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Quantifying Microbial Activity in Environmental Biotechnology

Explore the quantification of microorganisms and their activity in environmental biotechnology through microbial growth measurements, substrate disappearance analysis, batch growth curves, mass balance equations, and biogeochemical cycles. Learn about the nitrogen cycle, nitrogen fixation and assimilation, as well as processes like ammonification and nitrification with detailed kinetics. Enhance your understanding of microbial interactions and nutrient cycling in environmental systems.

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Quantifying Microbial Activity in Environmental Biotechnology

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  1. Quantifying Microorganisms and Their Activity CE 421/521 Environmental Biotechnology Lecture for September 19, 2006 Vaccari et al., Chapter 10

  2. Two Events • Microbial Growth (dX/dt) • Substrate Disappearance (dS/dt) • During balanced growth can use a surrogate measure of growth • Oxygen consumption • Carbon dioxide production • Methane production (anaerobic systems)

  3. Growth vs Substrate Disappearance

  4. Batch Growth Curve

  5. Exponential Growth • Doubling (generation) time

  6. CSTR or Chemostat General mass balance; in – out – generation = accumulation Q, Xe, Se Q, Xi, Si V,X,S air

  7. CSTR with settling Q-Qw, Xe, S Q+Qr, X, S Q, Xi, Si V,X,S air Qr, Xr, S Return activated sludge, RAS Waste activated sludge, WAS http://www.water-technology.net /projects/chicago/images/Chicago01.jpg

  8. CSTR mass balance equations

  9. 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 _____

  10. Nitrogen • Atmosphere is _____% nitrogen, yet nitrogen is considered a l__________ n__________ • required in p____________

  11. Nitrogen Cycle Organic nitrogen NO3- NH4+ N2 NO2-

  12. 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)

  13. Assimilation • NH3 (NH4+) preferred, will use NO3- but has to be reduced to NH4+ • C/N ratio is approximately • 10:1 for aerobes • 150:1 for anaerobes • 50:1 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

  14. Ammonification • Breakdown of organic N to NH4+ • Examples: • Urea • proteins

  15. Nitrification • Two step process: • requires 4.57 mg O2/mg NH4+- N converted to NO3- – N

  16. 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

  17. Nitrification Kinetics

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