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?

On a average work day more than work place firs are reorted

The thermal expansion or contraction of a given metal is a function of the f a)-density b)-initial temperature c)- temperature difference d)- linear coefficient of thermal expansion e)- final temperature f)- original length

A3-mm-thick panel of aluminum alloy (k 177 w/m-k, c 875 j/kg-k and ? = 2770 kg/m) is finished on both sides with an epoxy coating that must be cured at or above t,-150°c for at least 5 min. the production line for the curing operation involves two steps: (1) heating in a large oven with air at ts,0-175°c and a convection coefficient of h, 40 w/m2. k, and (2) cooling in a large chamber with air at 25°c and a con- vection coefficient of he 10 w/m2.k. the heating portion of the process is conducted over a time interval te which exceeds the ime required to reach 150°c by 5 min (h = r + 300 s). the coating has an emissivity of ? = 0.8, and the temperatures of the oven and chamber walls are 175 and 25°c, respectively. if the panel is placed in the oven at an initial temperature of 25°c and removed from the chamber at a safe-to-touch tempera ture of 37°c, what is the total elapsed time for the two-step curing operation?