The quantity of screenings varies depending on the type of rack or screen used as well as sewer system (combined or separate) and geographic location.
Quantity of screening removed by bar screen is 0.0035 to 0.0375 m3 / 1000 m3 of wastewater treated (Typical value = 0.015 m3 /1000 m3 of wastewater) (Metcalf & Eddy, 2003). In combined system, the quantity of screening increases during storm and can be as high as 0.225 m3 /1000 m3 of wastewater.
For industrial wastewaters quantity of the screening depends on the characteristics of the wastewater being treated.
1MGD Plant = 3,785 m3/day
If we take the highest figure of .0375m3
It would mean we have 0.0375x 3.785m3 of screenings per day = 0.14m3
1MGD = 0.14m3 per day of screenings
0.5MGD = 0.07m3 per day of screenings
0.25MGD= 0.035m3 per day of screenings
Our Screenings bags are 90 m long and D279mm Diameter
This results in 5.5m3 for the bag.
A Bag Change is required every
1MGD plant 39days (5.5/.14)
0.5MGD plant 78 days
0.25MGD 156 days
A 1 year bag supply for a
1MGD plant would then be 365/39 = 9.3 bags
0.5 MGD Plant , 365/78 = 4.7 bags
0.25MGD 365/156 days = 2.4 bags