Use of carbon sorbents in process of Hg-ions removal from treated wastewater

Abstract

Studies on the analysis of composition of wastewater from chlorine and alkali production process, sampled at the treatment different stages, treated by electrolysis and the mercury cathode use, are presented in this paper. It is demonstrated that Hg-content range in the wastewater entering the post-treatment stage is 14.06–14.15 mg/dm3. Hg-ions sedimentation and filtration allow to reduce such content to 0.005 mg/dm3, while the final post-treatment stage with use of the anionite of АВ-17-8 type allows to achieve Hg-concentration in effluents discharged to water bodies with range of 0.001–0.002 mg/dm3. In addition to mercury, the wastewater contains relatively high concentrations of sodium, potassium, iron, aluminum and calcium ions. The main anion type in waste water is a chlorine anion; its content can be significantly reduced only after the post-treatment with the anionites. Experimental studies were carried out on the use of carbon sorbents in the process of wastewater post-treatment with regard to Hg-ions after the sedimentation and filtration stage. Tests of modified carbon sorbents for Hg-ion removal from standardized test solutions with different concentrations were carried out under static conditions. It was demonstrated that the higher post-treatment degrees were achieved with active carbons of АГ-3 and АГ-5 types, modified with HNO3 and MnS. Purification degree was 97–99% with 1,0-11,8 mg/dm3 Hg-concentration in treated solutions. Usage effectiveness of active carbons of АГ-3 and АГ-5 types (produced at “Sorbent JSC” Perm, Russia), modified with active compounds, was demonstrated.