19257_Authority_June_2026

municipalauthorities.org │ 15 t Photo 1: The INVENT® iDEC®-SBR decanters. Photo credit: MASA personnel. T he Meadville Area Sewer Authority (MASA) is in the final stages of a $28M treatment plant upgrade. Located in Crawford County (northwestern PA), we serve more than 5,000 customers in the City of Meadville and West Mead Township. The wastewater treatment plant has a design capacity of 7.5 million gallons per day (MGD). It utilizes four Sequencing Batch Reactors (SBRs), two aerobic digesters, and ultraviolet disinfection. Our previous wastewater treatment plant was built from the ground up in 1997 and performed admirably for more than 25 years. The ‘bones’ of the plant (SBR tanks and digester tanks, plant piping, and operations building) are still in sound condition and we have adequate capacity for our daily flows. However, most of the mechanical equipment involved in the treatment process was at or near the end of its useful life. This, coupled with advancements in SBR treatment technology, warranted our upgrade. MASA owns a relatively small piece of property where the existing plant is located; acquiring new land for construction was not a feasible option. With PENNVEST funding, we began an ambitious project in the summer of 2023 to upgrade our entire treatment process, designed to be used in our existing treatment tanks, digesters, and operations building. Over a two-year period our staff and contractors successfully achieved this complex transformation without significant interruption to our daily operation. Components of the Upgrade The upgrade replaced mechanical components along the entire treatment sequence; we also invested in new treatment technology to address increasing variation in daily wastewater flow volumes as well as potential decreases to regulatory discharge limits. We increased the number of pumps used for treatment processes to more than 40 and added Variable Frequency Drives (VFDs) to control each of them. At the base of our collection system, two influent bar screen systems were installed in parallel and work in unison. The bar screen spacing was reduced from 3/4” to 1/4”, providing increased debris collection capability. Eight new pumps transport the screened wastewater into our new grit and grease removal channel; these are critical upgrades to our primary treatment process. Substantive improvements occurred in secondary treatment technology within our process tanks. After several years of research and site visits, we chose an SBR system provided by INVENT®. The INVENT iSBR®/iGSR® is an innovative SBR design to optimize the mixing, aeration, and decanting of wastewater. The system can be operated in continuous or batch flow modes and provides increased flexibility to successfully treat large variations in flow volumes. The hydraulic design of the decanters minimizes disturbance of the sludge layer, resulting in lower total suspended solid concentrations in treated wastewater (see Photo 1) . We have four mixers in each treatment tank and digester, powered by a motor at the top of each drive shaft (see Photo 2 on page 16) . The mixers are placed near the bottom of the tank and are designed to create discrete hydraulic zones during mixing and aeration while also reducing the formation of inactive regions in the bottoms and corners of each tank. The creation of these zones allows for customized treatment choices with respect to mixing rate and aeration amount within each tank. In addition, the Supervisory Control and Data Acquisition (SCADA) system can be modified to alter run times for treatment cycles, providing additional flexibility to optimize the duration of our treatment in response to wastewater volume and nutrient load. Aeration rings, installed to the bottom of the mixers, introduce bubbles which are then chopped by vertical metal fins on the mixer bottom (see Photo 3 on page 16) . This decreases the bubble size and increases the surface area between the gaseous and liquid phases in the tank. Two buildings were constructed on-site to house a total of ten blowers that supply air to the treatment tanks and digesters. A new ultraviolet disinfection array and belt press were improvements made downstream of secondary treatment. An important design decision was the addition of an advanced polymer mixing and dispenser system and increasing the contact time between the aqueous polymer and sludge prior to delivery to the belt press. This has improved our sludge dewatering efficiency and reduced our sludge volume for disposal. Lastly, two important upgrades were made to the power supply serving the plant. The first was monitoring incoming line power to the plant and employing an automatic transfer switch (ATS) to avoid complete outages and/or single phase power to the Everyone worked as a team, kept in regular communication, and rose to meet the challenges inherent in a project of this scope and size.