With water scarcity intensifying, wastewater treatment and reuse are gaining popularity. But some methods for killing microbes in wastewater create disinfection byproducts (DBPs) that could be harmful to human health.
Now researchers have found that ozone treatment and subsequent chlorination can convert trace amounts of some pharmaceuticals in wastewater into DBPs called halonitromethanes. They report their results in Environmental Science & Technology.
The combination of ozone and chlorine kills most bacteria and viruses in wastewater. Compared with chlorine treatment alone, ozone also reduces the formation of many DBPs. Recently, however, scientists have discovered that ozone can increase the formation of potentially toxic halonitromethanes, such as chloropicrin, in chlorine-treated wastewater. Jiaming Lily Shi and Daniel McCurry wanted to determine which molecules in the wastewater were being converted to chloropricin and how.
To find out, the researchers collected wastewater samples from three treatment plants in Southern California.
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