Ce421 521 environmental biotechnology
Download
1 / 46

CE421 - PowerPoint PPT Presentation


  • 225 Views
  • Uploaded on

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

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'CE421' - loren


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
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


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



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


Struvite as a problem

  • Scale build-up chokes pipelines, clogs aerators, reduces heat exchange capacity

  • Canned king crab industry

  • Kidney stones


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.


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


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


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


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



ad