I need your help in this problem ,,, Instructions Show all calculations to obtai
ID: 875173 • Letter: I
Question
I need your help in this problem ,,,
Instructions Show all calculations to obtain full credit. Submit homework by email. (100 pts) Raw sewage entering a wastewater treatment plant has a BoD5 of 550 mg/L and suspended solids concentration of 300 mg/L. The WWTP has an average daily flow of 5 MGD. After primary treatment, the primary effluent is ready for secondary treatment through two parallel trains of the completely mixed activated sludge process. Assume the following for the activated sludge process: WWTP effluent BODs (S) 10 mg/L Biomass yield (Y) of 0.55 g biomass g BOD Endogenous decay rate (Kd) 0.05 day Solids retention time 0 days MLVSS concentration (bacteria or sludge concentration) in the aeration tank (X) 32800 mg/L Waste and recycle solids concentration 13000 mg/L a) Determine the aeration tank volume in cubic meters. b) Once you know what the acration tank volume is, the next step in the design process is the aeration system for the tank. A standard requirement for diffused air systems (commonly used in activated sludge systems is that 20 to 30 cubic meters of air per minute are required per 1000 cubic meter of tank volume. Based on this information, determine 1) the volume of air needed to be supplied to the tank, 3-point bonus) the number of industrial-type air blowers and their cost. Include the link to the website where you found the blowers and the price. 2) the power input required to maintain the process, and 3) the electricity bill per month for the aeration tank.Explanation / Answer
(a) Aeration tank volume
Solid retention time
SRT = (MLVSS * Vat)/(Qw * Xw + Qe * Xe)....................(A) Units: days
Where MLVSS = Mixed liquor volatile suspended solids concentration in aeration tank (mg/L) = 2800 mg/L
Vat = Volume of aeration tank (106 gallons or MG) = ?
Qw = WAS flow rate (106 gal/day or MGD) = Kd = 5 MGD
Xw = Volatile suspended solids (VSS) concentration in WAS (mg/L) = 300 mg/L
Qe = Effluent flow rate (MGD) (Recall Qe = Q - Qw) = 0.05 day^-1
Xe = Effluent volatile suspended solids (VSS) concentration (mg/L) = 13000 mg/L
SRT = 10 days
Substitute all in A
10 = (2800 * Vat)/(5 * 300 + 0.05 * 13000)
(2800 * Vat)/(2150) = 10
Vat = 7.678 cm^3