A town has been directed to build an activated sludge plant that can meet an effluent standard of 13 mg/L BOD5. They have selected a completely mixed aeration tank. Calculate the volume of the aeration tank (V) (unit m3 ) using the following data:g/homework-help/questions-and- answers/determine-bod5-effluent-low -rate-trickling-filter-diameter-40- m-depth-15-m-flow-rate-2-200-q57182 303

To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.

Amass-spring-viscous damper system of mass 3 kg has a frequency of 100 rad/s and is critically damped. its initial conditions are x(0)-3 mm and (0)-2.3 m/s. does the system overshoot its equilibrium position? prove your answer

Which one of the following faults cause the coffee in a brewer to keep boiling after the brewing cycle is finished? a. an open circuit in the heating element b. a short circuit at the terminals c. welded contacts on the thermostat d. a leak around the gasket