Improvement of Arsenic Electro-Removal from Underground Water by Lowering the Interference of other Ions

Electrocoagulation (EC) has been evaluated as a treatment technology for arsenic (As) removal. Experiments were developed in an electrochemical reactor with three parallel iron plates. Current densities of 15, 30, and 45 A m(-2) were used to treat model water and 45 A m(-2) to treat underground water (GW). For both types of water, the EC process was able to decrease the residual arsenic concentration to less than 10 mu g L(-1). However, the treatment time for As removal from GW was higher. This phenomenon was attributed to the competition of dissolved species present in GW such as silica and calcium with arsenic for the adsorption sites on the ferric oxyhydroxides flocs generated during the EC process. A procedure is proposed to reduce such interference by the addition of a silica adsorption inhibitor compound into the GW achieving a reduction in the process time. The adsorption of arsenic species over adsorbent was found to follow Lagergren adsorption model.