Solids Handling
Anaerobic digestion stabilizes the solids removed from the primary tanks and final clarifiers. About 15,000 gallons of sludge are pumped daily to two anaerobic digesters. Inside the digester, the sludge is heated to 125° F or above for 10 to 14 days. Conditions in the digester are anaerobic (no oxygen present). Under these conditions anaerobic bacteria thrive. They consume organic molecules and produce methane gas and carbon dioxide. The methane gas that is produced is used to heat the sludge in the digesters creating a self-sufficient process. After digestion is complete, the sludge is sent to the belt filter press to remove water before disposal. Each digester has a volume of 500,000 gallons.