Organic and Hydraulic Loading of Lagoons
Loading is the single most useful concept in lagoon operation, because almost every lagoon
problem is a loading problem wearing a disguise.
Organic loading is expressed per unit of AREA
For a facultative pond the controlling expression is pounds of BOD per acre per day. That
is not an arbitrary convention. In a facultative pond the oxygen comes from the surface -
reaeration and algal photosynthesis - so the oxygen supply is proportional to surface area,
not to volume. Loading expressed per acre therefore compares the demand directly against the
supply.
For an aerated cell, where oxygen is delivered mechanically, loading is more usefully
expressed per unit volume (for instance pounds of BOD per 1,000 cubic feet per day),
because the oxygen supply is set by the aeration equipment distributed through the volume
rather than by