Organic Loading

The organic loading influences the performance of the filter.  The organic loading is the amount of B.O.D. applied to the filter per day per volume of filter media.  So the units of organic loading are typically pounds B.O.D./day/1000 ft3 of media.  

The organic loading can be calculated using the formula below.  This formula does not include recirculation, so the flow used is the influent flow rather than the total flow.

The B.O.D. is the concentration of B.O.D. in the filter influent.  The units of the filter volume are "1000 ft3", so a filter with a volume of 7,800 ft3 would have to have the units converted from "ft3" to "1000 ft3".  This conversion is accomplished by dividing the filter volume by 1,000, as shown below:

So let's calculate the organic loading of a 23,500 ft3 filter with an influent B.O.D. of 200 mg/L, and a flow of 3 mgd.

So the organic loading of the filter is 213 lbs/day/1000 ft