Research On Adsorption Of Antimony By Biochemical Treatment Activated Sludge From Printing And Dyeing Wastewater

Antimony is used as a catalyst and flame retardant in the printing and dyeing industry,it will be discharged into the environment along with the waste water.The heavy metal antimony has high potential toxicity to the environment and the human body.Therefore,antimony pollution caused by printing and dyeing wastewater has attracted much attention.At present,research reports on the removal of antimony from printing and dyeing wastewater include coagulation precipitation method,adsorption method,etc.,but these methods have problems such as high treatment cost and secondary pollution.Therefore,it is still necessary to develop a more cost-effective and efficient technology for removing antimony from printing and dyeing wastewater.To this end,this study used the excess activated sludge produced in the biochemical process of the sewage treatment plant,using methods such as adsorption to remove antimony from the printing and dyeing wastewater.On the one hand,the antimony removal efficiency and antimony removal mechanism of activated sludge are explored;on the other hand,the antimony removal process of activated sludge actual printing and dyeing wastewater is designed.The results of the study are as follows:(1)When two kinds of activated sludges of oxidation ditch and secondary sedimentation tank are used as antimony removal adsorbents,both sludges have better adsorption effect on antimony ions.The adsorption effect of secondary sedimentation tank sludge is better than oxidation ditch sludge,Na OH Pretreatment can improve the antimony removal efficiency of oxidation ditch sludge.The p H value and the sludge dosage are the main factors that affect the adsorption effect.In the range of p H 4-9,the removal rate of antimony by the two sludges increases first and then decreases with the increase of p H;within the range of 20-120 g/L sludge dosage,the removal rate of antimony by the two sludges increases with the increase of the sludge dosage.For wastewater with Sb(?)of 10 mg/L,when the p H is 5 and the sludge dosage is 120 g/L,the removal rates of antimony by oxidation ditch sludge and secondary sedimentation tank sludge are 71.56%and 76.03%,respectively.(2)SEM and FTIR analysis showed that both sludges have abundant pore sizes and active groups.The removal of antimony is mainly due to the interaction of adsorption and surface complexation,of which adsorption is dominant.The pore distribution of the sludge in the secondary settling tank is more abundant,and the groups involved in the reaction are more.The adsorption process of the two sludges follows pseudo-secondary adsorption kinetics,and the correlation coefficients of linear fitting are 0.996 and 0.994,respectively.Sludge elution rate:secondary sedimentation tank sludge<oxidation ditch sludge.(3)Under anaerobic conditions,anaerobic activated sludge has a good removal effect on antimony ions.For wastewater with Sb(?)less than 20 mg/L,when the sludge dosage is 100g/L and the reaction time is 24 h,antimony can be eliminated.Under anaerobic conditions,sulfate-reducing bacteria in anaerobic activated sludge can reduce sulfate to hydrogen sulfide.Hydrogen sulfide first reduces Sb(?)to Sb(?),and Sb(?)then forms Sb₂S₃ precipitation with hydrogen sulfide.(4)The process design and treatment cost estimation for the removal of antimony from the actual printing and dyeing wastewater of activated sludge are carried out,and the unit treatment cost is estimated to be 0.005 yuan/ton.Compared with the antimony removal process of coagulation precipitation,the treatment cost of the antimony removal process of activated sludge is lower and the operation is simpler,and this method reuses the remaining sludge.This research provides a theoretical basis for choosing more economical and practical treatment technologies for actual antimony-containing printing and dyeing wastewater.