12.50 Determine the activated-sludge aeration volume required to treat 2.64 mgd with a BODof 120 mg/l based on the criteria of a maximum BOD loading of 40 lb/1000 ft³/day and aminimum aeration period of 5.0 hr. Assuming an operating F/M of 0.20 lb BOD/day per lbof MLSS, calculate the MLSS to be maintained in the aeration tank. Estimate the operat-ing sludge age (mean cell residence time), assuming an effluent suspended solids of 30mg/l and the daily amount of waste-sludge solids from Figure 13.1. Determine the diame-ter and side-water depth of two identical final clarifiers of the type shown in Figure 10.12for this activated-sludge system.

The objective of the question is to determine the aeration volume, MLSS, sludge age, and the…

Answered: 12.50 Determine the activated-sludge…

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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The aeration tank for a completely mixed aeration process is being sized for a designwastewater flow of 4500 m3/d. The influent COD is 150 mg/L. The design effluent COD is7 mg/L. Recommended design parameters are a sludge age of 10 days and MLVSS of 1400 mg/L. The expected Sludge Volume Index is 100 ml/g. The selection of these values takes into account the anticipated variations in wastewater flows and strengths. The kinetic constants from a bench-scale treatability study are Y = 0.60 mg VSS/mg COD and ke = 0.06 per day. Calculate:a. the hydraulic residence time and volume of the aeration tankb. the food/microorganism ratioc. the sludge production rated. the sludge recycle ratioe. the oxygen requirement
The 550-bed Atlanta Hospital has a small, activated sludge plant to treat wastewater from the hospital. The average daily hospital discharge is 1.50 m3 per day per bed, and the average soluble BOD5 after primary settling is 450 mg/L. The aeration tank effective liguid dimensions of 10 m x 10 m x 5 m. The plant operating parameters are as follows: MLVSS - 2,600 mg/L; MLSS - 1.20 (MLVSS); Settling sludge volume after 30 min. = 200 mL/L. The aeration time is nearly?
The 550-bed Atlanta Hospital has a small, activated sludge plant to treat wastewater from the hospital. The average daily hospital discharge is 1.50 m3 per day per bed, and the average soluble BOD5 after primary settling is 450 mg/L. The aeration tank effective liguid dimensions of 10 m x 10 m x 5 m. The plant operating parameters are as follows: MLVSS - 2,600 mg/L; MLSS - 1.20 (MLVSS); Settling sludge volume after 30 min. = 200 mL/L. The F/M ratio is nearly?
The town of Gatesville has been directed to upgrade its primary WWTP to a secondary plant that can meet an effluent standard of 30.0 mg/L BOD5 and 30.0 mg/L suspended solids (SS). They have selected a completely mixed activated sludge system. Assuming that BOD5 of the SS may be estimated as equal to 57 percent of the SS concentration, estimate the required volume of the aeration tank. The following data are available from the existing primary plant. Existing plant effluent characteristics Flow =0.150 m3/s BOD5 =82.0 mg/L Assume the following values for the growth constants: Ks= 100 mg/L BOD5; µm =2.5 d-1; kd =0.050 d-1; Y = 0.50 mg VSS/ mg BOD5 removed. Assume the concentration of MLVSS is 2000 mg/L.
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.
An activated sludge plant treating a flow of 25 L/s has an aeration basin volume of 450 m³ and operates with a MLVSS concentration of 3250 mg/L. Sludge with a SVSS content of 15000 mg/L is wasted at a rate of 35 m3/day. Find the following- sludge age, hydraulic retention time.
a) An activated sludge plant with recycle is evaluating its secondary clarification system. Settling column tests are conducted and analyzed for settling velocities at different initial solids concentrations. The data are provided below. The plant flow rate is 10,000 m3/d, with a recirculation ratio of 0.5. The MLSS in the reactor is 4000 mg/L. The desired underflow concentration is 17,000 mg/L. Solids concentration mg/L Settling velocity m/h 1500 6.5 3000 5.1 4500 4 6000 2.95 7500 2 9000 1.4 12,000 0.5 15,000 0.27 17,000 0.2 b) Design secondary clarifiers for the activated sludge plant of problem a), with a recycle ratio of 0.6. Calculate the required surface area if two clarifiers are used. Also calculate underflow rate, underflow velocity, and overflow rates. Clearly state your assumptions.
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 complete mixed activated sludge process (CMAS) is to be designed to treat 5MGD of primary effluent having a BOD5 of 180 mg/L. The NPDES permit requires that the effluent BOD5 and TSS concentration be 20 mg/L or less on an annual average basis. The following biokinetic coefficient obtained at 15C: Y = 0.6 mg VSS/mg BOD5, k = 2.85d-1, Ks = 70 mg/L BOD5, and kd = 0.041 d-1. Assume that the MLVSS concentration in the aeration basisn is maintained at 2500 mg/L. Determine: a. The minimum MCRT (d) b. The MCRT necessary to meet the NPDES permit requirement (d) c. The volume of the aeration basin (ft3)
12.60 The aeration tank for a completely mixed aeration process is being sized for a design waste- water flow of 7500 m³/d. The influent BOD is 130 mg/l with a soluble BOD of 90 mg/l. The design effluent BOD is 20 mg/l with a soluble BOD of 7.0 mg/l. Recommended design para- meters are a sludge age of 10 d and volatile MLSS of 1400 mg/l. Selection of these values takes stants from a bench-scale treatability study are Y into account the anticipated variations in wastewater flows and strengths. The kinetic con- 0.60 mg VSS/mg soluble BOD and k₁ = 0.06 per day. Calculate the volume of the aeration tank, aeration period, food ganism ratio, and excess biomass th
(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 .
An activated sludge plant with recycle is evaluating its secondary clarification system. Settling column tests are conducted and analyzed for settling velocities at different initial solids concentrations. The data are provided below. The plant flow rate is 10,000 m3/d, with a recirculation ratio of 0.5. The MLSS in the reactor is 4000 mg/L. The desired underflow concentration is 17,000 mg/L. Solids concentration mg/L Settling velocity m/h 1500 6.5 3000 5.1 4500 4 6000 2.95 7500 2 9000 1.4 12,000 0.5 15,000 0.27 17,000 0.2 a. Calculate the required surface area if one clarifier is used. b. Calculate underflow rate, underflow velocity, and overflow rate for single clarifier design. Clearly state your assumptions. c. Calculate the required surface area if two clarifiers are used

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