UV Advanced Oxidation for Treatment of Taste and Odor and Algal ToxinsOhio AWWA Annual Conference Research WorkshopSeptember 20, 2011

Erik Rosenfeldt, PE, PhD

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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

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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

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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

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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

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Cyanotoxins

Species Dermatoxin (Irritant)

Hepatoxin (Liver) Neurotoxin (Nervous)

Taste/Odor Compound

Aphanacapsa spp. microcystins

Microcystis spp. microcystins, nodularin anatoxins

Snowella spp. microcystins

Synechococcus spp. microcystins MIB, Geosmin

Woronichinia spp. microcystins

Lyngbya spp. Lyngbyatoxins saxitoxins MIB

Oscillatoria spp. Aplysiatoxins microcystins anatoxins, saxitoxins MIB, Geosmin

Planktothrix agardhii Aplysiatoxins microcystins saxitoxins MIB, Geosmin

Pseudoanabaena spp. MIB, Geosmin

Anabaena spp. microcystins, cylindrospermopsin

anatoxins, saxitoxins MIB, Geosmin

Anabaenopsis elenkii microcystins

Aphanizomenon spp. microcystins, cylindrospermopsin

anatoxins, saxitoxins Geosmin

Cylindrospermopsis raciborskii cylindrospermopsin saxitoxins

Nordularia spp. microcystins, nodularin

Tedesco et al, 2011

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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

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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

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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?

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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

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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)

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What will OH’s climate look like?

2010 - 2039

2040 - 2069

2070 - 2090

2010 - 2039

2040 - 2069

2070 - 2090

Adapted from Frumhoff et al, 2007

Lower Emissions Scenario Higher Emissions Scenario

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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)

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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

• H2O2 absorbs UV energy and degrades to 2 OH radicals

• Only 1 OH radical per UV photon

• Due to “water caging”

UV/H2O2 AOP

H2O2• OH

• OH

H2O2

H2OH2O

H2O2

• OH

• OH

Org

Org

0

50

100

150

200

250

200 220 240 260 280 300Wavelength (nm)

e (M

-1 c

m-1

)

UV Absorbance of H2O2

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Pollutant or Constituent

OH radical rate constant (M-1 s-

1)

Reference

MTBEAtrazineNDMAMIBGeosminBisphenol-A17-b-Estradiol17-a-Ethinyl Estradiol4-NonylphenolPara-Chlorobenzoic AcidNitrobenzeneMethanolNOM (TOC)HCO3

-

CO3-2

H2O2

1.9x109

3x109

3.3x109

8.2x109

1.4x1010

1.02x1010

1.41x1010

1.08x1010

5.65x109

5x109

3.9x109

9.7x109

2.5x104 (L mg-1 s-1)8.5x106

3.9x108

2.7x107

Acero et al., 2001Acero et al., 2000

Wink and Desrosiers, 1991Glaze et al., 1990Glaze et al., 1990

Rosenfeldt and Linden, 2004Rosenfeldt and Linden, 2004Rosenfeldt and Linden, 2004

AWARF, 2006Elovitz and von Gunten, 1999

Buston et al., 1988Buxton et al., 1988

Larson and Zepp, 1988Hoigne et al., 1985; Buxton et al,

1988Hoigne et al., 1985; Buxton et al.,

1988Buxton et al., 1988

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”

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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

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UV AOP for Taste and Odor

UV Photolysis UV Advanced Oxidation

Rosenfeldt and Linden, 2005

UV Advanced Oxidation for Geosmin Oxidation at Cornwall, ON

TrojanUV, 2010

UV AOP for Algal Toxins

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UV AOP for MIB and algal toxins at Cornwall, ON

TrojanUV, 2010

UV and UV AOP for m-RR destruction

UV and UV AOP for m-LR destruction

Alvarez et al, 2010Approximate Geosmin removal

Qiao et al, 2005

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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

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Why UV AOP makes some sense

• “Instant-on” technology• Effective Disinfection / Innovative Technology• Comparable replacement for other T&O treatment

processes

Pantin, 2009

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Why UV AOP makes some sense

Cornwall, ON• Trojan UV SwiftTM ECT 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

Pantin, 2009

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

UV provides excellent disinfection barrier

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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”)

UV-H2O2 AOP PAC

Capital $2.5 mil $2.2 mil

O&M $200,000 $310,000

Equivalent Uniform Annual Cost (4%) $384,000 $475,000

Civardi and Lucca, 2010

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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

CH3CH3

OH OH

BPA

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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-a250 mg/kg

Anatoxin-a(S)20 mg/kg

MIBNo toxicity

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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

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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

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Questions?

Erik Rosenfeldt, P.E., PhD Hazen & Sawyer Fairfax

703-537-7920571-505-6601

erosenfeldt@hazenandsawyer.com