Grinding at the Headworks Improves Screens Performance

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Grinding at the Headworks Improves Screens Performance

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Is there an easy solution a wastewater treatment plant can implement at its headworks to protect fine screens from the surcharge of a first flush? The Moygashel WWTP in Dungannon, Northern Ireland, found one.

Operated by Northern Ireland Water Limited (NIW), Moygashel receives 25 mgd. For several years, the plant experienced repeated operational and maintenance issues with its existing fine band screens and screenings compactors. Due to heavy rainfall, especially in the winter months, the flush surcharge from the gravity main flowed immediately onto the 6 mm headworks band screens. This influx would cause the screens to overload and blind three to four times a week, requiring maintenance call-outs and manual labor to clean them. The ineffective headworks screens resulted in screenings being forced into the wastewater process. NIW estimated an additional 16 man-hours per week were needed to address these issues. 

JWC Environmental’s Channel Monster heavy-duty grinders were recommended to precondition the solids and debris in the flow and protect the screens from overload and damage by essentially acting as a control buffer. The Channel Monster consists of two rotating drums feeding the captured solids into a heavy-duty dual-shafted grinder. 

The grinding process reduces solids to a smaller uniform particle size, leveling the rate at which they hit the screen. The grinders also liquefy more of the solid fecal matter so it remains in the flow and enters the treatment process. Without the grinders, solid matter mixed with fecal is removed by the screens and dropped into dumpsters, generating foul odors. 

The mechanical and electrical installation of two Channel Monsters was completed in less than one working day. Their installation solved Moygashel’s issues with the headworks screens. Not only did they resolve the peaking factor at the headworks, but the Channel Monsters also solved problems with their existing compactors. Previously, the compactors were unable to process heavier plugs of rags and solids that were screened and removed from the flow by the inlet screens. The site operators continually had to unblock plugs that formed within the units. With the Channel Monsters grinding the heavy solids, the compactors are now able to process all the materials coming off the screens.

Both NIW senior management and the Moygashel site operators acknowledge the Channel Monster as a great success in their treatment process. This proves that installation of Channel Monsters can quickly and cost-effectively resolve operational issues on site with minimal disruption. Additionally, JWC has proven that grinding heavy solids in the incoming flow before headworks screens and compactors ensures these processes are far less problematic. 

“Fundamentally, meeting compliance at a reduction in overall operation costs is our game. Especially in today's economic climate where NIW is looking at ways of reducing our whole life costs, and at the same time, having to meet the ever-tighter environment consent standards,” says Michael McAlary, functional manager for NIW. “I needed a simple, easy to install and maintain solution to enhance the inlet works and in so doing, protect the entire process. In Moygashel, JWC has more than met my expectations and provided my team with a simple solution in the form of their Channel Monster grinders.”

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