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Example of Project Competition of Ammonia-Oxidizing and Nitrite-Oxidizing Bacteria. CE 60330 Environmental Biotechnology University of Notre Dame. Problem: Eutrophication. www.dep.state.pa.us. Major Cases of Eutrophication. Gulf of Mexico. Chesapeake Bay.

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example of project competition of ammonia oxidizing and nitrite oxidizing bacteria

Example of ProjectCompetition of Ammonia-Oxidizing and Nitrite-Oxidizing Bacteria

CE 60330

Environmental Biotechnology

University of Notre Dame

problem eutrophication
Problem: Eutrophication

www.dep.state.pa.us

major cases of eutrophication
Major Cases of Eutrophication

Gulf of Mexico

Chesapeake Bay

http://www.ncat.org/nutrients/hypoxia/hypoxia.html

http://www.cbf.org/site/PageServer?pagename=resources_facts_deadzone

Long Island Sound

http://www.longislandsoundstudy.net/pubs/reports/sh03_p1.pdf

biological nitrogen removal
Biological Nitrogen Removal

1) Nitrification

Ammonia oxidizing bacteria (AOB) (Nitrosomonas)

NH4+ + O2 NO2-

Nitrite oxidizing bacteria (NOB) (Nitrobacter, Nitrospira)

NO2- + O2 NO3-

biological nitrogen removal1
Biological Nitrogen Removal

2) Denitrification

Heterotrophic denitrifying bacteria (DB)

NO3- + BOD  NO2-

NO2- + BOD  N2

nitrogen removal
Nitrogen Removal

DB

DB

NO2-

N2

3e-

2e-

  • SHORTCUT:
  • 25% reduction in oxygen
  • 40% reduction in BOD

Conventional

N removal

Shortcut

N removal

NOB

AOB

NO2-

NH4+

NO3-

2e-

6e-

nitrification
Nitrification
  • Under ambient conditions and DO over 2 mg/L, growth kinetics are similar for AOB and NOB
  • High temperatures: AOB significantly faster than NOB
  • Low DO: AOB outcompete NOB for oxygen
hollow fiber membrane supported biofilms
Hollow-Fiber Membrane-Supported Biofilms

O2

BOD

O2

281 m

  • Hydrophobic polymers
  • High specific surface area
  • Variable driving force
    • J=K(CL-C)
  • Low energy consumption

Water

1 m

membrane aerated biofilm reactor mabr
Membrane Aerated Biofilm Reactor (MABR)

NB

BOD

Liquid (anoxic)

O2

DO

LDL

Biofilm

Membrane attachment

Alternative approach

HB

liquid (aerobic)

NB

HB

DO

BOD

Biofilm

LDL

Solid attachment surface

research needs
Research Needs
  • Under conditions observed in the HMBP process:
    • How does bulk liquid DO impact stratification and activity of AOB and NOB?
    • How does membrane gas pressure impact stratification and activity of AOB and NOB?
reactor conditions
Reactor Conditions
  • Anticipated effluent ammonia will vary between 2 and 3 mgN/L
  • Expose pressurized single membrane in a column to 3 mgN/L ammonia at a very high loading rate
    • Small decrease in ammonia will be observed due to high loading
reactor conditions1
Reactor Conditions
  • What does bulk liquid concentration matter?
    • Monod kinetics
    • Concentration observed by the biofilm controls growth of bacteria
    • Therefore, the effluent concentration expected in the HMBP will control the ecology of the biofilm
modeling
Modeling
  • Aquasim 2.0 software
  • Biofilm compartment and membrane compartment
  • Simulates impact of bulk liquid DO and membrane pressure on biofilm
  • Same modeling concepts as used for HMBP (Downing and Nerenberg, 2007b)
modeling1
Modeling
  • Conditions modeled
  • 50 day simulation
  • Steady-state conditions
modeling results activity
Modeling Results - Activity

10 psi, 2 mg/L DO

10 psi, 0 mg/L DO

Ammonia (♦), nitrite (■), and nitrate (□).

5 psi, 0 mg/L DO

modeling results ecology
Modeling Results - Ecology

10 psi, 2 mg/L DO

10 psi, 0 mg/L DO

AOB (♦) and NOB (◊)

5 psi, 0 mg/L DO

modeling results ecology1
Modeling Results - Ecology
  • NOB yield: 0.083 mgVSS/mgNO2-
  • AOB yield: 0.34 mgVSS/mgNH4+

NOB biomass with 10 psi and 2 mg/L DO (▲), 10 psi and 0 mg/L DO (■), and 5 psi and 0 mg/L DO (♦)

discussion
Discussion
  • Oxygen gradients select for AOB over NOB
  • Higher DO provides an advantage to NOB
  • Oxidation to nitrite rather than nitrate saves energy and addition of exogenous donor