Filtration Case Studies to Meet Low Level Effluent Limits

Presentation by: John Friel, PE 29th Annual Conference on the Environment, St. Paul, MN November 19, 2014

Filtration Case Studies to Meet Low Level Effluent Limits

Overview 1. Tertiary Filtration Drivers

2. Filtration Technologies Overview

3. Case Study Examples

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Tertiary Filtration Drivers • Typically used to:

– TSS < 10 mg/L – Turbidity < 2 NTU – BOD < 5 mg/L – Phosphorus < 1 mg/L – Improve disinfection – Recycled water (Title 22, disinfected tertiary) – Pretreatment for further advanced processes

(membrane) – Nutrient removal (low-level phosphorus) – Specific inorganics (heavy metal) or organics (MBTE)

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OLD

Phosphorus Regulations

Percentage of Major POTWs with P Limits

64%

0%

6.3% 45%

64%

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Mercury Regulations

Percentage of Major POTWs with P Limits

64%

0%

6.3% 45%

64%

47%

0%

0%

0% 27%

Percentage of Major POTWs with Hg Limits

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Tertiary Filtration Technologies – Old

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Depth Filtration

Upflow

Traveling Bridge

Single Media

Dual Media

Tertiary Filtration Technologies

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Depth Filtration

Upflow

Traveling Bridge

Single Media

Dual Media

Compressible Media

Reactive Media

Surface Filtration

Disc Cloth

Diatomaceous Earth

Membrane Filtration

Micro

Ultra

Nano

Reverse Osmosis

Tertiary Filtration Technologies

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Depth Filtration

Upflow

Traveling Bridge

Single Media

Dual Media

Compressible Media

Reactive Media

Surface Filtration

Disc Cloth

Diatomaceous Earth

Membrane Filtration

Micro

Ultra

Nano

Reverse Osmosis

Case Study Examples 1. Owatonna - Single Media 2. Virginia - Dual Media 3. Hibbing - Dual Media 4. Cambridge -Traveling Bridge 5. Princeton - Disc Cloth + Reactive Media + Membrane Bioreactors (MBRs)

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Design Considerations • Influent WW characteristics • Design and operation of the biological

treatment system • Available flow-control options • Available area and tankage • Removal objectives • Surface loading rate

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• 0.6 – 1.8 mm sand media

Single-Media Filters

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SINGLE MEDIA

Sand

Gravel

Underdrain

Clearwell

Mudwell

P B

• Driver – effluent TSS • Upstream Treatment – Conventional

Activated Sludge • Installed in 1987

Case Study – Owatonna, MN

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Case Study – Owatonna, MN

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0

0.5

1

1.5

2

2.5

3

TSS

(mg/

L)

2013-2014

TSS

Phosphorus

Dual-Media Filters

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• 0.35 – 0.65 mm sand media • 0.6 – 1.6 mm anthracite

DUAL MEDIA

Sand

Gravel

Underdrain

Clearwell

Mudwell

P B

Anthracite

Case Studies – Virginia, MN

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• Driver – effluent mercury limit • Upstream Treatment – Conventional

Activated Sludge w/Chem P removal • Challenges

– fit within existing hydraulics – meet effluent mercury limit of 1.8 ng/L

Case Studies – Virginia, MN

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R² = 0.4801

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 1 2 3 4 5 6

Mer

cury

Con

cent

ratio

n (n

g/L)

TSS Concentration (mg/L)

TSS Vs Mercury

R² = 0.6607

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 0.5 1 1.5 2 2.5 3 3.5 4

Mer

cury

Con

cent

ratio

n (n

g/L)

TSS Concentration (mg/L)

Turbidity Vs Mercury

Case Studies – Virginia, MN

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Case Studies – Virginia, MN

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Case Studies – Hibbing, MN

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• Driver – effluent mercury limit • Upstream Treatment – Trickling Filters

w/Chem P removal • Challenges

– compliance schedule with fines – meet effluent mercury limit of 1.8 ng/L

• Low loading rate

Case Studies – Hibbing, MN

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Case Studies – Hibbing, MN

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Traveling Bridge Filters

www.aqua-aerobic.com

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Case Studies – Cambridge, MN • Driver – effluent TSS, now P • Upstream Treatment – Oxidation Ditch now

w/Chem P removal • Challenges

– Upgrade 20-yr old system

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Disc Cloth Filters

Case Studies – Princeton, MN

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• Driver – effluent phosphorus and mercury limit

• Upstream Treatment – Oxidation Ditch w/Biological P removal

• Challenges – fit within existing hydraulics, – meet effluent phosphorus limit of 0.3 mg/L

Case Studies – Princeton, MN

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Case Studies – Princeton, MN

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Case Studies – Princeton, MN

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0%

1%

2%

3%

4%

5%

6%

7%

Princeton/DiscCloth

Owatonna/Sand Virginia/DualMedia

Hibbing/DualMedia

Backwash Volume as Percent of Influent

Filtration Depth

Filtration

Upflow

Traveling Bridge

Single Media

Dual Media

Compressible Media

Reactive Media

Surface Filtration

Disc Cloth

Diatomaceous Earth

Membrane Filtration

Micro

Ultra

Nano

Reverse Osmosis

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Filtration - Reactive-Media Filters

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https://www.bluewater-technologies.com/products/bluepro.html

• Pilot Testing • Hydrous Ferrous

Oxide adsorption • TP < 0.1 mg/L

Filtration – Membrane Bioreactor (MBR) • Smaller Footprint • Highly Automated • Majority of installations: <5mgd • Capital and O&M Costs have decreased with

increasing installations

Conclusions • Not a one-size fits all • New technologies for new effluent criteria • Old technologies still work well, some not as

cost-effective • Technologies may be piloted to determine

operating parameters

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Questions? Thank you John Friel Email: jfriel@sehinc.com

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Case Studies – Princeton, MN

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0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0

0.5

1

1.5

2

2.5

3

0 0.05 0.1 0.15 0.2 0.25

Turb

idity

(ntu

)

TSS

Conc

entr

atio

n (m

g/L)

Phosphorus Concentration (mg/L)

Phosphorus Compared to TSS and Turbidity

TSS Turbidity Linear (TSS) Linear (Turbidity)

US EPA webpage • http://echo.epa.gov/effluent-charts#MN0030643