You've Got Grit Slurry. Now What? Two Case Studies of Successful Grit Slurry Pumping Systems Serving Large Combined Sewer Systems

The purpose of preliminary treatment systems is to remove debris and grit from raw wastewater and protect downstream processes. Screening devices remove debris. Grit removal processes remove grit particles. Grit particles that accumulate and concentrate at the bottom of a grit removal system are referred to as grit slurry. Wastewater industry design manuals and standards offer guidance for the processes that remove grit particles from raw wastewater, but offer little information to guide the design of successful grit slurry extraction, pumping, conveyance, and concentrating systems. The lack of guidance may contribute to the fact that removing, conveying, and processing grit slurry has been problematic at many facilities, particularly those serving combined sewer collection systems. Ironically, a process that is intended to reduce downstream maintenance is often plagued with maintenance issues. Adherence to sound design and operating strategies can avoid or minimize the occurrence and/or severity of these problems.