Tag Archives: disinfection byproducts

Chlorine Dioxide DBPs in Drinking Water, Qatar

Al-Otoum F, Al-Ghouti MA, Ahmed TA, Abu-Dieyeh M, Ali M. Disinfection by-products of chlorine dioxide (chlorite, chlorate, and trihalomethanes): Occurrence in drinking water in Qatar. Chemosphere. 2016 Sep 13;164:649-656. doi: 10.1016/j.chemosphere.2016.09.008.

The occurrence of chlorine dioxide (ClO2) disinfection by-products (DBPs) in drinking water, namely, chlorite, chlorate, and trihalomethanes (THMs), was investigated. Two-hundred-ninety-four drinking water samples were collected from seven desalination plants (DPs), four reservoirs (R), and eight mosques (M) distributed within various locations in southern and northern Qatar. The ClO2 concentration levels ranged from 0.38 to <0.02 mg L-1, with mean values of 0.17, 0.12, and 0.04 mg L-1 for the DPs, Rs, and Ms, respectively. The chlorite levels varied from 13 μg L-1 to 440 μg L-1, with median values varying from 13 to 230 μg L-1, 77-320 μg L-1, and 85-440 μg L-1 for the DPs, Rs, and Ms, respectively. The chlorate levels varied from 11 μg L-1 to 280 μg L-1, with mean values varying from 36 to 280 μg L-1, 11-200 μg L-1, and 11-150 μg L-1 in the DPs, Rs, and Ms, respectively. The average concentration of THMs was 5 μg L-1, and the maximum value reached 77 μg L-1 However, all of the DBP concentrations fell within the range of the regulatory limits set by GSO 149/2009, the World Health Organization (WHO), and Kahramaa (KM).

Does Aluminum Ion Inhibit or Promote Disinfection Byproducts?

Shen H, Chen X, Chen H. Influence on the generation of disinfection byproducts in a tannic acid solution by aluminum ions. Environmental Technology. 2016 Aug 17:1-11.

Aluminum (Al) commonly exists in natural waters, and its salts are often used as coagulants in drinking water treatment. Therefore, associated with the security of drinking water, functions of Al ions (Al3+) on generation of disinfection byproducts (DBPs) should not be ignored. This study focuses on DBPs and the carcinogenic factor of chlorinated water samples after the addition of Al3+ with different Al3+/initial tannic acid molar ratios. The results imply that Al3+ acts as a promoter of haloacetic acids (HAAs) and an inhibitor of trihalomethanes (THMs) when tannic acid is selected as model compound of natural organic matter during chlorination. Depending on the results of size exclusion chromatography and ultraviolet spectrophotometer, an equilibrium system can be assumed between hydrolysis and flocculation in tannic acid solution with Al3+. Furthermore, influences on the equilibrium system for Al3+ addition may result in various effects on generation and distribution ratios of THMs and HAAs during chlorination. Finally, according to the analyses of a fluorescence spectrophotometer, it is demonstrated that the presence of Al3+helps to increase precursors of DBPs (humic acid-like organics) and then improve the generation of DBPs.

Disinfection Byproduct Formation During Biofiltration

Delatolla R, Seguin C, Springthorpe S, Gorman E, Campbell A, Douglas I. Disinfection byproduct formation during biofiltration cycle: Implications for drinking water production. Chemosphere 2015 Oct; Vol. 136, pp. 190-7.

The goal of this study was to investigate the potential of biofiltration to reduce the formation potential of disinfection byproducts (DBPs). Particularly, the work investigates the effect of the duration of the filter cycle on the formation potential of total trihalomethanes (TTHM) and five species of haloacetic acids (HAA5), dissolved oxygen (DO), organic carbon, nitrogen and total phosphorous concentrations along with biofilm coverage of the filter media and biomass viability of the attached cells. The study was conducted on a full-scale biologically active filter, with anthracite and sand media, at the Britannia water treatment plant (WTP), located in Ottawa, Ontario, Canada. The formation potential of both TTHMs and HAA5s decreased due to biofiltration. However the lowest formation potentials for both groups of DBPs and or their precursors were observed immediately following a backwash event. Hence, the highest percent removal of DBPs was observed during the early stages of the biofiltration cycle, which suggests that a higher frequency of backwashing will reduce the formation of DBPs. Variable pressure scanning electron microscopy (VPSEM) analysis shows that biofilm coverage of anthracite and sand media increases as the filtration cycle progressed, while biomass viability analysis demonstrates that the percentage of cells attached to the anthracite and sand media also increases as the filtration cycle progresses. These results suggest that the development and growth of biofilm on the filters increases the DPB formation potential.

Atrazine in Drinking Water Not Associated with Overian Cancer, Iowa

Inoue-Choi M, Weyer PJ, Jones RR, Booth BJ, Cantor KP, Robien K, Ward MH Atrazine in public water supplies and risk of ovarian cancer among postmenopausal women in the Iowa Women’s Health Study. Occupational and Environmental Medicine. 2016 Jul 1. pii: oemed-2016-103575. doi: 10.1136/oemed-2016-103575.

BACKGROUND: Few studies have evaluated environmental chemical exposures in relation to ovarian cancer. We previously found an increased risk of ovarian cancer among postmenopausal women in Iowa associated with higher nitrate levels in public water supplies (PWS). However, elevated nitrate levels may reflect the presence of other agricultural chemicals, such as atrazine, one of the most commonly detected pesticides in Iowa PWS.

METHODS: We evaluated the association between atrazine in drinking water and incident ovarian cancer (N=145, 1986-2010) among 13 041 postmenopausal women in the Iowa Women’s Health Study who used their PWS for ≥11 years as reported in 1989. Average levels of atrazine (1986-1987), nitrate-nitrogen (NO3-N, 1955-1988) and estimated levels of total trihalomethanes (TTHM, 1955-1988) from PWS monitoring data were linked to the participants’ cities of residence. We computed HRs and 95% CIs by categories of the average atrazine level (not detected, ≤ or >0.37 parts per billion=median) using Cox proportional hazards regression adjusting for ovarian cancer risk factors.

RESULTS: Atrazine was detected in water samples from 69 cities where 4155 women (32%) lived and levels were moderately correlated with NO3-N (ρ=0.35) and TTHM (ρ=0.24). Atrazine levels were not associated with ovarian cancer risk with or without adjusting for NO3-N and TTHM levels (p-trend=0.50 and 0.81, respectively). Further, there was no evidence for effect modification of the atrazine association by NO3-N or TTHM levels.

CONCLUSIONS: In our study with low atrazine detection rates, we found no association between atrazine in PWS and postmenopausal ovarian cancer risk.

Spain, Italy THM Exposure and Colorectal Cancer; No Association Found

Villanueva CM, Gracia-Lavedan E, Bosetti C, Righi E, Molina AJ, Martín V, Boldo E, Aragonés N, Perez-Gomez B, Pollan M, Gomez Acebo I, Altzibar JM, Jiménez Zabala A, Ardanaz E, Peiró R, Tardón A, Chirlaque MD, Tavani A, Polesel J, Serraino D, Pisa F, Castaño-Vinyals G, Espinosa A, Espejo-Herrera N, Palau M, Moreno V, La Vecchia C, Aggazzotti G, Nieuwenhuijsen MJ, Kogevinas M. Colorectal Cancer and Long-Term Exposure to Trihalomethanes in Drinking Water: A Multicenter Case-Control Study in Spain and Italy. Environmental Health Perspectives. 2016 Jul 6.

BACKGROUND: Evidence on the association between colorectal cancer and exposure to disinfection by-products in drinking water is inconsistent.

OBJECTIVES: We assessed long-term exposure to trihalomethanes (THMs), the most prevalent group of chlorination by-products, to evaluate the association with colorectal cancer.

METHODS: A multicentre case-control study was conducted in Spain and Italy in 2008-2013. Hospital-based incident cases, population-based (Spain) and hospital-based (Italy) controls were interviewed to ascertain residential histories, water type consumed in each residence, frequency and duration of showering/ bathing, and major recognized risk factors for colorectal cancer. We estimated adjusted odds ratios (OR) for colorectal cancer in association with quartiles of estimated average lifetime THM concentrations in each participant’s residential tap water (μg/L, from age 18 to two years before the interview) and estimated average lifetime THM ingestion from drinking residential tap water (μg/day).

RESULTS: Subjects analyzed were 2047 cases and 3718 controls. Median values (ranges) for average lifetime residential tap water concentrations of total THMs, chloroform, and brominated THMs were 30 (0-174), 17 (0-63), and 9 (0-145) μg/L, respectively. Total THM concentration in residential tap water was not associated with colorectal cancer (OR=0.92, 95%CI: 0.66-1.28 for highest vs. lowest quartile), but chloroform concentrations were inversely associated (OR=0.31, 95%CI: 0.24-0.41 for highest vs. lowest quartile). Brominated THMs concentrations showed a positive association among men at the highest vs. lowest quartile (OR=1.43, 95%CI: 0.83-2.46). Patterns of associations were similar for estimated average THM ingestion through residential water consumption.

CONCLUSIONS: We did not find clear evidence of an association between detailed estimates of lifetime total THM exposures and colorectal cancer in our large case-control study population. Negative associations with chloroform concentrations and ingestion suggest differences among specific THMs, but these findings need confirmation in other study populations.

BAC Effects on Haloacetaldehyde and Trihalomethane Formation Potentials

Mao YQ, Wang XM, Guo XF, Yang HW, Xie YF. Characterization of haloacetaldehyde and trihalomethane formation potentials during drinking water treatment. Chemosphere. 2016 Jun 16;159:378-384. doi: 10.1016/j.chemosphere.2016.05.088.

Haloacetaldehydes (HAs) are the third prevalent group of disinfection by-products (DBPs) of great health concern. In this study, their formation and speciation during chlorination were investigated for raw and process waters collected at three O3-biological activated carbon (BAC) advanced drinking water treatment plants. The results showed that all HA formation potentials (HAFPs) were highly enhanced whenever ozone was applied before or after conventional treatment. Sand filtration and BAC filtration could substantially reduce HAFPs. Trihalomethanes (THMs) were also measured to better understand the role of HAs in DBPs. Very different from HAFPs, THMFPs kept decreasing with the progress of treatment steps, which was mainly attributed to the different precursors for HAs and THMs. Brominated HAs were detected in bromide-containing waters. Chloral hydrate (CH) contributed from 25% to 48% to the total HAs formed in waters containing 100-150 μg L-1 bromide, indicating the wide existence of other HAs after chlorination besides CH production. In addition, bromide incorporation factor (BIF) in HAs and THMs increased with the progress of treatment steps and the BIF values of THMs were generally higher than those of HAs. The BAC filtration following ozonation could significantly reduce HA precursors produced from ozonation but without complete removal. The brominated HAFPs in the outflow of BAC were still higher than their levels in the raw water. As a result, O3-BAC combined treatment was effective at controlling the total HAs, whereas it should be cautious for waters with high bromide levels.

N-Nitrosamines in Drinking Water Around Mainland China

Er Bei, Yuanyuan Shu, Shixiang Li, Xiaobin Liao, Jun Wang, Xiaojian Zhang, Chao Chen, Stuart Krasner. Occurrence of nitrosamines and their precursors in drinking water systems around mainland China. Water Research 98 (2016)

N-Nitrosamines (NAs) in drinking water have attracted considerable attention in recent years due to their high carcinogenicity, frequent occurrence, and their potential regulation. During the past three years, we have collected about 164 water samples of finished water, tap water, and source water from 23 provinces, 44 cities from large cities to small towns, and 155 sampling points all over China. The occurrence of NAs in the finished and tap water was much higher in China than that in the U.S. Nine NAs were measured and NDMA had the highest concentration. The occurrence of NDMA was in 33% of the finished waters of water treatment plants and in 41% of the tap waters. The average NDMA concentration in finished and tap waters was 11 and 13 ng/L, respectively. Formation potentials (FPs) of source waters were examined with an average NDMA FP of 66 ng/L. Large variations in NA occurrence were observed geographically in China and temporally in different seasons. The Yangtze River Delta area, one sub-area in East China, had the highest concentrations of NAs, where the average NDMA concentrations in the finished and tap water were 27 and 28.5 ng/L, respectively, and the average NDMA FP in the source water was 204 ng/L. NA control may be achieved by applying breakpoint free chlorination and/or advanced treatment of ozone e granular activated carbon process to remove the NA precursors before disinfection.