The PEF, Inc. firm desires to utilize a complete-mix activated-sludge system with recycle to treat their municipal wastewater after primary sedimentation. The design parameters are: Flow rate=0.92m³/s Influent Soluble BOD5 = 292mg/L MLVSS=2,500mg/L Mean cell residence time = 7.24 d For any missing parameters, use typical values of growth constants for domestic wastewater (provided in your text, page 494). Assume that the solids lost in the secondary clarifier effluent are minor and can be neglected. Assuming a BOD, (S) concentration of 24 mg/L, the detention time (residence time or theta) in the activated sludge system is most nearly:

The PEF, Inc. firm desires to utilize a complete-mix activated-sludge system with recycle to treat their municipal wastewater after primary sedimentation. The design parameters are: Flow rate=0.92m³/s Influent Soluble BOD5 = 292mg/L MLVSS=2,500mg/L Mean cell residence time = 7.24 d For any missing parameters, use typical values of growth constants for domestic wastewater (provided in your text, page 494). Assume that the solids lost in the secondary clarifier effluent are minor and can be neglected. Assuming a BOD, (S) concentration of 24 mg/L, the detention time (residence time or theta) in the activated sludge system is most nearly:

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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A wastewater stream A with 200 m3 /h of flow rate and BOD of 300mg/I mixes with stream B having flow rate of 400m3/h and BOD 225mg/l. A completely mixed activated sludge process is used to treat the mixture. BOD of effluent stream is 10 mg/l. Given Y= 0.5, k=5 day", Kd=0.06 day ; Ks=100 mg/l and MLVSS= 2000 mg/l. Assume all other parameters if necessary Find (a) BOD and flow rate of mixture (b) Mean residence time (c) Oxygen requirement (d) F/M ratio (e) Recycle ratio (f) Sizing of the tank
Given the following information for wastewater plant, the plant is an activated sludge system with an aeration tank that has a volume of 7500m3. efficiency of aeration tank 85% ,SVI is 88ml/gm., volume of settled solids after 30min, is 220ml, Q=60000 m3/d, effluent BOD from aeration tank = 20mg/l. Calculate the values of BOD load, F/M, and efficiency of plant. %3D
A wastewater with a BOD of 25mg/L is discharged through an outfall to a freshwater stream of mean velocity 0.1m/s. The DO downstream of the outfall is 8.5mg/L. Assume the deoxygenation rate is 0.25/d, the reaeration rate is 0.4 /d and the temperature of 20 degree C (DOs = 9.09mg/L). Compute for the ff: a) Critical distance b) minimum DO c) Oxygen deficit d) Critical time
Problem 1. A wastewater sample is examined for its solid contents. The ionic strength (μ) of wastewater is 0.01. It is known that 30% of total dissolved solids (TDS) is organic. The volumetric settleable solid concentration is determined as 20 mL/L using Imhoff Cone. It is assumed that 40% of total suspended solids (TSS) is equal to dry-settleable solids. The volumetric settleable solids composes of 2% of dried solids and 98% of water. The density of volumetric settleable solid concentration is given as 1020 g/L. Use information given in problem, calculate: a) Total Dissolved Solids (TDS) concentration as mg/L. b) Total Suspended Solids (TSS) concentration as mg/L. c) Total Solids (TS) concentration as mg/L.
Two wastewater streams A and B, having an identical ultimate BOD are getting mixed to form the stream C. The temperature of the stream A is 20 °C and the temperature of the stream C is 10 °C. It is given that • The 5-day BOD of the stream A measured at 20 °C=50 mg/l • BOD rate constant (base 10) at 20 °C-0.115 per day Temperature coefficient = 1.135 The 5-day BOD (in mg/l, up to one decimal place) of the stream C, calculated at 10 °C, is ●
A municipal wastewater treatment plant processes an average of 14,000 m3 / day. The peak flow is 1.75 times the average. The wastewater contains 190mg/L BOD and 210 mg/L suspended solids at an average flow and 225 mg/L BOD and 365 mg/L suspended solids at peak flow. Determine the following for a primary clarifier with a 20-m diameter. Assume eff. BOD of 20 mg/L and effluent TSS of 30mg/L for average and peak flows. 1. Surface overflow rate and the approximate removal efficiency for BOD 5 and suspended solids @ average flow. 2. Surface overflow rate and the approximate removal efficiency for BOD 5 and suspended solids @ peak flow. 3. Mass of solids (kg/day) that is removed as sludge from average and peak flow conditions.
Chemistry A sewage treatment plant discharges 4 ML/d of effluent with 20.17 mg/L BOD5 into a stream. The stream discharge is 12 ML/d, and its initial BOD5 is 6.10 mg/L. The initial DO of the wastewater is 2.10 mg/L and in the stream, it is 7.91 mg/L. Assume the stream velocity is 0.31 m/s and the dissolved oxygen saturation concentration is 8.76 mg/L. The kd = 0.15 d-1 and kr = 0.31 d-1 values have been adjusted for temperature. Calculate the minimum DO in the stream and determine the distance (km) downstream that this minimum occurs. Is this a safe level for fish?
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
D Q1: Design an activated sludge process to treat a wastewater of 15000 m³/day with a BOD5 of 180 mg/l following primary treatment. The effluent BODs and SS are to be 20 mg/l. Assume Xr-15000 mg/l, X=2500 mg/l, ec=10 days, y=0.60, Kd=0.05. Determine the reactor volume, the sludge production rate, the circulation rate, the hydraulic retention time and oxygen required?
Determine the size (diameter and depth) of the secondary clarifier (s) in a municipal activated sludge treatment facility: The wastewater characteristics are: Population 250,000, Average per-capita flow rate = 380 1/capita-day and Peak factor = 2.2. The suspended solids concentration is assumed to be 2500 mg/L. The over flow rate is 110 and 60 m3/d-m2 for peak flow and average flow respectively and solids loading at average flow is 110 kg/d-m2. Estimate detention time if the depth is 4.5 m. What would be the weir loading? Also answer the following questions. (hint : you should use all 3 loading criteria) a. How many kilograms of solids are loaded onto each clarifier per day? b. If the removal efficiency is 65% then how many kilograms of solids are removed from the total flow per day? C. What is the concentration of solids in the wastewater leaving the clarifier? Determine the size (diameter and depth) of the secondary clarifier (s) at a municipal activated sludge treatment facility:…
After primary treatment, a municipal wastewater contains 150 mg/L BOD5. The wastewater flow of 0.44 m³/s (10 MGD) is then treated in an activated sludge system with an SRT of 12 d and an HRT of 6 h. Given the biokinetic parameters tabulated below, determine the limiting value of the minimum SRT (d). Parameter Hmax Ks ka Y Value 3 d¹ 60 mg/L BOD, 0.10 d ¹¹ 0.6 mg VSS/mg BODS