Secondary sedimentation

Wastewater leaving the activated sludge process is discharged into secondary sedimentation basins.

There are 12 secondary sediment basins at the facility – four rectangular basins and eight round basins.

The rectangular sedimentation basins have a total surface area of 2,500 m². Each of the round settlement basins has a diameter of 35 m have a surface area of 7,690 m². The total area of all of the facility's secondary sedimentation basins is [thus] 10,190 m².

Suspended particulates settle in these basins that primarily contain microbes active in the wastewater decomposition process.

Some of these settled microbes are re-circulated into the activated sludge process in order to maintain a high microbe concentration there.

The remainder of the settled material is added to the sludge from the primary settlement process and is transferred to the sludge treatment installations as will be detailed further on.

The treated wastewater leaving the secondary settlement basins is termed effluent.

Following treatment in the secondary settlement basins, the effluent is discharged into the operating reservoir of the Mekorot Water Company located next to the treatment facility, from which it is sent to the reservoirs of Tishlovet Kishon (farmers' association) in the Jezreel Valley where it is used in irrigation for various crops.
 

Secondary settlement basins