Sustainable Passive Wastewater Treatment · to adjacent wetland area to restore natural “wet”...

Troy D. Vassos, PhD FEC PEng

Technical Director

Integrated Sustainability (Calgary/Vancouver)

AOWMA 22ND ANNUAL CONVENTION & TRADE SHOW

“SUSTAINABLE PASSIVE WASTEWATER TREATMENT ” SEMINAR

Sustainable Passive

Wastewater Treatment

Outline

Wastewater Characteristics

Treatment Mechanisms

Lagoon & Wetland Treatment

Sustainability Considerations

Lagoon Upgrade Examples

Wastewater

Characteristics and

Treatment

Domestic Wastewater

5%TOILET

URINE

FAECES

KITCHENSINK

DISHWASHER

BATHSHOWER

LAUNDRY

MISC

BLACKWATER

GREYWATER

WASTEWATER

30% 10% 35% 20%

5%

LANDFILL

Compost

DigestBacteria

TREATMENT

BIOSOLIDS REUSE

DISPOSALor REUSE

Treatment

Toilets & Urinals

Bath & Shower

Laundry

Kitchen Sink

GREYWATER

BLACKWATER

Organic Solids

Fats Oils & Grease

Soluble Organics

Screenings, Sand & Grit

Pathogens

Toxic Organic & Inorganic

Nutrients (N & P)DISCHARGE

Disinfect DISCHARGE

Treatment Levels & Objectives

• Primary – remove coarse solids & FOG

• Secondary – remove soluble BOD & TSS

• Tertiary – remove N & P

– remove turbidity (filtration)

• Disinfection – remove microoganisms

Treatment Summary

1. Lower temperature → more time

2. Complex organics → more time

3. Long solids retention is better than short

4. Mechanical treatment simply mimics and accelerates natural processes

5. Mechanical high capital and O&M cost

6. Passive Treatment – more land

Bacteria &

Wastewater

Treatment

Aerobic Bacteria

Two general types of aerobic bacteria

1. Heterotrophic Bacteria Consume Organics

– Needs oxygen in proportion to the amount of organics consumed

– Rapid consumption & growth

2. Autotrophic Bacteria – uses CO2 as a carbon source – Nitrification: oxidize ammonia NH4 to

form nitrite (NO2) and nitrate (NO3)– Not a significant process in lagoons

due to limited bacteria in suspension – Lagoon nitrogen reduction generally

due to algae growth

Aerobic Bacteria

• Anoxic: No oxygen, but other electron acceptors present (NO2, NO3, SO4 etc.)

• Heterotrophic facultative bacteria digest and remove readily biodegradable soluble organics (electron donors) under anoxic conditions forming sludge, CO2and nitrogen gas (N2)

Anoxic Bacteria

• Anaerobic: No O2, NO2, NO3, SO4 etc. present

• Heterotrophic anaerobic bacteria fermentand consume biodegradable soluble and particulate organic constituents forming sludge, CH4, CO2 and odour compounds

• Very slow growing• Key condition for biological phosphorus

removal

Anaerobic Bacteria

Treatment Elements

AEROBIC

BOD REMOVAL

NH4 → NO3

TSS REMOVAL

RETURN BACTERIA

WASTEBACTERIA

Treatment Elements

BOD REMOVAL

NH4 → NO3

TSS REMOVAL

RETURN BACTERIA

WASTEBACTERIA

NO3 → N2

ANOXIC AEROBIC

RECIRCULATION LOOP

NITROGENREMOVAL

Treatment Elements

BOD REMOVAL

NH4 → NO3

TSS REMOVAL

RETURN BACTERIA

WASTEBACTERIA

NO3 → N2

AEROBICANOXICANAEROBIC

PHOSPHORUSRELEASE

PHOSPHORUSREMOVAL

RECIRCULATION LOOP

BACTERIA WITHOUT NO3

NITROGENREMOVAL

Lagoon Treatment

Treatment Elements

AEROBIC

BOD REMOVAL

NH4 → NO3

TSS REMOVAL

RETURN BACTERIA

WASTEBACTERIA

Treatment Elements

AEROBIC

BOD REMOVAL TSS REMOVAL

WASTEBACTERIA

Treatment Elements

AEROBIC

BOD REMOVAL TSS REMOVAL

WASTEBACTERIA

TSS REMOVAL

DUCKWEED HARVESTING N & P REMOVAL

Facultative Lagoons

2O

NH3

pH

10

5

NH4 PALGAE O2

BACTERIA

CO2

SLUDGE

NH4

AEROBIC(FAST)

ANAEROBIC(SLOW)

ANOXIC (FACULTATIVE)

WASTEWATER

C NH4 P

1.5

–2.

0 m

Facultative Lagoon

2O

NH3

pH

10

5

NH4 PALGAE O2

BACTERIA

CO2

SLUDGE

NH4

AEROBIC(FAST)

ANAEROBIC(SLOW)

ANOXIC (FACULTATIVE)

WASTEWATER

C NH4 P

1.5

–2.

0 m

Lagoon Advantages

• Achieves good treatment under cold climate conditions

• Withstands high flow and organic loading fluctuations

• Lower capital and operating cost than mechanical systems– Lower energy and Labour– Lower operator skill and attention– Easy to maintain

Lagoon Disadvantages

• Algae blooms affect TSS & BOD• Seasonal nitrogen removal (algae growth)• Limited phosphorus removal• Seasonal turnover and odours• Exfiltration concerns• Sludge accumulation & desludging• Land requirements

Algae Water Quality Impact

Algae Control Considerations

NH4 PO2

CO2

WASTEWATER

C NH4 PALGAE

NH4 PO2

CO2

WASTEWATER

C NH4 PBACTERIA

ALGAE


NH4 PO2

CO2

WASTEWATER

C NH4 P

NOT GENERALLY PRACTICAL

ALGAE


NH4 PO2

CO2

WASTEWATER

C NH4 PALGAE


NH4 P

O2

WASTEWATER

C NH4 P

O2

O2O2O2

O2

O2

O2

BACTERIABACTERIA

BACTERIABACTERIA AEROBIC

(FAST)

3.0

–5.

0 m

ALGAE


Size Comparison – 3,800 m3/d (1 MGD)

LAGOON SYSTEM LAND (m2)

FACULTATIVE 667,000

PARTIAL-MIX AERATED 200,000

COMPLETE-MIXED AERATED 20,000

Wetland Treatment

Constructed Wetlands

N & P REMOVAL BY HARVESTING

BACTERIA BOD REMOVALAMMONIA NITRIFICATION

Effluent

Quality

Requirements

Wastewater Effluent Systems Regulations

• Four “Prescribed Deleterious Substances”

1. 5-day Carbonaceous Biochemical Oxygen Demand (CBOD5) < 25 mg/L (avg)

2. Total Suspended Solids (TSS) < 25 mg/L (avg)3. Total Residual Chlorine < 0.02 mg/L (avg)4. Un-Ionized Ammonia (NH3) < 1.25 mg-N/L(max)

@ 15 OC +/- 1 OC

• Quarterly reports for average annual flows of 2,500 – 17,500 m3/d & HRT > 5 days

WSER and Lagoons

• WSER impacts small remote communities who rely on lagoon treatment

• Upgrading required to mitigate:– Algae growth effects on WSER TSS & BOD

effluent criteria– Effluent total & unionized ammonia – Fish toxicity (high pH → high NH3 )

Improved BOD & TSS Removal

• BOD REMOVAL– Increase Retention Time (Size & Depth)– Increase Oxygen (Mechanical Aeration)– Increase Bacteria (Attached Growth Media)– Primary Filtration (vs Anaerobic Lagoon)

• TSS REMOVAL– Inhibit Algae Growth– Mechanical Separation – Constructed Wetlands (Biofilter)

Algae & Ammonia

• Problem: Inhibiting algae growth reduces nitrogen and ammonia removal

• Seasonal nitrogen removal useful for only intermittent discharges

• Post-treatment ammonia nitrification is required for continuous discharges

Ammonia Removal Options

• INTERMITTENT DISCHARGE LAGOON– Algae Uptake & Seasonal Discharge– Wetland Post Treatment (Nitrification)– Attached-Growth Post Treatment– Attached-Growth In-situ Technology

• CONTINUOUS DISCHARGE LAGOON– Wetland Post Treatment (Nitrification)– Attached-Growth Post Treatment– Attached-Growth In-situ Technology

Additional Upgrade Measures

• Increase oxygen supply and efficiency• Increase depth• Add partitions to optimize HRT• Add media (Fixed film) to increase bacteria• Reduce BOD loading (primary filtration)• Add mechanical treatment components• Phosphorus precipitation & separation

Sustainability

Considerations

Economics

Environment

Social

ConventionalModel

OptimalSpot

Conventional Sustainability Model

Alternative Sustainability Model

Economics

Environment

Social

Alternative Model

Alternative Sustainability Model

Economics

Environment

Social

Regulations

Key Constraint

Cumberland

Lagoon Upgrade

Village of Cumberland

Vancouver

Victoria

Cumberland


• Coal mining town incorporated in 1898• Old combined (storm & sanitary) sewer• Discharge Permit issued in 1967• Provided 48 years to reduce flows• Authorized works (1967) mechanical

screens, aerated/facultative lagoon, phosphorus removal & disinfection

• 2-Cell Aerated & facultative lagoons• $2M - 85% Separation = no flow reduction


• Discharge to man-made drainage canal leading to fish bearing stream with extremely low summer flows

• 2018 ADWF = 800 m3/d PWWF > 20,000 m3/d• Permit Effluent Criteria

– CBOD5 & TSS < 30 mg/L (max) – Total-P < 1.0 mg-P/L– Fecal Coliforms < 200 MPN/100 mL (median)

• Design ADWF = 1,800 m3/d Pop = 3,800


SCREENS

MAPLE LAKE “CREEK”

Full-Flow Mechanical

Option 1 – “Lagoon Upgrade” using mechanical enhancements to remove phosphorus, disinfect, discharge to adjacent wetland area to restore natural “wet” conditions

and provide for natural polishing treatment.

Option 2 – “Excess Wet-Weather Lagoon Treatment” -Membrane Bioreactor (MBR) treatment for 2 x ADWF, wet weather flows directed to existing lagoons.

Option 3 – “Full Flow Mechanical” - Moving Bed Biofilm Reactor (MBBR) to treat and disinfect full wet weather flow, with additional tertiary filtration for 2 x ADWF. The lagoons would then be decommissioned.

Lagoon Upgrade

AERATED LARGE

LAGOON

FACULTATIVESMALL

LAGOON

SOLIDSSEPARATION

PERACETICACID

DISINFECTION

INLET CHANNEL

SCREENING

SOLIDSMANAGEMENT

BYPASS > 3,600 m3/d

MLCDISCHARGE

NATURALWETLANDS

> 3,600 m3/d

< 3,600 m3/d

Excess Wet-Weather Lagoon Treatment

FACULTATIVE LARGE

LAGOON

AERATEDSMALL

LAGOON

PERACETICACID

DISINFECTION

INLET CHANNEL

SCREENING

SOLIDSMANAGEMENT

> 3,600 m3/d

MLCDISCHARGE

< 3,600 m3/d

FINE SCREEN MBR

Full-Flow Mechanical

PERACETICACID

DISINFECTION

INLET CHANNEL

SCREENING

c

SOLIDSMANAGEMENT

> 14,500 m3/d

MLCDISCHARGE

> 3,600 m3/d

FINE SCREEN MBBR

< 3,600 m3/dc

SOLIDSMANAGEMENT

SOLIDSSEPARATION

FILTRATION

Community Sustainability

Assessment

• Community stakeholder sustainability assessment resulted in the Lagoon-Upgrade option achieving the highest score

Natural Wetlands Treatment

Treatment achieved by the lagoons and natural wetland combined is superior to most mechanical tertiary treatment processes

Phase 1 – Wetlands Tertiary

AERATED LARGE

LAGOON

FACULTATIVESMALL

LAGOON

SOLIDSSEPARATION

PERACETICACID

DISINFECTION

INLET CHANNEL

SCREENING

SOLIDSMANAGEMENT

BYPASS > 3,600 m3/d

MLCDISCHARGE

NATURALWETLANDS

> 3,600 m3/d

< 3,600 m3/d

Future -Tertiary Filtration - Reuse

AERATED LARGE

LAGOON

FACULTATIVESMALL

LAGOON

SOLIDSSEPARATION

PERACETICACID

DISINFECTION

INLET CHANNEL

SCREENING

SOLIDSMANAGEMENT

MLCDISCHARGE

FILTRATION

BYPASS > 3,600 m3/d

FINE SCREEN

BYPASS > 3,600 m3/d

Funding Received – August 2019

• High performance lagoon upgrade $9.7M

• Investing in Canada Infrastructure Program (ICIP-EQ) Environmental Quality Stream Award of $7,113,010

• Government of Canada ($3,880,000)

• Province of British Columbia ($3,233,010)

Kamloops

Lagoon-Based

BNR Process

Kamloops Lagoon Upgrade

• Population growth 80,000 – 125,000• Mechanical plant $73M estimate• Total-P objective of 1.0 mg-P/L• 20-year life• UV Disinfection• Lagoon-BNR Savings of $33M• Also saves $200,000/yr in chemicals

What’s

BNR?

Conventional Activated Sludge

Anoxic + Aerobic Zones

Anaerobic + Anoxic + Aerobic Zones

BNR Process

NH4 NO3

NO3 N2 Poly-P Rich Bacteria

PO4

Anaerobic Zone P-Release

NO2 NO3

O2

ANAEROBIC CELL

CARBON(PHB)

BIO-P BACTERIAPO4

PO4

PO4

PO4

PO4

PO4

PO4

VFA VFAVFA

POLY-P

O2

PO4

PO4

PO4ANOXIC CELL

POLY-P

CARBON

PO4

PO4 PO4PHB

POLY-P

PHB

P-UPTAKE

CELL DIVISION

Anoxic Zone P-Removal

Anoxic Zone Denitrification

O2N2

ANOXIC CELL

N2

N2

NO3 NO3

VFA

NO3VFAVFA

DENITRIFICATION

VFA

NO3

N2

CELL DIVISION

NH4NH4

NH4

CO2CO2

O2

O2 O2

O2O2 O2

O2

O2

NH4

O2

O2 O2

O2 O2N03

N03N03

N03

CELL DIVISION

CO2

CO2

AEROBIC CELL NITRIFICATION

Aerobic Zone Nitrification

PO4

PO4

AEROBIC CELL P-UPTAKE

O2

O2

PO4O2 O2 O2

O2

O2

POLY-P

PO4

PO4

O2

O2

O2O2

POLY-P

POLY-PCELL DIVISION

Aerobic Zone P-Uptake

Kamloops

BNR Adaptation


ANAEROBIC

ANOXICAEROBIC

Maximum N Removal

SECONDARYCLARIFIERS

Maximum N Removal

SECONDARYCLARIFIERS

WASTE ACTIVATED SLUDGE

Kamloops BNR Lagoon

Left – BNR Lagoon conversion.

Middle – membrane covered anaerobic lagoon (biogas).

Example

Design Checks &

Expected

Performance

Aerated Fraction

BNR plants are generally designed to ensure that the aerated fraction does not drop below 60%.

10,000 m3

4,000 m3

33,000 m3

Aerated Fraction= 33,000 / 47,000 m3

= 70 %

Maximum N Removal

RAS = 62,000 m3/d

25,000 m3/d95,000m3/d

25,000 m3/d

%NO3

−−N removed =

95,000 + 62,000

25,000 + 95,000 + 62,000= 86%

Total Recycle Ratio =95,000 + 62,000

25,000= 6.3

Alkalinity destroyed by nitrification = 219 mg/LAlkalinity recovered = 96 mg/L as CaCO3

Troy D. Vassos, PhD FEC [email protected]

Cell: +01-604-657-6559

Thank you!

Sustainable Passive Wastewater Treatment · to adjacent wetland area to restore natural “wet”...

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