| Antimony?Sb?pollution in wastewater is a new challenge for printing and dyeing industry.In order to meet the increasingly stringent emission standards,it is urgent to develop efficient,stable and economic control technologies of Sb pollution.But at present,a few of researches on Sb pollution control are reported,so it is necessary to carry out status evaluation of Sb pollution control in printing and dyeing enterprises as well as urban wastewater treatment plants,and based on these works,to develop pretreatment technologies and deep treatment technologies of Sb pollution,which has important practical value and strategic significance for healthy sustainable development of printing and dyeing industry.In this work,two typical dyeing enterprises and one urban wastewater treatment plant in Jiaxing city were chosen as study object,and Sb migration and transformation in wastewater treatment process was studied as well as removal effect evaluation in process units.Beyond that,the effect of Sb on biochemical system was also investigated.Based on these works,both enhanced pretreatment technologies of Sb contaminated wastewater for dyeing enterprises and deep treatment technologies of Sb contaminated wastewater for urban wastewater treatment plants were studied.The main results were as follows:1.Sb removal effect of wastewater pretreatment process had been proved in the two typical dyeing enterprises.The Sb concentration in inlet effluent was about 600-1200?g·L-1,and Sb removal efficiency of wastewater pretreatment process was about 51.51%-63.50%.The air flotation unit and coagulation precipitation unit were the major contributors,and the Sb removal efficiency in the two units was 22.08-41.92%and 51.67%,respectively.Although the Sb removal efficiency of wastewater pretreatment system was high,the Sb concentration in outlet effluent didn't meet the national emission standards.The dissolved Sb in both inlet and outlet effluents was in form of Sb?V?,and it was mainly removed through sludge discharge.2.Sb removal effect of wastewater treatment process in urban wastewater treatment plant C had been proved.A few of Sb contaminants were removed by wastewater treatment units,and the Sb concentration in the outlet effluent didn't meet the national emission standards.The dissolved Sb in both inlet and outlet effluents was in form of Sb???.Furthermore,the dissolved Sb had no effect on the biochemical system.3.Enhanced coagulation precipitation pretreatment technology for Sb contaminated wastewater in dyeing enterprise was developed.The effects of the coagulant type,initial pH,dosage and flocculation time on Sb removal efficiency were investigated,and the optimized operation parameters was determined.When pH was 11,the dosage of PFS was 100 mg·L-1,the flocculation time was 10 min,the initial Sb concentration of simulated wastewater was 300?g·L-1,the removal efficiency of Sb reached 78.0%,which was as 1.56-1.9 times as that of existing wastewater treatment system in the dyeing enterprises,and the Sb concentration of the outlet effluent was 71.4?g·L-1 and could meet the national emission standard.4.nZVI/AC adsorption technology was developed as a deep treatment technology for Sb contaminated wastewater in urban wastewater treatment plants.The adsorbents nZVI and nZVI/AC were successfully synthesized by reduction methods in the solution and the optimized operation parameters were determined.When gas source of aeration was nitrogen,initial pH was 7.5,the dosage of 15 wt%nZVI/AC was 0.2 g·L-1,the reaction time was 2 hours,the initial Sb concentration of simulated wastewater was 100?g·L-1,the removal efficiency of Sb reached 76.2%,and the Sb concentration of the outlet effluent was only 23.8?g·L-1 and the kinetic constant was 0.01168 min-1.It was found that the removal of dissolved Sb depend mainly on the reduction effect of both Fe?0?and Fe2+,when Sb???was reduced to Sb???,it became easier for Sb to be removed by absorbent adsorption. |
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