questions 12 7 a series of fermentation tubes containing varying conce
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12.7 A series of fermentation tubes containing varying concentrations of glucose in a nutrient
broth were inoculated with a pure bacterial culture. The concentrations of cells in the
broth media were determined after 16 hr of incubation at 37°C. Rates of growth and initial
glucose concentrations are listed below. Plot growth rate expressed as cell divisions per
hour versus initial glucose concentration. Estimate the maximum growth rate and the sat-
uration constant (glucose concentration at one-half the maximum growth rate). Write an
equation in the form of Eq. (12.25), and draw the curve for this equation on the graph with
the plotted data. Does the growth of this pure culture appear to be a hyperbolic function
as defined by the Monod relationship?
vd bou
Glucose
(moles × 10-4)
Cell Divisions
(per hr)
Glucose
Cell Divisions
(moles x 10-4)
(per hr)
0.1
0.23
0.8
0.94
0.1
0.28
1.6
1.06
0.2
0.32
3.2
1.15
0.4
0.71
12.15
The average wastewater flow and strength anticipated during the maximum month of the year
are often used for design. If the annual average wastewater flow and characteristics are
estimated to be 32,000 m^3/d with 250 mg/l of BOD and 280 mg/l of suspended solids, what are
the values likely to be for the peak month, using the equations in Section 12.10?
=
12.18 A pharmaceutical wastewater needs a minimum BOD/N/P of 100/3.0/0.7 for biological treat-
ment. The wastewater characteristics are BOD = 740 mg/l, suspended solids = 250 mg/l,
soluble nitrogen 24 mg/l, and soluble phosphorous 12 mg/l. What ammonium nitrate
and phosphoric acid additions would you recommend to ensure adequate nutrients for a daily
flow of 28 m³/d?
=
12.21 The domestic and industrial waste from a community consists of 100 gpcd from 7500 per-
sons; 65,000 gpd from a milk-processing plant with a BOD of 1400 mg/l; and 90,000 gpd
containing 450 lb of BOD from potato-chip manufacturing. Calculate the combined waste-
water flow, BOD concentration in the composite waste, and BOD equivalent population. low from the commuту аны
12.23 A town with a sewered population of 4000 has a daily wastewater flow (including indus-
trial wastewaters) of 1600 m³ and an average BOD of 280 mg/l. The industrial discharges
to the municipal sewers are 60 m³ at 1800 mg/l BOD from a meat-processing plant and
100 m³ at 400 mg/l BOD from a soup-canning plant. Determine the contribution of
domestic flow in liters per person and the BOD in grams per person based on the town's
wastewater, excluding the industrial wastewaters.
town is 1890 m³/d with an average BOD of 280/n Assignment 10
CE 431
Name:
Do the following problems from the textbook. Excel required for full-credit where indicated.
12.7 Must use Excel! (μm will be about 1.2 divisions per hour; Ks will be between 0.25 and 0.35)
(Hint: plot data on Excel, print, and hand-sketch curve. Initial data points may not fall on curve. Use the
hand-sketched curve to estimate max growth rate (μm) and saturation constant (Ks). Use those estimated
values to calculate and plot the Monod relationship as an overlay of your original plot of data points.
Experiment with adjusting Ks to see how closely the plotted Monod relationship will match the original data
points. Submit the original plot with your hand sketch, and the plot with the Monod relationship overlays.
Be sure to include axis labels and chart legend for full credit. Indicate which Ks is the best fit for the data).
12.15 (BOD load = 17,627 lb/day, Qm = 10.4 mgd, Bm = 254 mg/L)
12.18 (BOD:N is 100:3.2)
12.21 (Total flow is 905,000 gpd, BOD EP = 13,550)
12.23 (Total BOD load 300 kg/day, Q = 0.36 m³/capita-day; BOD = 75 g/capita-day)
and answer the following additional questions based on the lectures.
1. A "fresh" wastewater contains nitrate (NO3), dissolved oxygen (DO), and sulfate (SO4) and is sealed in an
airtight container.
In what order (first to last) are the compounds utilized by bacteria?
• Why are the compounds used in this order?
• At what point do obnoxious odors arise?
2. What is the relationship between biomass (microorganisms) and substrate (food) in the following growth
phases of a pure bacterial culture? [Or, what is biomass rate of increase vs. abundance of substrate?]
• Exponential growth phase
• Declining growth phase
• Endogenous phase