CE421/521 Environmental CE421/521 Environmental BiotechnologyBiotechnology

Nitrogen and Phosphorus CyclesNitrogen and Phosphorus CyclesLecture 9-11-08Lecture 9-11-08

Tim EllisTim Ellis

Biogeochemcial Cycles Biogeochemcial Cycles (C, N, P, & S)(C, N, P, & S)

composition of b_______ cell (molar composition of b_______ cell (molar formula: Cformula: C55HH77OO22N with P 1/5 of the N N with P 1/5 of the N requirement)requirement)

limiting nutrients are _____ and _____limiting nutrients are _____ and _____

NitrogenNitrogen

Atmosphere is _____% Atmosphere is _____% nitrogen, yet nitrogen nitrogen, yet nitrogen is considered a is considered a l__________ n__________l__________ n__________

required in required in p____________p____________

Organic nitrogen

N2NO3- NH4

+

NO2-

Nitrogen CycleNitrogen Cycle

FixationFixation 2x102x1088 metric tons/y compared to metric tons/y compared to

2.5x102.5x101010 metric tons C/y metric tons C/y cyanobacteria & few others cyanobacteria & few others

– non-symbiotic – non-symbiotic – ClostridiaClostridia– symbiotic – symbiotic – RhizobiumRhizobium

nitrogenase – requires Mgnitrogenase – requires Mg2+2+ & ATP & ATP (15 to 20 ATP/N(15 to 20 ATP/N22))

AssimilationAssimilation NHNH33 (NH (NH44

++) preferred, will use NO) preferred, will use NO33-- but has to be reduced to but has to be reduced to

NHNH44++

C/N ratio is approximately C/N ratio is approximately – 10:1 for aerobes10:1 for aerobes– 150:1 for anaerobes150:1 for anaerobes– 50:1 for anaerobes in highly loaded (high rate) system50:1 for anaerobes in highly loaded (high rate) system

cell composition is characterized by the empirical formula: cell composition is characterized by the empirical formula: ____________________________with the P requirement as 1/5 the N requirement with the P requirement as 1/5 the N requirement (alternatively C(alternatively C6060HH8787OO2323NN1212P)P)

in general cell composition is in general cell composition is 50% C50% C 20% O20% O 10-15% N10-15% N 8-10% H8-10% H 1-3% P1-3% P 0.5-1.50.5-1.5

AmmonificationAmmonification

Breakdown of organic N to NHBreakdown of organic N to NH44++

Examples:Examples:– UreaUrea– proteinsproteins

NitrificationNitrification Two step process:Two step process:

requires 4.57 mg Orequires 4.57 mg O22/mg NH/mg NH44++- N - N

converted to NOconverted to NO33-- – N – N

Nitrification KineticsNitrification Kinetics

max SK S

SK S

NH

S NH

O

O O

4

4

2

2

where μmax = maximum specific growth rate, h-1KS = half saturation coefficient for ammonia, mg/L as NH4-NKO = half saturation coefficient, mg/L as O2Yield = mg biomass formed/mg ammonia utilized

Nitrosomonas Nitrobacter

parameter range typical (@20°C)

range typical (@ 20°C)

μmax

KS

KO

Yield

0.014 - 0.0920.06 - 5.60.3 - 1.30.04 - 0.13

0.0321.00.50.1

0.006 - 0.060.06 - 8.40.3 - 1.30.02 - 0.07

0.0341.30.680.05

Optimum pH for nitrifiers is around 8.0, range 7.5 - 8.5 (higher than for most other biological processes).

Nitrification KineticsNitrification Kinetics

m ax SK S

SK S

NH

S NH

O

O O

4

4

2

2

where μmax = maximum specific growth rate, h-1KS = half saturation coefficient for ammonia, mg/L as NH4-NKO = half saturation coefficient, mg/L as O2Yield = mg biomass formed/mg ammonia utilized

Nitrification KineticsNitrification Kinetics

Nitrifiers are sensitive toNitrifiers are sensitive to d____________ o_____________d____________ o_____________ t______________t______________ p___p___ i_____________________i_____________________

where I = concentration of inhibitor, mg/Lwhere I = concentration of inhibitor, mg/LKKII = inhibition coeficient, mg/L = inhibition coeficient, mg/L

m ax SK S

KK I

NH

S NH

I

I

4

4

Effects of TemperatureEffects of Temperature derivation of the derivation of the A____________ equation A____________ equation

where kwhere k1,21,2 = reaction rate coefficient at = reaction rate coefficient at temperature Ttemperature T1,21,2

θ = t___________ c__________θ = t___________ c__________

k k T T2 1

2 1 ( )

k Ae RT

Typical Theta ValuesTypical Theta Values

theta values

Nitrosomonas Nitrobacter

μmaxKSkd

1.098 - 1.1181.1251.029 - 1.104

1.068 - 1.1121.1571.029 - 1.104

ln k

Temp (deg C or K)

ln θ

Calculating ThetaCalculating Theta given the following measured data, given the following measured data,

calculate the theta valuecalculate the theta value

T, °C b, h-1

10203040

0.00370.00950.02290.0372

DENITRIFICATIONDENITRIFICATION1.1. A_____________________ nitrate reduction: NO3- A_____________________ nitrate reduction: NO3-

➔ NH4+ nitrate is incorporated into cell material ➔ NH4+ nitrate is incorporated into cell material and reduced inside the celland reduced inside the cell

2.2. D___________________ nitrate reduction D___________________ nitrate reduction (denitrification)(denitrification)– NO3- serves as the t____________ e_______________ NO3- serves as the t____________ e_______________

a_________________ (TEA) in an anoxic (anaerobic) a_________________ (TEA) in an anoxic (anaerobic) environmentenvironment

NO3- ➔ NO2

- ➔ NO ➔ N2O ➔ N2 nitrate reductase nitrite r. nitric oxide r. nitrous oxide r.

summarized as:NO3

- ➔ NO2- ➔ N2

DENITRIFICATIONDENITRIFICATION

requires o______________ requires o______________ m________________(example: methanol)m________________(example: methanol)

kinetics for denitrification similar to kinetics for denitrification similar to those for heterotrophic aerobic growththose for heterotrophic aerobic growth

m ax S

K SNO

K NOS NO

3

3 3

DENITRIFICATIONDENITRIFICATION calculate COD of methanol:calculate COD of methanol:

calculate alkalinity:calculate alkalinity:

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

Nitrogen Removal in Wastewater Nitrogen Removal in Wastewater Treatment PlantsTreatment Plants

Total Kjeldahl Nitrogen (TKN) = o___________ Total Kjeldahl Nitrogen (TKN) = o___________ n___________ + a______________ n___________ + a______________

(measured by digesting sample with sulfuric acid (measured by digesting sample with sulfuric acid to convert all nitrogen to ammonia)to convert all nitrogen to ammonia)

TKN ~ 35 mg/L in influentTKN ~ 35 mg/L in influent p____________ t____________ removes p____________ t____________ removes

approximately 15%approximately 15% additional removal with biomass w______________additional removal with biomass w______________

Methods for Nitrogen RemovalMethods for Nitrogen Removal1.1. BiologicalBiological

– n_______________n_______________– d________________d________________– ANAMMOX: ammonium is the electron donor, nitrite is the TEAANAMMOX: ammonium is the electron donor, nitrite is the TEA

NHNH44++ + NO + NO22

-- ➔ N ➔ N22 + 2 H + 2 H22OOSuitable for high ammonia loads (typically greater than 400 Suitable for high ammonia loads (typically greater than 400

mg/L) and low organic carbonmg/L) and low organic carbon

2.2. Chemical/PhysicalChemical/Physical1.1. air s_______________air s_______________2.2. breakpoint c__________________breakpoint c__________________3.3. ion e_____________________ion e_____________________4.4. reverse o___________________reverse o___________________

Concerns for nitrogen discharge:Concerns for nitrogen discharge:

1.1.T________________T________________2.2.D________________ of DOD________________ of DO3.3.E__________________________E__________________________4.4.Nitrate in d________________ water – causes Nitrate in d________________ water – causes

methemoglobinemia (blue baby) oxidizes methemoglobinemia (blue baby) oxidizes hemoglobin to methemoglobinhemoglobin to methemoglobin

PhosphorusPhosphorus limiting n___________________ in algae (at limiting n___________________ in algae (at

approximately 1/5 the nitrogen approximately 1/5 the nitrogen requirement)requirement)

15% of population in US discharges to 15% of population in US discharges to l_________________l_________________

wastewater discharge contains wastewater discharge contains approximately 7- 10 mg/L as P approximately 7- 10 mg/L as P

o__________________o__________________ i______________: orthophosphatei______________: orthophosphate

Removal of PhosphorusRemoval of Phosphorus Chemical precipitation:Chemical precipitation:

– traditional p____________________ reactionstraditional p____________________ reactionsAlAl+3+3 + PO + PO44

-3-3 ➔ AlPO ➔ AlPO44

FeFe+3+3 + PO + PO44-3-3 ➔ FePO ➔ FePO44

– as s_______________ (magnesium ammonium as s_______________ (magnesium ammonium phosphate, MAP)phosphate, MAP)

MgMg+2+2 + NH + NH44++ + PO + PO44

-3-3 ➔ MgNH ➔ MgNH44POPO44

Struvite as a problemStruvite as a problem

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

Canned king crab industryCanned king crab industry Kidney stonesKidney stones

Struvite as a FertilizerStruvite as a Fertilizer Nonburning and long lasting source of Nonburning and long lasting source of

nitrogen and phosphorusnitrogen and phosphorus Found in natural fertilizers such as guanoFound in natural fertilizers such as guano Heavy applications have not burned crops Heavy applications have not burned crops

or depressed seed germination (Rothbaum, or depressed seed germination (Rothbaum, 1976)1976)

Used for high-value cropsUsed for high-value crops

For ISU study on removing ammonia from hog waste see:www.public.iastate.edu/~tge/miles_and_ellis_2000.pdf

SulfurSulfur inorganic: SOinorganic: SO44

-2-2 S° H S° H22SS

organic: R — O — SOorganic: R — O — SO33-2-2

four key reactions:four key reactions:1.1. HH22S o__________________ — can occur aerobically or S o__________________ — can occur aerobically or

anaerobically to elemental sulfur (S°)anaerobically to elemental sulfur (S°)– a___________________ : a___________________ : Thiobaccilus thioparusThiobaccilus thioparus oxidizes S-2 to S° oxidizes S-2 to S°

SS-2-2 + ½ O + ½ O22 + 2H + 2H++ ➔ S° + H ➔ S° + H22OO– a_______________________: — phototrophs use H2S as electron a_______________________: — phototrophs use H2S as electron

donordonor filamentous sulfur bacteria oxidize Hfilamentous sulfur bacteria oxidize H22S to S° in sulfur S to S° in sulfur

granules: granules: Beggiatoa, ThiothrixBeggiatoa, Thiothrix

SulfurSulfur2.2. Oxidation of E_______________ Sulfur (Thiobacillus thiooxidans at low Oxidation of E_______________ Sulfur (Thiobacillus thiooxidans at low

pH)pH) 2S° + 3 O2S° + 3 O22 + 2 H + 2 H22O ➔ 2 HO ➔ 2 H22SOSO44

3.3. A_______________________ sulfate reduction: proteolytic bacteria A_______________________ sulfate reduction: proteolytic bacteria breakdown organic matter containing sulfur (e.g. amino acids: breakdown organic matter containing sulfur (e.g. amino acids: methionine, cysteine, cystine)methionine, cysteine, cystine)

4. D_______________________ sulfate reduction: under anaerobic 4. D_______________________ sulfate reduction: under anaerobic conditionsconditions

— — s_____________ r________________ b_________________ (SRs_____________ r________________ b_________________ (SRSOSO44

-2-2 + Organics ➔ S + Organics ➔ S-2-2 + H + H22O + COO + CO22SS-2-2 + 2H + 2H++ ➔ H ➔ H22SS

DesulvibrioDesulvibrio and others and others Sulfate is used as a TEA & l_____ m____________ w___________ organics Sulfate is used as a TEA & l_____ m____________ w___________ organics

serve as the electron donorsserve as the electron donors Low cell y_______________Low cell y_______________ P___________________ of SRB depends on COD:S ratio, particularly P___________________ of SRB depends on COD:S ratio, particularly

readily degradable (e.g., VFA) CODreadily degradable (e.g., VFA) COD SRB compete with m_____________________ for substrate: high COD:S SRB compete with m_____________________ for substrate: high COD:S

favors methanogens, low COD:S favors SRBfavors methanogens, low COD:S favors SRB

Crown Sewer CorrosionCrown Sewer Corrosion