Experimental Study On The Further Treatment Of Aniline Wastewater By Absorption Methord

This technology is the part of the follow-up study of the technological breakthroughsproject of Gansu Province——《Study of Aniline Wastewater Treatment by BiologicalProcess》. Aniline wastewater has the features of high toxicity, high color, difficultbiodegradation, and so on. And if they are let to water without any disposals they will greatlyharm the environment. This article focuses on the follow-up treatment study of the industrialaniline wastewater with low concentration which has still not reached the emissions standardafter being treated by biological treatment, which has the ideas of using a modified zeolitesadsorption method to conduct a follow-up treatment of the wastewater, and it hopes thatthrough the study the emissions of major pollutants in water are up to the level two standardof the state《Wastewater Discharge Standards》(GB8978-1996), and the effluent of anilinewastewater can let upping to the standard through the two units' degradation, which are thebiological and adsorption methods. So an efficient, economic and easyly industrialized newprocess of aniline wastewater treatment can be found from the study.The test is divided into four parts. The first part is the study of modification of naturalzeolites, which compares the adsorption rates of aniline in simulant wastewater by the zeolitesmodified with various means of modification, and in order to find the best way of it. Thesecond part is the study of practical industrial aniline wastewater treatment by the staticadsorption of modified zeolites. From the study of influencing factors of anilinewastewater treatment to determine the optimum operating parameters, and meanwhile theadsorption laws of the modified zeolites for aniline, COD_cd, NH₃-N and color in wastewaterare researched under the best working conditions. The third part is the study of practicalindustrial aniline wastewater treatment by the dynamic adsorption of modified zeolites. Bythe study of influencing factors of dynamic adsorption the optimum operating parameters aredetermined which makes the effluent of aniline wastewater let upping to the standard afterbeing treated, and the aniline adsorption breakthrough curves are mapped meanwhile. Thefourth part is the study of modified zeolites regeneration, and by comparing the analysis ratesof aniline by the zeolites regenerated with various eluates in order to find the best way ofregeneration. In addition the study of influencing factors of regeneration efficiency has beendone.The study of the first part shows that the best way to modify natural zeolites is0.07mol/L sulfuric acid solution modification; the best conditions of modification are:modification temperature at room temperature, modification time 2h, the ratio of volume ofmodified solution with the mass of zeolites at 9ml/g. Meanwhile, the smaller the particle sizeof zeolites, the higher the adsorption removal rates of aniline by modified zeolites.The study of the second part shows that when the amount of zeolite 11g/L,adsorptiontime 2h,the reaction temperature at room temperature,pH of the wastewater at 3 the modified zeolites have good removal effects on aniline wastewater which has the concentration of50mg/L of aniline, and the removal rates of. aniline exceed 90%; the linear fittings of anilineadsorption isotherm to the models of Langmuir and Freundlich at room temperature revealsthat the adsorption law of the modified zeolites for aniline can better meet the Langmuiradsorption isotherm and the correlation coefficient R²=0.9952; in addition, COD_cr,NH₃-N andcolor can be effectively,quickly adsorbed and removed from the wastewater, and theexperimental results show that when the concentrations of COD_cr, NH₃-N and color in the rawwater are respectively 460mg/L,31mg/L and 40 times the highest removal rates of them bymodified zeolites are 69.6%,71.9% and 95%, and the export concentrations of COD_cr, NH₃-Nand color are respectively 140mg/L,8.7mg/L and 2 times.The study of the third part shows that when the adsorption layer height at 65cm,stayedtime 60minutes,room temperature and value of pH at 3 of the wastewater the concentrationsof aniline and COD_cr in exports of the wastewater are all up to the level two standard of thestate《Wastewater Discharge Standards》(GB8978-1996) aider being dynamically adsorbedby modified zeolites, in addition, it can be seen from the adsorption breakthrough curves ofaniline that when the accumulative time of export water reaches 148h the export concentrationof aniline will arrive at the leakage point of 2mg/L, and when the accumulative time reaches452h the adsorption column will be completely penetrated. Meanwhile when the time is lessthan 170h the concentrations of COD_cr in exports are always reaching the standard during thattime.The study of the fourth part shows that the best way to regeneration for the modifiedzeolites is the hydrochloric acid eluent regeneration which has the concentration of 7mol/L.Under conditions of regenerative time for 60minutes,the ratio of volume of eluent with themass of modified zeolites at 14ml/g the analysis rates and the second adsorption rates ofaniline by the regenerative modified zeolites are all round 90%, which has good regenerativeeffect. Meanwhile the test proves that the higher eluting temperature, the better effects ofregeneration, and it will cause higher handling costs and more complicated operation if thehigh-temperature regeneration is done, which are not conducive to the economic regenerationfor the modified zeolites.Through this thesis, the research results of the whole project of《Study of AnilineWastewater Treatment by Biological Process》have achieved the objective established at thebeginning of the setting up of the project. However, due to the constraints of time andconditions, the more perfect and reasonable reactor need to be designed and made to studyfurther the dynamic characteristics of the reaction systems and develop the research ofmechanism of reactors from tests, which can further optimize the technical flows andparameters of reactors, and to obtain better results. Also, because of the difference of sizes of the actual installation with the laboratorial, and therefore the middle study of reactors shouldbe conducted if there are enough conditions for the research.