In April 2025
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A perfectly mixed aeration pond with no recycle (return line) serves as the biological reactor for a small community. The pond receives 30 m3/d of influent with a BOD5 of 350 mg/L that must be reduced to 20 mg/L before discharge. It has been found that the kinetics constant for the system are Ks = 100 mg/L BOD5, kd = 0.10 d-1, um = 1.6 d-1, and Y is 0.60 mg BOD5.
A)What must the hydraulic detention time be in the aeration pond?
B) What mass of microbes will be produced in the pond each day?
A block project up an inclined plane at 20 degrees with horizontal and the block has
an initial velocity of 6 m/s. If the coefficient of kinetic friction is 0.25, how far will the
block go up the plane?
Two vessels, A and B each of volume 4m3 are connected by a tube of negligible volume. Vessel
A contains air at 0.8MPa, 1050C, while vessel B contains air at 0.45MPa, 2250C. When A is allowed
to mix with B and assuming the mixing to be complete and adiabatic, determine (a) the final
pressure and temperature of air after mixing, (b) the amount of entropy generation and (c) the
irreversibilities in the process. Take, T0=300C
Use langrange multiplier to determine the dimension of rectangular box open at the top, having a volume of 32ft^3 and requiring the least amount of material for it's construction
A total distance of travel of 1000 km breaks every 100 km of a pattern of East- South- East- South- continuously up to the end. The time of travel was recorded 5 hours. (a) Find the average velocity of the travel. (b) if the helicopter flies from the same origin, what will be it's average velocity in an hour travel?
