New Hampshire waste water treatment plant thickener to press transfer

Our hard working representatives continue to find new applications at a New Hampshire WWTP.

In 1994 the plant installed a belt filter press and needed a pump to deliver sludge from their thickener to the press. After pilot testing a peristaltic pump, they bought and installed a Watson-Marlow Bredel SP100 hose pump. Three years later they developed a need for increased sludge capacity, so they installed a sludge holding tank. They used their existing SP100 to transfer to the new storage tank, and bought a second SP100 to transfer from the tank to the belt filter press.

This facility had been using a Marlow (no relation) piston pump for pumping sludge from their secondary clarifiers to a sludge blending well, controlling the amount of secondary sludge that gets blended. The problem with this system is that the suction is always flooded and the piston pump cannot keep sludge from flowing through it when it is not pumping. A "flapper" valve was installed to try to keep a "no flow" situation when the pump was not pumping, but the valve never worked properly, so that plant personnel needed to continuously monitor the system and manually open and close valves when they wanted to waste sludge.

The high cost of maintaining the system caused the facility to hire an engineer to recommend a better method of controlling the sludge withdrawl. The engineer and owner investigated diaphragm, progressing cavity, piston, and peristaltic pumps to find a pumping solution that could guarantee zero flow at off times. The engineer recommended a peristaltic pump, despite its high initial purchase price, because the plant’s operators were familiar with the technology, and the pump offered an inherent check valve that could reliably guarantee "no flow" when the pump is not operating, allowing the removal of additional valving downstream.

Another SP100 was ordered and installed by plant personnel in less than 8 hours. The system is now on a timer that runs the pump for 5 minutes on, 25 mintues off, automatically. Now the plant is looking to pilot test smaller hose pumps for use on hypochlorite and magnesium hydroxide, an application where existing pumps require valving which cakes up, causing excessive downtime. Using Watson-Marlow Bredel hose pumps this problem would be eliminated.

This is an excellent example of how one success can lead to another in different applications within the same facility.

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