CE421/521 Environmental Biotechnology

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CE421/521 Environmental Biotechnology

• Nitrogen and Phosphorus Cycles
• Lecture 9-26-06
• Tim Ellis

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Nitrification Kinetics
where µmax maximum specific growth rate,
h-1 KS half saturation coefficient for ammonia,
mg/L as NH4-N KO half saturation coefficient,
mg/L as O2 Yield mg biomass formed/mg ammonia
utilized
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Nitrification Kinetics
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Nitrifiers are sensitive to

• d____________ o_____________
• t______________
• p___
• i_____________________
• where I concentration of inhibitor, mg/L
• KI inhibition coeficient, mg/L

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Effects of Temperature

• derivation of the
• A____________ equation
• where k1,2 reaction rate coefficient at
  temperature T1,2
• ? t___________ c__________

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Typical Theta Values
ln k
ln ?
Temp (deg C or K)
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Calculating Theta

• given the following measured data, calculate the
  theta value

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DENITRIFICATION

• 1. A_____________________ nitrate reduction
  NO3- ? NH4 nitrate is incorporated into cell
  material and reduced inside the cell
• 2. D___________________ nitrate reduction
  (denitrification)
• NO3- serves as the t____________
  e_______________ a_________________ (TEA) in an
  anoxic (anaerobic) environment

nitrate reductase nitrite r. nitric
oxide r. nitrous oxide r.
NO3- ? NO2- ? NO ?
N2O ? N2
summarized as NO3- ? NO2- ? N2
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DENITRIFICATION

• requires o______________ m________________(exampl
  e methanol)
• kinetics for denitrification similar to those for
  heterotrophic aerobic growth

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DENITRIFICATION
6NO3- 5CH3OH ? 3N2 5 CO2 7
H2O 6 OH-

• calculate COD of methanol
• calculate alkalinity

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Nitrogen Removal in Wastewater Treatment Plants

• Total Kjeldahl Nitrogen (TKN)
  o___________ n___________
  a______________
• (measured by digesting sample with sulfuric acid
  to convert all nitrogen to ammonia)
• TKN 35 mg/L in influent
• p____________ t____________ removes approximately
  15
• additional removal with biomass w______________

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Methods for Nitrogen Removal

• Biological
• n_______________
• d________________
• ANAMMOX ammonium is the electron donor, nitrite
  is the TEA
• NH4 NO2- ? N2
  2 H2O
• Suitable for high ammonia loads (typically
  greater than 400 mg/L) and low organic carbon
• Chemical/Physical
• air s_______________
• breakpoint c__________________
• ion e_____________________
• reverse o___________________

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Concerns for nitrogen discharge

• 1. T________________
• 2. D________________ of DO
• 3. E__________________________
• 4. Nitrate in d________________ water causes
  methemoglobinemia (blue baby) oxidizes hemoglobin
  to methemoglobin

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System Configurations

• Completely mixed activated sludge (CMAS)
• Conventional activated sludge (CAS)
• Sequencing Batch Reactor (SBR)
• Extended aeration, oxidation ditch, others

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Activated Sludge Wastewater Treatment Plant
Influent Force Main
Activated Sludge Aeration Basin
Bar Rack/ Screens
Primary Settling Tank
Grit Tank
Diffusers
Screenings
Grit
Air or Oxygen
Primary Sludge
Secondary Settling Tank
Waste Activated Sludge (WAS)
Cl2
Tertiary Filtration (Optional)
to receiving stream
Chlorine Contact Basin (optional)
wastewater flow
Return Activated Sludge (RAS)
residuals flow
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Completely Mixed Activated Sludge (CMAS)
to tertiary treatment or surface discharge
clarifier
aeration basin
air or oxygen
RAS
WAS
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Completely Mixed Activated Sludge (CMAS)
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Conventional (plug flow) Activated Sludge (CAS)
Primary effl.
plan view
to secondary clarifier
RAS
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Conventional Activated Sludge
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Conventional Activated Sludge
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Step Feed Activated Sludge
Feed
Feed
RAS
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CMAS with Selector
High F/M Selector
Low F/M
CMAS with Selector
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Contact Stabilization Activated Sludge
clarifier
aeration basin
air or oxygen
contact tank
RAS
WAS
air or oxygen
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Sequencing Batch Reactor
WASTEWATER
AIR
TREATED EFFLUENT
Sludge wastage at end of decant cycle
FILL
REACT
SETTLE
DECANT
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Phosphorus

• limiting n___________________ in algae (at
  approximately 1/5 the nitrogen requirement)
• 15 of population in US discharges to
  l_________________
• wastewater discharge contains approximately 7- 10
  mg/L as P
• o__________________
• i______________ orthophosphate

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Removal of Phosphorus

• Chemical precipitation
• traditional p____________________ reactions
• Al3 PO4-3 ? AlPO4
• Fe3 PO4-3 ? FePO4
• as s_______________ (magnesium ammonium
  phosphate, MAP)
• Mg2 NH4 PO4-3 ? MgNH4PO4

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Struvite as a problem

• Scale build-up chokes pipelines, clogs aerators,
  reduces heat exchange capacity
• Canned king crab industry
• Kidney stones

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Struvite as a Fertilizer

• Nonburning and long lasting source of nitrogen
  and phosphorus
• Found in natural fertilizers such as guano
• Heavy applications have not burned crops or
  depressed seed germination (Rothbaum, 1976)
• Used for high-value crops

For ISU study on removing ammonia from hog waste
see www.public.iastate.edu/tge/miles_and_ellis_2
000.pdf
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Full Scale ASBR

• 2300 head operation in central Iowa, USA
• methane recovery for energy generation
• site for full-scale study for struvite
  precipitation

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Biological P Removal

• Discovered in plug flow A.S. systems
• Requires anaerobic (low DO and NO3-) zone and
  aerobic zone
• Biological battery
• Grow phosphate accumulating organisms (PAO) with
  7 P content
• Need to remove TSS

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Key Reactions in Anaerobic Environment

• Uptake of acetic acid
• Storage polymer (PHB) is formed
• Polyphosphate granule is consumed
• Phosphate is released

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Key Reactions in Aerobic Environment

• Energy (ATP) is regenerated as bacteria consume
  BOD
• Phosphorus is taken into the cell and stored as
  poly-P granule
• When BOD is depleted, PAO continue to grow on
  stored reserves (PHB) and continue to store poly-P

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Anaerobic Zone (initial)
H3CCOOH
H3CCOO- H
ATP
PHB polymer
ADPPi
ATP
ADPPi
Pi
Pi
Polyphosphate Granule
ADPPi
H
ATP
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Anaerobic Zone (later)
H3CCOOH
H3CCOO- H
ATP
ADPPi
PHB polymer
ATP
ADP
ADPPi
Pi
Polyphosphate Granule
Pi
ADPPi
H
ATP
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Aerobic Zone (initial)
substrate
H
substrate
CO2 NADH
ADPPi
ATP
NAD
ATP
Polyphosphate Granule
ADPPi
PHB polymer
Pi
H2O
Pi
ATP
2H 1/2O2
ADPPi
H
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Aerobic Zone (later)
H
NAD
CO2 NADH
PHB polymer
ATP
ADPPi
ATP
ADPPi
Polyphosphate Granule
Pi
H2O
Pi
ATP
2H 1/2O2
ADPPi
H
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Bio-P Operational Considerations

• Need adequate supply of acetic acid
• Nitrate recycled in RAS will compete for acetic
  acid
• May need a trim dose of coagulant to meet permit
• Subsequent sludge treatment may return soluble
  phosphorus to A.S.

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A/O EBPR
Alum, Fe3 (optional)
air
Anaerobic Selector
Secondary Clarifier
Aeration Basin
return activated sludge (RAS)
waste activated sludge (WAS)
Phosphate Storage Battery
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Combined N and P Removal

• Competition between bio-P and denitrification
• BOD becomes valuable resource
• required for both N and P removal
• Operation depends on treatment goals
• One reaction will limit
• difficult to eliminate all BOD, N, and P
• Commercial models (BioWin, ASIM, etc.) useful to
  predict performance

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Combined Biological Phosphorus Nitrogen Removal
nitrate rich recirculation
Secondary Settling Tank
Anaerobic Selector
Anoxic Selector
Aeration Basin (nitrification zone)
air
return activated sludge (RAS)
waste activated sludge (WAS)
A2O
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Combined EBPR Nitrogen Removal
nitrate rich recirculation
Secondary Settling Tank
Anaerobic Selector
Secon- dary Aeration Basin
Anoxic Tank
Anoxic Selector
Primary Aeration Basin
air
air
return activated sludge (RAS)
waste activated sludge (WAS)
5-Stage Bardenpho
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Combined Biological Phosphorus Nitrogen Removal
nitrate rich recirculation
nitrate free recirculation
Secondary Settling Tank
Aeration Basin
First Anoxic Tank
Anaerobic Selector
Second Anoxic Tank
air
return activated sludge (RAS)
waste activated sludge (WAS)
Modified UCT
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Combined Biological Phosphorus Nitrogen Removal
nitrate free recirculation
nitrate rich recirculation
Secondary Settling Tank
Aeration Basin (nitrification zone)
Anaerobic Selector
Anoxic Selector
air
return activated sludge (RAS)
waste activated sludge (WAS)
Virginia Initiative Plant (VIP)
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Sulfur

• inorganic SO4-2 S
  H2S
• organic R O SO3-2
• four key reactions
• H2S o__________________ can occur aerobically
  or anaerobically to elemental sulfur (S)
• a___________________ Thiobaccilus thioparus
  oxidizes S-2 to S
• S-2 ½ O2 2H ? S
  H2O
• a_______________________ phototrophs use
  H2S as electron donor
• filamentous sulfur bacteria oxidize H2S to S in
  sulfur granules Beggiatoa, Thiothrix

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Sulfur

• 2. Oxidation of E_______________ Sulfur
  (Thiobacillus thiooxidans at low pH)
• 2S 3 O2 2 H2O ?
  2 H2SO4
• 3. A_______________________ sulfate reduction
  proteolytic bacteria breakdown organic matter
  containing sulfur (e.g. amino acids methionine,
  cysteine, cystine)
• 4. D_______________________ sulfate reduction
  under anaerobic conditions
• s_____________ r________________
  b_________________ (SR
• SO4-2 Organics ? S-2 H2O
  CO2
• S-2 2H ? H2S
• Desulvibrio and others
• Sulfate is used as a TEA l_____ m____________
  w___________ organics serve as the electron
  donors
• Low cell y_______________
• P___________________ of SRB depends on CODS
  ratio, particularly readily degradable (e.g.,
  VFA) COD
• SRB compete with m_____________________ for
  substrate high CODS favors methanogens, low
  CODS favors SRB

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Crown Sewer Corrosion