated activated carbon in the AC/H2O2 system,comprehensived it with Fenton reagent and AC/H202 for the economy.The experimental results showed that the catalytic effect of activated carbon is higher than ferrous ion in acid condition.Activated carbon and Fenton has cooperative effect,is the best way to remove TOC.Saturated activated carbon catalytic H2O2 decompose can be used repeatly,the TOC removal rate of mother liquors were more and more high in the reuse test of eight times.Using saturated acticated carbon catalytic H2O2 oxidation dealing with three waste mother liquors,the sulfutic acid can be recycling utilization if the mother liquor returns to process application,it is an economic processing methods.