A tannery wastewater flow of 0.011 m3 /s and a BOD5 of 590 mg/L discharges into river. The creek has a flow rate of 1.7 m3 /s. Upstreatm of the tannery wastewater discharge point, the BOD5 of the creek is 0.6 mg/L. The BOD rate constants (k) are 0.115 day-1 for the tannery waste and 3.7 day-1 for the creek. (a) Calculate the initial ultimate BOD after mixing.

Afluid flows with a velocity field given by v=(x/t)i.. determine the local and convective accelerations when x=3 and t=1.

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?

Wiy doeres rere okhn a pump whon working betwon the same pressure range?