4. design an aerated grit chamber installation (2 tanks in parallel) for an average flowrate of 0.3 m3/s and a peak flowrate of 1.0 m3/s. the average depth is 3 m, the width-to-depth ratio is 1.5: 1, and the detention time at peak flow is 3.5 min. the aeration rate is 0.4 m3/min per m of the tank length. determine the dimensions of the grit chambers and the total air required

Answer

given,

average flow rate = 0.3 m³/s

peak flow rate = 1 m³/s

width to depth ratio = 1.5 : 1

detention time = 3.5 min

average depth = 3 m

aeration rate = 0.4 m³/min/m

dimensions of grit chamber = ?

volume of grit chamber =

                                       = 105 m³

average depth = 3 m

width-to-depth ratio = 1.5:1,

width = 1.5 × 3 = 4.5 m

length of the grit chamber =

                                            = 7.78 m

increase length by 20% to account for inlet and outlet of the tank

length = 1.2 × 7.78 = 9.34 m

dimension of grit chamber = 9.34 m × 4.5 m × 3 m

air required = aeration rate × length

                    = 0.4 m³/min /m × 9.34

                    = 3.736 m³/min

this is an example of "committed" time.

committed time, as contracted time, takes need over essential and available time since it is seen as profitable work. it alludes to the time allotted to keep up a home and family. at the point when a man is commuting using committed time this individual may feel that the drive is an obligation to family, for example, strolling youngsters to class or driving a mate to work. contracted and committed time clients may feel that their commute could really compare to the commute of important or leisure time clients on the grounds that their commute is profitable work. in this manner, they might be more disposed to pick a mechanized method of movement.