Calculation of Detension Period of Tank

Problem 1. One million gallon liters of water (1 mgd) pass through a sedimentation tank. If the size of the tank is 20' Χ 50' Χ 10'. Find the detention time of the tank.
Exam Name: BPDB 2016

Solution: 
Volume V= 20' Χ 50' Χ 10'
                = 10000 ft³
            Q = 1 mgd
                = 1* 10⁶ gallon/day
                =  (10⁶/7.48) ft³/day
                = 133689.83 ft³/day

Detention period,
            T= V/Q
              = (10000/ 133689.83) day
              = 0.0748 day

Answer: 0.0748 day
               

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Problem 2: If the flow of water supply is 1023 m³/day and volum of this tank 93 m³/ day. Determine detention period of this tank.
Exam Name: DPDC 2014

Solution:   
Detention period,
            T= V/Q
           Here, V= 93m³
                     Q= 1023 m³/day
           ∴ T= (93/ 1023) day
                 = 0.09 day

Answer: 0.09 day

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