NPTEL Water and waste water treatment Week 2 Assignment Answers 2025
1. Choose the correct options for rate of loss for W(rl,W) and rate of formation for Y(rf,Y) from the below shown reaction
W + 2X –> Y + Z here, k=rate constant
- rl,W = k[W][X] and rf,Y = k[W][X]^2
- rl,W = k[W][X]^2 and rf,Y = k[Y][Z]
- rl,W = k[W][X]^2 and rf,Y = k[W][X]^2
- rl,W = k[W][X] and rf,Y = k[Y][Z]^2
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3. Choose the correct mass balance equations at steady state in the CSTR which is shown below and assume that no compounds are formed in the reactor. Here Qin = Qout = Q and Θ = Hydraulic retention time.
- Cout/Cin=1/(1-kΘ)
- Cout/Cin=1/[1+(Vk/Q)]
- Cout/Cin=1/[1-(Vk/Q)]
- Cout/Cin=1/(1+kΘ)
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4. A first-order dissociation reaction takes place in a batch reactor. The initial concentration of the reactant is C0= 18 mg/L, and the rate constant is 0.2/min. What is the concentration of the reactant after 10 minutes in mg/L______________
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5. Calculate the Cout for steady state CSTR shown below________ (mg/L)
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6. A liquid-phase first-order reaction occurs in a plug flow reactor. The inlet concentration of the reactant is 32 mg/L, and the outlet concentration is 5 mg/L. The rate constant for the reaction is k = 0.4/min, and the volumetric flow rate is 0.5 L/min. What is the required volume of the plug flow reactor in 10^4 m3_________
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7. Wastewater from the treatment plant is being discharged into the river, as illustrated below. Then what is the BOD at x-x cross section of the river__________ mg/L. (Assuming both streams properly mixed in at x-x section)
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8. Choose the correct options regarding non-ideal systems
- If number of reactors greater than one acts as real reactor
- If number of reactor equal to 1 act as CSTR
- If number of reactors are infinite act as plug flow reactor
- CSTR is always reflects ideal reactor
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