DBP Control Strategies: Source Water, Treatment, and Distribution System

Philip A. Tangorra

NYC WATERSHED / TIFFT SYMPOSIUM

September 17, 2013West Point, NY

TOC & DBPs

Source water characteristics Traditional Treatment Disinfection Distribution

Spatial/Temporal levels of TTHM that are “high”.

Long Term exposures - Large dataset on carcinogenicity of THM.

Stage 2 Compliance

TTHM REGULATIONS

1979 - Total Trihalomethanes Rule 0.100 mg/L MCL

1998 - Stage 1 D/DBP Rule 0.080 mg/L RAA MCL for TTHM 0.060 mg/L RAA MCL for HAA5

2006 - Stage 2 D/DBP Rule 0.080 mg/L LRAA MCL for TTHM 0.060 mg/L LRAA MCL for HAA5

19811982

19831984

19851986

19871988

19891990

19911992

19931995

19961997

19981999

20002001

20022003

20042005

20062007

20082009

20102011

2012

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

0.160

0.180

0.200

Annual Mean TTHM Concentrations(Compliance)1981-present

Mea

n C

on

c (u

g/L

)

2007

History of Recent MVWA Studies

1999 2002

Stage 2 D/DBP Rule Proposed

2003

Promulgation of Stage 2 D/DBP and LT2ESWTR

2004 2005

Stage 1 D/DBPCompliance

2012

DBP Control Study

TANCS Project

Nitrification Control Study

2001 2008 2010

GAC Pilot and Full Scale Demos

Cl-NH3 Conversion & Pipe Loop

2006

Stage 2 D/DBPCompliance

MVWA Studies for Stage 2 D/DBP Rule Compliance DBP Control Options Study – 2001 TANCS study – 2003 Nitrification Control Study – 2004 Chloramines System Pre-Design – 2005 Chloramines Conversion Master Plan – 2005 Corrosion Pipe Loop Testing – 2006 GAC Pilot scale testing – 2007 GAC Demonstration Scale Testing – 2008 Ongoing

Alternative coagulants DS corrosion chemistry modifications GAC Pilot Scale Testing

GAC Implementation Complete media change

out (63”) Timing Operational Issues

Flow/Demand Raw Water Quality Backwash frequency Staffing

Logistics Facilities Deliveries Noise

2011 – Full scale comparison of 8*30 GAC Wood Virgin Bituminous Reactivated

Bituminous 2012 - 8*20 Lignite 2013 - 8*20 Lignite

+ Underdrain Rehab

ANNUAL BUDGET $1,000,000

Apr-99

Apr-00

Apr-01

Apr-02

Apr-03

Apr-04

Apr-05

Apr-06

Apr-07

Apr-08

Apr-09

Apr-10

Apr-11

Apr-12

Apr-13

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

TOTAL ORGANIC CARBONMonthly Means

Raw TOC

Filtered TOC

Co

nc

en

tra

tio

n (

mg

/L)

Apr-99

Apr-00

Apr-01

Apr-02

Apr-03

Apr-04

Apr-05

Apr-06

Apr-07

Apr-08

Apr-09

Apr-10

Apr-11

Apr-12

Apr-13

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

TOC Percent RemovalMonthly Means

% R

em

ov

al

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.002011 -2013 WTP TOC

Raw

Clarified

Filtered

TO

C (

mg/L

)

May-11

Aug-11

Nov-11

Feb-12

May-12

Aug-12

Nov-12

Feb-13

May-13

Aug-13

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90C/Co

02/01/03

02/01/04

02/01/05

02/01/06

02/01/07

02/01/08

02/01/09

02/01/10

02/01/11

02/01/12

02/01/13

02/01/14

0

20

40

60

80

100

120

140

160

180

200

TTHMStage 1 & 2 Compliance

Endpoint

Co

nc

(u

g/L

)

02/01/03

02/01/04

02/01/05

02/01/06

02/01/07

02/01/08

02/01/09

02/01/10

02/01/11

02/01/12

02/01/13

02/01/14

0

20

40

60

80

100

120 TTHM - LRAA

Endpoint

Co

nc

(u

g/L

)

02/01/12

05/01/12

08/01/12

11/01/12

02/01/13

05/01/13

08/01/13

11/01/13

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0TTHM - Stage 2 Compliance

BELL HILL ROAD, DEERFIELD

LRAA

Co

nc

(u

g/L

)

MVWA Studies for Stage 2 D/DBP Rule Compliance DBP Control Options Study – 2001 TANCS study – 2003 Nitrification Control Study – 2004 Chloramines System Pre-Design – 2005 Chloramines Conversion Master Plan – 2005 Corrosion Pipe Loop Testing – 2006 GAC Pilot scale testing – 2007 GAC Demonstration Scale Testing – 2008 Ongoing

Alternative coagulants DS corrosion chemistry modifications GAC Pilot Scale Testing

OngoingAlternative coagulantsDS corrosion chemistry modifications

GAC Pilot Scale Testing

Alternative Coagulants

Applied Specialtie

s

Holland Chemical Delta Chemical

AS-4070 PCH180 GLP39 DeltaFloc1123

AS-4071 PCH182 GLP24 DeltaFloc1124

AS-3026 DelPac1525 DeltaFloc1173

AS-3027 DelPac2450 DeltaFloc842

AS-3032 DelPac2000 DeltaFloc807

AS-3034 DelPac2020 GLP23

AS-3036 DelPac2950 AL4P

AS-3003 DeltaPacXP GLP17

AS-3023

Distribution System

Recent DS Conditions pH 9.4 Alkalinity ~40mg

CaCO3/L PO4 0mg/L Optimized Corrosion UFWR offline

Experimental (CDM Smith) pH 7.8 Alkalinity ~40mg

CaCO3/L PO4 0.8 mg/L Cost Savings? TTHM Reduction?

MVWA HISTORICAL LEAD MONITORING DATA LCR Monitoring Period Lead Percentiles

   50th  75th 90th 

Initial Monitoring

1992 - 1st 6 Months 0.038 0.070  0.100

1992 - 2nd 6 Months 0.063 0.092 0.165

Follow-Up Monitoring

1993 - 1st 6 Months 0.021 0.040 0.055

1993 - 2nd 6 Months 0.014 0.024 0.043

1994 - 1st 6 Months 0.009 0.016 0.027

1994 - 2nd 6 Months 0.010 0.018 0.029

1995 - 1st 6 Months 0.003 0.006 0.010

1995- 2nd 6 months 0.003 0.007 0.011

1996 – 1st 6 months 0.003 0.005 0.009

1996- 2nd 6 months 0.004 0.008 0.012

Reduced Monitoring 1997 0.005 0.008 0.014

2000 0.005 0.008 0.013

2003 0.007 0.012 0.014

2006 0.005 0.008 0.011

2009 0.005 0.008 0.011

2012 0.003 0.005 0.008

0

20

40

60

80

100

120

140

160

0 2 4 6 8 10 12

TTHM

(ug/

L)

Holding Time (days)

pH 9.4

pH 7.8

MCL

Distribution Considerations

Unidirectional Flush Timeframe Lime / Soda Ash / Bicarb Pb/Cu compliance TTHM reductions

GAC Options Siemens Coconut shell Calgon Carbsorb 820 Factors

Cost RSSCT and pilot scale testing

EBCT at 20MGD 63” GAC = 14.5 min 55” GAC = 12.7 min

Regeneration??

In Situ GAC Regeneration

Dr. Paul Westerhoff at Arizona State University has developed a technique that may allow for in situ GAC regeneration

Iron nanoparticles (<100 nm) are combined with H2O2 to form hydroxyl radicals, which can oxidize adsorbed organic compounds, converting them to CO2 and H2O

Objectives

Determine if the in situ regeneration technique is suitable for recovering TOC adsorption capacity

Evaluate the effectiveness of the method under “more realistic” conditions Commercially available GAC

Full size GAC grains

Typical (full scale) GAC bed depth

Iron Nanoparticle Production

Commercial grade FeCl3 resulted in larger NPs than those produced from reagent grade FeCl3 (200 nm vs. 80-90 nm)

Methylene blue dye oxidation tests were used to gauge NP reactivity

Multiple batches of NPs appeared non-reactive

It was discovered that dye oxidation only occurred in a pH range of 2.6-2.8

Methylene Blue Oxidation Tests

Pilot Scale Filter Columns

Pilot Scale Recirculation System

Regeneration Results

Wood-based GAC - Three 1-hour regeneration cycles

No measureable change in effluent TOC

Lignite-based GAC One 1-hour regeneration cycle

No measureable change in effluent TOC

Regeneration Results

Coconut-based GAC Three 1-hour regeneration cycles

Effluent TOC reduced after each cycle First round: 1.25 mg/L → 0.85 mg/L

Second round: 0.65 mg/L

Third round: 0.55 mg/L

Effluent TOC Profile – Coconut GAC

Regeneration Considerations

Reagent v. Commercial FeCl3 pH control Peroxide measurement Biofilm?

Summary

In situ regeneration using Fe NPs and peroxide has been shown to be effective for recovering phenol adsorption capacity in bench scale tests

Pilot scale testing has demonstrated that recovering NOM adsorption capacity in full size GAC grains is possible

Achieving greater recovery may require further modifications, or simply more time

THE LAST SLIDE

Thanks Connie Schreppel, PhD

MVWA Director of Water Quality Kim Hoffman CDM Smith Kirk Nowack, PhD - Arcadis

Questions?