Researchers at the University of Massachusetts Amherst are raising a red flag over an unintended consequence of a common approach to textile wastewater treatment: the potential creation of toxic byproducts during electrochemical dye-removal processes. Their findings suggest that a routine ingredient salt can change the chemistry of treatment in ways that may expose workers to harmful compounds and increase downstream environmental risk.
The study examined electrochemical treatment systems that many textile operations use to break down dye pollutants before effluent is discharged. In these systems, sodium chloride is often added to improve conductivity and help drive reactions that degrade colour. The researchers found, however, that chloride can also generate reactive chlorine species during electrochemical reactions, which may then form chlorinated and brominated disinfection byproducts, including chloroform and bromoform.
“The focus of the paper really was the occupational hazards from formed byproducts on the people working in these factories,” said Sean McBeath, assistant professor in the Riccio College of Engineering at UMass Amherst.
McBeath’s team, the Water, Wastewater and Electrochemical Technologies (WWET) Lab, typically works on drinking water systems, where the formation of disinfection byproducts is a longstanding concern. In that context, earlier research by the group has shown that when chloride is present during certain electrochemical reactions, reactive chlorine intermediates can form—creating conditions that favour the production of potentially harmful byproducts.
In the textile-focused study, the researchers tested Azo dyes, which account for roughly half of global dye use, and detected chloride-related toxic byproducts at concentrations measured in the hundreds of parts per billion. They also evaluated dyes that contain bromine, reporting bromoform levels reaching 526 ppb following treatment.
While the US Environmental Protection Agency does not set limits for these compounds in industrial effluent from textile wastewater treatment, it does impose a strict benchmark in drinking water: a maximum of 80 ppb for total trihalomethanes. McBeath said the measured concentrations in the study would exceed that reference point by a wide margin.
“For Azo dyes, it is three times higher than what we are allowed to shower in or drink,” McBeath said, adding that bromine-containing dyes increased concentrations to more than ten times the EPA limit.
The researchers argue the issue has two layers of risk. First is potential exposure inside factories, where workers may inhale volatile byproducts generated during treatment or come into contact with contaminated water. Second is the downstream question: what happens when treated water containing these compounds enters rivers, coastal zones or other aquatic ecosystems and whether those pollutants could eventually affect human health through water supply pathways.
To reduce risk, the team outlined several mitigation options. One is process substitution: replacing sodium chloride with other salts such as sodium sulphate to reduce reactive chlorine chemistry. Another is technical optimisation, including catalysts that can limit byproduct formation while maintaining dye removal performance. The third is workplace control specifically improving ventilation and other protective measures to reduce occupational exposure where byproducts may be released into the air.
“It is companies’ responsibilities to make sure that they are not doing harm to their workers and to the downstream environment, added McBeath.
With wastewater standards differing widely between countries, the WWET Lab is calling for more attention to this emerging hazard in electrochemical dye-treatment technology particularly as adoption expands and as regulators and brands place greater emphasis on cleaner, safer manufacturing systems.
