1. Unregulated, Emerging DBPs
Why We Should Understand Them
March 26, 2018
Original title of this presentation was “Why Engineers Should Understand Them”. I think it everyone ought to understand them, and at least know what they are.
J. Clark Maness, EI
Staff Professional, WithersRavenel

2. PRESENTATION TOPICS What are DBPs? Unregulated, emerging DBPs
Alternative Disinfectants
Potential Control Options

3. Why disinfect? Needed to prevent microbial, waterborne diseases.
~ 2.4 million preventable deaths with full access to clean, reliable sanitation and drinking water (Bartram, Cairncross, 2010).
Why disinfect? Those who work at water plants know a lot of treatment goes in before disinfection.
Need to kill any remaining pathogens in the finished water product, and prevent re-growth in the distribution system.
Important step to prevent microbial, waterborne diseases.
“KILL THE BUGS”

4. Disinfection By-Products
An unintended consequence: formation of disinfection by-products (DBPs).
DBPs formed through oxidation and substitution reactions with organic matter
However, as with many good things there are a few side effects.
An unintended consequence of chemical disinfection is the formation of many different toxic disinfection-byproducts or DBPs.
There are many complex formation routes for each individual DBP. But generally, your disinfectant reacts with natural organic matter that is not removed in the water treatment process to form DBPs.
Humic, fluvic acids, etc.

5. Importance of DBP Control
Why DBP control?
Carcinogenic
Mutagenic
Teratogenic
Drinking water systems will continue to disinfect the water we drink and we’re forced to balance risks.
So, why worry about DBPs? We need to disinfect our water to prevent the spread of waterborne diseases.
DBPs are a side effect of a process necessary for preventing acute health risk, but they also pose a serious chronic health risk.
Yes, we need to protect the public from acute risks, but we also need reduce the life-time risk of developing cancer and teratogenic effects in fetuses.

6. Brief History of DBPs and Regulations
The Safe Drinking Water Act (SDWA) passed in 1974.
Environmental Protection Agency (USEPA) to establish and enforce drinking water standards.
Around the same time, trihalomethanes (THMs) were discovered, and subsequently regulated by the USEPA in 1979.
It’s always surprising to see that we have not been regulating DBPs, or other environmental hazards, for very long.
The SDWA was passed in the 1974, allowing the EPA to establish and enforce minimum drinking water standards.
Around the same time Rook et al., Bellar et al., and a few other groups discovered THMs, which were subsequently regulated in 1979

7. Brief History of DBPs and Regulations
1998: Stage 1 Disinfectants/Disinfection By-Products Rule (DBPR) regulated more DBPs and reduced acceptable THM levels
2006: Stage 2 DBPR implemented stricter monitoring requirements in distribution systems.
Today, still only 11 regulated DBPs.
4 Trihalomethanes (THM4)
5 Haloacetic Acids (HAA5)…but there are nine total HAAs (HAA9)
Bromate and chlorite (oxyhalides)
Many years would pass before more DBPs were regulated until 1998 that the Stage 1 Disinfectants/Disinfection By-Products Rule regulated more DBPs (haloacetic acids, HAAs).

8. Brief History of DBPs and Regulations
Many utilities struggled with Stage 1 and 2 DBPR regulations.
Popular way to comply was to switch to an alternative disinfectant and/or use multiple disinfectants.
Alternative disinfectants
Chloramines (mono-, di-, & tri-)
Ozone (O3)
Chlorine Dioxide (ClO2)
Ultra Violet (UV)
Many years would pass before more DBPs were regulated until 1998 that the Stage 1 Disinfectants/Disinfection By-Products Rule regulated more DBPs (haloacetic acids, HAAs).

9. Effect of alternative disinfectants
Positive: The reduction of regulated DBPs
Negative: The increased formation of emerging/unregulated DBPs
Alternative disinfectants and new multi-disinfectant practices reduce the formation of THMs and HAAs!
In chlorinated drinking water, the THMs and HAAs
are generally present at the highest levels of the DBPs
measured (mid-ppb levels), with chloroform generally
being the dominant THM (mean of 23 mg/L in the ICR,
with some samples above 100 mg/L) and dichloroacetic
acid and trichloroacetic acid being the dominant HAAs
(mean of 11 and 10 mg/L in the ICR, respectively). The
sum of the four regulated THMs (THM4) are generally
present at levels higher than the sum of the five
regulated HAAs (HAA5); however, the sum of the nine
total chloro-bromo-HAAs (HAA9, i.e., the five regulated
plus four unregulated HAAs) can be present at
levels comparable to THM4. Chloramination and
ozonation generally produce much lower levels of
THMs and HAAs relative to chlorine, although
ozonation can produce ppb levels of bromoform and
dibromoacetic acid in high-bromide source waters.
Chlorine dioxide can also produce HAAs (mean of
23 mg/L in the ICR for the five regulated HAAs). With
the U.S. Stage 1 and Stage 2 D/DBP regulations, the
current mean levels will likely be lower in the United
States than when the ICR data were collected (1997–
1998).

10. Emerging/Unregulated DBPs
Presently identified emerging DBP classes include:
Halonitromethanes (HNMs)
Halofuranones
Haloamides (HAMs)
Haloacetonitrile (HANs)
Tribromopyrrole
Haloacetaldehydes (HALs)
Iodo-Haloacetic Acids (I-HAAs)
Iodo-Trihalomethanes (I-THMs)
Nitrosamines
More than 600 identified DBPs
In the 30 years since the THMs were identified as
DBPs in drinking water, significant research efforts have
been directed toward increasing our understanding of
DBP formation, occurrence, and health effects [2,8–17].
Although more than 600 DBPs have been reported in the
literature [2,18], only a small number has been assessed
either in quantitative occurrence or health-effects studies.

11. What is an emerging DBP?
Have at least a moderate occurrence level in public drinking water systems (sub- to low µg/L)
Known or suspected to cause adverse toxicological effects in humans
Currently not regulated by the USEPA or individual state authority

12. Why care? It’s our duty to care about the health of the public.
With GenX, C8, and etc. our customers are more well-informed than ever.
Regulations will likely get stricter in the future.
Why care, they’re not regulated.
The decisions we make directly or indirectly impact public health.

13. Examples Ozone  Bromate Formation
Reduces or removes formation of THMs and HAAs
However, leads to elevated levels of bromate (known carcinogen in lab animals)
Big issue if elevated levels of bromide present.

14. Examples Chloramines  NDMA Formation
Reduces formation of THMs and HAAs
However, leads to elevated levels of Nitrosodimethlyamine (NDMA) (probable human carcinogen)
Big issue if elevated levels of tertiary amines present (think biopolymers and treatment polymers)

15. Examples Chlorine Dioxide  Chlorite Formation
Reduces formation of THMs and HAAs
However, leads to elevated levels of Chlorite (regulated DBP)
Chlorite causes anemia; nervous system damage in infants and young children)

16. Control of Emerging DBP Formation
Four (4) general options
DBP precursor material removal
Preformed DBP and precursor removal
DBP removal post disinfection
Distribution System Control

17. Control of Emerging DBP Formation
DBP precursor material removal
Activated carbon filtration
Granular activated carbon (GAC) or powdered activated carbon (PAC)
May lead to formation of more brominated/iodinated DBPs
Membrane filtration
Ultrafiltration, nanofiltration, and reverse osmosis
Expensive
Enhanced Coagulation and Sedimentation (increased TOC removal)
Increased coagulant costs
Capital cost for improved settling equipment (example: settling plates)

18. Control of Emerging DBP Formation
Preformed DBP and DBP precursor removal
Add disinfectant at different points in treatment process to preform DBPs
DBPs then removed during processes highlighted earlier
Activated carbon filtration
Granular activated carbon (GAC) or powdered activated carbon (PAC)
May actually
Membrane filtration
Ultrafiltration, nanofiltration, and reverse osmosis
Expensive

19. Control of Emerging DBP Formation
DBP Removal Post-Disinfection
Aeration (good for THM and other volatile DBP removal)

20. Control of Emerging DBP Formation
Distribution System Control
Tank aeration
Change chlorination points in system
Tank Recirculation

21. Great Resources on Emerging DBPs
Richardson, S., Plewa, M., Wagner, E., Schoeny, R., & Demarini, D. (2007). Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: A review and roadmap for research.
Krasner, S. W., Weinberg, H. S., Richardson, S. D., Pastor, S. J., Chinn, R., Sclimenti, M. J., Thruston, A. D. (2006). Occurrence of a New Generation of Disinfection Byproducts †. Environmental Science & Technology, 40(23), doi: /es060353j

22. Great Resources on Emerging DBPs
Richardson, S., Plewa, M., Wagner, E., Schoeny, R., & Demarini, D. (2007). Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: A review and roadmap for research. Mutation Research/Reviews in Mutation Research, 636(1-3), doi: /j.mrrev