China Nonferrous Metallurgy

The As content of arsenic-containing wastewater produced by a smelting enterprise in Shandong is 20251.6mg/L. In this paper, the sulfidization arsenic precipitation process was used to explore better process parameters, and response surface methodology was used for optimization. Test study was made on the effects of sulfidizing agent dosage, reaction time and stirring speed on arsenic precipitation. The optimum technological parameters were obtained as follows: sulfidizing agent dosage n(S^2-)/n(As)=1.2 reaction time 30min, stirring speed 80r/min. Under such conditions, the As content in the post As-precipitation solution was 0.24mg/L. The response surface methodology is used to analyze the significance and interaction of sulfidizing agent dosage, reaction time and stirring speed, and the quadratic regression model obtained is significant, with good fitting degree. The influence sequence of each factor on As precipitation in wastewater is reaction time ＞ sulfidizing agent dosage ＞ stirring speed. The optimum process parameters for response surface prediction were as follows: sulfidizing agent dosage n(S^2-)/n(As)=1.22 , reaction time 38min, stirring speed 64r/min. Under such conditions, the average As concentration in the precipitated solution was 0.15mg/L. The results show that the As concentration in the precipitated arsenic solution is less than 0.2mg/L by using the optimized sulfidizing arsenic precipitation process parameters, which meets the local discharge standard DB37/3416.5—2018 Integrated Wastewater Discharge Standard for Basin Part 5: Shandong Peninsula Basin required by Shandong Province.