Gorman-Rupp pumps, including the advanced Super T-Series and V-Series models, offer superior performance in evacuating grit chambers quickly, reliably, and efficiently. Gorman-Rupp pumps are made from durable ductile iron and other abrasion-resistant materials. This makes these pumps ideal for handling grit and other solids-laden wastewater.

The pump’s low Net Positive Suction Head Required (NPSHR) and excellent priming capabilities make them ideal for pumping grit from grit chambers in flooded suction and suction lift applications.

The Grit Removal Process

Grit removal is a vital initial step in wastewater treatment. This process, crucial for the smooth operation of a wastewater treatment plant (WWTP), protects downstream equipment by separating heavy inorganic materials like sand, gravel, and small debris from the incoming wastewater. These materials have a significantly higher specific gravity than the organic solids present. Essentially, grit removal aims to isolate these inorganic components right from the start.

Ineffective grit removal can lead to the following:

• Clogging of pipes and channels
• Premature wear of equipment like pumps, valves, and conveyors
• Reduced capacity in downstream treatment basins

Role of Grit Pumps in Wastewater Treatment

Grit pumps are critical for moving removed grit from the grit chambers to a grit classifier. This guide offers plant operators a practical understanding of these pumps, focusing on their operation, maintenance, and important considerations.

Design Guidelines for Pumping Grit

Recommended design guidelines for effective grit pumping:

• Pump Selection: It’s essential to select a pump that matches the application’s specific needs regarding flow rate, head, NPSHr, and motor horsepower. A poorly matched pump can lead to inefficiency and excessive wear.
• Material Composition: Due to grit’s abrasive nature, pumps should be constructed from wear-resistant materials such as hardened ductile iron or steel for greater durability.
• Flow Control: Grit pumps typically operate intermittently. Smaller grit systems often use full-voltage non-reversing (FVNR) starters. Larger systems frequently employ variable-frequency drives (VFDs) to adjust flow rates based on the system’s grit load.
• Agitation: Incorporate a method to resuspend settled grit before pumping to ensure efficient removal and prevent pump clogging. This typically involves air sparging or jet eductors.
• Access and Maintenance: Design the pump installation with adequate space for easy access for inspection, maintenance, and potential replacement. Include isolation valves upstream and downstream of the pump.
• Solids Handling Capability: Ensure the selected pump has sufficient solids handling capability to pass the expected size and concentration of grit without clogging.
• Positioning: Place grit pumps as close as possible to the grit chamber to keep suction piping as short as possible.
• Piping: Use a minimum of 3-inch diameter piping and maintain pipeline velocities between 3 and 5 feet per second.
• Freeze Protection: Pumps installed outdoors need casing heaters and insulation jackets. Suction and discharge piping should be heat-taped and insulated.

Why are Gorman-Rupp Pumps Ideal for Pumping Grit?

Gorman-Rupp pumps are well-suited for pumping grit due to several key design features that enhance their durability, reliability, and efficiency in challenging environments:

• Abrasion-Resistant Materials: Gorman-Rupp uses high-quality materials, such as hardened ductile iron and steel, in areas exposed to high wear, which helps withstand the abrasive nature of grit and other suspended solids.
• Robust Impeller Design: Impellers in Gorman-Rupp pumps are specifically engineered to handle solids and abrasive materials. These impellers maintain efficient operation while preventing clogging, even with high solids content.
• Easy Clearance Adjustment: Gorman-Rupp pumps have external clearance adjustments to enable operators to keep the pump operating at optimal hydraulic performance, maximizing flow rates, minimizing energy consumption, and resulting in less clogging.
• Ease of Maintenance: Gorman-Rupp’s self-priming pumps have a large removable inspection cover for easy access and servicing. This makes it simple to clear blockages, inspect wear components, and minimize downtime, which is crucial in demanding grit-handling applications.
• Flexible Installation Options: Gorman-Rupp pumps are flexible enough to operate effectively in flooded suction and suction lift installations. This provides consistent performance in various site conditions common to grit pumping.
• Longevity in Harsh Conditions: Focusing on rugged construction and wear-resistant components, Gorman-Rupp pumps offer extended service life even in highly abrasive environments, reducing the need for frequent replacements and providing reliable long-term operation.

Conclusion

Efficient wastewater treatment relies on effective grit removal to protect downstream equipment from abrasive damage. By understanding the specific needs of grit pumps and adhering to regular maintenance, operators can ensure consistent and reliable performance, preventing common problems. Gorman-Rupp pumps are a great choice for grit pumps at wastewater treatment plants.

Contact Envirep

Envirep/TLC serves the water and wastewater market in Pennsylvania, New Jersey, Maryland, Delaware, the District of Columbia, Virginia, and West Virginia.

Do you need help selecting the right equipment for your application? Contact Envirep at 717-761-7884 or sales@envirep.com.

By Michael Gillespie, President at Envirep/TLC