WWTP Tour - Secondary Treatment
Clarifiers

Secondary clarification has the function of separating the activated sludge and influent suspended solids from the treated wastewater stream by gravitational settling. The importance of liquid-solids separation to the waste treatment cannot be over-emphasized. The success of the process depends on liquid-solids separation because the solids must be recycled to the oxygenation basins to sustain the process, and any solids escaping separation will impair the quality of the effluent.

The mixed liquor from the oxygen trains is distributed to the individual clarifiers where the activated sludge solids settle out and are separated by gravity from the treated wastewater stream.. The bulk of the settled sludge is recirculated back to the oxygen trains where it mixes with wastewater, the remainder is diverted to the sludge handling facilities. The overflow from the clarifier is the plant's final treated effluent, which is chlorinated for disinfection purposes as it flows to the effluent pumping station. A scum baffle in the clarifiers prevents floating solids from overflowing the effluent weir. A scum skimmer moves these floatables to a discharge box. The floatables collected in the scum box flow to a wet well for disposal.

It's now time for some Chlorine Disinfection