Specifications include, but are not limited to: 1. Preliminary/Primary Treatment is comprised of screening and grit removal. a. Screening – Prior to raw wastewater entering the influent pump station, three Vulcan bar screens with a single conveyor and wash press are used to remove larger solids. b. Grit removal – Two Eutek systems plate settle type grit systems with slurrycup, grit snail, and added grit pumps provide the removal of grit and sediment. c. The PWWTP does not currently have any mechanism that consists of chemical precipitation or coagulation-aided sedimentation in our treatment process. 2. Secondary Treatment is accomplished with aeration and clarification. a. Aeration – The PWWTP has five rectangular basins, two basins serving as primary aeration basins followed by three basins serving as secondary aeration basins. The primary aeration basins are aerated and mixed using ceramic fine bubble aeration diffusers and three centrifugal air blowers. The secondary aeration basins are aerated and mixed using membrane fine bubble aeration diffusers and three centrifugal air blowers. b. Secondary Clarification – Clarification of activated sludge is accomplished in ten (10) circular tanks downstream from the secondary aeration tanks. 3. Tertiary Treatment includes chlorination/de-chlorination and re-aeration. a. Chlorination/de-chlorination – The effluent from the secondary clarification tanks passes into the chlorination/de-chlorination structure where at the head of the structure chlorine is injected into the stream and mixed. Sulfur dioxide is then injected into the stream at the end of the structure. b. Re-aeration is accomplished over the effluent weir and in the outfall ditch by subjecting the flow to several drops through grating structures. 4. Effluent Disposal – The effluent flow is discharged to the Pocotaligo River. 5. Residual Handling includes sludge digestion, sludge dewatering, and sludge drying. a. Sludge Digestion – Scum and waste activated sludge are pumped to one of two aerobic sludge digestion tanks for additional stabilization and thickening. Aeration is provided by fixed submerged discharged orifices with air supplied by two positive displacement blowers. b. Sludge Dewatering – Thickened sludge is removed from either of the two aerobic digesters and pumped to the Belt Filter Press Facility for dewatering at any of the three high solids presses. Liquid filtrate which drains from the sludge at the Belt Filter Press Facility is then returned to the influent pump station. c. Sludge Drying – Under normal operation, belt press dewatered sludge is conveyed to the sludge drum drying system for further processing. Final disposal of the dried sludge is by public distribution.
