A sedimentation basin in a water treatment plant treats a flow of 6 mgd and has the following dimensions: L = 120’; W = 12’; D = 12’. Water is being treated at an average temperature of 20oC. a. Calculate the water detention time (in hours and minutes), horizontal velocity (in ft/min), and overflow rate (in gpd/ft2, gpm/ft2 and ft3/ft2-day).b. If a particle is to be 100% removed and has a specific gravity of 2.5, what is the corresponding particle diameter (in mm)? Is Stoke’s Law appropriate for this situation? Why or why not?

An external consultant recommends that a plant installs a bank of capacitors for power factor correction. this will reduce the peak electrical demand charges by an average of 93 kw every month. the plant current pays $13 per kw in peak demand charges. the capacitor bank will include 223 kw of fixed capacitors, and 183 of variable capacitors. the fixed capacitors cost $59 per kw, and the variable capacitors will cost $65 per kw. the consultant charges 21% of the equipment costs to install the capacitors. because this project will reduce the demand for the electric utility, they are prepared to provide a one-time rebate of $42 per kw of reduced demand. what is the simple payback period for this project (in years)?