Wastewater Treatment
Wastewater collected by the interceptors flows to EBMUD's wastewater
treatment plant in Oakland near the entrance of the San Francisco-Oakland
Bay Bridge. Primary treatment removes floating material, oils and greases,
sand and silt and organic solids heavy enough to settle in water.
Secondary treatment biologically removes most of the suspended and
dissolved organic and chemical impurities that would rob life-giving oxygen
from the waters of the Bay if allowed to decompose naturally.
The treatment steps are pre-chlorination (for odor control), screening (to remove large objects), grit removal, primary sedimentation, secondary treatment using high-purity, oxygen-activated sludge, final clarification, sludge digestion, dewatering and composting. The treated effluent is then disinfected, dechlorinated and discharged one mile off the East Bay shore through a deep-water outfall into San Francisco Bay.
EBMUD provides secondary treatment for a maximum flow of 168 million gallons per day (MGD). Primary treatment can be provided for up to 320 MGD. Storage basins provide plant capacity for a short-term hydraulic peak of 415 MGD. The average annual flow is currently 80 MGD.