The organic loading on the unit averaged 32 lb of BOD/day or about 2 lb BOD/day 1000 cu ft aeration capacity. Needless to say, the organic load was very low on a volumetric basis, but was 270 lb BOD/day/acre on a surface loading basis. It seems that the aerated lagoon was a very heavily loaded oxidation pond or a lightly loaded activated sludge system.

The flow rate remained relatively constant during the winter months as shown in Table 1,. With the spring rains the flow rose rapidly due to infiltration in open sewers. As construction progresses, the volume of storm drainage will be sharply reduced. The retention period in the aerated lagoon ranged from 9.8 to 2.6 days, averaging 6.4 days.

The large amount of vegetable grindings from the grocery store in the shopping center created a suspended solids problem. The vegetables were not readily metabolized by the bacteria in the aeration unit and tended to float on the surface. A skimming device at the effluent weir prevented loss of most of these light solids. The average volatile suspended solids in the effluent was 75 mg/l while MLSS averaged 170 mg/l volatile suspended solids. The average sludge age based on displacement of solids was calculated to be 14.5 days. The oxygen uptake rate in the mixed liquor averaged 0.8 mg/l/hr during the first four months of this study. Variations in aerator speeds during the latter two months of this study caused increased mixing and increased oxygen demand. The increase in oxygen uptake rates from 1.2 to 2.6 mg/l/hr which followed an increase in rotor speed was believed to be related to resuspension of solids which had settled at the lower rotor speeds. It appeared that most of the mixed liquor suspended solids were active microbial solids with the heavier, less active solids settling out.