With increasing water scarcity, wastewater treatment has been widely promoted. But some such processes can lead to toxic byproducts.Researchers at the University of Southern California found out that some wastewater treatment processes can lead to the formation of chloropicrin, a toxic chemical.Wastewater treatment methods that involve ozonation and chlorination can produce Chloropicrin. It was first used by the Germans during the first world war. Nowadays it is used as a pesticide.
Researchers found out that ozonation and following chlorination of wastewater creates disinfection byproducts, called halonitromethanes. The research was conducted by the varsity's Assistant Professor, Daniel McCurry, and docgtoral student Jiaming Lily Shi. As part of the research, the team collected wastewater samples from three treatment plants in southern California.
Ozone-treated water has nitromethane, a chemical formed from some drugs containing nitrogen. The drugs are mainly anti-depressants and stimulants (ephedrine, methamphetamine, etc).When nitromethane interacts with chlorine, which is used to make the water drinkable — chloropicrin is formed. While ozonation has been proven technology which is very effective in removing many pharmaceutical compounds and trace contaminants from wastewater, it has been recently shown in certain circumstances that it increases the toxicity of the final wastewater effluent.
It can harm humans body, ranging from eye and skin to the respiratory system.  Alternate treatment methods, which uses biologically active carbon instead of chlorine, can prevent chloropicrin formation. In future, effective research work is needed to understand new technologies that can remove nitromethane when the ozonation method is involved in the treatment process, says the researchers.