Electrocoagulation at low conductivity for drinking water treatment. Pilot Research, Cost estimation and LCA

Electrocoagulation (EC) is a process in which iron sacrificial electrodes are submerged (and slowly dissolved) in water driven by an electric current, in which dissolved iron acts as a coagulant. It has been seen as a promising alternative to conventional chemical coagulation in drinking water treatment. The major reasons to consider electrocoagulation over conventional coagulation are (i) no chemical dosing, (ii) the creation of more settleable and heavier flocs, (iii) cheaper operational costs, (iv) a smaller environmental effect, and (v) no pH decrease and chloride increase in the treated water. Although electrocoagulation has been successfully applied to wastewater, it is still unknown whether successful application in sources for drinking water (in the Netherlands) is achieved with specific targets such as suspended solids, turbidity and TOC removal. Therefore, a pilot study on sources for drinking water was carried out to corroborate promising results already found at lab-scale experiments.
In this pilot study, the potential of electrocoagulation (EC) was investigated for treating three different types of water with a relatively low conductivity: surface (river) water from Dunea, backwash water from rapid sand filters of Dunea, and groundwater from Brabant Water. This project aims to evaluate electrocoagulation for treating water compared to conventional FeCl3 coagulation, by means of a pilot removal efficiencies, cost calculations and Life Cycle Assessment. It includes conceptual design, cost estimates, and environmental impact analysis, focusing on Ecopoints and CO2 emissions to assess electrocoagulation’s potential.
The results showed that electrocoagulation was capable of achieving similar removal efficiencies compared to conventional coagulation but higher iron dosages were needed to get floc formation. For sand filter backwash water, with a Fe dosage of approximately 42 mg/L for EC, removal efficiencies were 80% for arsenic, 75% for total suspended solids, 86% for total phosphorus, 43% for total organic carbon, 56% for turbidity, and 48% for total color. After 8 hours of settling, turbidity removal improved to 64-93% and color removal to 56-88%. Conventional FeCl3 coagulation achieved turbidity and color removals of 78-85% and 63-86%, respectively.