3.5 A sedimentation tank of surface dimensions of 20ft by 100ft and over flow design of 500 gpd/ ft² can b) 2.5 MGD treat water with flow rate of up to: a)1.0 MGD c) 5.3 MGD d) 8.9 MGD 4.1. What is mean cell residence time in a WWTP activated sludge system receives 6 MGD if there are five aeration basins at 100,000 ft³ eachand four of them are working at any time. The MLSS is 2,500 mg/L and the effluent SS is 25 mg/L. The sludge wasted is 30,000 gpd from the recycle line. The SS of the recycle flow is 7,500 mg/L. b) 2.31 day a) 5.21 day c) 6.25 day d) 7.15 day

C. What is the concentration UI SUINUS 5. Determine the size (diameter and depth) of the secondary clarifier (s) at a municipal activated sludge treatment facility: The wastewater flow is 25,000 m³/d, the recycle ratio (recycle sludge flow/wastewater flow) is 0.25. The suspended solids concentration is assumed to be 2500 mg/L in the activated sludge tank. The over flow rate is 50 m3/d- m2 and solids loading is 125 kg/d-m2. Estimate detention time if the depth is 4.5 m. What would be the weir loading? Department of Civil & Environmental Engineering P.O. Box 519 Mail Stop 2510, Prairie View, Texas 77446 w.pvamu.edu Phone (936) 261-1660/1665(dept) Fax (936) 261 1662 Ensuring o Using Zoom o

A conventional activated-sludge system treats 11,000 m3/day of wastewaterin an aeration tank with a volume of 3400 m3. The BOD after primary clarification is 180mg/l. Given the operation conditions below, calculate the  sludge residence timeMLVSS in the rector = 2,100 mg/lMLSS = (1.25)*MLVSSQw = 160 m3/daySVI = 125 mL/g (Ans.  SRT = 7.0 days)

Q 1. Calculate the volume and weight of sludge generated per day in circular primary settling tank by chemical coagulation. Find HRT of tank also. Data given as: Wastewater flow: 10000 m/d FeCl; added in PST: 500 mg/L Overall particle removal efficiency: 80% Sludge's specific gravity: 1.05 Assume STANDARD chemical reactions and their product's behavior (if any). TSS in influent: 1100 mg/L Ca(OH)2 added in PST: 400 mg/L PST depth: 3 m Sludge's moisture content: 95% Surface overflow rate: 40 m/d

The Lo value just downstream from a sewage outfall is 60 mg/L. The DO saturation levelat that point is 9 mg/L. Given a deoxygenation rate coefficient of 0.28 / day and a rearationrate coefficient of 0.8/day. Determine a. The critical distance downstream assuming the sewage outfall is the only source ofBOD for the river and that it flows at 50 miles / day. b. the minimum DO c. thet fraction of the BOD that would have to be removed by a waste water treatmentplant to ensure > 5 mg/L everywhere downriver.

(a) A groundwater borehole at USM engineering campus contains 3000 mg/L of TDS. The flow is 0.32 m3 /s. The design TDS concentration of the product water is below 400 mg/L. The net pressure is 40 atm. The membrane manufacturer provides that the membrane has a water flux rate coefficient of 2.2 x 10-6 s/m and a solute mass transfer rate of 1.5 x 10-6 m/s. Calculate the membrane area required for the RO system.   (B)  A water treatment at Nibong Tebal receiving a raw water contains a concentration of 0.5 µg/m3 atrazine from Kerian River. In order to comply with the drinking water quality guideline, the treatment plant should reduce the concentration of Atrazine to 0.1 µg/L. If the dosing of powdered activated carbon have been applied before the coagulation, calculate the minimal dose of PAC in mg/m3 .

1. A 770,000 gal conventional activated sludge pro- cess has a recycle ratio of 0.25, an influent flow rate of 1 MGD, a mixed liquor volatile suspended solids (MLVSS) concentration of 700 mg/L, and an influent BOD; of 160 mg/L. What is most nearly the F:M ratio of the process? (A) 0.1 lbm/day-lbm (B) 0.2 lbm/day-lbm (C) 0.3 lbm/day-lbm (D) 0.4 lbm/day-lbm В. D.

Question # 3 (a): Design a sedimentation tank used for a surface overflow rate of 16.0 m/day to treat a flow of 625 m3/hr. having detention time of 120 minutes. Provide a storage sludge capacity of 20 % of effective volume. Under ideal condition what size of particles will be removed 100% if specific gravity is 2.65, μ = 1* 10-3 kg/sec-m and density of water is 1000 kg/m3. Subject: Environmental Engineering

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 3. 20°C. Calculate the water detention time (in hours and minutes), horizontal velocity (in ft/min), and overflow rate (in gpd/ft², gpm/ft² and ft’/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? а.

Q1:) A circular coagulation basin has a diameter of 2.5 m and it's depth equal to 1.60 m. If the following data are available: Gt=27000, t-30 s, μ-1.003× 10³ kg/m.s,alum dosage=50 mg/l, determine: a) The required mixing power in unit of (kW). b) The daily quantity of alum added in unit of (kg/d). Q2:) The flow described in (Q1) above is to be flocculated in a basin having four flocculators with transverse paddle units. The basin may be a maximum of 6 m wide and 4 m deep to connect to the settling basin. Determine: (1) Basin dimensions: (2) power requirements. μ= 1.002× 10³ kg/m.s The best Gt value for the system has been found to be 5 x 104, and the G value is 40 s¹.