About Winslow Wastewater Treatment Plant...


Steps in Treatment at Winslow WTP:

BAR SCREEN

Preliminary treatment at Winslow WPCF is provided by means of a bar screen and aerated grit chamber. The bar screen removes solid objects, protecting the downstream facilities and equipment.

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AERATED GRIT CHAMBER

The water then enters the grit chamber, where small stones and sand settle out. Removing sand and larger solid objects helps extend the life of equipment. The grit and screenings are trucked to landfills. Air is mixed with the wastewater in the grit chamber.

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EQUALIZATION TANKS

Wastewater is held in the equalization tank to allow solids to begin settling. Activated sludge from the leveling ponds is mixed with the wastewater in the equalization tanks to begin biological digestion of organic contaminants. The equalization tank also helps to maintain a more constant flow rate through the treatment plant.

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OXIDATION DITCHES AND SECOND STAGE AERATION TANKS

In the oxidation tanks, primary sludge settles to the bottom and can be removed. The wastewater is mixed with air by large rotors. Activated sludge from the clarifiers is also mixed into the wastewater in the oxidation tanks.

Bacteria grow in the oxidation tanks to consume organic material in the wastewater. The ambient air process used at Winslow requires mixing air into the wastewater repeatedly to allow enough exposure to oxygen. Unlike the process at Delaware No. 1, where the aeration tanks are enclosed in a building and kept at an elevated temperature, the Winslow plant uses an open air process at ambient temperature.

If needed, the wastewater passes through the second stage aeration tanks for additional bacterial processing and de-nitrification.

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CLARIFIERS AND POLISHING PONDS

Solids are allowed to settle out of the wastewater in the three circular clarifiers. These solids are clumps of bacteria and organic materials ("activated sludge"). Activated sludge is removed from the bottom of the clarifiers and either returned to the oxidation ditches or sent to the digesters for further processing.

More sludge settles out in the polishing ponds. Sludge removed from the polishing ponds is returned to the equalization tank, at the beginning of the process.

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FILTERS AND BACKWASH DECANT TANK

Wastewater leaving the polishing ponds passes through sand filters to remove still more sludge. Backwash from the filters is held in the backwash decant tank, then returned to the equalization tank to be processed through the system again.

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CHLORINE CONTACT TANKS

The final stage of treatment takes place in the chlorine contact tanks. To kill any remaining bacteria, the water is mixed with a solution of sodium hypochlorite. (This is the same chemical found in household chlorine bleach.) Effluent monitoring is conducted at the discharge end of the chlorine contact tank.

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EFFLUENT PUMPING STATION AND OFF-SITE RECHARGE BASINS

Wastewater leaving the chlorine contact tank is first pumped to an equalization tank and then pumped to recharge basins some distance from the Winslow Wastewater Treatment Plant. These recharge basins are 18 large open-air lagoons. The bottom of each lagoon is lined with extra-fine sand, designed to percolate the treated wastewater.

The discharge is rotated among the recharge basins, allowing time for the water to percolate. A rest period is then provided allowing for each pond to recover before it is refilled to repeat the recharge process.

Ground water monitoring wells located around the perimeter of the recharge basins are sampled to monitor the impact of the wastewater recharge on the quality of groundwater in the area. The water seeps through the sand bottom and eventually reaches the aquifer (underground water supply). Ultimately, it drains into the Great Egg Harbor River.

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