Reduction of Disinfection Byproduct-associated Toxicity by Adjustment of Distribution System pH

Nitrogenous disinfection byproducts (N-DBPs) such as Haloacetonitriles (HANs) and haloacetamides (HAMs) have come under scrutiny in recent years due to their high toxicity compared to currently regulated carbonaceous disinfection byproducts (C-DBPs). Lowering concentrations of N-DBPs in drinking water is an important step for mitigating toxicity exposure to the public. A possible mitigation strategy may be to distribute water at increased pH, resulting in increased HAN hydrolysis to HAMs and HAM hydrolysis to haloacetic acids (HAAs). Because the ranked toxicity of these groups is HAN > HAM > HAA, such a hydrolysis scheme would result in reduced sample toxicity. The formation and degradation of HANs and HAMs was examined in conventionally treated surface water and in Milli-Q water spiked with two natural organic matter (NOM) isolates using formation potential (FP) tests at varying pH. HAN concentrations in finished drinking water at pH 6, 7.5, and 9 at the end of the 5-day experimental period were 12.5, 7.1, and 1.9 µg/L, respectively, equivalent to a 77% (pH 6 to 9) and 45% (pH 7.5 to 9) decrease in summed calculated toxicity from the DBPs measured. Similar conclusions followed from the FP tests with NOM isolates. Increasing distribution system pH is an effective method to reduce HAN-associated toxicity.

Level thesis:degree_level

Master's Degree

Year dc:date.issued

2022

Author dc:creator

• Stewart, Kevin

Advisor dc:contributor.advisor

• Hanigan, David J

Committee members dc:contributor.committeemember

• Pagilla, Krishna R
• Gustin, Mae

• Calculated Toxicity
• Disinfection Byproducts
• Haloacetamides
• Haloacetonitriles
• Nitrogenous DBPs

Handle dc:identifier.uri

http://hdl.handle.net/11714/8362

OAI identifier oai:identifier

oai:scholarwolf.unr.edu:11714/8362