Written by Abis Zaidi
Having met major success with improved performance, efficiency, and reduction in maintenance and operating costs over the past 8 years with a Schwing Bioset screw press, The Upper Moreland-Hatboro Joint Authority is now planning to replace their second belt filter press as well.
The Upper Moreland-Hatboro Joint Sewer Authority is located in Willow Grove, Pennsylvania, and services the Borough of Hatboro and the Upper Moreland Township. The Horsham Township contributes about 30% of the flow with a small amount also coming from Upper Dublin Township, the Borough of Bryn Athyn, and Warminster Township. The plant initially went into operation in 1931, serving a small catchment area of around a thousand homes. However, as the local population grew, flow into the wastewater treatment plant increased beyond its capacity. This led to the establishment of a new plant in 1955 as a Joint Authority. Today, the treatment plant is rated at 7.189 MGD, and the average daily flow and treated effluent discharged into Pennypack Creek is approximately 5.5 MGD.
The planning process to replace the aging belt filter press installed in the early 1990’s began nearly a decade ago. The project was undertaken to replace the aging dewatering equipment with newer and more innovative technology. Three main drivers for the project are noted below:
- There was a need to improve cake solids to optimize the incineration process and to reduce natural gas consumption, as the belt filter presses only produced an average of 17% dry cake.
- Rusting was another major issue the authority was facing because of the high concentration of H2S from the sludge in the dewatering room, as they have some primary sludge too. With the belt filter press being an open machine design, the dewatering building was full of moisture and odor. H2S gas that was prevalent throughout the room was corroding metallic surfaces that it would come in direct contact with.
- High maintenance costs – Belt filter presses have numerous moving components and points of service, which meant that the authority had to have a lot of spare parts inventory to keep their presses operational. They experienced a lot of downtime during this process, which further increased the maintenance and labor costs.
Schwing Bioset was able to resolve these issues by offering their state of the art, reliable, and efficient screw press. Screw presses are dewatering machines that use radial forces and backpressure to extract excess water out of biosolids. Schwing Bioset started its production of screw presses ten years ago and over the course of this time has supplied well over 100 screw presses just in North America. The Upper Moreland-Hatboro Joint Sewer Authority installed and started up one of our first screw presses in February 2016. This majorly transformed the productivity of the plant by providing solutions to the major problems as highlighted above. Some of those solutions include:
- Prior to its installation, the belt filter press would average 17% cake solids. However, with the new screw press, cake solids averaged at 25% (around 40% less water) leading to significantly reduced natural gas consumption, hence improving incinerator efficiency.
- These exceptional results in productivity led to maximizing the loading to the incinerator, which made it easier to meet the 85% load requirement for the Title V Air Permit.
- The problem with the strong odor, moisture, and high concentration of H2S was greatly reduced, as the screw press is an enclosed design that has been directly connected to an odor management system.
- The plant experienced minimal maintenance requirements, as the screw press runs at only a half rpm, minimizing the risk of any failure. Additionally, there is only one wear part in the Schwing Bioset screw press, which can be replaced every 2-3 years by plant personnel.
- The plant process was also improved because the Screw Press produced much cleaner filtrate by capturing 95% of solids in the influent.
- The plant was able to reduce operating hours (manpower) on the machine as Schwing Bioset’s Screw Press offers a much simpler start up and shut down cycle compared to the old belt filter press. It also allowed the ability for fully automatic/unattended operation. Plant personnel appreciate the fact that they can simply hit the start button on HMI and walk away from the press to address other matters at the plant that require their attention, while only periodically checking the operation.
Having met major success with improved performance, efficiency, and reduction in maintenance and operating costs over the past 8 years, The Upper Moreland-Hatboro Joint Authority is now planning to replace their second belt filter press as well. The Authority has been so satisfied with their decision to replace their first belt filter press with a Schwing Bioset Screw Press that they have already placed an order for their second screw press, which is now in production. This proves the strong commitment of Schwing Bioset to design equipment of the highest standards of performance, and to meet the needs of this growing population in a productive manner.