example of project competition of ammonia-oxidizing and nitrite-oxidizing bacteria
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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. - PowerPoint PPT PresentationTRANSCRIPT
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
http://www.longislandsoundstudy.net/pubs/reports/sh03_p1.pdf
Long Island Sound
http://www.cbf.org/site/PageServer?pagename=resources_facts_deadzone
Chesapeake Bay
http://www.ncat.org/nutrients/hypoxia/hypoxia.html
Gulf of Mexico
Biological Nitrogen Removal
1) Nitrification
Ammonia oxidizing bacteria (AOB) (Nitrosomonas)
NH4+ + O2 NO2
-
Nitrite oxidizing bacteria (NOB) (Nitrobacter, Nitrospira)
NO2- + O2 NO3
-
Biological Nitrogen Removal
2) Denitrification
Heterotrophic denitrifying bacteria (DB)
NO3- + BOD NO2
-
NO2- + BOD N2
N2 3e- 2e-
DB DBNO2-
Nitrogen Removal
NO2- NO3
-
AOB NOB
Conventional N removal
Shortcut N removal
NH4+
6e- 2e-
SHORTCUT: 25% reduction
in oxygen 40% reduction
in BOD
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
281 m
1 m
Water
O2
O2
BOD
Hydrophobic polymers
High specific surface area
Variable driving force
J=K(CL-C)
Low energy consumption
Hollow-Fiber Membranes for Gas Transfer
1 mm
1 mm 2 m
Membrane Aerated Biofilm Reactor (MABR)
Biofilm
liquid (aerobic)
Solid attachment surface
DO
BOD
NB
LDL
HB
Biofilm
Membrane attachment
Liquid (anoxic)
BOD
DO
O2
LDL
NB
Alternative approach
HB
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
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 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
XSK
SYq
max
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)
Modeling
Conditions modeled
50 day simulation Steady-state conditions
ExperimentAmmonia
Concentration
Intra-Membrane Pressure
Bulk Liquid Oxygen
(mgN/L) (psi) (mg/L)
1 3 10 2
2 3 10 0
3 3 5 0
Modeling Results - Activity
0
0.5
1
1.5
2
2.5
3
0 10 20 30 40 50 60
Distance from Membrane (m)
Nit
rog
en C
on
cen
trat
ion
(gN
/m3 )
0
0.5
1
1.5
2
2.5
3
0 10 20 30 40 50 60
Distance from Membrane (m)
Nitr
ogen
Con
cent
ratio
n
(gN
/m3 )
0
0.5
1
1.5
2
2.5
3
0 10 20 30 40 50 60
Distance from Membrane (m)
Nit
rog
en C
on
cen
trat
ion
(gN
/m3 )
10 psi, 2 mg/L DO
10 psi, 0 mg/L DO
5 psi, 0 mg/L DOAmmonia (♦), nitrite (■), and nitrate (□).
0.0
0.2
0.4
0.6
0.8
1.0
0 20 40 60 80 100
Distance from membrane (m)
Fra
ctio
n of
Bio
mas
s
Modeling Results - Ecology
0.0
0.2
0.4
0.6
0.8
1.0
0 20 40 60 80
Distance from membrane (m)
Fra
ctio
n of
Bio
mas
s
10 psi, 2 mg/L DO
10 psi, 0 mg/L DO
5 psi, 0 mg/L DO
0
0.2
0.4
0.6
0.8
1
0 10 20 30 40 50 60 70
Distance from membrane (m)
Fra
ctio
n of
Bio
mas
s
AOB (♦) and NOB (◊)
Modeling Results - Ecology
0
0.05
0.1
0.15
0.2
0.25
0 20 40 60 80 100
Distance from membrane (m)
Fra
ctio
n of
Bio
mas
s
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 (♦)
•NOB yield: 0.083 mgVSS/mgNO2-
•AOB yield: 0.34 mgVSS/mgNH4+
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