The sludge and skimmings from the primary and final clarifiers flow to a pit at the east side of the operations building. Pumps in the lower level of the building move the sludge to the aerated sludge lagoon. Alternatively, the sludge can be pumped directly to a sludge tank wagon for disposal on agricultural land if, for some reason, the sludge cannot be pumped to the lagoon system.
Sludge Lagoon System
The waste sludge is pumped to what was formerly the lagoon system. It has been modified to accomplish sludge treatment, however, instead of wastewater treatment. The waste sludge goes first into the aerated lagoon, which has both diffused aeration plus continuous recirculation pumping. The solids are, thus, kept in suspension and are provided with oxygen. In this aerobic environment, the solids decompose, or stabilize, without causing odor problems.
After receiving treatment in the aerated lagoon, waste sludge flows into the large lagoon cell for storage. There is no discharge from the large cell, so excess water is removed only by evaporation.