Faced with an increase in extreme weather events, together with an increase in nontreatable solids such as “flushable” wipes, wastewater treatment plants are under pressure to improve the resilience of their operations. As influent flows rise and fall, removing debris from headworks to prevent negative downstream effects can be especially challenging. To meet that challenge, the Saginaw (Michigan) Charter Township Wastewater Treatment Plant turned to an innovative screening solution that offers a new level of adaptability to changing wastewater conditions.

The challenge

The Saginaw Charter Township WWTP has two headworks, one with two influent pipes of 21 and 36 inches, and another that serves the neighboring community of Thomas Township. The flows are combined prior to going through grit removal, primary treatment, oxidation and clarification. The system handles stormwater runoff as well as sewage, resulting in dramatic increases in flows during periods of wet weather. 

“Our facility has a design flow of 4.65 mgd. But when we have rain together with melting snow, we can peak at 20 mgd,” explains Saginaw Township treatment coordinator Tim Shepherd, noting that the storm system also brings lots of debris to the plant. “It’s amazing what finds its way into that stream. Everything from large chunks of wood and building materials to dead animals to trash and leaves.” This is in addition to the typical debris in the sanitary waste stream, including rags and grease. 

To handle debris removal, the plant installed a Duperon FlexRake bar screen in 2002 with 1⁄2-inch openings at the headworks serving Thomas Township. 

Download the case study to learn more about the success of this solution.