Transformation of emerging disinfection byproducts Halobenzoquinones to haloacetic acids during chlorination of drinking water

Hundreds of different disinfection byproducts form in drinking water following necessary treatment with chlorine and other disinfectants, and many of those byproducts can damage DNA and increase the risk of cancer. This study offers the first side-by-side comparison of cancer risk assessments based on toxicological and epidemiological studies of disinfection byproducts using a comprehensive contaminant occurrence dataset for haloacetic acids and trihalomethanes, two groups of disinfection byproducts that are regulated in drinking water. We also provide the first analysis of a new occurrence dataset for unregulated haloacetic acids that became available from the latest, fourth round of the U.S. EPA-mandated unregulated contaminant monitoring program (UCMR4). A toxicological assessment indicated that haloacetic acids, and in particular brominated haloacetic acids, are more carcinogenic and are associated with a greater number of attributable cancer cases than trihalomethanes. Based on the toxicological analysis, cumulative lifetime cancer risk due to exposure to trihalomethanes and haloacetic acids for community water systems monitored under UCMR4, estimated with standard default parameters for body weight and water intake, corresponds to 7.0 × 10−5 (3.5 × 10−5–1.3 × 10−4). The same analysis conducted with age sensitivity factors to account for elevated risk in infants and children yielded a cumulative risk estimate of 2.9 × 10−4 (1.7 × 10−4–6.2 × 10−4). Epidemiological data suggest that lifetime cancer risk from disinfection byproducts for the U.S. population served by community water systems is approximately 3.0 × 10−3 (2.1 × 10−4–5.7 × 10−3), or a lifetime cancer risk of three cases per thousand people. Overall, this analysis highlights the value of using human data in health risk assessments to the greatest extent possible.

Download Full-text

Resorcinarene Cavitand Polymers for the Remediation of Halomethanes and 1,4-Dioxane

10.26434/chemrxiv.8847839 ◽

2019 ◽

Author(s):

Luke Skala ◽

Anna Yang ◽

Max Justin Klemes ◽

Leilei Xiao ◽

William Dichtel

Keyword(s):

Drinking Water ◽

Activated Carbon ◽

High Capacity ◽

The United States ◽

Water Sources ◽

Disinfection Byproducts ◽

Porous Polymer ◽

Organic Micropollutants ◽

Executive Summary ◽

Regulatory Limits

Executive summary: Porous resorcinarene-containing polymers are used to remove halomethane disinfection byproducts and 1,4-dioxane from water. Disinfection byproducts such as trihalomethanes are some of the most common micropollutants found in drinking water. Trihalomethanes are formed upon chlorination of natural organic matter (NOM) found in many drinking water sources. Municipalities that produce drinking water from surface water sources struggle to remain below regulatory limits for CHCl3 and other trihalomethanes (80 mg L–1 in the United States). Inspired by molecular CHCl3⊂cavitand host-guest complexes, we designed a porous polymer comprised of resorcinarene receptors. These materials show higher affinity for halomethanes than a specialty activated carbon used for trihalomethane removal. The cavitand polymers show similar removal kinetics as activated carbon and have high capacity (49 mg g–1 of CHCl3). Furthermore, these materials maintain their performance in real drinking water and can be thermally regenerated under mild conditions. Cavitand polymers also outperform activated carbon in their adsorption of 1,4-dioxane, which is difficult to remove and contaminates many public water sources. These materials show promise for removing toxic organic micropollutants and further demonstrate the value of using supramolecular chemistry to design novel absorbents for water purification.

Download Full-text

DISINFEKSI UNTUK PROSES PENGOLAHAN AIR MINUM

Jurnal Air Indonesia ◽

10.29122/jai.v3i1.2314 ◽

2018 ◽

Vol 3 (1) ◽

Author(s):

Nusa Idaman Said

Keyword(s):

Drinking Water ◽

Water Purification ◽

Distribution System ◽

Residual Effect ◽

Drinking Water Treatment ◽

Disinfection Byproducts ◽

Water Disinfection ◽

Pathogenic Microorganisms ◽

Microbiological Contamination ◽

Disinfection Process

Water disinfection means the removal, deactivation or killing of pathogenic microorganisms. Microorganisms are destroyed or deactivated, resulting in termination of growth and reproduction. When microorganisms are not removed from drinking water, drinking water usage will cause people to fall ill. Chemical inactivation of microbiological contamination in natural or untreated water is usually one of the final steps to reduce pathogenic microorganisms in drinking water. Combinations of water purification steps (oxidation, coagulation, settling, disinfection, and filtration) cause (drinking) water to be safe after production. As an extra measure many countries apply a second disinfection step at the end of the water purification process, in order to protect the water from microbiological contamination in the water distribution system. Usually one uses a different kind of disinfectant from the one earlier in the process, during this disinfection process. The secondary disinfection makes sure that bacteria will not multiply in the water during distribution. This paper describes several technique of disinfection process for drinking water treatment. Disinfection can be attained by means of physical or chemical disinfectants. The agents also remove organic contaminants from water, which serve as nutrients or shelters for microorganisms. Disinfectants should not only kill microorganisms. Disinfectants must also have a residual effect, which means that they remain active in the water after disinfection. For chemical disinfection of water the following disinfectants can be used such as Chlorine (Cl2), Hypo chlorite (OCl-), Chloramines, Chlorine dioxide (ClO2), Ozone (O3), Hydrogen peroxide etch. For physical disinfection of water the following disinfectants can be used is Ultraviolet light (UV). Every technique has its specific advantages and and disadvantages its own application area sucs as environmentally friendly, disinfection byproducts, effectivity, investment, operational costs etc. Kata Kunci : Disinfeksi, bakteria, virus, air minum, khlor, hip khlorit, khloramine, khlor dioksida, ozon, UV.

Download Full-text

The Role of Catalytic Ozonation Processes on the Elimination of DBPs and Their Precursors in Drinking Water Treatment

Catalysts ◽

10.3390/catal11040521 ◽

2021 ◽

Vol 11 (4) ◽

pp. 521

Author(s):

Fernando J. Beltrán ◽

Ana Rey ◽

Olga Gimeno

Keyword(s):

Drinking Water ◽

Water Treatment ◽

Humic Substances ◽

Hypochlorous Acid ◽

Drinking Water Treatment ◽

Disinfection Byproducts ◽

Catalytic Ozonation ◽

Operating Conditions ◽

Halogen Compounds ◽

Radiation Sources

Formation of disinfection byproducts (DBPs) in drinking water treatment (DWT) as a result of pathogen removal has always been an issue of special attention in the preparation of safe water. DBPs are formed by the action of oxidant-disinfectant chemicals, mainly chlorine derivatives (chlorine, hypochlorous acid, chloramines, etc.), that react with natural organic matter (NOM), mainly humic substances. DBPs are usually refractory to oxidation, mainly due to the presence of halogen compounds so that advanced oxidation processes (AOPs) are a recommended option to deal with their removal. In this work, the application of catalytic ozonation processes (with and without the simultaneous presence of radiation), moderately recent AOPs, for the removal of humic substances (NOM), also called DBPs precursors, and DBPs themselves is reviewed. First, a short history about the use of disinfectants in DWT, DBPs formation discovery and alternative oxidants used is presented. Then, sections are dedicated to conventional AOPs applied to remove DBPs and their precursors to finalize with the description of principal research achievements found in the literature about application of catalytic ozonation processes. In this sense, aspects such as operating conditions, reactors used, radiation sources applied in their case, kinetics and mechanisms are reviewed.

Download Full-text