Grit is a problem for all publicly owned treatment works (POTWs). It is small dense material, such as broken glass, metal shavings and particles, silt, pebbles, and aggregate that ends being captured in the collection system and transported to the POTW. It ranges in size from very fine (approximately 50 mesh or 300 microns) to fairly coarse. If these particles are not removed they abrade pumps and other mechanical devices, causing undue wear and increased maintenance costs. In addition, grit has the tendency to settle and collect in corners and bends, reducing flow capacity and ultimately clogging pipes and channels. It also collects in sludge treatment processes such as digesters, which reduces the active volume and treatment capacity of the digester. Removing grit from a digester and repairing equipment damaged or worn by grit, is a difficult and costly burden for maintenance personnel and their budgets. This issue of the ProactiView digs in to the Grit, and invites you to attend a 4-hour comprehensive “Grit School”.