The Charles E. Via, Jr. Department of Civil ... · (c) Literature data from Payne et al. (2014) ......

The Potential of Using Biological Nitrogen Removal Technique for

Stormwater Treatment

May 18, 2017

Yewei Sun, PhD StudentZhi‐Wu Wang, Assistant Professor

Sustainable Environment Research Laboratory

The Charles E. Via, Jr. Department of Civil & Environmental Engineering

Agenda


Introduction

Material and Methods

Results

Discussion

The Potential of Using Biological Nitrogen Removal Technique for Stormwater Treatment

Introduction: Background

“Dead Zones”

https://nofishleft.wordpress.com/tag/marine‐dead‐zones/

What is “Dead Zones”? -----NO FISH!!

Introduction Material and Methods Results Discussion

Introduction: Background

Increased

• Urbanization• Climate Change

Increased

• Stormwater Runoff• Nitrogen Pollutant

Formed• “Dead Zones”

“Dead Zones” Formation


Introduction: Biological Nitrogen Removal (BNR)

What is Biological Nitrogen Removal (BNR)?


Introduction: BNR for stormwater

Biological Nitrogen Removal


Applications Models

ASM1ASM2ASM3CWM1

High affinity of BNR communities to

nitrogen pollutants

Applicability of wastewater BNR models to low nitrogen concentration environment

Introduction: BNR for stormwater

Stormwater Characteristics (National Stormwater Quality Database)

TKN TN

BOD5 NOX (TN‐TKN)


Material and Methods: Model development

Bioretention System


Biofilm

Soil

Pore Water

Biofilm ThicknessConfocal image from Meherunnesha et al. (2008)


Bacterial Model

• Five substrates in the liquid phase• Dissolved oxygen (DO) • Nitrate (NO3

-)• Nitrite (NO2

-)• Ammonium (NH4

+)• Biodegradable organic carbon source expressed as chemical oxygen

demand (COD)

• Three types of autotrophic bacteria• Ammonia-oxidizing bacteria (AOB)• Nitrite-oxidizing bacteria (NOB)• Anammox bacteria (AMX)

• Three types of heterotrophic bacteria• Oxygen-respiring heterotroph (ORH)• Nitrite denitrifier (NID)• Nitrate denitrifier (NAD)



Plant Model

• Capability of assimilating both NH4+ and NO3

-

• Nitrogen is only temporarily stored in plant and will be eventually released back to the downstream water at their death and decay.

• Since this study focused on biological nitrogen removal and plant assimilation will reach its limit soon, plant nitrogen uptake was only considered in model calibration and validation.


Material and Methods: Model kinetics


Material and Methods: Model calibration and validation

0

2

4

6

8

10

0 10 20 30

Am

mon

ium

C

once

ntra

tion

(g N

m-3

)

Time (hour)

Experimental DataModel Simulation

R2=0.99

0

2

4

6

8

10

0 10 20 30

Nitr

ate

Con

cent

ratio

n (g

N m

-3)

Time (hour)

Experimental DataModel Simulation

R2=0.98

Model Calibration

Model Validation

0%

20%

40%

60%

80%

100%

experi

ment

model

Nitr

ate

fate

(a) 0%

20%

40%

60%

80%

100%

experi

ment

model

(b) 0%

20%

40%

60%

80%

100%

experi

ment

model

(c)

Literature data from Payne et al. (2014)


Results: Effect of HRT on steady-state NH4+ and TN removal efficiencies

• 0.5 days HRT should be sufficient for stormwater NH4+ removal.

• TN removal efficiency improves along with the increase of stormwater reducing power (NH4

+ and COD).• The contribution of AMX to TN removal increases along with the increase of

stormwater reducing power (NH4+ and COD).

0%

4%

8%

12%

16%

20%

60%

70%

80%

90%

100%

0 0.5 1 1.5 2

TN

rem

oval

eff

icie

ncy

NH

4+ rem

oval

eff

icie

ncy

HRT (day)

(a)

0%

4%

8%

12%

16%

20%

60%

70%

80%

90%

100%

0 0.5 1 1.5 2

TN

rem

oval

eff

icie

ncy

NH

4+ rem

oval

eff

icie

ncy

HRT (day)

(b)

0%

4%

8%

12%

16%

20%

60%

70%

80%

90%

100%

0 0.5 1 1.5 2

TN

rem

oval

eff

icie

ncy

NH

4+ rem

oval

eff

icie

ncy

HRT (day)

(c)

0%

4%

8%

12%

16%

20%

60%

70%

80%

90%

100%

0 0.5 1 1.5 2

TN

rem

oval

eff

icie

ncy

NH

4+ rem

oval

eff

icie

ncy

HRT (day)

(d)

Low NH4+

High COD High NH4+

High COD

Low NH4+

Low COD High NH4+

Low COD

Black: NH4+

removal

Green: TN removal with AMX

Red: TN removal without AMX


Results: Substrate distribution in biofilm

• COD can be oxidized within the top 50 µm layer in the biofilms.• NH4

+ oxidation occurs further inside biofilm beneath the layer where COD oxidation occurs.• The extent of NH4

+ oxidation depends on the penetration of remaining DO.

Dark blue: NH4+

Green: NO2-

Purple: NO3-

Blue: COD

Maroon: DO

2.178

2.182

2.186

2.190

2.194

2.198

0.00

0.05

0.10

0.15

0 100 200 300

NO

3- -N (g

m-3

)

N (N

H4+ ,N

O2- ),

DO

, CO

D

(g m

-3)

Lf (µm)

(d)

1.254

1.258

1.262

1.266

1.270

1.274

0.00 0.03 0.06 0.09 0.12 0.15 0.18

0 300 600 900

NO

3- -N (g

m-3

)

N (N

H4+ ,

NO

2- ), D

O, C

OD

(g

m-3

)

Lf (µm)

(b)

0.6

0.8

1.0

1.2

1.4

0.00

0.04

0.08

0.12

0.16

0 200 400 600 800

NO

3- -N, D

O (g

m-3

)

N (N

H4+ ,

NO

2- ), C

OD

(g

m-3

)

Lf (µm)

(a)

0.0

1.0

2.0

3.0

4.0

5.0

0.00

0.02

0.04

0.06

0.08

0 50 100 150 200

NO

3- -N, D

O (g

m-3

)

N (N

H4+ ,N

O2- ),

CO

D

(g m

-3)

Lf (µm)

(c)

Low NH4+

High COD

Low NH4+

Low COD

High NH4+

Low COD

High NH4+

High COD


Results: Bacteria distribution in biofilm

• Heterotroph, AOB and NOB predominate the top layers of biofilms where COD and DO are depleted.

• AMX only grow deep inside the biofilms where COD and DO are lean but NO2- and NH4

+ are affluent.

• Only stormwater with a relatively high reducing power (NH4+ and COD) offers the possibility to

cultivate biofilms with an anoxic local environment for AMX prosperity.

0

2000

4000

6000

8000

0 400 800

1200 1600 2000 2400

0 100 200 300

Het

erot

roph

, Ine

rt

(g C

OD

m-3

)

AO

B, N

OB

, AM

X

(g C

OD

m-3

)

Lf (µm)

(d)

0

3000

6000

9000

0

400

800

1200

1600

2000

0 300 600 900

Het

erot

roph

, Ine

rt

(g C

OD

m-3

)

AO

B, N

OB

, AM

X

(g C

OD

m-3

)

Lf (µm)

(b)

0

3000

6000

9000

0

25

50

75

0 200 400 600 800

Het

erot

roph

, Ine

rt

(g C

OD

m-3

)

AO

B, N

OB

, AM

X

(g C

OD

m-3

)

Lf (µm)

(a)

0

3000

6000

9000

0

30

60

90

0 50 100 150 200

Het

erot

roph

, Ine

rt

(g C

OD

m-3

)

AO

B, N

OB

, AM

X

(g C

OD

m-3

)

Lf (µm)

(c)

Low NH4+

High COD

Low NH4+

Low COD High NH4+

Low COD

High NH4+

High CODDark blue: AMX

Purple: NOB

Maroon: AOB

Green: Inert

Blue: Heterotroph


Results: Effect of COD on BNR

• TN keeps decreasing to almost zero as the influent COD increases to a threshold COD value (COD*).

• Continuous increase of influent COD will result in increase of TN and effluent COD concentration.

Dark blue: NH4+, Green: NO3

-, Maroon: NO2-, Purple: TN, Blue: COD

0

2

4

6

8

10

12

14

0

0.4

0.8

1.2

1.6

2

2.4

0 10 20 30 40

Eff

luen

t CO

D (g

m-3

)

N (g

m-3

)

COD (g m-3)

(b) Threshold COD*


Results: BNR at COD*

Dark blue: AMX

Purple: AOB

Blue: NOB

Maroon: NID

Green: NAD0

10

20

30

40

50

60

70

80

0

2

4

6

8

10

12

14

0 200 400 600 800

N tu

rnov

er r

ate

by

NID

and

NA

D (g

m-3

d-1

)

N tu

rnov

er r

ate

by

AO

B, N

OB

, AM

X (g

m-3

d-1

)

Lf (µm)

(a)

Two major characteristics of BNR at COD*:

i) Majority (90%) of nitrogen (NH4+ or NO3

-) is removed through AMX while only 10% through NID.

ii) Only partial nitritation occurred with no need of NOB. Therefore, the primary BNR pathway at COD* is through partial nitritation and AMX for the least COD consumption.


Results: BNR at COD*

COD* must be provided to enable the co-existence of aerobic and anoxic conditions required by BNR.

• COD < COD* leads to BNR failure because of the inadequate reducing power (NH4

+ and COD) for anoxic condition establishment.

• COD > COD* causes insufficient NH4+ nitrification due to inadequate DO

remains for AOB after COD oxidation.

0

2

4

6

8

10

12

14

0

0.4

0.8

1.2

1.6

2

2.4

0 10 20 30 40

Eff

luen

t CO

D (g

m-3

)

N (g

m-3

)

COD (g m-3)

(b)

Dark blue: NH4+

Green: NO3-

Maroon: NO2-

Purple: TN

Blue: COD


Discussion: Stoichiometric estimation of COD*


Exemplary

ratio

Percentage of nitrogen being removed by different pathways

Denitrification AMX Bacterialuptake Residual

Scenario 1 2.50 6.6% 84.3% 9.1% 0.0%

Scenario 2 0.50 61.3 10.0% 28.7 0.0%

Scenario 3 0.30 35.3% 0.0% 23.1% 41.6%

• Three scenarios can be generalized for stormwater BNR with regard to COD* demand.

Fraction of U.S. stormwater runoff in NSQD with NH4+-N to NO3

--N ratio under scenario

1 (blue), scenario 2 (orange), and scenario 3 (green)

71.10%

19.30%

9.60%

Discussion: Stoichiometric estimation of COD*

• About 9.6% stormwater events in National Stormwater Quality Database (NSQD) are subjected to NH4

+ limitation (scenario 3).


Discussion: Stormwater COD availability for BNR

0

1

2

3

4

5

0 0.5 1 1.5 2 2.5 3

NH

4+ -N

(g m

-3)

NO3--N (g m-3)

(a)

0

10

20

30

40

50

0 10 20 30 40 50

BO

D5 (

g m

-3)

COD* (g m-3)

(b)

• 82.6% U.S. stormwater in NSQD contains BOD5 lower than COD* required for complete BNR.

• Vegetation planted in the topsoil of bioretention system may release some COD.

• The slow COD-releasing biofilm carriers developed in recent years may be applied as an alternative for COD supplementation.

(a) BOD5 : (black circle size) COD* (red circle size)

(b) BOD5 vs COD* plot


Discussion: Importance of AMX for stormwater BNR

• COD* without AMX can be two-fold higher than the COD* with AMX. • BNR efficiency can be significantly compromised without AMX, which is true

especially at higher S : S ratio.

NO3- (g N m-3) = 0.5 (black)

1 (red)1.5 (orange)2 (green)2.5 (blue)3 (purple)

Solid line: with AMXDashed line: without AMX


Discussion: Model limitations and future work

• Homogeneous condition was assumed in bioretention systems in which heterogeneous environment may exist.

• The effect of inter-event duration was not considered in current model development.

• Experimental validation of the mathematical model is needed in future work.

Validation study is being carried out in ourcollaborator’s (Dr. Changwoo Ahn) mesocosmcomplex in George Mason University


Daily average rainfall graph in Goa, India (Jun to Sept. 2014)

http://weatheringoa.blogspot.com/2014/10/goa-monsoon-2014-analysis-happy-ending.html

• A mathematical model was for the first time developed tosimulate the spatial distribution of BNR activity in biofilmsgrowing on bioretention media for stormwater treatment.

• A threshold influent carbon source concentration (COD*) wasfound for maximizing BNR efficiency. Application of AMXcan significantly lower COD* and enhance BNR efficiency.

• 71.1% urban stormwater runoff contains adequate NH4+ for

both AMX and denitrification, 19.3% contains adequate NH4+

for denitrification but inadequate for AMX, while the NH4+

content in 9.6% urban stormwater is inadequate for neitherAMX nor denitrification.

Concluding remarks:



We would like to extend our sincerest thanks to 4-VA Competitive Research Grants and Sussman Internship funding for supporting this project.

Yewei Sun

PhD StudentOccoquan LaboratoryDepartment of Civil and Environmental Engineering, Virginia Tech9408 Prince William Street, Manassas, VA 20110-5670

Office: 703-361-5606 x 136 Fax: 703-361-7793 Email: [email protected]

The Potential of Using Biological Nitrogen Removal Technique for Stormwater Treatment

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