Controlling Algae-related Tastes and Odors:
From Source to Tap
VA AWWA Water Quality and Research
Committee Seminar
March 23, 2016
Gary C. Schafran
Old Dominion University
Drinking Water Taste and
Odor Events are Common
and Occur World Wide
And as a consequence most
utilities have had to respond to
customer T&O complaints
The importance of T&O events to the
water industry is clear and based on the
customer’s perspective that:
If it doesn’t look, taste, or smell
“good” or “right”– it is not good
quality water.
Aesthetics are not covered by
NPDWR, but secondary MCLs address
aesthetic conditions of water
Table of Secondary Drinking Water Standards
Contaminant
Aluminum
Chloride
Color
Copper
Corrosivity
Fluoride
Foaming agents
Iron
Manganese
Odor
pH
Silver
Sulfate
Total Dissolved
Solids (TDS)
Zinc
Secondary MCL
0.05 to 0.2 mg/L*
250 mg/L
15 color units
1.0 mg/L
Non-corrosive
2.0 mg/L
0.5 mg/L
Noticeable Effects above the Secondary MCL
colored water
salty taste
visible tint
metallic taste; blue-green staining
metallic taste; corroded pipes/ fixtures staining
tooth discoloration
frothy, cloudy; bitter taste; odor
rusty color; sediment; metallic taste; reddish or
0.3 mg/L
orange staining
black to brown color; black staining; bitter metallic
0.05 mg/L
taste
3 TON (threshold odor number) "rotten-egg", musty or chemical smell
low pH: bitter metallic taste; corrosion
6.5 - 8.5
high pH: slippery feel; soda taste; deposits
skin discoloration; graying of the white part of the
0.1 mg/L
eye
250 mg/L
salty taste
hardness; deposits; colored water; staining; salty
500 mg/L
taste
5 mg/L
metallic taste
Table of Secondary Drinking Water Standards
Contaminant
Aluminum
Chloride
Color
Copper
Corrosivity
Fluoride
Foaming agents
Iron
Manganese
Odor
pH
Silver
Sulfate
Total Dissolved
Solids (TDS)
Zinc
Secondary MCL
0.05 to 0.2 mg/L*
250 mg/L
15 color units
1.0 mg/L
Non-corrosive
2.0 mg/L
0.5 mg/L
Noticeable Effects above the Secondary MCL
colored water
salty taste
visible tint
metallic taste; blue-green staining
metallic taste; corroded pipes/ fixtures staining
tooth discoloration
frothy, cloudy; bitter taste; odor
rusty color; sediment; metallic taste; reddish or
0.3 mg/L
orange staining
black to brown color; black staining; bitter metallic
0.05 mg/L
taste
3 TON (threshold odor number) "rotten-egg", musty or chemical smell
low pH: bitter metallic taste; corrosion
6.5 - 8.5
high pH: slippery feel; soda taste; deposits
skin discoloration; graying of the white part of the
0.1 mg/L
eye
250 mg/L
salty taste
hardness; deposits; colored water; staining; salty
500 mg/L
taste
5 mg/L
metallic taste
Algae-related T&O not directly seen in
these Secondary MCLs …
and only through the Threshold Odor
Number (TON) do we see some type
of guidance
Focus of This Presentation – Controlling AlgaeRelated Tastes and Odors
Managing your
Source Water
Treatment Options
Distribution System
Not Considered
Point of Use
Devices
If you have a surface water, you
have the potential for a
biologically-induced Taste and
Odor event …Chinese Proverb
To Address T&O Issues You Have to
Know Causative Agent/Condition
Local, National, and International Surveys of
Utilities and Customers Concerning
Tastes and Odors in DW
Identified Sources of T&O Problems
Reported by US Utilities
Number of Responses
300
250
Surface Water Supply
200
150
100
50
0
Suffet et al., 1996. AWWA Taste and Odor Survey. J.AWWA p. 168-180
T&O Event Complaints Reported by Season by
US Utilities With Surface Water Sources*
18
7
29
Winter
Spring
Summer
46
Fall
* % of total complaints
Suffet et al., 1993. AWWA Taste and Odor Survey. Proc. of AWWA Water Quality and Technol. Confer., Mia, FL.
Taste and Odors in Surface Waters Often Related
to the Presence of Geosmin and MIB
CH3
CH3
CH3
Geosmin
CH3
2-Methylisoborneol
Human detection (earthy-musty taste/smell) at 5-15 ng/L in water
Geosmin and MIB are metabolites associated with
certain algae and bacteria in surface waters and often
associated with more productive lakes (i.e. high
nutrient concentrations)
High concentrations of planktonic algae
Benthic and Epibenthic Algae can
Contribute Substantially to T&O Events
Lyngbya
Lyngbya
Macrophyte (rooted
aquatic vegetation)
abundance is also
related to the
availability of
nutrients
But Geosmin and MIB can Occur in LowNutrient Concentration, Clear Water
Oligotrophic Lakes
Wachusetts Reservoir
Aquatic Plant Production
(algae/macrophytes)
ͳͲ͸‫ܱܥ‬ଶ + ͳ͸ܰ ܱଷି + ‫ܱܲܪ‬ସଶି + 122‫ܪ‬ଶܱ+ 18‫ ܪ‬ା
photosynthesis
→ ‫ܥ‬ଵ଴଺‫ܪ‬ଶ଺ଷܰଵ଺ܲ + 138ܱଶ
N and/or P usually the limiting nutrient so when more
N and/or P enter the aquatic system, algae and/or
macrophytes can proliferate
Lakes/Reservoirs are Dynamic and Complex
Systems
WINTER
Aquatic
Plants
Soil biota,
organic
matter,
nutrients,
plankton
Biofilm,
benthic mats
Plankton
This
image
cannot
currentl
y be
display
ed.
LATE SPRING-SUMMER-EARLY FALL
Aquatic
Plants
Soil biota,
organic
matter,
nutrients,
plankton
Biofilm,
benthic
mats,
macrophytes
Plankton
thermocline
TURNOVER
Aquatic
Plants
Soil biota,
organic
matter,
nutrients,
plankton
Biofilm,
benthic mats
TURNOVER
Aquatic
Plants
Soil biota,
organic
matter,
nutrients,
plankton
Biofilm,
benthic mats
P,N
TURNOVER
Aquatic
Plants
Soil biota,
organic
matter,
nutrients,
plankton
Biofilm,
benthic mats
P,N
TURNOVER
Aquatic
Plants
Soil biota,
organic
matter,
nutrients,
plankton
Biofilm,
benthic mats
P,N
TURNOVER
Aquatic
Plants
Soil biota,
organic
matter,
nutrients,
plankton
Biofilm,
benthic mats
P,N
Conditions in Your Source Water Control What
Organisms are There
In exemplary Darwinian “Survival of the Fittest”
fashion, organism populations rise and fall as
conditions and competition changes
Phytoplankton Blooms Often Accompany Warm
Water Temperatures
This typically accompanies the stratification of
lakes/reservoirs
Temporal Trends in MIB Concentrations
at Bartlett Lake, AZ
Upstream (), downstream (), epilimnion (■), hypolimnion (▵) sampling
sites for Bartlett Lake. Total MIB mass in the reservoir (*) is also
indicated.
Westerhoff et al., 2005. Water Research, Volume 39, Issue 20, 2005, 4899–4912
Cyanobacteria (blue-green algae) have
been the most widely identified group
producing T&O compounds
Common T&O Cyanobacteria
Cyanobacteria Genera
Anabaena
Aphanizomenon
Fischerella
Hyella
Lyngbya
Nostoc
Oscillatoria
Phormidium
Planktothrix
Pseudanabaena
Synechocystis
Geosmin
X
X
X
X
X
X
X
X
X
X
MIB
X
X
X
X
X
X
X
X
Other Phytoplankton and Bacteria that
Produce Geosmin and MIB
Plankton
Diatoms (Asterionella, Cyclotella)
Chrysophytes (Dinobryon, Synura, Uroglena)
Dinoflagellates (Ceratium, Peridinium)
Green algae
Bacteria
Actinomycetes (Streptomycetes, Nocardia)
Geosmin and MIB Production – Intra and
Extracellular and Dissolved and Bound
MIB
MIB
MIB
MIB
MIB
MIB
MIB
MIB
MIB
MIB
Intracellular Geosmin and MIB can be bound to
proteins with the bound fraction being dominant
Dissolved geosman and MIB can readily
enter the water column whereas the
bound forms are retained within the cell
This situation has potential ramifications
for treatment and management efforts
Approaches to T&O Events
Short-term response:
MIB
Focus on eradicating the offending
chemical constituent(s) causing the T&O
event and possibly the producers
Long-term approach:
Focusing on managing the
condition(s) that caused the event
Managing T&O Event in Source Waters
Short-term Management Efforts
Source Water Short-term Management
• Shift or blend raw water sources
Source Water Short-term Management
• Shift depth at which water is withdrawn
(selective withdrawal)
0
10
20
30
Geosmin (ng/L)
40
Source Water Short-term Management
• Discharge water from the reservoir from
depths that have high geosmin & MIB
0
10
20
30
Geosmin (ng/L)
40
Source Water Short-term Management
• Application of an algaecide (copper
sulfate, other copper-based products,
non-copper algaecide)
Release of internal geosmin/MIB? Short term spike?
Little Success
6
0
6
6
5
2
2 2
2
0 0
0
Others
17
Alum addition
Works Welll
Works Somewhat
Inter-source water
transfers
10
Artificial
destratification
20
Lake oxygenation/
aeration
.
21
Non-copper based
algicides
0
15
Other copperbased algicides
15
Copper sulfate
applications
% of Responses
Q13: Effectiveness
of Algal
Control
Q13. Effectiveness
of Algal Control
Methods Methods
25
21
19
17
15
8
6
4
2
2
0
Managing T&O Events Through Treatment
Short-term Response Efforts
Treatment Plant Short-term T&O Event
Response
• Powdered activated carbon (PAC)
addition
Particle
size/dist
ribution,
pore
size/dist
ribution
Wood based
Coconut Shell based
Coal based
Geosmin and MIB Response to PAC Dose
MIB
Geosmin
Geosmin and MIB Uptake Over Time
PAC Addition in a Conventional Process Train
PAC
Alum
Polymer + pH
adjustment
Raw
Water
Transmission Main
Rapid Mix
NaOCl
Flocculation/
Sedimentation
Caustic + Fl + Zn
Orthophosphate
Filter
Ammonia
Clearwell
NaOCl
Distribution System
Treatment Plant Short-term T&O Event
Response
• For a plant using pre- or intermediateozonation, increase in dose may be
required to depress T&O below
detection
Wert et al., 2014. Effect of oxidant exposure on the release of intracellular microcystin, MIB, and geosmin from three
cyanobacteria species. Wat Res. 52(1): 251-259.
Treatment Plant Longer-Term T&O Event
Preparation
Modify existing process train or develop
new treatment process train
• PAC feed point to maximize
contact before coagulant
addition
• Identify PAC that maximizes
• Ozone + BAC/biofiltration
• UV + peroxide
Longer-Term Management of Surface
Water Supplies
Manage watershed activities to lower N, P,
and sediment (actinomycetes) inputs
• Stormwater BMPs
• Agricultural BMPs
Longer-Term Management of Surface
Water Supplies
Manage water transfers (e.g. interbasin
transfers) with a goal of minimizing
enhancing conditions that favor T&O algae
• Timing of transfers
• Source waters
Longer-Term Management of Surface
Water Supplies
Enhanced water column circulation
•
Can move phytoplankton out of their
optimum light environment
•
Where oxygen is added to the hypolimnion
it can reduce the N and P flux to the water
column
Bubble Plume
May achieve full water column
destabilization or only partial mixing
Graphic courtesy of Brad Sherman, CSIRO
Changes in TP and Algal Biovolume
in Chaffee Dam
Top Down Mixing
Bottom Up Mixing
Hypolimnetic Aeration/
Layer Aeration
Limits the amount of vertical
circulation, but adds dissolved
oxygen to lower waters
Surface Water Monitoring to
Support Operational Decisions
Don't it always seem to go,
That you don't know what you've till you
monitor it …. Lyric from
“Big Yellow Taxi”, Counting Crows
Monitoring is key to
understanding the
conditions in your
source water.
Having this information
provides the opportunity
to manage/intervene
prior to or at the
beginning of an event
Reilley-Matthews, B. 2007. Monitoring and Control of Nuisance Algae, AWWA ACE.
Monitoring for MIB and Geosmin
Directly Can be Expensive
$200+ per sample by commercial laboratories
Turn-around times are sometimes 7 to 14 days
Detection of Taste and Odors by Flavor
Profile Analysis is conducted by a number of
utilities. Dr. Andrea Dietrich (VA Tech) is a
national/international expert in this area.
Monitoring Locations and Frequency
At sufficient spatial distribution (horizontally
and vertically) and frequency to be able to
detect the onset of an event and what
specific regions (including depths) that the
event is occurring
Long-term monitoring allows reservoir
managers to develop predictive capabilities
What to Monitor
• Regular (weekly to monthly) monitoring
of dissolved oxygen, temperature,
conductivity, nutrient suite (N, P, Si),
chlorophyll-a, algal counts, algal taxa
(planktonic), Secchi disk, turbidity, pH,
cyanobacteria (phycocyanin sensor)
• Periodic (annual)
aquatic vegetation
survey (macrophytes,
benthic algae,
periphyton)
Real-Time Collection of Water Quality Information –
Fixed Depths or Automated Profiling
Real-Time Collection of Water Quality Information –
Fixed Depths or Automated Profiling
“Automated” particle
imaging for algal taxa
identification
Requires development
of a library for your
source water from
which identification can
be matched
Comparison of Total Filaments Manually Counted
Versus by Flow CAM
Tarrant et al. 2009. Feasibility Study for Early Warning Systems for Algae-induced Tastes and Odors.
Final Report submitted to the AWWA T&O Project Sub-committee. A TEC-funded project.
Summary
• T&O events are widespread and due to a number of
different planktonic and benthic algae and also
bacteria (actinomycetes)
• Conditions in sources waters (reservoir/lake) dictate
the timing, duration, and severity of the event
• Monitoring is important to understand the
biogeochemical processes occurring in source waters
and early intervention
• Treatment options exist – PAC dominates, ozonebiofiltration
• Reservoir management can minimize T&O events
Both AWWA and WRF
Have Addressed
T&O Issues Through
• Conference sessions, workshops, presentations
• Taste and Odor Committee (Water Quality Division)
• J. AWWA published articles
• AWWA Monographs (books)
• Water Research Foundation – sponsored research
WRF-Funded Research
Identification and Treatment of Tastes and Odors in
Drinking Water, Project 118, published 1987.
"Taste and Odor in Drinking Water Supplies" published
in 1989.
Taste-and-Odor Problems Associated With Chlorine
Dioxide, published 1991.
Identification and Control of Odorous Algal Metabolites,
published 1996.
Optimization of Powdered Activated Carbon Application
for Geosmin and MIB Removal, published 2000.
Distribution Generated Taste-and-Odor Phenomena,"
Project 365, published 2002.
Public Perception of Tap Water Chlorinous Flavor,
published 2004.
Practical Taste-and-Odor Methods for Routine
Operations: Decision Tree, published 2004.
Water Utility Self-Assessment for the Management of
Aesthetic Issues," published 2004.
Ozone-Enhanced Biofiltration for Geosmin and MIB
Removal, published 2005.
Early Warning and Management of Surface Water
Taste-and-Odor Events, published 2006.
IWA Specialist Group on Offflavours in the Aquatic
Environment, 2015 Publication.
AWWA Water Supply Manual
of Practice, 2011 Publication
Questions?
Got Algae?
Fluorescence
Detection of
Individual Algal
Species
Wachusett Reservoir (Massachusetts)
Oligotrophic (low nutrient concentrations)
Anabaena – Trigger 50 ASU (250 colonies/mL)-cyanobacteria
Synura – Trigger 20 ASU (2 colonies/mL)-golden algae
Asterionella – Trigger 1000 ASU (1200 colonies/mL)-diatom
Dinobryon – Trigger 300 ASU (350 colonies/mL)-golden algae
Uroglena – Trigger 300-400 ASU (3 colonies/mL)
Synura – family Chrysophyceae
(chrysophyte) – golden algae
Chlorophyll-a Measurements Along
the Transect
Cyanobacteria Measurements Along
the Transect