| Printing-Dyeing wastewater is the largest emitter of industrial wastewater in China.Due to its characteristics of deep chromaticity,complex composition and bad biodegradation,the secondary effluent by physicochemical and biochemical treatment still cannot achieve the emission standards and thus advanced treatment is needed.So far,China lacks cost-effective advanced treatment.This article puts forward a method that firstly using activated carbon to adsorb and enrich the dye,slurry,surfactant,microbial metabolites and other organic matter in biochemical effluent of Printing-Dyeing wastewater and then through advanced oxidation process(AOP),regenerating the saturated activated carbon.This method reduces the processing cost and provides technical support for activated carbon’s large-scale industrial application.The main research content is as follows.(1)Using activated carbon adsorption as the advanced treatment of the biochemical effluent of Printing-Dyeing wastewater Through the results of adsorption experiment and surface properties,selecting the most fitactivated carbon in the market.Study the affecting factors and adsorption characteristics of the biochemical effluent of Printing-Dyeing wastewater.When the dosage of activated carbon is 10 g/L,not adjusting the origin pH value of the wastewater,after 120 min adsorption process,the COD and TOC removal ratio achieve 73.01%and 86.82%.The COD and TOC value of the effluent is respectively 76.81 mg/L and 12.95 mg/L.(2)Fenton oxidation regeneration of the activated carbonThrough a series of single factor experiment,investigate the effects of regeneration time,hydrogen peroxide dosage,pH value,the molar ratio of H2O2 and Fe2+,the way to add Fenton reagent and other factors on regeneration adsorption.When pH value is 1,the dosage of hydrogen peroxide is 1 mL,the molar ratio of H2O2 and Fe2+ is 20:1,regenerating time is 180 min,the effect is best.Calculated on COD removal rate,the regenerating rate is 49.93%and 36.80%respectively.(3)In situ Oxidation Regeneration of the Used Activated Carbon with Advanced Oxidation Technology Based on Sulfate RadicalsThe thermal activation of peroxymonosulfate(PMS)and sodium peroxydisulfate(SPS)based on peroxydisulfate radical has good effect on activated carbon regeneration,which has stable properties that can overcome the defects of severe Fenton regeneration reaction process.When temperature is 100℃,of oxidant dose is lg/gAC,regeneration time is 60 min,without adjusting the origin pH value,after PMS and SPS regeneration,the activated carbon’s regeneration rate(calculated on COD removal rate)is 53.9%and 55.98%respectively.SPS regeneration effect is slightly better than the PMS.Use Fenton,hydrogen peroxide + SPS,hydrogen peroxide and thermal activation of SPS for the pilot-scale test of the activated carbon regeneration.The results show that after regenerating three times,the four methods achieve similar regeneration efficiency which is between 54.42%and 60.07%.The regeneration efficiency cannot increase with the increasing dosage of oxidant and there is a certain limit.In practical process,the dosage of oxidant should be reasonably controlled.(4)Surface properties of activated carbonText the BET specific surface area,iodine value,the adsorption value of phenol,methylene blue value and the content of surface functional groups of new carbon,saturated carbon and the renewable carbon.The results show that after regeneration the specific surface area of activated carbon returns to 231～376 m2·g-1 compared with the saturated carbon which is 70.48 m2·g-1.Fenton regeneration method recovers the highest specific surface area,but still far less than the 1157 m2·g-1 of new carbon.The adsorption value of phenol,iodine value,and methylene blue value of renewable carbon has certain recovery compared with the saturated carbon.The recovery degree of phenol adsorption value is bigger,about 50%.Boehm titration shows that the content of surface groups of saturated activated carbon is lower than new carbon.After three kinds of advanced oxidation technology,the content of the surface acid groups of the renewable carbon increases,however,the base groups content reduce.FT-IR analysis results show that the infrared spectroscopy of the new,saturated and renewable carbon is basically identical.The contents of C—O of the saturated and renewable carbon are less than the new carbon.SEM analysis shows that after Fenton regeneration,saturated activated carbon increases small holes,but still has close texture.Rather,after the regeneration of thermal activation of PMS and SPS,although a few holes added,texture of the surface becomes looser.SEM,EDS,XRD,XPS analysis results show that the new activated carbon do not contain iron and its compounds,but after adsorbing biochemical wastewater of Printing-Dyeing wastewater,the saturated carbon contains a small amount of iron,and along with activated carbon’s catalytic effect on hydrogen peroxide,which explain the fact that only adding hydrogen peroxide still has regeneration effect.At the same time,activated carbon can catalyze the decomposition of peroxide... |
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