Disinfection By-Products Rule Research Articles

Evaluating regulatory scenarios to limit U.S. nationwide exposure to cytotoxic haloacetic acids

AbstractThe U.S. Environmental Protection Agency (EPA) is considering a regulatory revision of the Disinfectant and Disinfection Byproduct Rule (DBPR) with a goal of limiting nationwide exposure to DBPs of emerging health concern. The occurrence of four brominated haloacetic acids (HAAs), which are generally more toxic in in vitro assays than the five currently regulated HAAs and are candidates for future regulation, were surveyed in 4924 public water systems under EPA's fourth unregulated contaminant monitoring rule (UCMR4). Using UCMR4 data, this study evaluated the nationwide occurrence of nine HAA species and the potential for two regulatory scenarios (the mass sum of all nine HAA species, HAA9, or just the six brominated HAA species, HAA6Br) to control nationwide exposure to the most toxic HAAs. Neither HAA9 nor HAA6Br approaches were effective for identifying water systems that exhibit high HAA exposure, assessed as additive cytotoxicity, because they are more specific to the HAA species that form at high concentrations rather than the species that are most toxic. However, the effectiveness of HAA6Br is highly sensitive to the relative toxicity of one HAA compound, monobromoacetic acid, which has the highest in vitro toxicity among HAAs but also the lowest occurrence and about which little is known regarding in vivo health risks. In contrast to HAA9, systems with high HAA‐associated additive toxicity tend to share similar treatment and disinfectant characteristics as systems with high HAA6Br concentrations. Systems with high source water bromide and total organic carbon were far more likely to use chloramines as a disinfectant residual compared to other systems, but were no more likely to adopt organic precursor removal technologies (biofiltration, granular activated carbon, and ion exchange) than other systems, on average.

Assessing national HAA9 occurrence and impacts of a potential HAA9 regulation

AbstractThe US Environmental Protection Agency is tasked with proposing revisions to Microbial and Disinfectant and Disinfection Byproducts rules (DBPR) by 2025. Disinfection byproducts are currently regulated by the Stage 2 DBPR, inclusive of total trihalomethane and five haloacetic acids (HAA5). EPA's Fourth Unregulated Contaminant Monitoring Rule (UCMR4) included monitoring for HAA5, six brominated haloacetic acids (HAA6Br), and nine haloacetic acids (HAA9). UCMR4 and state‐managed compliance data were utilized to assess the potential impacts of regulating HAA9. HAA9 modeling techniques were validated and applied for greater representation of smaller systems. Outcomes suggest a HAA9 maximum contaminant level (MCL) equivalent to the HAA5 MCL by number of public water systems (PWSs) implicated would be between 72–77 μg/L. An additional 395 PWSs (2%) not currently implicated by Stage 2 DBPR would have compliance challenges if HAA9 is regulated with an MCL equal to the 60 μg/L HAA5 MCL.

The Municipal Water Quality Investigations Program: A Retrospective Overview of the Program’s First Three Decades

This paper presents the history and evolution of the California Department of Water Resources’ Municipal Water Quality Investigations (MWQI) program. This program tracks source water quality in the Sacramento–San Joaquin Delta (Delta) for drinking water supply for nearly two-thirds of California. The program provides early warning of changing conditions in source water quality, provides data and knowledge-based support for operational decision making, and provides scientific support to a variety of urban water users. This retrospective (i) documents program formation, (ii) describes its evolution in response to regulations and technological advances in water treatment and field monitoring, and (iii) notes how the development of federal drinking water quality regulations such as the Disinfection By-Products Rule impacted the program. The MWQI program is believed to be the first drinking water supply program in the United States to conduct continuous, real-time monitoring of organic carbon, bromide, and other anions and to report these data on the internet. In addition to its regular use for operational decision making, the data may be used for evaluating long-term trends and responses to specific changes in the Delta and its watershed. Future program directions will likely be guided by factors that may trigger changes in treatment plant processes and operations, such as emerging contaminants, changes in land and water management practices, permanent Delta island flooding, sea level rise, and climate change. While this retrospective focuses on one region, its multi-decade interplay of science, treatment and monitoring technology, and regulations (as well as practical aspects of managing such a large-scale program) are broadly relevant to professionals engaged in drinking water quality management in other urbanized and developed regions of the world.

Drivers of Spatiotemporal Variability in Drinking Water Quality in the United States.

Approximately 10% of community water systems in the United States experience a health-based violation of drinking water quality; however, recently allocated funds for improving United States water infrastructure ($50 billion) provide an opportunity to address these issues. The objective of this study was to examine environmental, operational, and sociodemographic drivers of spatiotemporal variability in drinking water quality violations using geospatial analysis and data analytics. Random forest modeling was used to evaluate drivers of these violations, including environmental (e.g., landcover, climate, geology), operational (e.g., water source, system size), and sociodemographic (social vulnerability, rurality) drivers. Results of random forest modeling show that drivers of violations vary by violation type. For example, arsenic and radionuclide violations are found mostly in the Southwest and Southcentral United States related to semiarid climate, whereas disinfection byproduct rule violations are found primarily in Southcentral United States related to system operations. Health-based violations are found primarily in small systems in rural and suburban settings. Understanding the drivers of water quality violations can help develop optimal approaches for addressing these issues to increase compliance in community water systems, particularly small systems in rural areas across the United States.

Formation of disinfection by-products under influence of shale gas produced water

Accidental spills and surface discharges of shale gas produced water could contaminate water resources and generate health concerns. The study explored the formation and speciation of disinfection by-products (DBPs) during chlorination of natural waters under the influence of shale gas produced water. Results showed the presence of produced water as low as 0.005% changed the DBP profile measurably. A shift to a more bromine substitution direction for the formation of trihalomethanes, dihaloacetic acids, trihaloacetic acids, and dihaloacetonitriles was illustrated by exploring the individual DBP species levels, bromine substitution factors, and DBP species fractions, and the effect was attributable to the introduction of bromide from produced water. The ratio of dichloroacetic and trichloroacetic acids also increased, which was likely affected by different bromination degrees at elevated bromide concentrations. Increasing blend ratios of produced water enhanced the formation of DBPs, especially the brominated species, while such negative effects could be alleviated by pre-treating the produced water with ozone/air stripping to remove bromide. The study advances understandings about the impacts of produced water spills or surface discharges regarding potential violation of Stage 2 DBP rules at drinking water treatment facilities.

Control Disinfection Byproducts With Spray Stripping in Storage Tanks

Compliance with the Stage 2 Disinfectants and Disinfection Byproducts (DBP) Rule is often achieved by treating water at a treatment plant to reduce DBP formation. However, it could be more cost-effective to use localized treatment in the distribution system to target specific problem areas.

Disinfection Byproduct Occurrence at Large Water Systems After Stage 2 DBPR

Disinfection byproducts (DBPs), including total trihalomethanes (TTHM) and the sum of five haloacetic acids (HAA5) are regulated by the US Environmental Protection Agency Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR). This study compiled DBP and related water quality parameter data for 395 public drinking water systems serving populations greater than 100,000 across 44 US states from 1980 to early 2015. Assessing DBP occurrence data from two years before (2010–2012) and after (2012–2014) Stage 2 DBPR implementation shows improved capture of higher DBP exposure locations within water distribution systems due to the initial distribution system evaluation. After Stage 2 DBPR implementation, TTHM and HAA5 concentrations have mean values of 30.5 µg/L and 19.6 µg/L and 95th percentile values of 71.2 µg/L and 46.5 µg/L, respectively. Comparing this data set with the 1997–1998 Information Collection Rule data set suggests a 20 µg/L reduction in average TTHM occurrence for the highest 5% of systems nationally from 1997–1998 to 2010–2014.

Chlorine Dioxide Preoxidation for DBP Reduction

Using chlorine dioxide for preoxidation is helping water treatment plants meet the requirements of Stage 2 Disinfectants and Disinfection Byproducts Rule.

Assessment of HAA9 Occurrence and THM, HAA Speciation in the United States

Both chlorinated and brominated trihalomethanes (THMs) and haloacetic acids (HAAs) are regulated under the US Environmental Protection Agency's Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR). All four chlorinated and brominated THMs are regulated as total THMs (TTHM) and of the nine HAAs, the sum of five HAAs (HAA5) are regulated; the four unregulated HAAs are all brominated species. The objective of this study was to assess national occurrence of all nine HAAs (HAA9) and disinfection byproduct (DBP) speciation. Modeling techniques are applied and validated to estimate HAA9 concentrations using TTHM and HAA5 species, as HAA9 data are limited. DBP speciation is assessed using bromine incorporation factors (BIFs). While national HAA9 occurrence, assessed using modeled HAA9 concentrations, decreased from 2005 through 2014, it increased in the two years after the Stage 2 DBPR implementation (when different sampling locations were used) compared with the two years prior. BIF values increased from 2005 through 2014, and spatial analysis showed higher BIF values in Southern California and Texas.

Assessment of water quality in distribution networks through the lens of disinfection by-product rules

Disinfection with chlorine is a common practice to ensure secured drinking water, but results in potentially harmful disinfection by-products (DBPs), when excess chlorination is done. The US Environmental Protection Agency (US EPA) has established Stage 1 and Stage 2 disinfection by-product Rules (DBP rules) to control DBP exposure. A modified version of the Canadian Council of Ministries of the Environment water quality index (CCME WQI) is used to assess water quality. CCME WQI is a globally accepted index to assess water quality, but is too generic to be used for DBP rules. The study developed a scheme to make the index suitable for DBP rules. A scoring method based on an analytic hierarchy process (AHP) is applied to assign weights based on DBP rules. A previously modified CCME WQI (Islam et al., 2014) is adapted along with the weights to perform the assessment at the distribution network (DN). A case study was performed on 7 sampling stations in a Quebec City DN. The spatial water quality variations are presented using kriging – a geostatistical method, which identifies the regions with relatively poor water quality and highlights the potential locations for re-chlorination points. The proposed assessment formulation is flexible to handle situations with limited data, which makes it especially suited to smaller municipalities. Keywords: CCME water quality index, Stage 1 DBP Rule, Stage 2 DBP Rule, chlorination

Trihalomethanes in Comerio Drinking Water and Their Reduction by Nanostructured Materials

The formation of disinfection by-products (DBPs) during chlorination of drinking water is an issue which has drawn significant scientific attention due to the possible adverse effects that these compounds have on human health and the formation of another DBPs. Factors that affect the formation of DBPs include: chlorine dose and residue, contact time, temperature, pH and natural organic matter (NOM). The most frequently detected DBPs in drinking water are trihalomethanes (THMs) and haloacetic acids (HAAs). The MCLs are standards established by the United States Environmental Protection Agency (USEPA) for drinking water quality established in Stage 1, Disinfectants and Disinfection Byproducts Rule (DBPR), and they limit the amount of potentially hazardous substances that are allowed in drinking water. The water quality data for THMs were evaluated in the Puerto Rico Aqueduct and Sewer Authority (PRASA). During this evaluation, the THMs exceeded the maximum contamination limit (MCLs) for the Comerio Water Treatment Plant (CWTP). USEPA classified the THMs as Group B2 carcinogens (shown to cause cancer in laboratory animals). This research evaluated the THMs concentrations in the following sampling sites: CWTP, Río Hondo and Pinas Abajo schools, Comerio Health Center (CDT), and the Vázquez Ortiz family, in the municipality of Comerio Puerto Rcio. The results show that the factors affecting the formation of THMs occur in different concentrations across the distribution line. There are not specific ranges to determine the formation of THMs in drinking water when the chemical and physical parameters were evaluated. Three different nanostructured materials (graphene, mordenite (MOR) and multiwalled carbon nanotubes (MWCNTs)) were used in this research, to reduce the THMs formation by adsorption in specific contact times. The results showed that graphene is the best nanomaterial to reduce THMs in drinking water. Graphene can reduce 80 parts per billion (ppb) of THMs in about 2 hours. In addition mordenite can reduce approximately 80 ppb of THMs and MWCNTs adsorbs 71 ppb of THMs in the same period of time respectively. In order to complement the adsorption results previously obtained, total organic carbon (TOC) analyses were measured, after different contact times with the nanomaterials. During the first 30 minutes, graphene C/Co was reduced to c.a. 0.9, in presence of each THMs solution. MWCNTs and MOR show similar adsorptions trends in comparison with graphene.

EPA's Stage 2 Disinfection Byproducts Rules (DBPR) and Northern Kentucky Water: An Economic and Scientific Review.

Implementation of EPA's Stage 2 Disinfection Byproducts Rules (DBPR) in Northern Kentucky will cause a water rate increase of over 25%. Hence a review was undertaken, considering both economics and science in the context of President Obama's 2009 scientific integrity directive. The rules purport to avoid up to 0.49% of new bladder cancers by reducing the levels of DBPs in drinking water - a benefit so small that failure to implement will not cause unreasonable risk to health (URTH). It suggests at most one Northern Kentucky death avoided over 17 years for a cost of $136,000,000 ($1700 per household). Even this small benefit is probably overstated. EPA finds no "causal link" between DBPs and bladder cancer, and EPA acknowledges problems with the epidemiological data used in their calculation: the data appear contradictory and inconsistent, may be skewed toward "positive" results, and suggest different cancer sites than animal studies. Two similar international agencies disagree with EPA's conclusions. The science is based on the Linear No Threshold (LNT) dose response model for DBPs, but this may not be the correct model. 83% of EPA's epidemiological data show a statistical possibility that low levels of DBPs might be beneficial or have no effect.

Simultaneous Compliance of TOC and Turbidity Related to Pathogen Breakthrough and THMs Control by Enhanced Coagulation

Since discovery of harmful disinfection by products (DBPs) like trihalomethanes (THMs)
 and haloacetic acids (HAAs) in chlorinated waters the removal of organic DBPs precursors
 gained priority in drinking water treatment. Historically, coagulation process was arranged
 to remove turbidity, typically related to pathogens occurrence, but nowadays it is usually
 optimized/enhanced for total organic carbon (TOC) reduction.
 This work dealt with the removal of TOC and turbidity by means of enhanced coagulation
 process using Al2(SO4)3⋅18 H2O and FeCl3⋅6H2O as coagulants for jar test without pH
 adjustment according to USEPA procedure. 15% of TOC removal required by USEPA
 D/DBPs rule (1998) was achieved using 30-50 mg l-1 of both coagulants. On the other
 hand, for compliance with more stringent MCL for total THMs in Italy (30 μg l-1) higher
 TOC removal (>30%) which needed of higher coagulants doses (80 mg l-1), was obviously
 required. Those high coagulant doses were also to be used for the compliance with the
 turbidity standard (<1NTU).

Optimization of methods for the determination of DBPs

Chloroform and other bromochlorotrihalomethanes were first identified as disinfection
 byproducts (DBPs) in chlorinated water in 1970s. Since then, many other DBPs have
 been identified such as haloacetonitriles, haloacetaldehydes, cyanogen halides,
 aldehydes, ketoacids, chlorite, bromate and other organic and inorganic compounds. Due
 to their occurrence and potential health risks, the U.S.EPA promulgated the Stage I
 Disinfectants and Disinfection Byproducts (D-DBP) Rule in 1998. To assist water utilities
 monitoring DBPs in their finished water, the U.S. EPA published a list of approved
 analytical methods under the D-DBP Rule. In 1996, the U.S. EPA also promulgated the
 Information Collection Rule (ICR) to collect brackground information on DBPs and
 pathogens for the Stage II D-DBP-Rule. Actually 500 DBPs are known but few have been
 investigated for their quantitative occurrence and health effects. Due to the fact that their
 identification and quantitation have become extremely important to drinking water
 companies in order to reduce or remove their presence, other analytical methods different
 from those proposed by U.S. EPA have been optimized and are now commented in this
 article.

Best Practices: Complying With the Stage 2 D/DBP Rule

Based on a series of AWWA webcasts, this article is the third of three on important distribution system issues. This article provides operations and maintenance options for complying with the U.S. Environmental Protection Agency's Stage 2 Disinfectants and Disinfection Byproducts Rule. The first article (Opflow, July 2012) focused on storage tank operations and maintenance, and the second article (Opflow, August 2012) focused on best practices for cleaning water mains.

Best Practices Cleaning Mains: Clean, Pig, or Dig?

Based on a series of AWWA webcasts, this article is the second of three on important distribution system issues. This article details best practices for cleaning water mains, as regular main cleaning can help extend distribution system service life. Last month's article focused on storage tank operations and maintenance. The final article will provide operations and maintenance options for complying with the U.S. Environmental Protection Agency's Stage 2 Disinfectants and Disinfection Byproducts Rule.

Nitrosamines: Economics of the Unknown

This article discusses the effectiveness of using chloramination to comply with the Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR), if potential nitrosamine formation during and after chloramination might be the result.

How Old Is Too Old for Distribution System Water?

There are several ways to estimate residence time in distribution systems. For simple networks and dead‐end legs, water age can be calculated by dividing the pipe volume by flow rate. More involved water age calculations can be made with spreadsheet models, system hydraulic models, and computational fluid dynamics models. Many utilities chose to conduct the Initial Distribution System Evaluation mandated in the Stage 2 Disinfectants and Disinfection Byproducts Rule by using hydraulic models instead of extensive monitoring. This practice can be used to calculate water age at various points in the system under different operating conditions and potential system modifications.

Survey Says?: Major Water Utilities Shed Light on Chloramine Disinfection

This article discusses a survey conducted by the New York City Department of Environmental Protection to assess the city's options for complying with the U.S. Environmental Protection Agency's Stage 2 Disinfectant and Disinfection Byproducts Rule. The survey asked 13 major U.S. water utilities to report their history of chloramine use, facilities used, dosages and chemicals used, operational procedures, environmental review required, public health impacts, advantages and disadvantages, and source water quality.

Hydraulic Models Shed Light on Water Age

This article discusses water quality in terms of disinfection byproducts (DBPs) related to distribution system water age. The Stage 2 Disinfectants and Disinfection Byproducts Rule requires utilities to conduct initial distribution system evaluations (IDSEs) to select new DBP sampling sites. DBP compliance monitoring begins in 2012 or 2013, depending on the population served. Many utilities have chosen to conduct IDSEs using hydraulic models instead of extensive monitoring programs. This article discusses the benefits of using hydraulic modeling, along with methods for reducing water age that were originally demonstrated by case studies.