Arsenic removal using electrocoagulation followed by hematite granular filter

Abstract

Abstract Drinking water contaminated with arsenic is a threat to human health. The present study attempts to remove arsenic using electrocoagulation with iron electrodes (ECFe) in continuous flow mode. Two experimental runs were separately conducted using untreated and treated (acid treatment followed by pH neutralization step) hematite as granular bed. The treatment of the hematite formed ferric oxy-hydroxides on hematite surface which was beneficial for arsenic removal. Total arsenic concentration reduced below 10 ppb from initial concentration of 500 ppb [As(III): As(V) = 1:1] with Fe dose of 5 mg/L after 48 h and 2 h of run conducted with untreated and treated hematite granular bed, respectively. The required Fe/As ratio of 10 was much lesser than the reported requirement of 250 in conventional systems. In the filter prototype using market-available filter cartridge, arsenic concentration reduced below 10 ppb from an initial concentration of 500 ppb [As(III): As(V) of 1:1] in both the absence and presence of phosphate (2 ppm) and silicate (30 ppm).