p

A. The design flow for a water treatment plant (WTP) is 1 MGD (3.785101m3/d). The rapid mixing tank will have a mechanical mixer and the average alum dosage will be 30mg/l. The theoretical mean hydraulie detention time of the tank will be 1 minute. Determine the following: 1. The quantity of alam needed on a daily basis in kg/d, II. The dimensions of the tank in meters for a tank with equal length, width, and depth, 1II. The power input required for a G of 900sec1 for a water temperature of 10C (express the answer in kW ). B. Disinfection is to be added to a wastewater treatment plant with an average daily flow of 13MGD, and an bourly peak factor of 2.5. The average coliform bacteria count No=10000 organism/100 mL. must be reduced to 200 organism 100mL. Codes require a I5-minute contact time for peak hourly flow and 30-minute contact time for average daily flow, and a maximum chlorine dose rate of 15madL NtN0=(1+0.23ctt)3 Equation (1) describes the chlorination process where: Nt= number of coliform bacteria at any time t. N0= number of coliform bacteria at any time to. ct= total chlorine residual at time t in mg/L. t= residence time in minutes. 1. Detemine the total chlorine residual (mgL) after 15 minutes contact time under peak conditions. II. Determine the chlorine dosage rate in lb/day