treatment options for habs impacted waters · 2020. 2. 6. · u.s. environmental protection agency,...

U.S. Environmental Protection Agency, Office of Research and Development

Treatment OptionsFor

HABs Impacted Waters

Nicholas Dugan, PETom Waters, PE

Kansas HAB Meeting - Topeka KS January 22, 2020

Outline

A. Background and definitions

B. Drinking water treatment options:

i. Permanganate

ii. Powdered activated carbon (PAC)

iii. Coagulation/flocculation/sedimentation

iv. Filtration

v. Chlorination

vi. UV/ozone/chlorine dioxide

C. Analytical methods (if time and interest)

Background

All water bodies contain suspended (planktonic) micro-organisms. They are an essential part of the aquatic food web and include single-cell phototrophic micro-organisms such as:oAlgae (eukaryotic)oCyanobacteria (prokaryotic)

A harmful algal bloom (HAB) occurs when these micro-organisms multiply to the point that they disturb the baseline ecology of the water body If a bloom is caused by cyanobacteria, why is it called a “harmful algal

bloom?”oPrior to the use of DNA sequencing, cyanobacteria were

classified as “blue-green algae”oTerms such as “cyanobacteria” and “blue-green algae” are still

used interchangeably

Background

Why is a bloom potentially harmful?oUnpleasant appearanceoUnpleasant tastes and/or odorsoCyanobacterial toxinsoNegative impacts on aquatic food webo Increased difficulty in treating drinking water:

• Maintenance & operation issues• Potential for exceeding health advisory toxin concentration

values• Potential for loss of confidence in the quality of treated

drinking water

Water potentially unsuitable for body-contact recreation by

humans and animals

Background

Figure adapted from: Kamennaya, N.A., et al; Minerals 2012:2:338-364

Dissolved CO2

Complex organic compounds

Not all cyanobacteria produce toxins In toxin-producing cyanobacteria – timing of toxin production can vary When toxins produced, they are usually contained within the cell membrane Sometimes toxins released from cells into solution

All cyanobacteria contain light harvesting pigments:• Chlorophyll• Phycocyanin

Background

Microcystin → liverCylindrospermopsin → kidneys & liver

Anatoxin → central nervous system

Background

IntracellularToxins contained inside the cell

ExtracellularToxins in solution outside the cell

CombinedExtracellular + intracellular toxin

Water sample

Federal Finished Drinking Water Toxin Health Advisory Levels

Toxin Children < 6 yearsChildren ≥ 6 years

& adults

Microcystin 0.3 1.6

Cylindrospermopsin 0.7 3.0

US EPA 10-day health advisory levels (µg/L)

Bloom Response: Iowa

July 2016 – July 2017: conducted weekly raw water microcystin sampling at all surface water and GWUDI systems → no finished water detects in participating systems

No ongoing monitoring requirements for surface water or GWUDI systems; a few systems are monitoring as they deem necessary

2016 – 2017 study report: https://www.iowadnr.gov/Portals/idnr/uploads/water/wso/files/Microcystin_Surveillance_Study_Report_of_Findings_6-2018.pdf

Flowcharts from 2016 – 2017 study: https://www.iowadnr.gov/Portals/idnr/uploads/water/wso/do

cs/Microcystin_Flow_Chart.pdf https://www.iowadnr.gov/Portals/idnr/uploads/water/wso/do

cs/Cylindrospermopsin_Flow_Chart.pdf

https://www.iowadnr.gov/Portals/idnr/uploads/water/wso/files/Microcystin_Surveillance_Study_Report_of_Findings_6-2018.pdfhttps://www.iowadnr.gov/Portals/idnr/uploads/water/wso/docs/Microcystin_Flow_Chart.pdfhttps://www.iowadnr.gov/Portals/idnr/uploads/water/wso/docs/Cylindrospermopsin_Flow_Chart.pdf

Bloom Response: Missouri

If a bloom is observed in the vicinity of the system intake → contact the state

Conduct jar test or observe sample using microscope If positive for cyanobacteria → screen raw water using Abraxis test strips If screening test is: Positive, immediately conduct finished water screening, and contact

the state. Additional treatment guidance will be provided as needed Negative, continue observing bloom

If finished water screening is: Positive, contact the state, submit sample to state lab for confirmation,

develop monitoring plan, additional response actions, and public notification in consultation with relevant agencies

Negative, continue observing bloom, additional screening if warranted

Bloom Response: Kansas and Nebraska

Kansas:o Raw water detect → contact the state → possibly increase

monitoring frequency and PAC concentrations (if equipped) Nebraska:

o Only 4 surface water systems in the stateo Proactively sampled raw water at SW and GWUDI systems in

2018 & 2019o Utilizing 18/19 sampling results and approaches from other

states to formalize 2020 sampling and response plan

Links to R7 State Response Information

MO: https://dnr.mo.gov/env/esp/wqm/docs/HABDrinkingWaterSamplingProtocol.pdfIA:https://www.iowadnr.gov/Portals/idnr/uploads/water/wso/docs/Microcystin_Flow_Chart.pdfIA:https://www.iowadnr.gov/Portals/idnr/uploads/water/wso/docs/Cylindrospermopsin_Flow_Chart.pdfKS: http://www.kdheks.gov/algae-illness/2019_Symposium/Rob_Gavin_2019-01-20_HAB_PWS_Response_Planning_and_Risk_Communication.pdf

https://dnr.mo.gov/env/esp/wqm/docs/HABDrinkingWaterSamplingProtocol.pdfhttps://www.iowadnr.gov/Portals/idnr/uploads/water/wso/docs/Microcystin_Flow_Chart.pdfhttps://www.iowadnr.gov/Portals/idnr/uploads/water/wso/docs/Cylindrospermopsin_Flow_Chart.pdfhttp://www.kdheks.gov/algae-illness/2019_Symposium/Rob_Gavin_2019-01-20_HAB_PWS_Response_Planning_and_Risk_Communication.pdf

Conventional Surface Water Treatment

Sedimentation

Source Water

Chlorine(Cl2)

Permanganate(MnO4-)

Powdered activated carbon

(PAC)

Coagulant

Rapidmix Flocculation

Filtration

Chloramine(NH2Cl)

Clearwell

Distribution systemSludge

Permanganate

Permanganate (MnO4-):oApplied early in the treatment process – often the 1st chemical

addedoApplied as a sodium or potassium saltoTaste and odor controloDBP precursor controlo Iron and manganese controloControl of zebra mussels in intake structures o Induces oxidative stress in cyanobacterial cells → may lead to

the release of toxins into solutionoOxidizes toxins released into solution

Permanganate – Reaction Rates

Reaction rate constant (M-1s-1)

10-1 100 101 102 103 104 105

Cylindrospermopsin

Microcystin

Anatoxin

Laboratory waterpH 7 - 820 - 22 C

67 X faster

1200 X faster

Permanganate – Reaction Rates

• The permanganate/toxin reaction rate depends on the type of toxin: anatoxin >> microcystin >> cylindrospermopsin

• The permanganate/toxin reaction rate will increase with increasing temperatures

• Within the pH range of 7 – 9, the permanganate/toxin reaction rate does not change significantly with pH

• Dissolved natural organic matter (NOM) and inorganic constituents such as iron and manganese can react with permanganate → possibility of competing reactions → potentially slower degradation of toxins

Time (minutes)

0 20 40 60 80 100

Cel

ls w

ith d

amag

ed m

embr

anes

(Ct /

Co)

0

2

4

6

8

10

0

2

4

6

8

10

Dose = 1 mg/LDose = 2.5 mg/LDose = 5 mg/L

Impact of KMnO4 on Cyanobacterial Cell Membrane Integrity

Source: US Environmental Protection Agency

Permanganate exposure increases the concentration of cells with membrane damage

Time (minutes)

0 20 40 60 80 100

Chl

orop

hyll

(Ct /

Co)

0.5

0.6

0.7

0.8

0.9

1.0

1.1

0.5

0.6

0.7

0.8

0.9

1.0

1.1


Impact of KMnO4 on Chlorophyll in Cyanobacterial Cells


Permanganate exposure decreases chlorophyll concentrations inside cells

Time (minutes)

0 20 40 60 80 100

Extra

cellu

lar m

icro

cyst

ins

(Ct /

Co)

1

10

100

1

10

100


Impact of KMnO4 on Toxin Release from Cyanobacterial Cells


Permanganate exposure increases extracellular microcystin concentration

Operational Considerations for Permanganate Pre-Oxidation

If possible, monitor for toxins in the treatment plant influent in addition to the source water:o Extracellular toxinso Extra + intracellular toxins (requires freeze/thawing of

samples) The degree to which toxins exist as extracellular versus

intracellular may drive treatment decisions


If primarily extracellular, continuing permanganate feed will not hurt and increasing the dose may help:o Consider site-specific considerations regarding

production of colored watero Consider locations of permanganate and powdered

activated carbon (PAC) application – PAC has the potential to adsorb toxins but also to neutralize permanganate


If significant intracellular toxins, have a contingency plan in place for temporarily suspending permanganate application:o Potential for color, taste & odor (T & O), DBP, or

operational issues if permanganate is used for T & O, iron, DBP precursor, or color control

o Be prepared to increase PAC dose and modify coagulation conditions to maximize removals of extracellular toxins and toxin-containing cells through coagulation, flocculation, and sedimentation

o If possible, increase post-filtration chlorine dose


Sedimentation

Source Water

Chlorine(Cl2)

Permanganate(MnO4-)


(PAC)

Coagulant


Filtration

Chloramine(NH2Cl)

Clearwell


Background:Powdered Activated Carbon

Powdered activated carbon (PAC):oTaste and odor controloSeasonal control of trace organics (herbicides, insecticides,

etc.)oAdsorbs cyanobacterial toxins released into solutionoNeutralizes MnO4-

PAC Treatment

PAC effectiveness depends on:o Type of carbon (wood, coconut,

coal)o Type of cyanotoxin or other

compounds to be adsorbedo Dose and contact timeo Natural organic matter (NOM)

interference

Micropores: < 2 nmMesopores: 2 - 50 nmMacropores: > 50 nm

vs. microcystin-LR: 1-3 nm

Effectiveness of PAC in Natural Waters

Toxin

Toxin concentration

(µg/L) PAC typePAC dose

(mg/L)Contact time

(min) % Removal

MYC 5 ? 10 60 92

MYC 22 ? 10 15 41

MYC 22 Coal 10 60 30 – 60

MYC 22 Coal 50 60 ≥ 90

CYL 20 Coal 25 30 60 - > 90

ANA 73 Coal 30 864* > 80

* Approximately 14 hours

Impact of PAC Addition


Time (minutes)

0 20 40 60 80 100

Extra

cellu

lar t

oxin

con

cent

ratio

n (

g/L)

0

5

10

15

20

25

Time (minutes)

0 20 40 60 80 100

Extra

cellu

lar t

oxin

con

cent

ratio

n (

g/L)

0

5

10

15

20

25

With PACNo PAC

– Carbon added after toxin release from cyanobacterial cells

Impact of PAC Addition


Operational Considerations for PAC

• Consider sufficient supply, storage space, and safety prior to HAB season

• Consider operational impacts of adding PAC on sedimentation and filtration processes

• More frequent sludge removal, higher volumes

• Potential for filter clogging• Test higher PAC feed rates, if

needed, prior to HAB season to evaluate potential for line clogging at higher doses


Sedimentation

Source Water

Chlorine(Cl2)

Permanganate(MnO4-)


(PAC)

Coagulant


Filtration

Chloramine(NH2Cl)

Clearwell


Background:Coagulation/Flocculation/Sedimentation

Particulate removal (turbidity) DBP precursor removaloTo some degree when adding coagulant with primary goal of

optimizing settled water turbidityoTo a greater degree when increasing coagulant dose and

lowering pH in order to achieve enhanced coagulation Physical removal of Giardia cysts and Cryptosporidium oocysts Coagulant chemical addition destabilizes particles → particles

remaining after sedimentation are more amenable to filtration Sedimentation basin provides contact time for PAC and

permanganate Potentially effective barrier to the passage of cyanobacterial cells

Cell removal (%)0 10 20 30 40 50 60 70 80 90 100

Cell Removals through Coagulation and Sedimentation

Jar test, 65 mg/L alum2

Pilot-scale, 70 mg/L alum2

Full-scale, 150-220 mg/LPolyaluminum chloride1

1Zamyadi et al; Species Dependence of Cyanobacteria Removal Efficiency by Different Drinking Water Treatment Processes; Water Research; 2013:47:2689-27002Drikas et al; Using Coagulation, Flocculation and Settling to Remove Toxic Cyanobacteria; Journal AWWA; 2001:93:2:100-111

Bench-Scale Coagulation Experiments with M. aeruginosa

Water source/pH

Dose necessary to achieve 80% removal of cells (mg/L)

Aluminumchlorohydrate

(ACH) Ferric chloride Aluminum sulfate

Myponga Reservoir

pH 7.5 – 7.8 40 40 60

pH 6.3 20 40 60

River Murray

pH 7.2 – 7.6 20 40 80

pH 6.3 20 20 60

Myponga turbidity = 1.2 – 8.7 NTU, DOC = 10 – 12 mg/LMurray turbidity = 23 – 101 NTU, DOC = 5.3 - 17Source: Newcombe, G. et al; Optimizing Conventional Treatment for the Removal of Cyanobacteria and Toxins; Water Research Foundation, Denver CO; 2015

Toxin Removals through Pilot-Scale Coagulation, Sedimentation, and Filtration

Microcystin-LR concentration(µg/L)

Sample point Toxin type Trial 1 Trial 2

Influent Combined 119 60

Extracellular 3 2

Effluent Combined 3 2

Extracellular 3 2

Source: Drikas et al; Using Coagulation, Flocculation and Settling to Remove Toxic Cyanobacteria; Journal AWWA; 2001:93:2:100-111

Microcystin-LR concentration(µg/L)

Sample point Toxin type Trial 1 Trial 2

Influent Combined 119 60

Extracellular 3 2

Effluent Combined 3 2

Extracellular 3 2

Source: Drikas et al; Using Coagulation, Flocculation and Settling to Remove Toxic Cyanobacteria; Journal AWWA; 2001:93:2:100-111

Toxin Removals through Pilot-Scale Coagulation, Sedimentation, and Filtration

Cell Propagation through a Full-Scale Lake Erie Treatment Facility

Raw

Post

MnO

4

Post

PAC

Filte

r inf

luen

t

Filte

r effl

uent

Fini

shed

Chl

orop

hyll

a (

g/L)

0.001

0.01

0.1

1

10

100

0.001

0.01

0.1

1

10

100

May 19July 1July 21

Most of the cell removal work is accomplished prior to filtration

Physical Removal of Cells through Seven Full-Scale Lake Erie Facilities

West East150 miles

Each data point represents the average of 5 – 7 samples collected between May and October

Filtration of M. aeruginosaPilot-Scale Seeding Trial Results

Coagulant

Baseline filter loading rate

(m/hr)

Steady-state removal of

chlorophyll-a(∆ log)

Alum+

cationic polymer

7 2.8

10 2.5

Ferric chloride+

cationic polymer

7 2.9

10 3.8

• Average influent chlorophyll-a concentration = 26 µg/L (SD = 12 µg/L) • 1 m/hr = 0.41 gal/min•ft2

Jar Testing

Optimizing coagulant and polymer dosing can maximize cell removal through the treatment process. This can be effectively evaluated in most plants using jar testing.

To evaluate optimal coagulant and polymer dosing for cyanobacteria cell removal, the following parameters can be monitored:o Turbidityo NOMo Pigments (chlorophyll-a, phycocyanin)o Coloro UV254o Particle countso Streaming current or zeta potential

Jar Testing Case Study

Objectives: Understand effect of coagulant on

cyanobacteria cell removal.

Understand effect of KMnO4 on coagulation efficacy and cyanotoxin release from cyanobacteria cells.

Experimental setup: 4 jars stirred at mixing speed

equivalent to turbulence in raw water main.

Raw water sample augmented with concentrated cyanobacteria solution obtained with a phytoplankton net.

Coagulant added at plant’s dose.

KMnO4 added at plant dose and high dose.

Bench-scale Coagulation Experiments with Lake Erie Water and Cyanobacteria

Cyanobacterial cells may have different surface chemistry than suspended clay and silt

Cyanobacterial cells will have lower specific gravity (1.0 – 1.1) than inorganic particles (> 2)

Some species of cyanobacteria have gas vacuoles → positive buoyancy

Cyanobacteria can be found as single cells, “clumps” of individual cells, individual filaments, or “mats” of filaments

For the reasons outlined above, different coagulation chemicals and doses may be required during blooms

Optimizing coagulation conditions for cyanobacterial cell removal during sedimentation is worth the effort because it will protect the filters

Operational considerations for Coagulation, Flocculation, Sedimentation and Filtration

Optimize coagulation, flocculation and sedimentation process through jar testing

Filters that regularly achieve turbidity ≤ 0.10 NTU are better suited to remove cyanobacteria in the event of a HAB

Backwashing filters based on water quality data, such as effluent turbidity, rather than length of time in service can lead to more optimal filter operation

Trend water quality data regularly to understand baseline operation

More frequent clarifier sludge removal may be necessary during a HAB

Operational considerations for Coagulation, Flocculation, Sedimentation and Filtration


Sedimentation

Source Water

Chlorine(Cl2)

Permanganate(MnO4-)


(PAC)

Coagulant


Filtration

Chloramine(NH2Cl)

Clearwell


44

Permanganate and Chlorine – Reaction rates

10-1 100 101 102 103 104 105

Cylindrospermopsin

Microcystin

Anatoxin

Apparent rate constant (M-1s-1)

10-1 100 101 102 103 104 105

Cylindrospermopsin

Microcystin

Anatoxin

Cl2Laboratory waterpH 4 - 9T = 20 C

KMnO4Laboratory waterpH 7 - 8T = 20 - 22 C

Impact of Chlorination on Microcystin Concentrations

> 2X increase in

CT

> 3X increase in CT

*Figure based on data from Acero et al, Water Research, 2005:39:1628-1638

CT for 3-log Giardia inactivation@ 1.0 mg/L Cl2, t = 25° C:• pH 7: 37• pH 8: 54• pH 9: 78

(CT = 26)

(CT = 71)

(CT = 235)

Oxidation of Microcystins with Chlorine:Kinetic Study

Objective: evaluate microcystin oxidation by chlorine in the plant’s raw water at the plant’s typical chlorine dose.

Augmented a raw water sample with concentrated solution of cyanotoxins obtained from another water body that was experiencing a HAB.

Cyanobacteria subjected to freeze/thaw and a filtration step to ensure that toxins were extracellular.

Compared experimental results with AWWA’s CyanoTOX model results: o Calibrated “model” using free chlorine sample results.o Interested in predicted vs. observed microcystins.o Difference is raw water vs. lab water.o Presence of ammonia, other inorganics, and NOM in raw water reduces

efficacy of chlorine against microcystins.o Understand if a safety factor necessary when predicting chlorine dose

necessary to oxidize extracellular microcystins in a full-scale wastewater treatment plant (WTP). 47

Chlorine and Microcystins Kinetic Study

CyanoTOX Inputs

CALCULATOR INPUT PAGE

STEP 1. Select the cyanotoxin of interest from the dropdown list Variant MC-LR MC-RR MC-YR MC-LA MC-LY MC-LF MC-MixCyanotoxin Type Microcystin-Mix (MC-Mix) → Percent 5% 20% 50% 10% 5% 10% 100%

STEP 2. Input the following system parameterspH (between 6-10) 9.2

Temperature (between 10-30°C) 10

STEP 3. Input the initial cyanotoxin concentrationCyanotoxin Initial Concentration (µg/L) 3.79(If not known, enter an assumed value for the scenario)

STEP 4. Select your target option from the dropdown listTarget. Options: 1) Input target cyanotoxin conc. 1) Input target cyanotoxin conc.

2) No targetTarget cyanotoxin concentration (µg/L) 0.3

STEP 5. Select the oxidant of interest from the dropdown listOxidant Type Free Chlorine

STEP 6. Go to your chosen calculator version: CT based or Dose-decay based (tabs in blue)

STEP 7. Input the following parameters

Baffling Factor 1Oxidant Dose (mg/L) 7

Instantaneous oxidant demand (mg/L) 2.95Contact Time (i.e., hydraulic detent. time, min) 300

Effective Oxidant Half Life (min) 360(Enter a value in minutes OR "ND" for No Decay")

American Water Works Association 49

CyanoTOX Oxidation Calculator

Dose-decay based results: CT-based results:

Operational Considerations for Chlorination

Consider the toxin:o Chlorine is effective for microcystin and cylindrospermopsino Chlorine is not effective for anatoxin

Consider pH:o As pH increases, chlorine reaction rate with microcystin

decreaseso As pH increases, chlorine reaction rate with

cylindrospermopsin increases and peaks at pH = 7, then begins to decrease

Consider temperature – all reaction rates increase with temperature

51

Operational Considerations for Chlorination

Consider competing oxidant demands:o NOMo Iron, manganeseo Ammonia

Consider the potential for formation of disinfection byproducts Consider contact time:

o In the treatment planto Between the treatment plant and the first connectiono Other locations in the distribution system (storage tanks)

Consider where chlorine is dosed and if any competing technologies would limit its effectiveness

52

UV Irradiation

UV contactors installed toward the end of the treatment process –cells and intracellular toxins have been removed, only extracellular toxin remaining.

Required UV doses for 2-log disinfection of Cryptosporidium = 5.8 mJ/cm2, Giardia = 5.2 mJ/cm2, virus = 100 mJ/cm2.

These doses drive full-scale UV contactor design.

UV doses required for microcystin degradation are significantly higher – existing UV infrastructure not a barrier to toxin passage.

53

Ozone and Chlorine Dioxide

Chlorine dioxide, at the doses used in drinking water treatment (to limit the formation of chlorite) is not considered effective against microcystins – reaction rate is approximately 3 orders of magnitude lower than permanganate.

Ozone has been proven effective at degrading microcystins as well as cylindrospermopsins and anatoxin – reaction rate is sufficient to achieve degradation within the confines of ozone contactors used in full-scale drinking water treatment.

54

When optimized, conventional treatment processes (coagulation, flocculation, sedimentation, filtration) are highly effective at removing cyanobacterial cells.

PAC effectively adsorbs microcystins however, the exact carbon dose will vary depending on the type of cyanotoxin, type of carbon, and the NOM background.

Conclusions

Chlorine effectively degrades microcystins – but the rate of degradation is temperature and pH dependent.

Ozone effectively degrades microcystins.

Chlorine dioxide and UV, at the dose levels commonly employed in drinking water treatment, are not effective.

Permanganate effectively degrades dissolved microcystins –however, the typical location for permanganate addition, early in the treatment process where cyanobacterial cell concentrations are still high, sets up a potential for toxin release – vigilance is recommended.

Conclusions

Disclaimer

57

The U.S. Environmental Protection Agency, through its Office of Research and Development, funded and managed, or partially funded and collaborated in, the research described herein. It has been subjected to the Agency’s internal peer and administrative review and has been approved for external publication. Any opinions expressed in this presentation are those of the author(s) and do not necessarily reflect the views of the Agency, therefore, no official endorsement should be inferred. Any mention of trade names or commercial products does not constitute endorsement or recommendation for use. This presentation is for informational purposes only and is not intended as legal advice. You are urged to consult legal counsel concerning any specific situation or legal issues. This presentation does not address all federal, state, and local regulations, and other rules may apply. This presentation does not substitute for any EPA regulation and is not an EPA rule.

Analytical Methods

Enzyme linked immunosorbent assay (ELISA)

Toxin molecule Antibody (specific to toxin molecule)

“Immunosorbent”

+Toxin-antibodycomplex Enzyme

“Enzyme-linked immunosorbent”

Analytical Methods


+Toxin-antibody

complex Enzyme

+Reagent

Enzyme catalyzes reactionthat results in color change

proportional to toxin concentration

Analytical Methods


ELISA plate ready for reading

Analytical Methods

Liquid chromatography with tandem mass spectrometer (LC/MS/MS)

Sample

Chromatographycolumn

Mass spectrometer∆ t

Separation by mass andfragmentation pattern inthe mass spectrometer

Separation by timeon the column

ELISA versus LCMS(Extracellular Toxin)

ELISA vs. LCMS (Extra + Intracellular Toxin)

EPA Water Treatment Document

https://www.epa.gov/sites/production/files/2018-11/documents/water_treatment_optimization_for_cyanotoxins.pdf

Bibliography

65

Permanganate:o Kim et al, Environmental Science & Technology:2018:52:12:7054-7063o Jeong et al, Water Research:2017:114:189-199o Ding et al, Journal of Environmental Engineering:2010:136:1:2-11o Rodriguez et al, Water Research:2007:41:15:3381-3393o Rodriguez et al, Water Research:2007:41:9:2048-2056o Rodriguez et al, Water Research:2007:41:1:102-110

Powdered activated carbon:o Park et al, Chemosphere:2017:177:15-23o Vlad, MS Thesis, University of Waterloo, 2015, http://hdl.handle.net/10012/9392o Drogui et al, Environmental Technology:2012:33:4:381-391o Ho et al, Water Research:2011:45:9:2954-2964o Cook & Newcombe, Environmental Technology:2008:29:5:525-534o Cook & Newcombe, Water Science and Technology: Water Supply:2002:2:5-6:201-207

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treatment options for habs impacted waters · 2020. 2. 6. · u.s. environmental protection agency,...

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