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CE421/521 Environmental Biotechnology. Nitrogen and Phosphorus Cycles Lecture 9-26-06 Tim Ellis. Nitrification Kinetics. where μ max = maximum specific growth rate, h-1 K S = half saturation coefficient for ammonia, mg/L as NH 4 -N K O = half saturation coefficient, mg/L as O2

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ce421 521 environmental biotechnology

CE421/521 Environmental Biotechnology

Nitrogen and Phosphorus Cycles

Lecture 9-26-06

Tim Ellis

nitrification kinetics
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

nitrifiers are sensitive to
Nitrifiers are sensitive to
  • d____________ o_____________
  • t______________
  • p___
  • i_____________________

where I = concentration of inhibitor, mg/L

KI = inhibition coeficient, mg/L

effects of temperature
Effects of Temperature
  • derivation of the
  • A____________ equation
  • where k1,2 = reaction rate coefficient at temperature T1,2
  • θ = t___________ c__________
typical theta values
Typical Theta Values

ln θ

ln k

Temp (deg C or K)

calculating theta
Calculating Theta
  • given the following measured data, calculate the theta value
denitrification
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

denitrification1
DENITRIFICATION
  • requires o______________ m________________(example: methanol)
  • kinetics for denitrification similar to those for heterotrophic aerobic growth
denitrification2
DENITRIFICATION

6NO3- + 5CH3OH ➔ 3N2 + 5 CO2 + 7 H2O + 6 OH-

  • calculate COD of methanol:
  • calculate alkalinity:
nitrogen removal in wastewater treatment plants
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______________
methods for nitrogen removal
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___________________
concerns for nitrogen discharge
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

system configurations
System Configurations
  • Completely mixed activated sludge (CMAS)
  • Conventional activated sludge (CAS)
  • Sequencing Batch Reactor (SBR)
  • Extended aeration, oxidation ditch, others
slide15
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

completely mixed activated sludge cmas
Completely Mixed Activated Sludge (CMAS)

to tertiary treatment

or surface discharge

clarifier

aeration basin

air or

oxygen

RAS

WAS

slide18
Conventional (plug flow) Activated Sludge (CAS)

Primary effl.

plan view

to secondary clarifier

RAS

cmas with selector
CMAS with Selector

High

F/M

Selector

Low F/M

CMAS with Selector

contact stabilization activated sludge
Contact Stabilization Activated Sludge

clarifier

aeration basin

air or

oxygen

contact

tank

RAS

WAS

air or

oxygen

sequencing batch reactor
Sequencing Batch Reactor

WASTEWATER

AIR

TREATED

EFFLUENT

Sludge wastage at end

of decant cycle

FILL

REACT

SETTLE

DECANT

phosphorus
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
removal of phosphorus
Removal of Phosphorus
  • Chemical precipitation:
    • traditional p____________________ reactions

Al+3 + PO4-3 ➔ AlPO4

Fe+3 + PO4-3 ➔ FePO4

    • as s_______________ (magnesium ammonium phosphate, MAP)

Mg+2 + NH4+ + PO4-3 ➔ MgNH4PO4

slide27
Struvite as a problem
  • Scale build-up chokes pipelines, clogs aerators, reduces heat exchange capacity
  • Canned king crab industry
  • Kidney stones
slide28
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_2000.pdf

full scale asbr
Full Scale ASBR
  • 2300 head operation in central Iowa, USA
  • methane recovery for energy generation
  • site for full-scale study for struvite precipitation
biological p removal
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
key reactions in anaerobic environment
Key Reactions in Anaerobic Environment
  • Uptake of acetic acid
  • Storage polymer (PHB) is formed
  • Polyphosphate granule is consumed
  • Phosphate is released
key reactions in aerobic environment
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
anaerobic zone initial
Anaerobic Zone (initial)

H3CCOOH

H3CCOO- + H+

ATP

PHB

polymer

ADP+Pi

ATP

ADP+Pi

Pi

Pi

Polyphosphate

Granule

ADP+Pi

H+

ATP

anaerobic zone later
Anaerobic Zone (later)

H3CCOOH

H3CCOO- + H+

ATP

ADP+Pi

PHB

polymer

ATP

ADP

ADP+Pi

Pi

Polyphosphate

Granule

Pi

ADP+Pi

H+

ATP

aerobic zone initial
Aerobic Zone (initial)

substrate

H+

substrate

CO2 + NADH

ADP+Pi

ATP

NAD

ATP

Polyphosphate

Granule

ADP+Pi

PHB

polymer

Pi

H2O

Pi

ATP

2H+ + 1/2O2

ADP+Pi

H+

aerobic zone later
Aerobic Zone (later)

H+

NAD

CO2 + NADH

ATP

PHB

polymer

ADP+Pi

ATP

ADP+Pi

Polyphosphate

Granule

Pi

H2O

Pi

ATP

2H+ + 1/2O2

ADP+Pi

H+

bio p operational considerations
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.
slide38
A/O EBPR

Alum, Fe+3 (optional)

air

Anaerobic

Selector

Secondary

Clarifier

Aeration Basin

return activated sludge (RAS)

waste activated

sludge (WAS)

Phosphate Storage “Battery”

combined n and p removal
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
combined biological phosphorus nitrogen removal
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

slide41
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

slide42
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

slide43
Combined Biological Phosphorus & Nitrogen Removal

nitrate free

recirculation

nitrate rich recirculation

Secondary

Settling

Tank

Anoxic

Selector

Anaerobic

Selector

Aeration Basin

(nitrification zone)

air

return activated sludge (RAS)

waste activated

sludge (WAS)

Virginia Initiative Plant (VIP)

sulfur
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
sulfur1
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 COD:S ratio, particularly readily degradable (e.g., VFA) COD
  • SRB compete with m_____________________ for substrate: high COD:S favors methanogens, low COD:S favors SRB
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