Sludge Bin Rotary Discharger Part 1: Design & Fabrication
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Sludge Bin Rotary Discharger Part 1: Design & Fabrication
Sludge Bin Rotary Discharger Part 1: Design & Fabrication

PROJECT: Sludge Bin Rotary Discharger
PROJECT TYPE: Fabrication – Wastewater Treatment Equipment
CLIENT: RDP Technologies, Inc.

RDP Technologies, Inc. is a leader in water and wastewater technologies. They have been awarded numerous patents for their solutions, including those in their specialties: lime prep and feed systems for the water industry, lime stabilization systems, and biosolids truck loading systems. Headquartered in Conshohocken, PA, RDP systems are used across the nation, and they are known for delivering “robust equipment backed by dependable process performance.”

In April 2018, RDP filed for a patent for a device to solve the problem of sludge getting stuck to the bin walls rather than dropping down to a waiting truck. This rotatable discharge device would allow the walls of the bin to be scraped, sending sludge cake down a chute. After filing for the patent, RDP needed a fabrication partner to create the very first rotary discharger of their design.

GSM Industrial had a track record of successfully partnering with RDP to fabricate high-quality stainless steel tanks for wastewater applications. This made GSM Industrial a top choice to fabricate this innovative system to the exacting standards necessary to deliver RDP’s “dependable process performance.”


One of the primary challenges of working on a brand-new design is the inevitability of variance between design intention and real-world application. The design and its process hadn’t been tested or proven: GSM Industrial would need to work closely with RDP to work out all of the design kinks as the project progressed. This project would also require scheduling and project management with subcontractors for all of the pieces to work fluidly together.

One critical challenge was in making sure there would be a proper seal on the rotary discharger. The material in the bins can weigh as much as 100,000 pounds, which would exert significant pressure on the rotary table. The design/fabrication required a seal between the bottom discharge opening and the rotatable driven table. This required precision fabrication to allow for a high-pressure seal and motor-driven movement.


GSM Industrial was chosen for this project for the proven ability to complete high-pressure projects, and this depth of experience equipped the team to tackle the completely custom nature of this new patent design. GSM Industrial partnered with RDP to tackle any design issues that arose as the fabrication began to take shape. We also needed to work closely with additional subcontractors to ensure moving pieces – driven by a variable speed gear motor – worked even against varying volume, viscosity, and other variables within the bin. The process required a high level of expertise and flexibility to ensure the new design achieved the best possible performance. The project started in August 2019 and finished in March 2020.


As leaders in their field, RDP maintains high standards and strict testing expectations. In particular, they worked closely with GSM Industrial to ensure the seal passed the Hydro Pressure Test. GSM Industrial is an ASME-certified fabrication shop, which means our qualified personnel were able to ensure the project could withstand high pressure testing. Our in-house certified inspectors completed the necessary Hydro Pressure Test to prove the seal’s integrity. (See our ASME and AWS Certifications.)


GSM Industrial translated the innovative, new design into the 13’ diameter Sludge Bin Rotary Discharger RDP needed to solve the problem of compacted sludge in their biosolids bins. By partnering closely with RDP, the design’s challenges were met, and a new standard for the rotary discharger was set. This project has been sent to its final destination in Potomac, Maryland.

Learn more about how this Sludge Bin Rotary Discharger was installed in Part 2 of this project profile, coming soon.

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