Study On The Pretreatment Of Aniline Series Dye Intermediate Wastewater

Dye intermediate is a kind of typical fine chemical product, and thecharacteristics of its wastewater are high concentration, complication of organiccomponents,more difficultly reduced substances, high concentration of salinity, highchroma and poison, etc. At present, the treatment of dye intermediate wastewater isstill a difficult problem in our country.Therefore, the study on the treatment processhas important and practical significance.By means of comprehensive references and examples of dye intermediatewastewater, the general technology and development of the treatment for productivewastewater of high concentration and salinity were briefly summarized. Consideringthat the special characteristics of the wastewater and the requests of the engineeringfeasibility and so on, the optimum experiment conditions and process techniques wererecommended, such as aeration, electrolysis and other processes. A better result wasattained in the study by respectively treatment technique according to theconcentration of wastewater. It had been scarcely reported about the use in thetreatment of dye intermediate wastewater so far.Study on the wastewater treatment was divided into two parts in the paper. TheCOD, chroma and absorbency were the test indexs, the inert graphite was used as theelectrode, the orthogonal design of L9(34) was to introduced to optimize experimentconditions.First, aniline -2,5-disulfonic acid wastewater and m-hydroxy-N,N-diethyl anilinewastewater were respectively investigated in details. For the former, the optimalelectrolysis conditions were obtained and the electrobath voltage was 12.0V,remaining time was 2.0h, electrode space δ was about 30mm and pH value was 6~8.After getting rid of surplus chlorine, the discharge's COD was less than 200mg/L andchroma removal rate was more than 96%. Therefore, the drainage could approachrequirements of wastewater standards. For the latter treatment method, the first stepwas the associated technique of aeration-electrolysis, and the next wasbiodegradability. The optimal operating conditions were obtained and pH value was i陶新河: 染料中间体生产废水预处理的研究 2004 年 5 月about 7.0, aerating time was about 100min, the electrobath voltage was 7.0V,remaining time was 2.0h, and electrode space δ was 30mm. After treatment, theCOD removal rate was about 82%. The results proved that the treatment of dyeintermediate wastewater was feasible by means of the associated technique ofaeration-electrolysis.Secondly, the manufactory's synthetical wastewater was further study in thesame measure. The condition of associated technique of aeration-electrolysis wasimproved. The results showed that the optimal operating conditions were: aerationtime was 120min, aeration capacity was 150L/h, aeration pH value was about 5.0,electrobath voltage was 8.0V, remaining time was 110~120min, electrode space δwas 30mm alike, electrolysis pH value was about 7.0 and circumfluence percentagewas 10%. At the optimal operating condition, the optimal COD & chroma removalrates were obtained and the ratio of BOD5/COD increased and biodegradabilitypromoted. The results proved that the treated high concentration wastewater couldreach the requirements of discharge standards after treatment by bioprocess. Thedischarge's stabilization could be improved and the amount of drainage could bedecreased by means of the associated technique of aeration-electrolysis.