Nitrate is one of the most common groundwater contaminants globally, posing a major human health risk to individuals relying on affected drinking water sources. Existing distributed treatment technologies, such as ion exchange and reverse osmosis, typically produce concentrate waste streams that require further management, that adds to the cost or shifts the burden of contamination. Electrochemical treatment methods are a promising option for point-of-use removal of nitrate; however, these technologies are limited by slow kinetics, the high costs of platinum-group catalysts used in many electrodes, and the mixture of products (i.e., N2 and NH4+). To address these shortcomings, we developed and studied the performance of a modular electrochemical system that selectively reduces NO3- to NH4+ via a flow-through electrode and subsequently uses breakpoint chlorination to remove NH4+. The electrode was fabricated by electrodepositing Cu-Ni catalysts on a carbon felt substrate, resulting in high activity for NO3- reduction to NH4+. Flow-through experiments demonstrated significant removal of NO3- in a single pass. A zero-chemical-input electrochlorinator that generated chlorine from the chloride ions already present in source water was used for breakpoint chlorination and production of a residual disinfectant. Cost estimates demonstrated this modular electrochemical approach was competitive with ion exchange and reverse osmosis units at the point-of-use scale.

Modular point-of-use treatment of groundwater nitrate by electro-reduction and electrochlorination

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.