“How Do Operating Conditions Affect As(III) Removal by Iron Electrocoagulation?”. Delaire et al., 2017. Water Research

Iron electrocoagulation (Fe-EC) has been shown to effectively remove arsenic from contaminated
groundwater at low cost and has the potential to improve access to safe drinking water for millions of
people. Understanding how operating conditions, such as the Fe dosage rate and the O2 recharge rate,
affect arsenic removal at different pH values is crucial to maximize the performance of Fe-EC under
economic constraints. In this work, we improved upon an existing computational model to investigate
the combined effects of pH, Fe dosage rate, and O2 recharge rate on arsenic removal in Fe-EC.We showed
that the impact of the Fe dosage rate strongly depends on pH and on the O2 recharge rate, which has
important practical implications. We identified the process limiting arsenic removal (As(III) oxidation
versus As(V) adsorption) at different pH values, which allowed us to interpret the effect of operating
conditions on Fe-EC performance. Finally, we assessed the robustness of the trends predicted by the
model, which assumes a constant pH, against lab experiments reproducing more realistic conditions
where pH is allowed to drift during treatment as a result of equilibration with atmospheric CO2. Our
results provide a nuanced understanding of how operating conditions impact arsenic removal by Fe-EC
and can inform decisions regarding the operation of this technology in a range of groundwaters.

Delaire, C.; Amrose, S.; Zhang, M.; Hake, J.; Gadgil, A. J. How Do Operating Conditions Affect As(III) Removal by Iron Electrocoagulation? Water Research. 2017, 112, 185-194.

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