Process Description

The Moore County Water Pollution Control Plant is an activated sludge treatment facility with two stages of aeration and three stages of sedimentation. Anaerobic digestion is utilized to reduce the volume of sludge, which is subsequently spread to the drying beds.

Raw sewage enters the wet well of the Raw Sewage Pump Station by gravity and is screened and pumped to the Grit Removal Unit where grit is separated from the raw flow. The sewage then flows to the primary clarifiers (two) from which the primary sludge flows to the digesters. Flow then enters the First Stage Aeration Basin where diffused aeration is employed to reduce the BOD of the wastewater. The Intermediate Clarifiers (two) receive the flow, and the settled sludge is returned to the aeration basin with excess going to the digester. The wastewater then enters the Second Stage Aeration Basin where diffused aeration further reduces the BOD and also accomplishes nitrification. The Final Clarifiers (two) then provide final sedimentation of the activated sludge, which is returned to the aeration basin with excess to the digesters. The liquid flowing over the wier of the Final Clarifier is then allowed to flow into the Chlorine Contact Basin where chlorination is accomplished. The flow is de-chlorinated at the end of the Chlorine Contact Basin using Sulfur Dioxide. The final step in treatment is the Cascade Aerator, which allows the remaining elevation to be employed to increase the oxygen content of the treated effluent.

The primary sludge and the waste activated sludge from the Intermediate Clarifiers and the Final Clarifiers is pumped to the Anaerobic Digesters. Digested sludge is withdrawn from the digesters and spread on the Sludge Drying Beds to allow for final disposal at either a landfill or composting facility.