Toxic disinfection byproducts, including chloroform and bromoform, were detected at concentrations far exceeding US drinking water safety thresholds in electrochemical treatment of textile dye wastewater. Sodium chloride, routinely added to boost treatment efficiency and reduce energy costs, produces reactive chlorine species that drive harmful byproduct formation. No US regulatory limits exist for these compounds in textile wastewater treatment.
- Azo dyes, which represent 50% of the global dye market, produced chloride-based toxic byproducts at levels of hundreds of parts per billion during electrochemical treatment.
- Bromoform concentrations in wastewater from bromine-containing textile dyes reached 526 ppb; Azo dye byproducts were detected at three times the EPA trihalomethane drinking water limit of 80 ppb.
- The textile industry accounts for as much as 20% of the world's wastewater, and previous research has shown textile wastewater can be harmful to the environment, crop production, and human health.
- The findings have been published in 'Oxidation byproduct formation by electro-oxidation of textile dye wastewater: Occurrence, characterization and mitigation', Journal of Hazardous Materials, by Faye Kuszewski, Annabella Colavito, Patrick Wittbold and Sean T McBeath.
BEHIND THE RESEARCH: Researchers at the University of Massachusetts Amherst investigated toxic disinfection byproduct formation during electrochemical treatment of textile dye wastewater, applying the WWET Lab's established expertise in drinking water treatment to examine the same chemical processes in an industrial textile context. The study tested Azo dyes and bromine-containing textile dyes under industrially relevant conditions.
- Electrochemical treatment passes electricity through wastewater, causing electrodes to exchange electrons with organic pollutants and break down dye compounds, ideally to carbon dioxide.
- Sodium chloride is added to increase water conductivity, reduce energy consumption, and accelerate dye degradation, producing reactive chlorine species as a consequence of the electrochemical reaction.
- The study scope covered both chloride-driven and bromine-driven byproduct formation, examining how different dye chemistries interact with the electrochemical treatment process.
- The WWET Lab's prior drinking water research has shown that when chloride is present in electrochemical reactions, reactive chlorine species are formed, raising concern that the same process occurs in textile wastewater treatment.
- The study was led by Faye Kuszewski, a master's graduate of UMass Amherst, with co-authors Annabella Colavito, Patrick Wittbold, and Sean T. McBeath of the Riccio College of Engineering.
WHAT COMES NEXT: The study identified three mitigation options for industries seeking to reduce disinfection byproduct formation during electrochemical textile wastewater treatment, each involving a different balance of cost, speed, and byproduct output. Researchers also outlined future investigations into pre-treatment steps and the broader range of byproducts that may be generated across textile wastewater treatment processes, with McBeath noting that treatment is often not pursued and that regulations vary widely between countries.
- Sodium sulfate can replace sodium chloride as the conductivity-enhancing additive, avoiding the harmful byproducts associated with chloride, though the process operates more slowly.
- Novel catalysts offer a faster reaction rate than sodium sulfate substitution but carry higher costs and still generate some byproducts, though at reduced levels.
- Worker protections, including proper ventilation in textile factories, represent a third option for companies that continue current practice while seeking to reduce occupational exposure.
- The next steps involve understanding process modifications that balance treatment costs, efficiency, and safety hazards, reducing reliance on sodium chloride without requiring full substitution.
- Pollutants entering water sources may affect aquatic life and human health, and further investigation into whether additional byproducts are generated during textile wastewater treatment is also among the stated next steps.
WHAT THEY SAID
You add salt. It brings down your energy costs, and it increases your degradation performance, so your treatment performance goes up. But the side that no one's looking at now is, at what cost does it do that? … For Azo dyes, it's three times higher than what we're allowed to shower in or drink.
— Sean McBeath
Assistant Professor, Riccio College of Engineering
University of Massachusetts Amherst
