Taste and Odor Mitigation Strategy - PNWS-AWWA

Copyright 2013 by CH2M HILL Engineers, Inc.

Taste and Odor Mitigation Strategies Laboratory-Based Analysis

2013 PNWS-AWWA Conference

Spokane, WA

Kim Ervin, P.E., West Region Drinking Water Service

Lead, CH2M HILL


Outline

Introduction - Sources of Taste and Odor

Treatment Effectiveness

– DAF with Ozone

– Biological Filtration

– Powdered Activated Carbon (PAC) and Superfine PAC

– Oxidants and Advanced Oxidation

Comparing the Results


INTRODUCTION


Significance of Taste and Odor Occurrence

Survey of 800 utilities in the U.S

and Canada showed:

– 16% experience taste and odor

(T&O) problems

– 4.5% of their total budget is

spent on T&O control

Survey of 100 utilities by

Summers et al. found:

– 15% experience problems for

more than 4 months of the year

– Raw water concentrations as

high as 1,700 and 240 ng/L

were reported


Types of Odor Problems Experienced by U.S. Utilities (Suffet, 1993)

0

50100

150

200

250300

350

Chlo

rinou

s

Ear

thy

Fishy

Med

icinal

Chem

ical

Gra

ssy

Swam

py

Sulfid

e

Pet

roleum

Sep

tic

Oth

er

Resp

on

ses


CONTROL AND TREATMENT LABORATORY-BASED ANALYSIS


CONTROL AND TREATMENT

DISSOLVED AIR FLOATATION (DAF) AND OZONE


Winnipeg High-Rate DAF Pilot Test

One of the first high-rate

DAF evaluations for a

large (105 mgd) WTP

Extensive piloting of both

conventional and high-

rate DAF reduced

construction costs

DAF cost model allowed

comparison of overall

costs for different

systems

Pre-negotiated DAF

equipment bid process to

shorten the construction

schedule


Winnipeg Pilot Results - DAF & Ozone

0

20

40

60

80

100

120

140

160

180

2-

Apr-

15-

Apr-

29-

Apr-

12-

May-

27-

May-

10-

Jun-

23-

Jun-

7-

Jul-

22-

Jul-

13-

Aug-

26-

Aug-

2-

Sep-

23-

Sep-

TO

N

Raw Post DAF Post O3



BIOLOGICAL FILTRATION


What is Biological Filtration?

Conventional Filtration

Raw Water

Sedimentation

Filtration

Common points of chlorine application…

Flocculation

Rapid Mix


What is Biological Filtration?

Biological Filtration

Raw Water

Sedimentation

Filtration

No chlorine upstream of filters…

Flocculation

Rapid Mix

Filter media

supports

biomass


What’s the Difference Between BAC Filtration and GAC Adsorption?

GAC adsorption requires regular replacement of GAC (depends

on water quality, but could be 1x/yr or more)

In filters, GAC typically has less empty bed contact time (EBCT),

resulting in even more frequent replacement of GAC

Post-filter GAC contactors expensive, but provide longer EBCT

and less frequent GAC replacement versus GAC adsorption in

filters

With BAC filters, GAC replacement frequency extends to 5-10

years or more, resulting in reduced O&M costs

BAC provides less removal of TOC and micro-constituents

BAC is still an important barrier in a robust, multi-barrier water

treatment train


Acclimation Experiment Objectives

To investigate the impact of:

– Time on acclimation to MIB and geosmin

– Empty bed contact time (EBCT)

Tank 1 Tank 2

Sand BAC

Sand

Low

Temp

Sand

Low Ozone

MIB/Geosmin

Low Ozone

Sand BAC Sand

GAC

Backwash

Tank

To Waste

To Waste

Sand

Low

Temp

Feed

MIB (ng/L): 24

Geosmin (ng/L): 21 Feed

MIB (ng/L): 0

Geosmin (ng/L): 0


Impact of Acclimation Time on Sand Biofilter Performance

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

8-Jun 28-Jun 18-Jul 7-Aug 27-Aug 16-Sep 6-Oct 26-Oct

2003

Rem

oval P

erc

enta

ge

MIB EBCT = 13 min

GSM EBCT = 13 min

Significant time was

required for acclimation

to MIB and Geosmin.


Impact of Empty Bed Contact Time

0

10

20

30

40

50

60

70

80

90

100

4 13

Perc

en

t R

em

oval

(%)

Empty Bed Contact Time (min)

MIB

Geosmin

Note: Initial concentration of MIB and geosmin were 20 ng/L each.


“Steady-State” Experiment Objectives

To investigate the impact of the following on biofilter performance:

– Preacclimation to MIB and geosmin

– Media type

– Temperature

– Empty bed contact time (EBCT)

– Influent concentration

Tank 1 Tank 2

Sand BAC

Sand

Low

Temp

Sand

Low Ozone

MIB/Geosmin

Low Ozone

Sand BAC Sand

GAC

Backwash

Tank

To Waste

To Waste

Sand

Low

Temp

Feed

MIB (ng/L): 23, 88

Geosmin (ng/L): 17, 82 Feed

MIB (ng/L): 20, 98

Geosmin (ng/L): 11, 98


“Steady-State” Biomass Concentrations

0

20

40

60

80

100

120

140

Preacclimated BAC Low Temp Sand Sand

Filter

Bio

ma

ss

nm

ol P

O4/g

dry

med

ia Top

Middle

Sand


“Steady-State” Biofilter Performance

0

10

20

30

40

50

60

70

80

90

100

Sand

(20)

Sand

(80)

BAC

(20)

BAC

(80)

Sand Low Temp (20)

Sand Low Temp (80)

Sand

(20)

Sand

(80)

Perc

ent R

em

oved (

%)

MIB

Geosmin

Preacclimated to MIB

and Geosmin Unacclimated to MIB and Geosmin


Biological Filtration Summary

Preacclimation to MIB and geosmin was critical for biofilter

performance on sand media in pilot scale experiments.

BAC sustained higher concentrations of biomass and showed

increased removals of MIB and geosmin.

The lower temperature column showed lower removals of MIB

and geosmin.

Longer EBCTs may be required for adequate removal of MIB and

geosmin.

A “reacclimation” to higher influent concentrations was observed.



POWDERED ACTIVATED CARBON (PAC)


Powdered Activated Carbon

Contact Time

Application (or Dosing) Point

Adsorption capacity,

– Brand and Type of PAC

Interferences: natural organic matter (NOM), coagulants (such as

alum), chlorine

Chlorine consumption


Compared Two PACs for T&O Control (Spiked #1 - Reservoir Water)

45

65

44

11

64

20

811

0

20

40

60

80

100

120

MIB 2I3M Geosmin

Co

nce

ntr

atio

n,

ng

/L

T&O Compound

Spiked - Reservoir

Calgon - 20Norit - 20

Task 2.2A: PAC Pretest - Reservoir WaterMixing = 10 minutes at 50 rpmNote: Numbers next to PAC type in legend are doses in mg/L


Compared Two PACs for T&O Control (Spiked #2 – Lake Water – Higher TOC)

62

7678

27

18

32

38

32

49

0

20

40

60

80

100

120

MIB 2I3M Geosmin

Co

nce

ntr

atio

n,

ng

/L

T&O Compound

Raw - HodgesCalgon - 20Norit - 20

Task 2.2A: PAC Pretest - Lake Water

Mixing = 10 minutes at 50 rpmNote: Numbers next to PAC type in legend are


PAC Summary

PAC products vary in terms of effectiveness

20 minutes of simultaneous coagulation/flocculation and PAC

contact time provided T&O removal

In Sample #1 Reservoir water, PAC provided:

– 90% Geosmin removal

– 50% MIB removal

– 80% 2I3M removal

In Sample #2 Lake water, TOC competition reduced effectiveness

significantly for Geosmin (50-80% removal) and MIB (40%

removal)


Superfine PAC

Research by Susan Dunn under the direction of Dr. Detlef Knappe

at North Carolina State University, compared the performance of

as-delivered PAC with wet-milled superfine PAC.

The delivered PAC was wet-milled on site.

Source: Susan Dunn, Master’s Thesis, 2011


Comparison of PAC to Superfine-PAC

Superfine PAC was wet milled on site to two sizes from 5 different

sources of PAC including wood-based, coconut shells, and coal.

Table below is for wood-based PAC from “Effect of Powdered Activated

Carbon Base Material and Size on Disinfection By-Product Precursor and

Trace Organic Pollutant Removal,” Master’s thesis by Susan Ennis Dun,

North Carolina State University, 2011.

PAC Superfine-PAC 1 Superfine-PAC 2

Particle Size (um)

Mean diameter

Range diameter

9

2 - 18

0.63

0.21 – 1.58

0.12

0.07 – 0.33

BET Surface

Area (m2/g)

912

950

917

Micropore

Volume (cm3/g)

0.313

0.323

0.294

Mesopore

Volume (cm3/g)

0.225

0.339

0.565


How did Superfine PAC compare?

Wood-based PACs outperformed

coal, lignite, and coconut-shell

based PAC.

MIB removal with PAC ranged

from 33% to 69% in 60 minutes.

Faster adsorption kinetics were

observed with the Superfine PACs

compared to their as-received

forms. For example the coconut-

shell PAC removed only 33% but

the superfine versions removed

94% under the same conditions. Source: “Effect of Powdered Activated Carbon Base Material

and Size on Disinfection By-Product Precursor and Trace

Organic Pollutant Removal,” Master’s thesis by Susan Ennis

Dun, North Carolina State University, 2011.


Results of PAC and Superfine PAC testing

0.0

2.5

5.0

7.5

10.0

12.5

15.0

0 5 10 15 20 25 30

MIB

(n

g/L

)

PAC Dose (mg/L)

MIB Concentration

Control Concentration SNR

Hydrodarco

Calgon WPH

Superfine WPH

Target



OXIDANTS


Fishy/Swampy/Grassy T&O Control

ClO 2 KMnO 4 PAC

Fishy/Swampy/Grassy T&O 1-hr 5-min 25-min 1-hr 1 mg/L 25 mg/L

Dimethyl Trisulfide Yes Yes Yes Yes Yes Yes

2,3-Benzopyrrole (Indole) Yes Yes Yes Yes Yes Yes

Dimethyl Disulfide Yes Yes Yes Yes Yes No

Cis, 3-Hexen-1-ol No No Yes** Yes NA No

Cis, 4-Heptenal No No Yes** Yes Yes No

Trans, 2-cis, 6-Nonadienal No No Yes** Yes NA Yes

Cis, 3-Hexenyl Acetate No No No Yes* Yes Yes

1-Heptanal No No No No No Yes

Trans, trans-2,4-Heptadienal No No No No Yes Yes

2-Isobutyl-3-methoxypyrazine No No No No No Yes

Trans, trans-2,4-Decadienal No No No No NA Yes

1-Hexanal No No No No No No

*Yes in 50% SPW, no in 100% CRW and 100% SPW

**Yes in 100% SPW, no in 100% CRW

>50% Removal in CRW/SPW

Cl 2


Ozone Treatment Example Cedar Water Treatment Facility Seattle, Washington


UV-Peroxide AOP Removes Algal Compounds

Spiked Riverbank Filtration Water

0.0

0.5

1.0

1.5

2.0

0 50 100 150 200 250 300

LPCB Exposure Time (min)

Lo

g R

em

oval

Geosmin Removal MIB Removal Microcystin Removal

Hydrogen Peroxide Dose of 5 mg/L

68.4%

90.0%

96.8%

99.0%


Summary of Results

Treatment

Technique

Geosmin

Removal

MIB Removal TON

Reduction

DAF 50 – 75%

DAF + Ozone 50 – 85%

Biological Sand

Filtration

5 – 70% 10 – 80%

Biologically Active

Carbon (BAC)

>90% >95%

Powdered Activated

Carbon (PAC)

40 – 90% 40 – 75%

Superfine PAC 85%

UV-Peroxide AOP >95% >90%


THE END

References and Acknowledgements:

1. “Effect of Powdered Activated Carbon Base Material and Size on Disinfection By-

Product Precursor and Trace Organic Pollutant Removal,” Master’s thesis by

Susan Ennis Dun, North Carolina State University, 2011.

2. CH2M HILL Applied Sciences Laboratory

3. Kerry Meyer/CH2M HILL, et al, “Biofiltration for MIB and Geosmin Removal”,

ACE 2005 podium presentation.

4. Others as cited.


EXTRA SLIDES


DETECTION MEASUREMENT


Drinking Water Taste and Odor Wheel


Traditional Sensory & Chemical Evaluation Techniques

Threshold Number (TON)

– A threshold dilution test

Flavor Profile Analysis (FPA)

– A panel of trained analysts evaluates the T&O characteristics

– Standardized qualitative and quantitative T&O characterization (Flavor Rating Scale, Flavor Rating Assessment, Flavor Threshold Test)

Gas Chromatography (GC)


New Sensory Techniques

Attribute Rating Test

Rating Method “difference method”

2-of-5 Odor Test


New Sensory Techniques Attribute Rating Test

Paired comparison test

Identify Geosmin or 2-MIB 15ng/L standard

Sample is < or = or > standard

Compared well with GC

More effective than TON

– American Water (PAC testing)

– Korea (PAC testing)


New Sensory Techniques Rating Method “difference method”

Used primarily for distribution system evaluations

Compare sample at end of plant to one drawn from point in

distribution system

FPA basic technique, looking for difference


New Sensory Techniques 2-of-5 Odor Test

Forced choice method

2 flasks test sample & 3 flasks control sample

Blind test, group in 2 and 3, correct sort indicates a T&O change

that can then be

– Describe odor difference in standard terms

Very reliable US and Korea analyses


“Smell Bell” (River Trent)


Smelling the Water (Aerosol) at Osaka


Marconi - eNOSE 5000 System



FILTRATION AND OZONE


T&O Treatment Examples Southern Delivery System – Lab Testing Colorado Springs, Colorado

0

20

40

60

80

100

120

140

160

Co

nc

en

tra

tio

n,

ng

/L

Raw Settled Ozonated Filtered

MIB (AM)

MIB (PM)

Geosmin (AM)

Geosmin (PM)

Human Detection Limit


Common Causes of Taste and Odor Geosmin and MIB

Geosmin (Trans-1,10-dimethyl-trans-9-decalol)

MIB (2-Methylisoborneol)

Produce earthy/musty odors not removed during conventional

treatment

Metabolic byproducts of algae (blue-green algae and

actinomycetes)

Occurrence – seasonal (summer and fall)

Geography – global, significant research conducted in Japan and

the U.S.

Odor threshold concentration (OTC) - 2 to10 ng/L

For comparison hydrogen sulfide (H2S) odor threshold - 5,000

ng/L


Current Taste and Odor Observations

Surface water supplies in the Northwest are subject to seasonal

T&O events due to algae

Watershed influences for T&O include

– Storage reservoirs / forbays that favor algae proliferation

– Nutrient loadings (point source & non point discharges)

– Climate Change impact (temperature, vegetation)

– Wildfire

Extreme Wet and Dry periods

– Changes in conveyance and storage

– Variations in run-off

Monitoring programs beginning to establish baseline

understanding of cycles and trends

Taste and Odor Mitigation Strategy - PNWS-AWWA

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