Removing arsenate from water using batch and continuous-flow electrocoagulation with diverse power sources

Abstract

Recently, electrocoagulation (EC) has emerged as a promising method to treat contaminated water. In this study, a novel EC system using stainless steel electrodes was applied to remove arsenate (As(V)) in water. An operation time of 5 min, electrical potential difference of 7.5 V, and inter electrode distance of 1 cm were identified as optimal condition for removing As(V) (eliminated 92 % of As(V) from 0.1 mg As(V)/L solution). In the batch study using a 9 V rechargeable battery and a small 12 V solar panel, the EC reactor removed 93 % and 98 % of As(V) from 0.1 mg As(V)/L solution, respectively, and As(V) concentration in treated water was lower than that of the drinking water guideline of World Health Organisation (WHO) (0.01 mg/L). In the continuous water flow study, a small cost-effective system (reactor volume of 1 L, cost $15 AUD) using a small 12 V solar panel could successfully treat 12 L contaminated water per hour. During 4 h of continuous testing, the system’s efficiency in removing As(V) remained constant at >91 %. The operation cost for the treatment of As(V) – contaminated water in continuous operation mode is $0.240 AUD/m3 water for the direct current (DC) electrical system and $0.262 AUD/m3 for the solar system. In a pilot field study with contaminated groundwater (0.03 mg total As/L) in Hanam province, Vietnam, the EC system using solar energy (12 V) was able to reduce As concentration to below the Vietnamese and WHO permissible drinking water limit in 1 min.