Primary Treatment
 		 Secondary Treatment
 		 Solids Handling
 

Headworks

Influent Pumps

  Raw sewage or influent enters the plant through the headworks. In the headworks, six centrifugal pumps lift the influent into two open channels where devices known as Parshall flumes measure the flow rate. The water then passes through two mechanically operated bar screens which remove large objects that may clog pumps and pipes.  

Influent Channel Bar Screen

Grit Chamber

Aerated Grit Tank

  Once screened, the wastewater passes into two aerated grit chambers. Low-pressure air entering the grit chamber creates a rolling motion that causes grit and dense solids to settle to the tank bottom.

Primary Clarifiers

Screened and degritted wastewater is evenly divided among three circular primary sedimentation basins. Here, gravity separates heavier solids (sludge) from floatable solids (scum). Rotating arms collect the sludge that is pumped to a lime stabilization tank prior to dewatering. Primary effluent then flows to the secondary processes for further treatment.  

Primary Clarifiers

 

© 2005 Vallejo Sanitation and Flood Control District