Laboratorial Study On Technology Of Controlling Harmful Microelements From Wuhan Iron And Steel Corp's Coking Wastewater

Fly ash was employed for removal of As,Pb,Hg,Cr from simulated coking wastewater to determine the effect of grain size,fly ash dosage,contacting time and pH on the single element(As,Pb,Hg,Cr)removal efficiency and the coalesce removal efficiency of the 4 elements.Base on the single factor experiments and orthogonal experiment,the optimum conditions were obtained as follow:In the process of As adsorption, grain size was 75μm,fly ash was 100 g/L,contacting time was 30 min and pH was 11. Under the optimum conditions,94.92% of As in simulated coking wastewater was removed. And in the process of Pb adsorption, grain size was 75μm,fly ash was 3.00 g/L,contacting time was 40 min and pH was 5. Under the optimum conditions,98.95% of As in simulated coking wastewater was removed. In the process of Hg adsorption, grain size was 75μm,fly ash was 10 g/L,contacting time was 30 min and pH was 7. Under the optimum conditions,99.18% of As in simulated coking wastewater was removed. In the process of Cr adsorption,grain size was 150μm,fly ash was 4.00 g/L,contacting time was 40 min and pH was 3. Under the optimum conditions,98.82% of Cr in simulated coking wastewater was removed. The optimum conditions of the coalesce removal efficiency of the 4 elements were obtained as follow:grain size was 96μm, fly ash was 100 g/L,contacting time was 35 min and pH was 3.The optimum conditions also had perfect performance for actual coking wastewater treatment,and the As removal rate could reach 86.00%,with Pb reach 92.00%, Hg reach 95.00%, Cr reach 90.00%. And the concentration of harmful elements of the treated wastewater was less than emission standards those in the GB8978-1996 "Integrated Wastewater Discharge Standard".