Wasterwater Engineering Civil engineering 25. An activated sludge system is designed to treat a domestic wastewater from apopulation of 50 000. The wastewater that enters into the aerated reactor with BODs of200 mg/L has to be reduced to 20 mg/L in order to comply with the Standard A.A complete-mix reactor is to be used and from a pilot plant study, the Y and kavalues are 0.5 kg/kg and 0.05 per day respectively.(¹1)If the food and micro organism ratio is given as 0.3 kg BOD, perkg MLSS per day and the biomass concentration in the aeratedreactor has to be maintained at 2500 mg/L, calculate the volume ofthe aerated reactor.(ii)Determine the mean cell-residence time.(iii)From the answers obtained in part (i) and (ii) and also theinformation given above, compute the daily amount of biomass tobe wasted.(iv)Determine the recycle ratio of the system. Assuming an underflowconcentration of 8,000 mg/L from the secondary clarifier.

Answered: Image /qna-images/answer/11090522-00d0-4cf3-9f4f-99d192f49892.jpg

25. An activated sludge system is designed to treat population of 50 000. The wastewater that enters into 200 mg/L has to be reduced to 20 mg/L in order to co A complete-mix reactor is to be used and from a values are 0.5 kg/kg and 0.05 per day respectively. (i) If the food and micro organism rat Ica 00

25. An activated sludge system is designed to treat population of 50 000. The wastewater that enters into 200 mg/L has to be reduced to 20 mg/L in order to co A complete-mix reactor is to be used and from a values are 0.5 kg/kg and 0.05 per day respectively. (i) If the food and micro organism rat Ica 00

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

See similar textbooks

Similar questions

a) A wastewater treatment plant consists of primary treatment followed by an activated-sludge secondary system. The plant processes 7000 m3/d of wastewater with 180 mg/L of BOD5 and 150 mg/L of suspended solids. The primary sludge contains 500 kg of dry solids per day with 4.5% solids content. The plant produces 760 kg of total sludge (primary and secondary) per day. Assume 30% removal efficiency of the primary clarifier and F/M ratio of 0.2 for the aeration tank. b) The thickened sludge from problem a) is to be digested in a standard-rate mesophilic anaerobic digester (MAD). The sludge has 68% organic content, and approximately 60% of the organic fraction is digested after a 30-d period. The digested sludge has a solids content of 6% and is stored for a period of 90 d. Calculate the volume of the standard-rate digester
Underneath a conventional plug flow reactor and a plug flow reactor with tapered aeration that both use sludge recycle, sketch graphs of DO, DO Uptake, S, and Xa, versus distance from the inlet of the reactor
Wastewater from a primary treatment tank is to undergo secondary treatment in an activated sludge unit. The following data and operational parameters are specified: Hydraulic detention time= 6h Mean cell residence time= 7days BOD content at inlet of reactor = 150 mg/L Food to microorganism ratio=0.3gm BOD/gm VSS-day Two identical units are designed to operate in parallel and to process a combined wastewater flowrate of 0.7m3/s. How large must each reactor be (m3)? What is the rate at which cell mass must be discharged from the units in steady state operation (kg/day)?
Consider a wastewater treatment reactor where with an influent flow rate of 2,500 m3/day and where the biomass has the following kinetic characteristics: fs0 = 0.7, KS = 10 mg/l, k= 10 mg/mg VSS-day, b = 0.1/day, Y=0.50 g VSS/g substrate, fd=0.8, and Xa=1,500 mg VSS/l. If the reactor was designed with a safety factor of 30, what is its design fs value.
Assume that DLSUD lake is 100m2 and its average height is 5ft. Wastewater that flows into the lake are the following: Food square kitchen waste 7 m3/sec; Total Dissolved Solids (TDS) is 25,000 mg/L which operates 8hrs per day CIH 5m3 /hr kitchen waste; TDS is 20mg/L which operates 4hrs per day PCH 20m3 /day diluted laboratory waste ; TDS = 40mg/L (1)Determine the volumetric flow rate of the lake water can still accommodate prior to rainfall.
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?
8 Determine the solid loading rate on a secondary circular clarifier (diameter = 20 m) if the plant influent load is 2 ML/d. The recycle flow from secondary clarifier to the activated sludge system (aeration basin) is set to 10% of the influent load. It is also known that the aeration basin produces an MLSS (mixed liquor suspended solids) concentration of 3000 mg/L.
The rate of eradicating microbes through chlorination process is 0.22/min when the wastewater is flowing at a rate of 36 m3/h. If the depth of chlorination tank is 1.6 m and the width is 1.2 m, determine the required length of the tank to achieve 98% removal.
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
As an operator of a wastewater treatment facility, you have learned that your plant runs well at an SRT (based on MLVSS (X) in the aeration basin) of 12 days. If today’s MLVSS (X) concentration is 2,700 mg/L and the RAS (Xr) concentration is 5,500 mg/L, how many L of sludge should you waste from the secondary clarifier today? Other design conditions: Average influent flow = 12,000 m3/d Influent soluble BOD = 150 mg/L Required effluent TSS = 30 mg/L Aeration tank Volume = 1,000 m3
What is the required free chlorine concentration to inactive 2 logs of Cryptosporidium at a water temperature of 25oC, if the flow rate is 1000 m3/day and the clearwell storage tank is 2 m wide by 2 m long and 1 m deep? (Assume plug flow conditions and full basin) *Hint : final answer C = 26 mg/L