Title: CE421/521%20Environmental%20Biotechnology
1CE421/521 Environmental Biotechnology
- Nitrogen and Phosphorus Cycles
- Lecture 9-11-08
- Tim Ellis
2Biogeochemcial Cycles (C, N, P, S)
- composition of b_______ cell (molar formula
C5H7O2N with P 1/5 of the N requirement) - limiting nutrients are _____ and _____
3(No Transcript)
4Nitrogen
- Atmosphere is _____ nitrogen, yet nitrogen is
considered a l__________ n__________ - required in p____________
5Nitrogen Cycle
Organic nitrogen
NO3-
NH4
N2
NO2-
6Fixation
- 2x108 metric tons/y compared to 2.5x1010 metric
tons C/y - cyanobacteria few others
- non-symbiotic Clostridia
- symbiotic Rhizobium
- nitrogenase requires Mg2 ATP (15 to 20
ATP/N2)
7Assimilation
- NH3 (NH4) preferred, will use NO3- but has to be
reduced to NH4 - C/N ratio is approximately
- 101 for aerobes
- 1501 for anaerobes
- 501 for anaerobes in highly loaded (high rate)
system - cell composition is characterized by the
empirical formula ______________ - with the P requirement as 1/5 the N requirement
(alternatively C60H87O23N12P) - in general cell composition is
- 50 C
- 20 O
- 10-15 N
- 8-10 H
- 1-3 P
- 0.5-1.5
8Ammonification
- Breakdown of organic N to NH4
- Examples
- Urea
- proteins
9Nitrification
- Two step process
- requires 4.57 mg O2/mg NH4- N converted to NO3-
N
10Nitrification 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
11Nitrification Kinetics
12Nitrification 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
13Nitrifiers are sensitive to
- d____________ o_____________
- t______________
- p___
- i_____________________
- where I concentration of inhibitor, mg/L
- KI inhibition coeficient, mg/L
14Effects of Temperature
- derivation of the
- A____________ equation
- where k1,2 reaction rate coefficient at
temperature T1,2 - ? t___________ c__________
15Typical Theta Values
ln k
ln ?
Temp (deg C or K)
16Calculating Theta
- given the following measured data, calculate the
theta value
17DENITRIFICATION
- 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
18DENITRIFICATION
- requires o______________ m________________(exampl
e methanol) - kinetics for denitrification similar to those for
heterotrophic aerobic growth
19DENITRIFICATION
6NO3- 5CH3OH ? 3N2 5 CO2 7
H2O 6 OH-
- calculate COD of methanol
- calculate alkalinity
20Nitrogen 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______________
21Methods 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___________________
22Concerns for nitrogen discharge
- 1. T________________
- 2. D________________ of DO
- 3. E__________________________
- 4. Nitrate in d________________ water causes
methemoglobinemia (blue baby) oxidizes hemoglobin
to methemoglobin
23Phosphorus
- 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
24Removal 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
25Struvite as a problem
- Scale build-up chokes pipelines, clogs aerators,
reduces heat exchange capacity - Canned king crab industry
- Kidney stones
26Struvite 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
27Sulfur
- 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
28Sulfur
- 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
29Crown Sewer Corrosion