Performance of continuous aerated iron electrocoagulation process for arsenite removal from simulated groundwater and management of arsenic-iron sludge

Abstract

Removal of arsenite from the simulated arsenite contaminated groundwater by using continuous aerated iron electrocoagulation process (CAIEC) (iron electrodes as both anode and cathode) was examined in the present study. The experiments to treat 1 mg L−1 arsenite concentration at two distinctive flow rates i.e. 5 L h−1 and 10 L h−1 were performed. During the process, it was observed that electrode passivation can lead to a reduction in arsenic removal efficiency. The layer formation/passivation of the electrode during the process cannot be controlled but it can be lowered up to some extent by changing the polarity after each run. The average arsenic-iron sludge generated from the process was 35.8 to 70.64 mL L−1 per cycle. Highlighting the proper arsenic-iron sludge management, reusability of this sludge as a binding material in concrete was investigated through solidification and stabilization techniques. A slight variation in the compressive strength of concrete was observed with the addition of arsenic-iron sludge. The presence of arsenic in the concrete mix was confirmed by XRD analysis. The arsenic leachability from the sludge samples as well as stabilized concrete cubes was analyzed with toxicity characteristic leaching procedure (TCLP) (both static and dynamic) and observed insignificant arsenic leaching.