GATE CE 2017 Set 1 — Question 55
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Environmental Engineering → Wastewater Treatment Processes → BOD Kinetics
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Question
The wastewater having an organic concentration of is flowing at a steady rate of through a detention tank of dimensions . If the contents of the tank are well mixed and the decay constant is , the outlet concentration (in mg/l, up to one decimal place) is
Correct answer
17.9 to 18.1
Solution
To find the outlet concentration of the wastewater, we follow these steps:
1.Identify the reactor type: The problem states that the contents of the tank are "well mixed", which indicates that the tank behaves as a Continuous Stirred Tank Reactor (CSTR).
2.List the given parameters:
- Inlet concentration () =
- Flow rate () =
- Tank dimensions =
- Decay constant () =
4.Calculate the hydraulic detention time ():
5.Apply the mass balance equation for a CSTR with first-order decay:
For a steady-state CSTR with first-order kinetics, the outlet concentration () is given by:6.Substitute the values into the equation:
Rounding to one decimal place as requested, the outlet concentration is .Continue learning with Success Tracker
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