Topic: Ch 7

1. HW2 going out today, due next Friday 2. Wiley next Wed 3. March 20 th Field trip w/ Jason Assoiline 4. me about DimDim Recordings 5. Tentative Carpool Plan – Time/Location 1. Merced to Clovis is 1hr drive 6. Experiment with mic’s and video

1. Background Review - Today 2. Stoichiometry - Today 3. Energetics - Wed 4. Microbial Growth Kinetics - Wed

 Capture nonsetteable solids into a biological floc or biofilm  Biomass has specific gravity greater than water  Must remove settled bacteria or won’t reduce BOD  Transform or remove nutrients (N and P)  Oxidize consituents into an acceptable end product

 Typically aerobic (need aeration… energy!)  Sometimes anaerobic for cases of highly concentrated wastewater  Anaerobic typically used for sludge treatment but this is not usually suspended growth

 C 5 H 7 O 2 N  Growth rates double every 10ºC until optimum temp reached  pH optimum  Nutrients may be limited in industrial wastewaters

 Why does death phase occur?  Draw DO curve?  Draw BOD curve?

 Bacteria Cells = Biomass  Often measured as volatile suspended solids (VSS)  Is VSS entirely biomass?  Other approaches: particulate COD, protein,,DNA  Biomass yield (Y) = g biomass produced / g substrate consumed  Substrate is typically the constituent in the wastewater that is electron donor (energy source)  What would be the units for the yield for nitrification bacteria (what is the substrate)?

 Cellular Mass Balance (Stoichiometry)  Assume substrate as glucose  Neglect nutrient other than N  How much substrate leaves system as sludge vs. gas?  What is the yield (Y) based on this stoichiometry?

 COD Mass Balance (Stoichiometry)  Assume substrate as glucose  Neglect nutrient other than N  What is the yield (Y) based on this stoichiometry?

 Cellular Mass Balance (Stoichiometry)  Assume substrate as glucose  Neglect nutrient other than N  What is the yield (Y) based on this stoichiometry (change in O 2 over change in glucose)?

 Cellular Mass Balance (Stoichiometry)  Assume substrate as glucose  Neglect nutrient other than N  What is the yield (Y) based on this stoichiometry (change in O 2 over change in glucose)?

 Maximum yield… actual yield will be more because not all substrate is converted to cell mass (synthesis) since some is needed for cell maintenance  Solve for the theoretical yield given the following

 Solve for the theoretical yield

 Recall that biomass must be removed by settling (as sludge) or effluent will have large BOD  Calculate COD of Cells given,

 Organics molecules are converted into cellular molecules but still are BOD  Recall that biomass must be removed by settling (as sludge) or effluent will have large BOD  Calculate COD of Cells given,

 Draw Schematic?

 Calculate Observed Yield (g cell / g substrate COD removed) ?

 Calculate Observed Yield? vs. Theoretical Yield?

 Oxygen Used per COD removed?  “Oxygen Used”: oxygen consumed by bacteria during synthesis of substrate. ▪ Calculate as difference between COD in and total COD out (substrate COD out + biomass COD out)  “COD removed”: Decrease in substrate COD. Ignores COD of biomass. ▪ Calculate as difference of COD in and COD out

 “Oxygen Used”: oxygen consumed by bacteria during synthesis of substrate. ▪ Calculate as difference between COD in and total COD out (substrate COD out + biomass COD out)

 “COD removed”: Decrease in substrate COD. Ignores COD of biomass. ▪ Calculate as difference of COD in and COD out

 Oxygen Used per COD removed?

Why is theoretical yield less than actual yield? How was the sound quality today? Where did you login from? Did you use best practices? High speed ethernet (not wireless) Turn off addon/toolbars on browser Close other open applications and background internet applications