Removal of trace metal contaminants from potable water by electrocoagulation

Abstract

This study investigated the effects of four operational and environmental variables on the removal of trace metal contaminants from drinking water by electrocoagulation (EC). Removal efficiencies for five metals (arsenic, cadmium, chromium, lead and nickel) were compared under varying combinations of electrode material, post-treatment, water composition and pH. Iron electrodes out-performed aluminum electrodes in removing chromium and arsenic. At pH 6.5, aluminum electrodes were slightly more effective at removing nickel and cadmium, while at pH 8.5, iron electrodes were more effective for these metals. Regardless of electrode, cadmium and nickel removal efficiencies were higher at pH 8.5 than at pH 6.5. Post-EC treatment using membrane filtration (0.45 μm) enhanced contaminant removal for all metals but nickel. With the exception of lead, all metals exhibited poorer removal efficiencies as the ionic strength of the background electrolyte increased, particularly in the very high-solids synthetic groundwaters. Residual aluminum concentrations were lowest at pH 6.5, while iron residuals were lowest in low ionic strength waters. Both aluminum and iron residuals required post-treatment filtration to meet drinking water standards. EC with post-treatment filtration appears to effectively remove trace metal contaminants to potable water standards, but both reactor and source water parameters critically impact removal efficiency.

Electrocoagulation as a green technology for phosphate removal from river water

“…Electrocoagulation technology is an electrochemical process that depends on the in-situ generation of coagulants by passing an electric current through a sacrificial metallic anode to destabilise suspended pollutants in an aqueous media, the cathode producing hydrogen gas that floats the pollutants (Essadki et al, 2009;Vasudevan et al, 2012;Heffron, 2015;Hashim et al, 2017a). The type of coagulants generated depends on the material of electrodes, which is selected depending on the characteristics of the targeted pollutants, cost of material and oxidation potential (Hashim et al, 2017c).…”

Water Treatment Using Metallic Iron: A Tutorial Review

“…Another approach is to use a single natural water or tap water as a background electrolyte. More reliable approaches exist [142,143]; the one introduced by Heffron et al [142] is to use four synthetic waters representing the ionic composition of a wide range of natural waters. These synthetic test waters mimicked low and high ionic concentrations for both surface and groundwater (Table 1).…”

“…Table 1. Composition of the four water matrices used by Heffron et al [142]. Ion concentrations are in mmol L −1 (mM).…”

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“…The 75% of arsenic (As) was removed by the Electrocoagulation technique at 20V 31 . Arsenic (As) is removed by the electro coagulation with iron and aluminium electrodes to the US EPA drinking water standard 32 . This method is suitable for a rural area due to absence of any chemicals.…”