optimizing nutrient removal review & case studies

1

Optimizing Nutrient Removal Review &

Case StudiesWebinar for TennesseeWastewater Operators

February 17, 2021

Grant Weaver, PE & wastewater [email protected]

Strategies for Optimizing Nutrient Removal

Week 1: Nitrogen RemovalWeek 2: Phosphorus Removal

Today: Nitrogen & Phosphorus Review & Case StudiesFeb 24: N&P Removal in Oxidation Ditch wwtpsMar 3: N&P Removal in SBRsMar 10: N&P Removal in Conventional Activated Sludge

Mar 17: Brainstorming N&P Removal Opportunities for Tennessee Wastewater Treatment Plants

2

Nutrient Removal Knowledge

3

Step 1: Convert Ammonia (NH4) to Nitrate (NO3)

Step 2: Convert Nitrate (NO3) to Nitrogen Gas (N2)

Oxygen-rich Aerobic ProcessDon’t need BOD for bacteria to growBacteria are sensitive to pH and temperature

Oxygen-poor Anoxic ProcessDo need BOD for bacteria to growBacteria are hardy

Ammonia Removal -1st Step of N Removal

Ammonia (NH4)

Ammonia RemovalAmmonia (NH4) is converted to Nitrate (NO3)

Ammonia Removal

Ammonia (NH4)

Oxygen (O2)

Ammonia Removal

Ammonia (NH4)

Alkalinity

Oxygen (O2)

H+

Ammonia (NH4)

Nitrite (NO2)

Alkalinity

Oxygen (O2)

H+

Ammonia Removal

Ammonia Removal

Ammonia (NH4)

Nitrite (NO2)

Alkalinity

Oxygen (O2) Oxygen (O2)

H+

Ammonia Removal

Ammonia (NH4)

Nitrite (NO2)

Nitrate (NO3)

Alkalinity

Oxygen (O2) Oxygen (O2)

H+

Nitrification:Ammonia (NH4) is converted to Nitrate (NO3)

Oxygen Rich HabitatMLSS* of 2500+ mg/L (High Sludge Age / MCRT / low F:M)ORP* of +100 to +150 mV (High DO)Time* (high HRT … 24 hr, 12 hr, 6 hr)Low BOD

Consumes Oxygen Adds acid - Consumes 7 mg/L alkalinity per mg/L of NH4 → NO3

*Approximate, each facility is different.

Nitrate Removal - 2nd

Step of N removal

Nitrate Removal

Nitrate (NO3)

Nitrate Removal

Nitrate (NO3)

BOD

Nitrate Removal

Nitrate (NO3)

Nitrogen Gas (N2)

BOD

Nitrate Removal

Nitrate (NO3)

Nitrogen Gas (N2)

OxygenBOD

Nitrate Removal

Nitrate (NO3)

Nitrogen Gas (N2)

Alkalinity

OxygenBOD

Adds DO (dissolved oxygen)Consumes BODGives back alkalinity … beneficially raises pH

Denitrification: Nitrate (NO3) is converted to Nitrogen Gas (N2)

Oxygen Poor HabitatORP* of -100 mV or less (DO less than 0.3 mg/L)Surplus BOD* (100-250 mg/L: 5-10 times as much as NO3)Retention Time* of 1-2 hours

Gives back OxygenGives back Alkalinity (3.5 mg/L per mg/L of NO3 → N2)

*Approximate, each facility is different.

Nitrogen Removal

DO: Dissolved Oxygen

ORP: Oxygen Reduction Potential

MLSS: Mixed Liquor Suspended Solids

HRT: Hydraulic Retention Time

BOD: Biochemical Oxygen Demand

Alkalinity

Note: All numbers are approximations, “rules of thumb”

Step 1: Nitrification (Ammonia Removal)

1 mg/L or more

+100 mV or more +

2500 mg/L or more

6 or more hours

less than 20 mg/L

60 mg/L or more

Alkalinity is lost

Step 1: Denitrification (Nitrate Removal)

Less than 0.2 mg/L

Less than -100 mV

Same

1 or more hours

100 mg/L or more

Alkalinity is gained

Grant [email protected]

22

MLE Process(Modified Ludzack-Ettinger)

Internal Recycle

Secondary Clarifier

Return Sludge

Aerobic Zone

Anoxic Zone

NH4 NO3

MLE (Modified Ludzack-Ettinger) Process

Internal Recycle

Secondary Clarifier

Return Sludge

Aerobic Zone

Anoxic Zone

NH4


NO3

Internal Recycle

Secondary Clarifier

Return Sludge

Aerobic Zone

Anoxic Zone

NH4N2


NO3


27

Sequencing Batch ReactorSBR

IdleAir ON

Sequencing Batch Reactor (SBR)Ammonia (NH4) Removal: Nitrification

Sludge Storage

NO3NH4

SBR #1 SBR #2

IdleAir OFF

Sequencing Batch Reactor (SBR)Nitrate (NO3) Removal: Denitrification

Sludge Storage

N2NO3

SBR #1 SBR #2

Air ONDecant / Waste

Sequencing Batch Reactor (SBR)Settle, Decant & Waste Sludge

Sludge Storage

SBR Process Control:Establish cycle times that are long enough to provide optimal habitats.And, short enough to allow all of the flow to be nitrified and denitrified.

SBR #1 SBR #2


32

Oxidation Ditch

Secondary Clarifier

Oxidation Ditch

Anoxic Zone

Aerobic Zone

Anoxic Zone

Aerobic Zone

NH4

Secondary Clarifier

Oxidation Ditch

Anoxic Zone

Aerobic Zone

Anoxic Zone

Aerobic Zone

NO3

NH4

Secondary Clarifier

Oxidation Ditch

Anoxic Zone

Aerobic Zone

Anoxic Zone

Aerobic Zone

NO3

N2


37

Biological Phosphorus Removal

Step 1: prepare “dinner”

VFA (volatile fatty acids) production in anaerobic/fermentive conditions

Step 2: “eat”

Bio-P bugs (PAOs, “phosphate accumulating organisms”) eat VFAs in anaerobic/fermentive conditions … temporarily releasing more P into the water

Step 3: “breathe” and grow

Bio-P bugs (PAOs) take in almost all of the soluble P in aerobic conditions as they grow and reproduce


40

Biological Phosphorus Removal:Mainstream Flow Fermentation Processes

Primary Clarifier

Bio-P Removal: Mainstream Fermentation Process

Aeration Tank

Secondary Clarifier

Anaerobic Tank

Gravity Thickener Sludge

Storage

In Anaerobic Tank …

Bacteria break down complex BOD into VFAs (volatile fatty acids).

VFAs

Primary Clarifier


Aeration Tank

Secondary Clarifier

PO4

Anaerobic Tank


Storage



PAO bacteria (phosphate accumulating organisms) take in VFAs as energy source & temporarily release PO4 (phosphate) into solution.

VFAs

Primary Clarifier


Aeration Tank

Secondary Clarifier

PO4

Anaerobic Tank


Storage




In Aeration Tank …

Energized PAO bacteria take PO4 out of solution.

Primary Clarifier


Aeration Tank

Secondary Clarifier

Anaerobic Tank

PO4


Storage




In Aeration Tank …

Energized PAO bacteria take PO4 out of solution.

Primary Clarifier


Aeration Tank

Secondary Clarifier

Anoxic Tank


Storage

Pre-anoxic zone to …

Strengthen anaerobic conditions in anaerobic tank

Minimize VFA use by denitrifying bacteria – the ones that convert Nitrate (NO3) to Nitrogen Gas (N2) – by “feeding” influent to the denitrifiers.

Anaerobic Tank

Primary Clarifier


Aeration Tank

Secondary Clarifier

Anoxic Tank


Storage




PO4

Anaerobic Tank

VFAs

Primary Clarifier


Aeration Tank

Secondary Clarifier

Anoxic Tank


Storage




PO4

Anaerobic Tank


50

Biological Phosphorus Removal: Combined Sidestream & Mainstream Fermentation

Primary Clarifier

Bio-P Removal: Sidestream Fermentation Process

Aeration Tank

Secondary Clarifier

Anaerobic Tank


Storage

VFAs

Fermentation

Primary Clarifier


Aeration Tank

Secondary Clarifier

VFAs

Anaerobic Tank


StorageFermentation

Primary Clarifier


Aeration Tank

Secondary Clarifier

PO4

Anaerobic Tank


StorageFermentation

Primary Clarifier


Aeration Tank

Secondary Clarifier

Anaerobic Tank

PO4

Nitrogen Interference: Nitrate (NO3) will consume VFAsGravity

Thickener Sludge Storage

Fermentation

Primary Clarifier


Secondary Clarifier


StorageFermentation

Anoxic Tank

Anaerobic Tank

Aeration Tank


58

Primary Clarifier

Less than 3x ortho-P leaving Anaerobic Tank

Aeration Tank

Secondary Clarifier

Anaerobic Tank


StorageFermentation

If Anaerobic Tank isn’t really anaerobic …

… turn off mixer(s)

Primary Clarifier

3x ortho-P leaving Anaerobic Tank but high effluent P

Aeration Tank

Secondary Clarifier

Anaerobic Tank


StorageFermentation

1. Poor removal in Aeration Tank …

2.0 mg/L DO / +150 mV ORP6.8+ pHIf seasonal, maybe too little BOD

2. Rerelease … most likely in clarifier(s)

Profile ortho-P through the plant

Optimizing Bio-P Removal: Mainstream or Sidestream Fermentation

Anaerobic Tank2 hour HRT (hydraulic retention time)*ORP of -200 mV* 25 times as much BOD as influent ortho-P*Ortho-P release (3 times influent ortho-P)*

Aeration TankDO of 2.0 mg/LORP of +150 mVpH of 7.0+*Ortho-P concentration of 0.05 mg/L*

*Approximate: Every Plant is Different


63

Getting creative …

Biological Phosphorus removal from plants not designed as EBPR (enhanced biological

phosphorus removal) facilities

64

Primary Clarifier

Home Grown Sidestream Fermenter

Aeration Tank

Secondary Clarifier

Anaerobic Tank


StorageFermentation

Primary Clarifier


Aeration Tank

Secondary Clarifier


Storage

Primary Clarifier


Aeration Tank

Secondary Clarifier


StorageFermenter

Primary Clarifier


Aeration Tank

Secondary Clarifier

Gravity Thickener Fermenter

69


Number of Operators at your plant

70

TENNESSEE71

AthensColliervilleCookevilleCowan

HarrimanLafayetteNashville Dry CreekNorris

Cookeville, Tennessee Population: 33,500 15 MGD design flow

72

73

Cookeville

Cookeville - As Designed

Cookeville - As Now Operated

81


Norris, Tennessee Population: 1,450 0.2 MGD design flow

82

83

Norris

86

Norris

87

Norris

88


Nashville Dry Creek Population: 678,000 24 MGD design flow

90

Nashville Dry Creek

91

Nashville Dry Creek

92

Nashville Dry Creek

93

Nashville Dry Creek


94

Harriman, Tennessee Population: 6,200 1.5 MGD design flow

Harriman, Tennessee

Actual Flow Effluent Nitrogen (mg/L) Effluent Phosphorus (mg/L)

(MGD) Historical Average After Optimization Historical Average After Optimization

1.2 21.5 2.3 2.9 1.4

97

Harriman - As Designed

98

Harriman - As Operated

99


100


101


102


103


Athens, Tennessee Population: 13,850 6.0 MGD design flow

104

106

Athens

107


Pratt, Kansas Population: 6,600 1.0 MGD design flow

109

111


Wichita, Kansas Population: 390,000 54.4 MGD design flow

112

113

Wichita Pilot Study

Nitrogen RemovalCycle aeration on/off in Aeration Basin 6

Phosphorus RemovalSide stream fermenter using abandoned centrate tanks

114


MONTANA

115

Conrad, Montana Population: 2,500 0.5 MGD design flow

116

Conrad, Montana - Nitrogen Removal

Conrad, Montana - Phosphorus Removal

122


Chinook, Montana Population: 1,250 0.5 MGD design flow

123

126


Helena, Montana Population: 31,500 5.4 MGD design flow

130

Helena, Montana - Nitrogen Removal

131

Helena, Montana - Phosphorus Removal

132


Acknowledgements, Part 1

TENNESSEE DEPARTMENT OF ENVIRONMENT & CONSERVATION (TDEC)Karina Bynum, Sherry Wang, George Garden, Jenny Dodd, Jason Benton, Eddie Bouzied, Bryan Carter, David Duhl, Jordan Fey, Oakley Hall, Michael Murphy, Steve Owens, Rob Ramsey, Sherwin Smith, Robert Tipton, Sandra Vance, John West, Ariel Wessel-Fuss … ATHENSGreg Hayes, Russell Coleman & John SullivanCOOKEVILLERonnie Kelly, Tom Graham & John BufordHARRIMANRay Freeman NASHVILLEJohnnie MacDonald & David TuckerNORRISTony Wilkerson & Doug Snelson

…

133

Acknowledgements, continued

TENNESSEE, continued Brett Ward (UT-MTAS), Dewayne Culpepper (TAUD), Larry Gamblin (Bartlett), Danny Neely (Baileyton), David Harrison (Collierville), Nic Willis (Cowan), Darryl Green (Henderson), Jack Hauskins & Rocky Hudson (Lafayette) …

KANSAS Tom Stiles … Rod Geisler … Shelly Shores-Miller … Nick Reams … Ryan Eldredge … Kyle Salmon … Mike Disipio … Dave Carr … Clint Gregor … Bruce Hurt … Anthony Zell … Jeff Shanline & Jay Angood (PRATT) … Jamie Belden & Becky Lewis (WICHITA)

MONTANA Paul LaVigne … Pete Boettcher … Josh Viall … Mike Abrahamson … Drue Newfield … Bill Bahr … Dave Frickey … Curt Konecky … Del Phipps … Aaron Losing … Robert Seamons … Grant Burroughs … Gene Connell … Terry Campbell … Anna Miller … Eric Miller & Cory Fox (CHINOOK) … Keith Thaut (CONRAD) … Mark Fitzwater & entire staff (HELENA)

EPA Paul Shriner … Tina Laidlaw … Brendon Held … Craig Hesterlee … Tony Tripp …

… and, many more!

Nutrient Removal Knowledge

135

Nitrogen & Phosphorus Removal in Oxidation DitchesWednesday, February 2410:00 - 11:45 AM Central Time…………………………………………………………

Mar 3: N&P Removal in SBRsMar 10: N&P Removal in Conventional Activated SludgeMar 17: Brainstorming N&P Removal Opportunities for Tennessee Wastewater Treatment Plants

Great Bend, Kansas Population: 13,400 3.6 MGD design flow

137

138


Helena, Montana Population: 31,500 5.4 MGD design flow

TENNESSEE145

optimizing nutrient removal review & case studies

Documents