Environmental Protection Agency Wastewater Technology Fact Sheet Screening and Grit Removal DESCRIPTION Wastewater contains large solids and grit that can interfere with treatment processes or cause undue mechanical wear and increased maintenance on wastewater treatment equipment. To minimize potential problems, these materials require separate handling. Preliminary treatment removes these constituents from the influent wastewater. Preliminary treatment consists of screening, grit removal, septage handling, odor control, and flow equalization. This fact sheet discusses screening and grit removal. Screening Screening is the first unit operation used at wastewater treatment plants (WWTPs). Screening removes objects such as rags, paper, plastics, and metals to prevent damage and clogging of downstream equipment, piping, and appurtenances. Some modern wastewater treatment plants use both coarse screens and fine screens. Figure 1 depicts a typical bar screen (a type of coarse screen). Coarse Screens