1. [Aeration tank sizing, oxygen requirements] A water company is to install an activated sludge treatment plant to treat the effluent from a village and associated industry. The total volumetric flowrate of incoming wastewater to be treated is 8000 m³/day. Preliminary calculations have determined that after preliminary and primary treatment, the average BOD5 concentration of wastewater entering secondary treatment is 537.6 mg/L. For the activated sludge treatment, assume an OLR of 0.5 gвOD5/(gsludge.day) and a sludge concentration of 6000 mg/l. a) Assume that the company wants to build a long and thin "plug-flow like" aeration tank. Calculate the volume and physical dimensions of the aeration tank assuming a depth of 3 m and a ratio of width to length of 1:12. [Ans: 1434 m³] b) Calculate the hydraulic retention time. Is this a reasonable value? How does this compare with typical values stated in the lecture slides? [Ans: 0.179 days] c) From simple mass balance, it can be calculated that the treatment plant will remove sludge (via treated effluent + wastage/purge) at a rate of 3,188.0 kg of sludge/day. Calculate the solids retention time. Is this a reasonable value? If not what can be done to obtain a value within the typical range? [Ans: 2.7 days]
1. [Aeration tank sizing, oxygen requirements] A water company is to install an activated sludge treatment plant to treat the effluent from a village and associated industry. The total volumetric flowrate of incoming wastewater to be treated is 8000 m³/day. Preliminary calculations have determined that after preliminary and primary treatment, the average BOD5 concentration of wastewater entering secondary treatment is 537.6 mg/L. For the activated sludge treatment, assume an OLR of 0.5 gвOD5/(gsludge.day) and a sludge concentration of 6000 mg/l. a) Assume that the company wants to build a long and thin "plug-flow like" aeration tank. Calculate the volume and physical dimensions of the aeration tank assuming a depth of 3 m and a ratio of width to length of 1:12. [Ans: 1434 m³] b) Calculate the hydraulic retention time. Is this a reasonable value? How does this compare with typical values stated in the lecture slides? [Ans: 0.179 days] c) From simple mass balance, it can be calculated that the treatment plant will remove sludge (via treated effluent + wastage/purge) at a rate of 3,188.0 kg of sludge/day. Calculate the solids retention time. Is this a reasonable value? If not what can be done to obtain a value within the typical range? [Ans: 2.7 days]
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
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Question
![1. [Aeration tank sizing, oxygen requirements]
A water company is to install an activated sludge treatment plant to treat the effluent from a village
and associated industry. The total volumetric flowrate of incoming wastewater to be treated is
8000 m³/day. Preliminary calculations have determined that after preliminary and primary
treatment, the average BOD5 concentration of wastewater entering secondary treatment is 537.6
mg/L.
For the activated sludge treatment, assume an OLR of 0.5 gвOD5/(gsludge.day) and a sludge
concentration of 6000 mg/l.
a) Assume that the company wants to build a long and thin "plug-flow like" aeration tank.
Calculate the volume and physical dimensions of the aeration tank assuming a depth of 3 m
and a ratio of width to length of 1:12.
[Ans: 1434 m³]
b) Calculate the hydraulic retention time. Is this a reasonable value? How does this compare
with typical values stated in the lecture slides?
[Ans: 0.179 days]
c) From simple mass balance, it can be calculated that the treatment plant will remove sludge
(via treated effluent + wastage/purge) at a rate of 3,188.0 kg of sludge/day. Calculate the
solids retention time. Is this a reasonable value? If not what can be done to obtain a value
within the typical range?
[Ans: 2.7 days]](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fde55ad6b-27eb-44c5-bca1-afdb32f2dfc7%2F65ca6977-e487-4d4b-8e02-73eadeeab4d3%2F8dys17o_processed.png&w=3840&q=75)
Transcribed Image Text:1. [Aeration tank sizing, oxygen requirements]
A water company is to install an activated sludge treatment plant to treat the effluent from a village
and associated industry. The total volumetric flowrate of incoming wastewater to be treated is
8000 m³/day. Preliminary calculations have determined that after preliminary and primary
treatment, the average BOD5 concentration of wastewater entering secondary treatment is 537.6
mg/L.
For the activated sludge treatment, assume an OLR of 0.5 gвOD5/(gsludge.day) and a sludge
concentration of 6000 mg/l.
a) Assume that the company wants to build a long and thin "plug-flow like" aeration tank.
Calculate the volume and physical dimensions of the aeration tank assuming a depth of 3 m
and a ratio of width to length of 1:12.
[Ans: 1434 m³]
b) Calculate the hydraulic retention time. Is this a reasonable value? How does this compare
with typical values stated in the lecture slides?
[Ans: 0.179 days]
c) From simple mass balance, it can be calculated that the treatment plant will remove sludge
(via treated effluent + wastage/purge) at a rate of 3,188.0 kg of sludge/day. Calculate the
solids retention time. Is this a reasonable value? If not what can be done to obtain a value
within the typical range?
[Ans: 2.7 days]
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