Reductive Electrochemical Activation of Hydrogen Peroxide as an Advanced Oxidation Process for Treatment of Reverse Osmosis Permeate during Potable Reuse

Cindy Weng, Yi Hsueh Chuang, Bradley Davey, William A. Mitch

Research output: Contribution to journalArticlepeer-review

Abstract

The UV/hydrogen peroxide (H2O2) advanced oxidation process (AOP) frequently employed to generate hydroxyl radical (•OH) to treat reverse osmosis permeate (ROP) in potable reuse treatment trains is inefficient, using only 10% of the H2O2. This study evaluated ·OH generation by electron transfer from a low-cost stainless steel cathode. In deionized water, the electrochemical system achieved 0.5 log removal of 1,4-dioxane, a benchmark for AOP validation for potable reuse, within 4 min using only 1.25 mg/L H2O2. Hydrogen peroxide and 1,4-dioxane degradations were maximized near -0.18 and + 0.02 V versus standard hydrogen electrode, respectively. Degradations of positively and negatively charged compounds were comparable to neutral 1,4-dioxane, indicating that degradation occurs by ·OH generation from neutral H2O2 and that electrostatic repulsion of contaminants from the electrode is not problematic. For ROP without chloramines, 0.5 log 1,4-dioxane removal was achieved in 6.7 min with 7 mM salts for ionic strength and 2.5 mg/L H2O2. For ROP with 1.4 mg/L as Cl2 chloramines, 0.5 log 1,4-dioxane removal was achieved in 13.2 min with 7 mM salts and 4.5 mg/L total H2O2 dosed in three separate injections in 5 min intervals. Initial estimates based on lab-scale electrochemical AOP treatment indicated that, except for the cost of salts, the electrochemical AOP featured lower reagent costs than the UV/H2O2 AOP but higher electricity costs that could be reduced by optimization of the electrochemical design.

Original languageEnglish
Pages (from-to)12593-12601
Number of pages9
JournalEnvironmental Science & Technology
Volume54
Issue number19
DOIs
StatePublished - 6 Oct 2020

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