Arectangular well-mixed aeration lagoon is 60m long, 5m wide, and 2m deep. it receives 400 cubic meters/day of wastewater with a bod5 of 336mg bod5/l for treatment. the biodegradation rate constants for the wastewater are yield coefficient = 0.8mg vss/mg bod5, endogenous decay constant=0.08 d^(-1), maximum specific microbial growth rate =1.10 d^(-1), and the half velocity constant = 76.0mg bod5/l. the pond's efficiency depends on oxygen being always available for the microbes to use in degrading the wastewater organic carbon. how much oxygen (in kg) must be supplied daily to the pond?

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false

The higher the astm grain size number, the finer the gran is. a)-true b)-false