secondary sedimentation tank scraper system Non-Metallic Sludge Scrapers for Corrosive Media | 18-Yr Expertise

The secondary sedimentation tank scraper system is a precision component critical to the activated sludge process. Its primary function is to gently separate and return biologically active floc (return activated sludge, or RAS) to the aeration tank while simultaneously removing excess, treated sludge (waste activated sludge, or WAS) for further processing. The biological floc in these tanks is light and fragile; therefore, the scraper system must operate with extreme care to avoid shearing the flocculent particles and causing them to resuspend into the effluent, which would result in high turbidity and permit violations. Scraper mechanisms for circular secondary clarifiers are typically designed with a slow, continuous rotation and blades that are carefully angled to minimize turbulence. In a municipal wastewater plant, the performance of this system is directly tied to the health of the entire biological treatment unit. A reliable, well-maintained scraper ensures a consistent and high-quality RAS flow, maintaining the necessary microorganism population in the aeration basin for effective organic matter breakdown. Conversely, a malfunctioning scraper can lead to a process failure, including solids washout and a drop in treatment efficiency. Given the critical nature of this application, secondary tank scrapers are built for utmost reliability, often featuring non-corrosive materials to handle the moist environment and designs that allow for maintenance without draining the large tank.