WQTC, Toronto - November 2018

11/14/2018

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METHODS FOR NEAR REAL-TIME ANALYSIS OF DBP PRECURSORS AND RELATED NOM PROPERTIES

Dave Reckhow, Griffin Moriarty, Yue Sun, Patrick WittboldUniversity of Massachusetts – Amherst

Celina DozierArizona State University - Tempe

WQTC, Toronto - November 2018

1

Formation of Cl2-driven DBPs

2

Natural OrganicMater

AnthropogenicChemicals(PPCPs, Ag &

industrial products)

Cl2NaOCl

NH3

Br-, I-

OBr-, I3-

~90%

CO2 + Oxidized Organic Compounds• Acids• Aldehydes• Ketones• Nitrosamines

NH2Cl The non-halogenated DBPs

The Halogenated DBPs• THMs• HAAs and other haloacids• Haloaromatics• N-halo compounds• Halo-nitriles, aldehydes, nitros, etc

~10%

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Reasons for studying DBP precursors

• Long Term Goals: New knowledge on the structure and origin of DBP precursors• Science endpoints

• Informs watershed and lake models for precursors

• Engineering and management endpoints• Helps guide management of watersheds and lakes

• Helps with planning for climate change

• Short term goals: Fast or real-time assessment of precursors• Science Endpoints

• Understanding the dynamics of watersheds and impacts of rain events

• Engineering and Management Endpoints• Selection of raw waters (sources and intake levels)

• Need for changes in chemical dosing or other operations

3

Why and Where• Possible precursor monitoring locations

Dist.Sys.Clear

well

Coagulant Chlorine

Settling

Corrosion ControlFluoride

raw water

flocculationrapidmix

Filtration

Oxidant

Intermediate oxidation/

disinfection

Reservoir A

Reservoir B

5 6

4

3

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Raw water specific precursor content: broad surveys

5

Chapra et al., 1997, J. Env. Eng. ASCE, 123(7)714-715

248.0)(78.43 TOCTOC

THMFP

• Chapra, Canale & Amy, 1997• Related TOC to

THM precursor content• THMFP = 43.78 TOC1.248

• Used data from:• Amy, Edzwald, Miller, Bader

• FP tests were under varying conditions

NYC System

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• West of Hudson• Cat/Del

• Unfiltered

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Can we rely on DOC?

• DOC (mg/L) in NYC Reservoirs• Typical annual

cycle

7Date

10/1

/200

6

11/1

/200

6

12/1

/200

6

1/1/

2007

2/1/

2007

3/1/

2007

4/1/2

007

5/1/

2007

6/1/2

007

7/1/

2007

8/1/2

007

9/1/2

007

10/1

/200

7

11/1

/200

7

12/1

/200

7

1/1/2

008

2/1/

2008

3/1/

2008

4/1/

2008

5/1/

2008

6/1/

2008

7/1/

2008

Dis

solv

ed O

rgan

ic C

arb

on

(m

g/L

)

0.0

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

3.2

Dis

solv

ed O

rgan

ic C

arb

on

(m

g/L

)

0.0

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

3.2

Tunnel #1Tunnel #2Tunnel #3CannonsvillePepactonNeversinkRondoutAshokanSchoharieKensico: DelKensico: Cat

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• 2006-2009; 2013• UMass/ H&S Studies

• Showing similar behavior among reservoirs

• Substantial seasonal variability

• Other precursor data• 1995 & 1998

• New data: 2017?

• Surrogates• DOC/TOC data

• From mid 80’s

• Absorbance spectra

THM Precursors

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Specific-THM Precursors

• Normalized to DOC• Big drop in fall

• Not consistent!

9Date

10/1/2

006

11/1/

2006

12/1

/2006

1/1/2

007

2/1/2

007

3/1/2

007

4/1/2

007

5/1/

2007

6/1/2

007

7/1/

2007

8/1/2

007

9/1/2

007

10/1

/2007

11/1/2

007

12/1/2

007

1/1/2

008

2/1/

2008

3/1/2

008

4/1/

2008

5/1/2

008

6/1/

2008

7/1/2

008

Sp

eci

fic

TH

MF

P (g

/mg

-C)

0

10

20

30

40

50

60

70

80

90

100

Sp

eci

fic

TH

MF

P (g

/mg

-C)

0

10

20

30

40

50

60

70

80

90

100


9

• Dichloroacetonitrile• From Amino acids?

• Algal activity

10

Date

10/1

/200

6

11/1

/200

6

12/1

/200

6

1/1/

2007

2/1/

2007

3/1/

2007

4/1/

2007

5/1/

2007

6/1/

2007

7/1/

2007

8/1/

2007

9/1/

2007

10/1

/200

7

Dic

hlo

roa

ceto

nitr

ile F

P ( g

/L)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

7.0

8.0

9.0

10.0

11.0

12.0

Dic

hlo

roa

ceto

nitr

ile F

P (g

/L)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

7.0

8.0

9.0

10.0

11.0

12.0


Amanda KeyesMeasuring Org-N

NYC Reservoirs

HAN example

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DOC is a blunt tool

• At 25g-THM precursor/mg-C, • 0.25% of the NOM carbon become incorporated into THMs,

• 99.75% of NOM carbon does not form THMs

• Using DOC as a proxy for THM precursors is a bit like using TDS for iodide• It might correlate, but it might not

• Can we do better: yes!• Spectral based parameters

• UV Abs, full UV/Vis spectra, fluorescence

• Reactivity based parameters• Chlorine demand, COD

• Accelerated DBP formation

11

Elemental: C & N Analysis

• Technology

• Combustion/NDIR for Carbon

• Chemiluminescence for Nitrogen

• Use

• Stand alone analyzers for bulk samples

• Detectors for HPLC

12

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Bulk NOM Absorbance Spectra• What information can we extract from this?

• Problem of particles

Wavelength (nm)

200 250 300 350 400 450 500

Ab

sorb

an

ce (

cm-1

)

0.0

0.1

0.2

0.3

0.4

0.5Kensico January Shoharie January Ashokan January Cannonsville January Pepacton January Neversink January

Problem with light scattering

Fluorescence• Sensitive to a wide range of

compounds

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Electron Donating Capacity (EDC)

• Donation to a strong oxidant (Metal in high OS)• Permanganate or Dichromate: Chemical Oxygen Demand (COD),

slow, usually done at elevated temperature

• Donation to a more selective oxidant• ABTS+ =>2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonate)

radical cation• Especially phenolics (Aeschbacher et al., 2010;

Önnby et al., 2018)

• Donation to photocatalytic oxidant• UV/TiO2: The PeCOD method (Mantech)

15

EDC relates to loss of oxidant residual (i.e., oxidant demand) in water treatment

Study Objectives & Design• Objectives

• To assess and fine tune a new rapid precursor analyzer

• To look for a combination of real-time measurements that can be separately or together for accurate prediction of DBP precursor concentration

• Study Design: use of Mill River site• Continuous in-line monitoring of Mill River water with:

• The accelerated THM precursor analyzer

• A UV-Vis multi-spectral analyzer, as well as a fixed wavelength analyzer

• A DOC analyzer

• Two chemical oxidant demand analyzers (PeCOD & a UMass prototype)

• Collection of grab samples (ISCO timed sampler) and analysis in the lab of:• daily during dry periods and as much as hourly during heavy rain events.

• Conventional precursor tests in accordance with standard procedures.

• Fluorescence EEMs, and other advance techniques that are not amenable to on-line measurements

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• Located in north Amherst and goes through a natural greenbelt southwest to Hadley and the Connecticut River

• Above-average water quality

• Feeds to Connecticut River

• Continuously pumped into Water and Energy Testing Facility for sampling and water quality monitoring

• Pressure transducers for continuous measurement of stage, translated to discharge

Mill River

Field Site

• Mill River

Land Use Percent of Total

Forest 58.3

Cropland 8.3

Pasture 5.1

Forested Wetland 3.3

Urban Public/Institutional 3.3

Non‐Forested Wetland 3.0

Low Density Residential 2.8

Medium Density Residential 2.3

Very Low Density Residential 2.2

Open Land 1.8

Multi‐Family Residential 1.5

Water 1.4

Commercial 1.1

Participation Recreation 1.0

Brushland/Successional 1.0

Other 3.6

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Flow characteristics

Date

Jan May Sep Jan May Sep Jan May Sep

Flo

w (cf

s)

0

50

100

150

200

250

300

2014 2015 2016

• Pre-study flow estimated from nearby Mill River in Northampton

Current System• Spinning Disc Filters

• AMS prototype

• RealTech: 254nm

• & full scan

• GE Seivers DOC analyzer

• Inficon P&T GC

• PeCOD analyzer

• UMass prototype (coming soon)

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25 point medians

Date

Mar Apr May Jun Jul

DO

C (m

g/L

)

2

4

6

8

Dissolved organic Carbon• Continuous monitoring in 2017

• 65,000 measurements over 5 months

• Smooth trends reflecting external changes

• very little random variation

Date

Mar Apr May Jun Jul

Flo

w (

cfs)

0

50

100

150

200

DO

C (

mg/

L)

0

2

4

6

8

FlowDOC

2017

TOC and Flow• TOC tracks flow in rising portion of hydrograph, but lags

in tailing portion

• Seasonal trends

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DOC vs UV254: Apr-May 2017

23

DOC

UV254

The two measurement track each other well,But some changes in UV/DOC even over a short time frame

4.3 5.2∗

Monitoring Instrumentation

• COD Mantech PeCOD

Type Manufacturer and Model

Time/analysis #/day

DOC GE Sievers M5310

2 min 715 (Continuous)

UV Absorbance

RealTechUV254

8 sec Continuous

Multi-spectral RealTech(196/scan)

5 min 270 (Continuous)

COD MantechPeCOD

10 min 20 (1x per hour plus QC)

Accelerated Precursor

AMS prototype

3 hrs 8

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Aquametrology THM-100 FP prototype

• Existing on-line THM analyzer• Purge & Trap

• Fujiwara Reaction

• New accelerated pre-chlorination unit• High dose: ~40 mg/L

• High temp: 60-70C

• Short reaction time: 60 min

Alkaline pyridine reaction

Partial Kinetic Deconvolution

• asdas

26

Absorbance at 90 secs

Absorbance at 900 secs

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27

Conditions Resulting in Same THM Formation

Reaction Time (hrs)

0 10 20 30 40 50 60 70 80

Rea

ctio

n T

empe

ratu

re (

oC

)

0

10

20

30

40

50

60

70

2.5 mg/L dose5 mg/L dose10 mg/L dose20 mg/L dose40 mg/L doseStandard Lab Method

• Based on: Owen et al., 1992 (WQTC)• Using Colorado River & SPW

How to Accelerate: Guidance from Existing THM models

Expanded scale

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Conditions Resulting in Same THM Formation

Reaction Time (hrs)

0 1 2 3 4 5

Re

actio

n T

empe

ratu

re (

oC

)

0

10

20

30

40

50

60

70

80

90

2.5 mg/L dose5 mg/L dose10 mg/L dose20 mg/L dose40 mg/L doseStandard Lab Method

• Looking for a 1-hr time

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Feb-March 2017•

Fun

ctio

n of

chl

orin

e do

se•

Insu

ffici

ent d

ose

can

give

co

ntra

ry r

esul

ts

Mar

Flo

w (

cfs)

0

50

100

150

200

FlowDOC

2017

May 2017

• m\

30

May

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16

31

March – July 2017

• sadas

32

Blue is TOCRed is THM-FP

2018

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Predictors: DOC or TOC

33

As of 1 Nov 2018

TOC (mg/L)

0 2 4 6 8 10 12 14

Cla

ssic

al T

HM

For

mat

ion

Tes

t ( g

/L)

0

100

200

300

400

500

600

700

b0 = -8.0

b1 = 52.8

r² = 0.749

• Against lab 72-hr THM Precursor test & EPA 551.1

Predictor: UV Abs

34

As of 1 Nov 2018

UV Abs (cm-1)

0.1 0.2 0.3 0.4 0.5 0.6

Cla

ssic

al T

HM

For

mat

ion

Tes

t (

g/L)

100

150

200

250

300

350

400

450

500

b0 = 70.2

b1 = 699

r² = 0.828


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Predictors: Cl2 Demand


35

As of 1 Nov 2018

Chlorine Demand (mg/L)

2 4 6 8 10 12 14 16 18 20

Cla

ssic

al T

HM

For

ma

tion

Te

st ( g

/L)

0

100

200

300

400

500

600

700

b0 = -32.4

b1 = 36.8

r² = 0.696

Predictors: AMS THM

36

As of 1 Nov 2018

THM formation by AMS Method

200 300 400 500 600 700 800 900 1000

Cla

ssic

al T

HM

For

mat

ion

Tes

t (

g/L)

100

200

300

400

500

600

700

b0 = -58.7

b1 = 0.757

r² = 0.912


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Predictors: Accelerated Lab Test

37

As of 1 Nov 2018

Accelerated Lab THM Formation (g/L)

100 200 300 400 500 600

Cla

ssic

al T

HM

For

mat

ion

Tes

t (

g/L)

100

200

300

400

500

600

700

b0 = 0.030

b1 = 1.10

r² = 0.960


Summary to date

Surrogate r2

DOC 0.749

UV 254 0.828

Cl2 Demand 0.696

AMS THM 0.912

Accelerated Lab THM 0.960

PeCOD

Other UV-Vis

Fluorescence

38

Target Parameter: 3-day Lab THM Precursor test

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General Conclusions

• Precursor to DOC ratios (i.e., specific precursor levels) for regulated DBPs vary substantially (e.g., factor of ~5) across season and location in a watershed• Thus DOC is a poor predictor of precursor for fine changes in

precursor levels

• Precursors must still be measured using lab tests• Some new on-line methods are showing promise

• The best to date are the:• Accelerated lab test with GC/ECD

• On-line accelerated test with Fujiwara-based quantification

39

Conclusions specific to AMS system

• Accelerated tests require high chlorine doses (e.g., 20 mg/L) to fully measure the THM precursors• Low doses can even show reverse correlation with precursors

• Like the UV absorbance, accelerated THM formation tracks DOC quite well• There are some important departures

• Opportunities exist to assay fast and slow precursors• Possibly by varying chlorine dose, reactor temperature

• The accelerated (1hr) and system conditions (e.g., 72 hr) tests correlate very well

• Fujiwara method seems to be reliable and reflective of the GC/ECD results

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Acknowledgments

• Massachusetts Clean Energy Center

• Hazen & Sawyer Engineers

• Water Research Foundation

• NYSERDA• New York State Energy Research & Development Authority

• Many past students and utility personnel in other locations

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Documents

WQTC, Toronto - November 2018