Oxygen Requirement...
The theoretical oxygen requirements can be determined from the BOD5 of the waste and the amount of organisms
wasted from the system per day. The reasoning is as follows. If all the BOD5 were converted to end products,
the total oxygen demand would be computed by converting BOD5 to BODL, using an appropriate conversion
factor. It is known that a portion of the waste is converted to new cells subsequently wasted from the system; therefore,
if the BODL of the wasted cells is substracted from the total, the remaining amount represents the amount of
oxygen that must be supplied to the system. From equation given below, it is known that the BODL of one mole
of cells is equal to 1.42 times the concentration of cells.
"Theoretical Oxygen Demand"...
Theoretical Oxygen Requirements for the Removal of Carbonaceous Organic Matter...
Therefore, the theoretical oxygen requirements for the removal of the carbonaceous organic matter in wastewater for an
activated sludge system can be computed as follows :
"Oxygen Requirement for C - BOD Removal"...
Sludge Production...
It is important to know the quantity of sludge to be produced per day because it will affect the design of the sludge -
handling and disposal facilities necessary for the excess sludge. The quantity of sludge that is produced on a daily basis
can be estimated by equation given below :
"Net Waste Activated Sludge"...
Theoretical Oxygen Requirements for Nitrification...
When nitrification has to be considered, the total oxygen requirements can be computed as kg O2/day for removal
of carbonaceous organic matter plus the kg O2/day required for nitrogen conversion, as follows :
"Oxygen Required for Nitrification"...
Unit Requirements...
For F : M raios greater than 0.3, the air requirements for the conventionel process amount to 30 to
55 m3/kg of BOD5 removed for coarse bubble diffusers and 24 to
36 m3/kg of BOD5 removed for fine bubble diffusers. At lower F:M ratios,
endogenous respiration, nitrification, and prolonged aeration periods increase air use to
75 to 115 m3/kg of BOD5 removed. For mechanical aeration system, unit oxygen
requirement varies between 1.0 to 1.2 kg O2/kg BOD5 removed.
Aeration System Design for Peak Loadings...
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| redvalve.pdf |
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Red Valve Company, Inc.
