The document discusses hydraulic head calculations for a grease separator. It presents the Weissbach equation used to calculate flow rate based on overfall height, channel width and other variables. It then lists design parameters for the grease separator including influent and effluent water levels, chamber capacity at different levels, rising bubble velocity, number of chambers, and detention and reaction times.

1. Hydraulic Head Calculations on the Grease SeparatorHydraulic Head Calculations on the Grease SeparatorHydraulic Head Calculations on the Grease SeparatorHydraulic Head Calculations on the Grease Separator
1 System Grease Separator (YSWSTW)(YSWSTW)(YSWSTW)(YSWSTW)
2 Application Free overfall on sharp crested weir without any side contraction
3 Formula Weissbach Equation:
Q = 2/3 · µ · b · (2g)
1/2
· [(v
2
/ 2g)
3/2
- (v
2
/ 2g)
3/2
]
Variables mPD Water Channel m
1 Q Volumetric flow rate, m
3
/s 0.0105530.0105530.0105530.010553 m
3
/s
2 µ discharge coefficient, dimensionless 0.6351840.6351840.6351840.635184 - 4.7367
3 g acceleration due to gravity 9.819.819.819.81 m/s2
overfall 0.0367 h
4 v mean velocity 0.0127270.0127270.0127270.012727 m/s
5 h overfall height 0.0367 m weir 1 M
6 b width of channel (weir) 0.80.80.80.8 m 3.7
7 M height of the weir crest above the headwater bottom 1 m 0.8
Design Parameters
1 Q0 Sewage Flow 912 m3
/day = 0.010555556 m
3
/s
2 L0 FSL at the entrance of GS 3.7 mPD
3 M + h weir + overfall 1.03671.03671.03671.0367 m
4 L1 FSL at the exit of GS 4.73674.73674.73674.7367 mPD
5 V0 Capacity of GS at L0 52.67 m3
6 V1 Capacity of GS at L1 76.4104376.4104376.4104376.41043 m3
7 vb Bubble rising velocity 0.350.350.350.35 m/s (The equipment suplier defined)
8 n No. of GS chamber in operation 1111
Surface Scum Scrapper Induced Air Aerator
FSL Influent Channel Effluent Channel Effective Volume
1000
5.20 mPD
4.74 mPD 76.41 m3
3.70 mPD M 52.67 m3
14.73 m3
1.9 mPD
1.4 mPD
Grease Separator
2500 mm
4000 mm
5400 mm
The depth for the bubble reaction = 4.74 m
Bubble rising time = 13.53 s
Wastewater detention time = 7238.883 s ( 120.648 mins )
Bubble reaction time = 1395.474 s ( 23.25789 mins )