Challenges and Opportunities for Electrochemical Processes as Next-Generation Technologies for the Treatment of Contaminated Water

TLDR

Electrochemical processes have been extensively studied for removing diverse organic and inorganic contaminants, yet most work uses simple nitrate‑, perchlorate‑, sulfate‑, or chloride‑based electrolytes, and real‑world mixtures can alter performance by affecting chloride/bromide‑dependent oxidation and generating harmful chlorate, perchlorate, and organohalogen by‑products. This review highlights the need for new strategies to reduce toxic by‑product formation and efficiency losses from mass‑transfer limits and side reactions, and stresses that identifying when these constraints pose health risks is essential for designing and operating electrochemical treatment systems. The authors examine electrolytic systems for decentralized treatment of domestic wastewater, greywater, and source‑separated urine, illustrating their potential for industrial and municipal applications.

Abstract

Electrochemical processes have been extensively investigated for the removal of a range of organic and inorganic contaminants. The great majority of these studies were conducted using nitrate-, perchlorate-, sulfate-, and chloride-based electrolyte solutions. In actual treatment applications, organic and inorganic constituents may have substantial effects on the performance of electrochemical treatment. In particular, the outcome of electrochemical oxidation will depend on the concentration of chloride and bromide. Formation of chlorate, perchlorate, chlorinated, and brominated organics may compromise the quality of the treated effluent. A critical review of recent research identifies future opportunities and research needed to overcome major challenges that currently limit the application of electrochemical water treatment systems for industrial and municipal water and wastewater treatment. Given the increasing interest in decentralized wastewater treatment, applications of electrolytic systems for treatment of domestic wastewater, greywater, and source-separated urine are also included. To support future adoption of electrochemical treatment, new approaches are needed to minimize the formation of toxic byproducts and the loss of efficiency caused by mass transfer limitations and undesired side reactions. Prior to realizing these improvements, recognition of the situations where these limitations pose potential health risks is a necessary step in the design and operation of electrochemical treatment systems.