A Stage 3 (Three!) Disinfection Byproduct Rule: What Could It Mean
for GAC and Disinfection?
Julie Herzner, P.E.
Ben Stanford, Ph.D.
Allison Reinert, E.I.
Erik Rosenfeldt, Ph.D., P.E.
Presented at
NYSAWWA
TIFFT 2015
September 23, 2015
First, A Review
• Born before 1976?
• THMs discovered in
1974, regulated by
1979
• Cancer cohort control
group?
• Changing time horizon
on regulations
DBP Formation
HOCl + Natural Organics (NOM)
Distribution System
Formation
Instantaneous
3
Plant formation
Oxidized NOM and
inorganic chloride
• Aldehydes
Chlorinated
Organics
• TOX
• THMs
• HAAs
What Are Disinfection Byproducts?
• Chemicals formed as a byproduct of disinfection
• Trihalomethanes (THMs, 4 currently regulated)
• Haloacetic Acids (HAAs, 5 currently regulated, 9
often counted)
• Nitrosamines (e.g., NDMA, 6 on docket for UCMR3)
• The “DBP Iceberg”
• Aldehydes and Ketones (Ozonation byproducts)
• Bromate (Ozonation byproduct)
• Chemicals added as a byproduct associated with
disinfectants
• Perchlorate (bulk hypochlorite, onsite-generated (OSG)
hypochlorite)
• Chlorate (Bulk, OSG, and chlorine dioxide)
• Chlorite (chlorine dioxide)
But, There Are Many Unknown DBPs!
Free Cl2
μg/L
TOX
878
UTOX
465
THM
203
DHAN
10
DCP
1
TCP
7
CP
1
DHAA
57
THAA
134
ClNH2
μg/L
106
88
2.33
0.42
0.95
0.00
0.11
13.8
0.32
Chloramines form a FRACTION of the DBPs that occur under chlorination!!
Disinfectant and Disinfection Byproduct (D/DBP) Rules
• Objectives of the D/DBP Rules
• Limit concentration of known and unknown
DBPs that may have adverse health effects
• Assumes THMs and HAAs are appropriate
surrogate
• Balance risks and benefits from other rules
• SWTR, Pb & Cu rule, TC rule
• Features
• MCLGs for 3 THMs and DCAA set to zero
• TOC used as a surrogate for precursors to
unknown DBPs
Compound(s)
TTHMs
HAA5
Bromate
Chlorite
Chlorine
Chloramines
Chlorine Dioxide
Stage 1 & 2
0.080
0.060
0.010
1.0
4.0
4.0
0.8
Running Annual Average—TTHM Example
(Units = ppb)
“Site A”
Feb:
May:
Aug:
Nov:
“Site B”
Feb:
May:
Aug:
Nov:
RAA = 73
53 ppb
62
70
35
48
82
45
49
68
108
59
“High TTHM”
Feb:
55
May:
75
Aug:
133
Nov:
88
“High HAA”
Feb:
58
May:
72
Aug:
111
Nov:
85
Locational Running Annual Average—TTHM
Example (Units = ppb)
“Site A”
Feb:
35
May:
48
Aug:
82
Nov:
45
LRAA = 53 ppb
“Site B”
Feb:
49
May:
68
Aug:
108
Nov:
59
LRAA = 71 ppb
“High TTHM”
Feb:
55
May:
75
Aug:
133
Nov:
88
5LRAA = 82 ppb
“High HAA”
Feb:
58
May:
72
Aug:
111
Nov:
85
LRAA = 88 ppb
Drivers that Challenge Compliance
Drivers that Challenge Compliance
So Where Does the EPA Stand and What Can We Do?
Stage 3, Seriously? I’m not making this up…
• Grouped contaminant
strategy
• Could GAC be an effective
strategy?
6-year
review in
2016
Regulated HAA5 Compounds
Order of Cytotoxicity
BAA
1.00 × 10-5
TBAA
8.50 × 10-5
DBCAA
2.02 × 10-4
DBAA
5.90 × 10-4
BDCAA
6.85 × 10-4
BCAA
7.78 × 10-4
CAA
8.10 × 10-4
TCAA
2.40 × 10-3
DCAA
7.30 × 10-3
More Toxic
Order of Genotoxicity
BAA
1.70 × 10-5
CAA
4.10 × 10-4
DBAA
1.80 × 10-3
TBAA
2.50 × 10-3
BCAA
3.64 × 10-3
DBCAA
1.40 × 10-2
DCAA
NS
TCAA
NS
BDCAA
NS
Less Toxic
Less Toxic
More Toxic
Problem: Genotoxicity and Cytotoxicity of
HAA5 (Green) vs. HAA9 (all)
What About those Pesky Other DBPs?
• Chlorate
• Perchlorate
• NDMA
Perchlorate
• Can be in source waters
• IX is treatment of
choice
• Also forms in
hypochlorite but is
controllable
•
•
•
•
Bulk
Hypochlorite
Web Model
Dilute
Cool
Manage pH
Buy filtered bleach
www.awwa.org/hypochlorite
Chlorate
• Sources
HRL = 210 ug/L
•
•
•
•
Bulk hypo
OSG
ClO2
Agriculture
Nitrosamines: NDMA Occurrence By State
National Nitrosamine Occurrence Rate
40%
Nitrosamines Occurrence Rate, Organized by
Disinfectant
34.4%
35%
Occurrence Rate
30%
25%
20%
Opflow, June 2011
14.2%
15%
10%
5%
2.7%
2.4%
3.1%
0%
Free Chlorine
Chloramine
Not Indicated No Disinfectant
Other
19
What Could Stage 3 DBP Rule Look Like?
• Perchlorate—has been due for several years
• Chlorate and NDMA likely as additions to the 3rd Six Year
Review (2016)
• Mixed DBPs could become the basis for a Stage 3 Rule
• Perchlorate ~15 – 24 μg/L?
• Chlorate ~800 μg/L? (Range 210 – 1000 μg/L)
• NDMA—only likely nitrosamine to be regulated
• 100 ng/L?—CA action level is 300 ng/L; notification level is 10 ng/L
• Bromate, chlorite, MRDL unlikely to change
• Unclear if HAA5 shifts to HAA6 or HAA9; Other DBPs?
• BUT, could there be a TT for the organic DBPs?
• Implies GAC use
WaterRF 4560: GAC Control of Regulated and Emerging DBPs of
Health Concern
WaterRF 4560 Project Objectives
• GOAL: to evaluate the efficacy, design, and cost implications
of using GAC to remove precursors and pre-formed C-DBPs
and N-DBPs of concern
• Evaluate the impact of GAC treatment
• Evaluate the impact of various chlorination strategies
• Quantify the breakthrough of C-DBP and N-DBP precursors
relative to TOC breakthrough.
• Evaluate the impact that GAC design, operation, and
maintenance
• Compare the costs of various GAC usage scenarios and
disinfection practices based on several case study sites
DOC is The First “Contaminant” to
Breakthrough GAC
Cotinine
f = a/(1+exp(-(x-x0)/b))
1.2
1.0
C/C0
0.8
0.6
0.4
0.2
0.0
-0.2
0
2e+4
4e+4
Bed Volumes
x column 4 vs y column 4
Cotinine BV vs Cotinine C/C0
95% Confidence Band
95% Prediction Band
6e+4
8e+4
1e+5
HazenGAC: How the Model Works
• Historical TOC
• Future Flows
• Number of
contactors
Input
• Number of GAC
contactors
• Change out
schedule
Cost
Partial
Treatment
• How much future
flow will be
bypassed with a
certain # of GAC
contactors
DBPs
• Blended TOC
effluent
• THM and HAA
Yields
• RSSCT equation (can
be validated by pilot
data, if available)
RSSCT
• GAC Treated
TOC
• Bypassed TOC
TOC
Key Conclusions and Summary
• A Stage 3 D/DBP Rule is on the horizon
• Outcome and timing are uncertain—12 years?
• Specific impact on HAAs, THMs, and other DBPs unclear
• Chlorate and perchlorate likely to be included
• Strongly implicates OSG and bulk hypochlorite systems
• For utilities with NDMA concerns, chloramines may become a
less-favorable option
• But chloramines are excellent for THM and HAA control
• GAC may become a larger part of future compliance nation-wide
• WaterRF 4560 and other projects to help provide guidance on
unintended consequences
Water JAM 2011
Ben Stanford
Director of Applied Research
[email protected]
(919) 863-1027
Research Manager:
Djanette Khiari
[email protected]
Water JAM 2011
Thank you!!!!!
Julie Herzner
Senior Associate
[email protected]
(212) 539-7256