Disinfection by-products in drinking water
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Disinfection By-Products in Drinking Water: Formation and Types
Disinfection by-products (DBPs) are chemicals formed when disinfectants like chlorine, chloramines, ozone, or chlorine dioxide react with natural organic matter, bromide, iodide, or anthropogenic pollutants in water during the disinfection process 1248. The most common DBPs include trihalomethanes (THMs) and haloacetic acids (HAAs), but there are hundreds of other compounds such as haloacetonitriles, halopropanones, chloral hydrate, chloropicrin, and various nitrogenous DBPs (N-DBPs) 1234+3 MORE. The formation of DBPs is influenced by factors like disinfectant type, dose, reaction time, temperature, pH, and the presence of natural organic matter and ammonia 478.
Health Risks and Toxicity of Disinfection By-Products
DBPs are a public health concern due to their potential toxicity. Exposure to DBPs has been linked to increased risks of bladder cancer, early-term miscarriage, birth defects, and respiratory issues, especially in settings like swimming pools 2458. Nitrogen-containing DBPs (N-DBPs), such as nitrosamines, are generally more genotoxic and cytotoxic than carbon-based DBPs 246. Both ingestion and non-ingestion routes (inhalation and dermal absorption) contribute to human exposure and health risks 258. Studies have shown that cancer risks from DBPs in drinking water can range from 10⁻⁶ to 10⁻⁴, with non-carcinogenic risks generally below 1 .
Occurrence and Regulation of DBPs in Drinking Water
THMs and HAAs are the most frequently detected DBPs in treated water, often at concentrations that can exceed regulatory limits set by organizations like the WHO and USEPA 1348. Other DBPs, such as bromate, chlorite, and emerging compounds like iodo-acids and halonitromethanes, are less commonly regulated but are gaining attention due to their toxicity 2410. The occurrence and concentration of DBPs can vary seasonally and spatially, depending on water source characteristics and treatment practices 357.
Factors Influencing DBP Formation
Key factors that increase DBP formation include high chlorine dose, high natural organic matter, longer reaction times, higher temperatures, and specific pH levels 478. For example, high pH favors THM formation, while low pH favors HAA formation . The presence of ammonia and bromide can also significantly affect the types and amounts of DBPs produced . Switching from chlorination to chloramination can reduce some regulated DBPs but may increase the formation of more toxic N-DBPs 246.
Control and Removal of Disinfection By-Products
Several methods are used to control and remove DBPs and their precursors from drinking water. These include:
- Adsorption (e.g., activated carbon), which can remove up to 90% of DBPs .
- Advanced oxidation processes (AOPs), coagulation, and membrane filtration to remove natural organic matter before disinfection 14810.
- Biofiltration and step-wise chlorination to reduce precursor levels and minimize DBP formation 46.
- Post-formation removal methods like air stripping and additional adsorption 48.
Research Trends and Future Directions
Research on DBPs has grown steadily, with a focus on understanding their formation, toxicity, and removal methods . There is increasing attention on emerging DBPs, especially those containing nitrogen, bromine, or iodine, due to their higher toxicity 24610. Future research priorities include improving analytical techniques, better understanding health effects, and developing more effective water quality standards and control strategies .
Conclusion
Disinfection by-products are an unavoidable consequence of water disinfection, especially with chlorine-based methods. While essential for public health, the formation of DBPs poses significant health risks, prompting ongoing research and regulatory efforts to minimize their presence in drinking water. Effective control strategies focus on removing precursors, optimizing disinfection processes, and developing advanced treatment technologies to ensure safe and clean drinking water for all.
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Disinfection by-products in drinking water: Occurrence, toxicity and abatement.
Disinfection by-products (DBPs) in drinking water, such as Trihalomethanes and Haloacetic acids, can be harmful to human health, but techniques like adsorption can effectively remove up to 90% of these contaminants.
Drinking Water Disinfection By-products
Drinking water disinfection by-products (DBPs) pose potential health risks, including bladder cancer, early-term miscarriage, and birth defects, and can be exposed to through ingestion, bathing, showering, and swimming.
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