Case Study
This local creek receives treated wastewater discharged from Boulder's Water Resource Recovery Facility.
Boulder Creek
These reactors allow reactants to enter and products to leave continuously during operation.
CSTRs
This type of reactor assumes the contents are completely mixed, so the outlet concentration equals the concentration inside the tank.
an ideal CSTR
The term for the average time a fluid spends in a reactor, calculated as volume divided by flow rate
Residence time (τ)
Mike's full legal name
Micheal Patrick Hannigan
Boulder's Water Resource Recovery Facility treats approximately this many million gallons of wastewater per day.
13 million gallons per day (MGD)
CSTRs are commonly used in this environmental process to treat contaminated water before it is released.
wastewater treatment
This equation is used to calculate the average hydraulic residence time of a CSTR.
Tau=V/Q
In an ideal CSTR, the concentration inside the reactor is equal to the concentration at this location, because of complete mixing.
The exit (outlet)
Mike's favorite class to advertise
PBL
Unlike the two anaerobic digesters, Boulder's post-aerobic digester introduces this substance to support additional biological treatment.
oxygen (O₂)
This benefit of continuous stirring helps maintain relatively uniform concentrations throughout an ideal CSTR.
uniform mixing
This type of tracer input involves adding a tracer to the reactor all at once at the beginning of an experiment.
pulse input
To find the starting concentration (C₀) right after a pulse of tracer is mixed in, divide the mass of tracer added by this quantity
The volume of the reactor
The name of one of Mike's sons
Galileo, Calder, Darwin
In the Boulder case study, the two anaerobic digesters operating in series had a combined solids retention time of approximately this many days.
46 days
In wastewater treatment, microorganisms break down organic sludge in these reactors, potentially producing methane-rich biogas
anaerobic digesters
This distribution describes the fraction of fluid leaving the reactor at different residence times.
exit age distribution, E(t)
This distribution describes the normalized rate at which molecules exit the reactor, and for a CSTR it is given by (1/τ)e^(−t/τ)
The exit age distribution, E(t)
The year Mike graduated high school
1986
In the Boulder case study, the post-aerobic digester reduced total inorganic nitrogen from approximately 1,587 mg-N/L to this effluent concentration.
318 mg-N/L
Engineers use tracer experiments and residence-time data to evaluate this aspect of reactor operation and identify possible short-circuiting or inefficient mixing.
reactor performance
This modeling approach connects multiple CSTRs together to represent a reactor system and compare its predicted behavior with actual tracer data.
tanks-in-series model
This function, equal to 1 − e^(−t/τ) for a CSTR, tells you the fraction of molecules that have a residence time less than t
The cumulative age distribution, F(t)
The square footage of Mike's house
3785 ft^2