Factors Impeding Replacement of Ion Exchange with (Electro)Catalytic Treatment for Nitrate Removal from Drinking Water

Nitrate (NO3–) has impacted more groundwater supplies than any other pollutant in the world. It is currently removed at water treatment plants by ion exchange, which is effective but comes at a steep financial and environmental cost. (Electro)catalytic treatment of nitrate has emerged as a promising alternative technology, which relies on reducing nitrate to dinitrogen gas or ammonium via reduction on a bimetal catalyst with atomic hydrogen oxidation. The bimetal catalyst contains a platinum group metal, and atomic hydrogen is either generated from supplied hydrogen gas (catalytic) or an applied current (electrocatalytic). However, (electro)catalytic treatment of nitrate is not being implemented at water treatment plants. This perspective addresses the most important technical challenges limiting widespread adoption of (electro)catalytic nitrate removal in drinking water treatment. These challenges affect precious metal amounts and cost, the efficiency and safety of hydrogen use, and end-product selectivity. This perspective is concluded by a prioritization of technology challenges, and their implications for attracting industry investment and achieving regulatory acceptance.