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UV Advanced Oxidation for Treatment of Taste and Odor and Algal Toxins. Ohio AWWA Annual Conference Research Workshop September 20, 2011 Erik Rosenfeldt, PE, PhD. Presentation Agenda. Algae issues Taste and Odor Toxic Substances Climate change impacts on algae events

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uv advanced oxidation for treatment of taste and odor and algal toxins

UV Advanced Oxidation for Treatment of Taste and Odor and Algal Toxins

Ohio AWWA Annual Conference

Research Workshop

September 20, 2011

Erik Rosenfeldt, PE, PhD

presentation agenda
Presentation Agenda
  • Algae issues
    • Taste and Odor
    • Toxic Substances
  • Climate change impacts on algae events
  • UV Advanced Oxidation
    • Fundamentals
    • Treatment of taste and odor, toxins
    • Comparisons with other technologies
  • Summary and Conclusions
algae issues
Algae Issues
  • Seasonal algae blooms present many problems for water utilities
    • Depleted oxygen
    • Turbidity
    • Taste and Odor
  • Cyanobacteria
    • “Blue-green” algae
    • Not quite algae, not quite bacteria
      • Photosynthetic but lack well-defined nucleus
    • Responsible for Taste and Odor compounds
    • Create and may release toxic compounds
algal taste and odor compounds
Algal Taste and Odor Compounds
  • Methylisoborneol (MIB) and geosmin
    • Musty/earthy odor detectable at low (5-10 ng/L levels)
    • Non-toxic
    • Released by cyanobacteria
    • Not regulated, but public perception rules
cyanotoxins
Cyanotoxins
  • Some blue-green can produce one or more toxins
    • Do not produce toxins at all times
  • Toxins can affect
    • Fish and other aquatic life
    • Livestock
    • Pets
    • Humans
  • Exposure routes in humans
    • Dermal
    • Oral (water or food)
    • Inhalation
    • Dialysis
  • Included on US EPAs CCL3
cyanotoxins1
Cyanotoxins

Tedesco et al, 2011

cyanotoxin occurrence
Cyanotoxin Occurrence

Indiana data

  • Yearly occurrence
  • Occurs during algal blooms
    • Late summer, early fall
  • Toxins typically released during lysis
    • Algae mitigation processes can make problem worse

Tedesco et al, 2011

cyanotoxins in ohio
Cyanotoxins in Ohio
  • Lake Erie and Grand Lake

St. Marys Algal Blooms

  • Last year: Ohio EPA testing

revealed 0.23 and 0.16 ppb

Microcystin in two treated

drinking waters

    • Lake Erie Source:
      • Potassium Permanganate, PAC, Lime Softening, Filtration, Chlorine
    • Lake Erie Source:
      • Raw water filtration, Ozone, adsorption clarifier, chlorine disinfection
cyanotoxins and taste and odor
Cyanotoxins and Taste and Odor
  • USGS 2010 study (ES&T 44, 7361 – 7368)
  • Sampled 23 Midwest lakes
    • Multiple toxin classes co-occurred in 48%
    • Toxins and T&O co-occurred in 91%
  • No health risks during T&O outbreaks?
climate impacts on algae
Climate Impacts on Algae
  • Temperature
    • Warmer temperatures encourage blooms (Pearl and Huisman, 2008)
    • Warmer temperatures increase the odor intensity of VOCs at very low concentrations, increasing consumer detection (Whelton et al., 2004)
  • Precipitation
    • Long antecedent dry periods increase nutrient content of runoff
    • Low rainfall can cause stagnant conditions in the watershed
  • Wind/storms
    • Heavy storms and strong wind can mix reservoirs, reintroducing nutrients into the water column from bottom sediments
northeast climate projections
Northeast Climate Projections
  • Temperature
    • 3° to 7°C temperature increase by 2100 (Frumhoff et al, 2007)
    • More frequent days over 35°C (Karl et al, 2009)
  • Precipitation
    • 5 to 10% increase, mostly in fall and winter (Frumhoff et al, 2007)
  • Storms
    • Increasing trends in extreme precipitation (Spierre and Wake, 2010)
what will oh s climate look like
What will OH’s climate look like?

Lower Emissions Scenario

Higher Emissions Scenario

2010 - 2039

2010 - 2039

2040 - 2069

2070 - 2090

2040 - 2069

2070 - 2090

Adapted from Frumhoff et al, 2007

what can be done
What can be done?
  • Algae blooms are getting more prevalent and potentially more dangerous
  • Fortunately, algae typically only occur in the summer months
  • Several treatment processes are effective
    • Activated Carbon
      • GAC
      • PAC
    • Ozone
    • UV Advanced Oxidation (UV AOP)
advanced oxidation processes
Advanced Oxidation Processes
  • An effective process for disinfection and chemical oxidation, capable of providing barriers for protecting public health and improving public perception
    • Pharmaceuticals, Personal Care Products, EDCs
    • Crypto, Viruses, E. coli, etc.
  • AOPs work by creating hydroxyl radicals (•OH)
    • •OH then blast away at organic chemicals
  • Usually an expensive chemical process
  • Complex chemistry
  • UV Based AOPs
    • UV/H2O2, UV/O3, UV/HOCl, etc.
  • Ozone Based AOPs
    • Ozone/H2O2, Ozone/NOM, Ozone/pH
uv h 2 o 2 aop

Org

Org

H2O

H2O

H2O2

H2O2

H2O2

  • OH
  • OH
  • OH
  • OH
UV/H2O2 AOP
  • H2O2 absorbs UV energy and degrades to 2 OH radicals
  • Only 1 OH radical per UV photon
    • Due to “water caging”

UV Absorbance of H2O2

fundamentals uv h 2 o 2 aop

16

Fundamentals – UV/H2O2 AOP
  • AOP  High powered oxidation of contaminants via OH radical intermediate
    • OH radical is very reactive with “targets”
    • OH radical is also reactive with “scavengers”
differences between uv disinfection and aop
Differences between UV disinfection and AOP
  • Some fundamental differences in
    • Levels of Applied UV Energy
    • Fundamental Mechanisms
    • UV Dose (ie what does it mean?)
  • Different “Targets”

Disinfection

Photolysis

AOP

uv aop for taste and odor
UV AOP for Taste and Odor

UV Advanced Oxidation

UV Photolysis

Rosenfeldt and Linden, 2005

UV Advanced Oxidation for Geosmin Oxidation at Cornwall, ON

TrojanUV, 2010

uv aop for algal toxins
UV AOP for Algal Toxins

UV and UV AOP for m-LR destruction

UV AOP for MIB and algal toxins at Cornwall, ON

Alvarez et al, 2010

Approximate Geosmin removal

UV and UV AOP for m-RR destruction

TrojanUV, 2010

Qiao et al, 2005

taste and odor as a surrogate for toxin oxidation
Taste and Odor as a surrogate for toxin oxidation?
  • Characteristics of a good surrogate
    • Co-occurrence (Graham et al, 2010)
      • Microcystin co-occurred with geosmin in 87% of blooms, with MIB in 39%.
      • Anatoxin-a co-occurred with geosmin in 100% of blooms, with MIB in 43%.
    • Similar trends of occurrence (Graham et al, 2010)
      • Although toxins and T&O frequently co-occurred, concentrations were not strongly correlated (r < 0.4, p > 0.1)
      • Not surprising because they are not produced by the same biochemical pathways
    • Surrogate is conservative
      • Microcystin LR and Anatoxin degraded faster than MIB, but not geosmin
why uv aop makes some sense
Why UV AOP makes some sense
  • “Instant-on” technology
  • Effective Disinfection / Innovative Technology
  • Comparable replacement for other T&O treatment processes

Pantin, 2009

why uv aop makes some sense1
Why UV AOP makes some sense

Cornwall, ON

  • Trojan UV SwiftTMECT Reactors (MP technology)
    • UV system serves in disinfection mode” most of the year (4 of 8 lamps running)
    • Can “ramp-up” to AOP conditions seasonally (8 lamps running, add H2O2)
      • 5 operational levels  UV dose ~ 400 – 60 mJ/cm2
        • H2O2 varies 1, 2, 4, 8, 15 mg/L

UV AOP replaces GAC filter caps for T&O control ($100,000/yr for GAC replacement).

UV provides excellent disinfection barrier

Pantin, 2009

why uv aop makes some sense2
Why UV AOP makes some sense

Neshaminy Water Treatment Plant

  • Civardi and Lucca, 2010 (OAWWA and Tricon) compared costs and carbon footprint for 20 year design life
    • 15 MGD Plant, Desired 1 log removal of “Geosmin and MIB”
    • Assume 90 days per year of use (each is “instant-on”)

Civardi and Lucca, 2010

why uv aop makes some sense3
Why UV AOP makes some sense
  • Byproducts?
    • In most cases, this is a major impact on AOP feasibility
      • Eg: Estrogenic activity of BPA goes away slower than BPA

BPA

byproducts
Byproducts
  • In the case of UV AOP treatment of taste and odor and toxins, the story is simpler…
    • Taste and odor and toxic action are very dependent on molecular structure
    • Small changes in structure (ie oxidation, phototransformation, etc.) will likely diminish toxicity significantly

Anatoxin-a

250 mg/kg

Anatoxin-a(S)

20 mg/kg

MIB

No toxicity

wrap up
Wrap Up
  • Algal toxins and algae related taste and odor outbreaks are both caused by seasonal, cyanobacteria outbreaks
  • Recent research has indicated that presence of taste and odor (geosmin particularly), correlates well with presence of algal toxins
  • UV Advanced Oxidation effectively degrades both T&O and algal toxins
    • In general, MIB < Geosmin ~ Anatoxin << Microcystin
    • Cost and carbon footprint similar to Activated Carbon
    • “Instant-on” Technology
parting thought
Parting thought…

“Drinking water purveyors frequently tell customers during taste-and-odor outbreaks that there are no health risks. In our study, however, taste-and-odor causing compounds were always accompanied by cyanotoxins, highlighting the need for water purveyors to increase cyanotoxin surveillance during taste-and-odor outbreaks so that treatment can be modified accordingly, and to verify that cyanotoxins are not present at or above thresholds of potential health risk.”

Graham et al, 2010

questions
Questions?

Erik Rosenfeldt, P.E., PhD

Hazen & Sawyer Fairfax

703-537-7920

571-505-6601

erosenfeldt@hazenandsawyer.com