Advanced Treatment Of The Effluent From Textile Dyeing Wastewater Treatment Plant Using Biochar

At present,faced with the severe water shortage and growing water pollution problems,the cyclic reuse of wastewater has been imperative in our country.For textile industry,water consumption is very large,and the wastewater discharge is also very large.After the textile wastewater was treated by conventional process,the effluent has been satisfied the indirectly discharge standard of "Discharge Standards of Water Pollutants for Dyeing and Finishing of Textile Industry"(GB 4287-2012).However,some residual toxic and harmful pollutants still exist in the effluent.If the effluent discharges to waterbody,these residual toxic and harmful pollutants would threaten water ecosystem and human health.Therefore,it is necessary to reduce the discharge of these pollutants to waterbody.To sum up,in order to achieve the arms of saving water resources and protecting environment,further reducing the concentrations of these pollutants in effluent,decreasing the pollution of water environment and realizing reuse of partial effluent are the task which are urgent need to solve.The effect of each factor(biochar dose,temperature,time,pH and so on)on performance of treating simulated effluent and actual effluent from textile dyeing wastewater plant was explored in this study,moreover,the regeneration characteristic of adsorption saturated carbon using microwave technology was also explored,and the optimal microwave regeneration conditions were obtained.The main results are as follows:(1)Reactive turquoise blue KN-G,acid great red GR,and direct fast black VSF-600 were used to prepare the simulated biological treatment effluent of textile wastewater,and the experimental conditions including temperature,contact time,pH,and biochar dose and so on,which affect the color removal of the simulated effluent,were optimized in this study.The obtained results showed that under the conditions of temperature of 25?,pH of 12,the biochar doses of 1.25g/30mL,0.03g/30mL,1.00g/30mL respectively in Reactive turquoise blue KN-G,acid great red GR,and direct fast black VSF-600 simulated biological treatment effluent,the optimal contact times were 150,60 and 210 min,respectively.And the maximal color removal rates are 98.22%,98.16%,and 79.30%,respectively.(2)Taking the actual effluent from a textile dyeing factory in Nantong as the treatment target,the removal efficiencies of COD,UV254 and color by biochar were investigated,and the experimental conditions such as contact time,pH,and biochar dose were optimized in this study.The obtained results indicated that when the biochar dose was 2g/30mL and adsorption time was 2h,the removal rates of COD,UV254 and color were maximal,and the values were 80.99%,85.56%and 100%,respectively.Corresponding COD,UV254 and color were 48.8 mg/L,0.47 cm-1 and 0,respectively,which satisfy the directly discharge standard of "Discharge Standards of Water Pollutants for Dyeing and Finishing of Textile Industry"(GB 4287-2012).And the effluent of advanced treatment by biochar could satisfy"Quality Standards of Reuse Water for Textile Dyeing and Finishing Industry"(FZ/T 01107-2011),"Water Quality Control Standards for Reclaimed Water for Cooling Water"(GB/T 19923-2005),and "The Reuse of Urban Recycling Water--Water Quality Standard for Urban Miscellaneous Water Consumption"(GB/T 18920-2002).(3)The effects of the microwave conditions including microwave power,treatment time,and biochar moisture content on regeneration rate of biochar were investigated.The obtained results showed that optimal microwave conditions were microwave power of 800 W,treatment time of 10 min,and biochar moisture content of 20%.Under the optimal conditions,the COD removal rate of actual effluent from textile dyeing wastewater plant reached 70.7%by the regenerated biochar,and the regeneration rate of biochar was 88.7%.And too high or too low biochar moisture content would be harmful to its regeneration using microwave technology.In addition,under the optimal microwave conditions and optimal advanced treatment conditions,the treatment efficiencies of actual effluent by the multiple regenerated biochar were investigated,and the regeneration rates of the first to the fifth regenerated biochars were 88.7%,74.5%,70.9%,64.5%and 48.8%.