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 V,X,S Q, X i, S i Q, X e, S e General mass balance; in – out – generation = accumulation air

7. CSTR with settling V,X,S Q, X i, S i Q+Q r, X, S Q-Q w, X e, S Q r, X r, S Return activated sludge, RAS http://www.water-technology.net /projects/chicago/images/Chicago01.jpg Waste activated sludge, WAS air

8. CSTR mass balance equations

9. Biogeochemcial Cycles (C, N, P, & S) composition of b_______ cell (molar formula: C 5 H 7 O 2 N with P 1/5 of the N requirement) limiting nutrients are _____ and _____

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

12. Organic nitrogen N2N2 NO 3 - NH 4 + NO 2 - Nitrogen Cycle

13. Fixation 2x10 8 metric tons/y compared to 2.5x10 10 metric tons C/y cyanobacteria & few others –non-symbiotic – Clostridia –symbiotic – Rhizobium.nitrogenase – requires Mg 2+ & ATP (15 to 20 ATP/N 2 )

14. Assimilation NH 3 (NH 4 + ) preferred, will use NO 3 - but has to be reduced to NH 4 + 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

15. Ammonification Breakdown of organic N to NH 4 + Examples: –Urea –proteins

16. Nitrification Two step process: requires 4.57 mg O 2 /mg NH 4 + - N converted to NO 3 - – N

17. 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 Yield = mg biomass formed/mg ammonia utilized

18. Nitrification Kinetics