Environmental Engineering Reference
In-Depth Information
Width = 80 ft
Water depth = 12 ft
Secondary settling tank
Number = 4
Diameter = 100 ft
Water depth = 18 ft
12.18 The effluent weir on the secondary settling tank is located along
the outer edge of the tank. What is the weir length (in feet) for
each settling tank?
12.19 What is the surface area (in square feet) of each of the primary
settling tanks?
12.20 What is the volume (in cubic feet) of each of the aeration tanks?
12.21 You wish to install a fence around each aeration tank to prevent
falls into the tanks. How many feet of fence must be ordered?
12.22 The lab test indicates that a 500-g sample of sludge contains 22 g
of solids. What is the percent solids in the sludge sample?
12.23 The depth of water in a grit channel is 28 in. What is the depth in
feet?
12.24 A fecal coliform sample preserved at 4°C can be held up to how
many hours before beginning the test?
12.25 Mixing biosolids with a filler material and allowing it to stand in
piles (windrows) to allow natural oxidation to occur is known as
.
12.26 The operator withdraws 5350 gal of solids from the digester. How
many pounds of solids have been removed?
12.27 Sludge added to the digester causes a 1900-ft
3
change in the vol-
ume of sludge in the digester. How many gallons of sludge have
been added?
12.28 What is the purpose of heating and mixing a primary anaerobic
digester?
12.29 A composite sample will give a(n)
.
12.30 The main action of a mixed media filter is
.
12.31 The plant effluent contains 32 mg/L solids. The effluent flow rate is
3.10 MGD. How many pounds per day of solids are discharged?
12.32 The plant effluent contains 25 mg/L BOD
5
. The effluent flow
rate is 7 MGD. How many kilograms per day of BOD
5
are being
discharged?
12.33 The operator wishes to remove 3000 lb/day of solids from the
activated sludge process. The waste activated sludge concentra-
tion is 3050 mg/L. What is the required flow rate in million gal-
lons per day?
