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CE421/521%20Environmental%20Biotechnology

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Title: CE421/521%20Environmental%20Biotechnology


1
CE421/521 Environmental Biotechnology
  • Nitrogen and Phosphorus Cycles
  • Lecture 9-11-08
  • Tim Ellis

2
Biogeochemcial 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)
4
Nitrogen
  • Atmosphere is _____ nitrogen, yet nitrogen is
    considered a l__________ n__________
  • required in p____________

5
Nitrogen Cycle
Organic nitrogen
NO3-
NH4
N2
NO2-
6
Fixation
  • 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)

7
Assimilation
  • 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

8
Ammonification
  • Breakdown of organic N to NH4
  • Examples
  • Urea
  • proteins

9
Nitrification
  • Two step process
  • requires 4.57 mg O2/mg NH4- N converted to NO3-
    N

10
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
11
Nitrification Kinetics
12
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
13
Nitrifiers are sensitive to
  • d____________ o_____________
  • t______________
  • p___
  • i_____________________
  • where I concentration of inhibitor, mg/L
  • KI inhibition coeficient, mg/L

14
Effects of Temperature
  • derivation of the
  • A____________ equation
  • where k1,2 reaction rate coefficient at
    temperature T1,2
  • ? t___________ c__________

15
Typical Theta Values
ln k
ln ?
Temp (deg C or K)
16
Calculating Theta
  • given the following measured data, calculate the
    theta value

17
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
18
DENITRIFICATION
  • requires o______________ m________________(exampl
    e methanol)
  • kinetics for denitrification similar to those for
    heterotrophic aerobic growth

19
DENITRIFICATION
6NO3- 5CH3OH ? 3N2 5 CO2 7
H2O 6 OH-
  • calculate COD of methanol
  • calculate alkalinity

20
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______________

21
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___________________

22
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

23
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

24
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

25
Struvite as a problem
  • Scale build-up chokes pipelines, clogs aerators,
    reduces heat exchange capacity
  • Canned king crab industry
  • Kidney stones

26
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
27
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

28
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

29
Crown Sewer Corrosion
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