A characteristic of the Smurf language is the frequent use of the undefinable word smurf and its derivatives in a variety of meanings. The Smurfs frequently replace both nouns and verbs in everyday speech with the word smurf: We're going smurfing on the River Smurf today..
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
Sewage sludge treatment describes the processes used to manage and dispose of sewage sludge produced during sewage treatment. Sludge is mostly water with lesser amounts of solid material removed from liquid sewage. Primary sludge includes settleable solids removed during primary treatment in primary clarifiers. Secondary sludge separated in secondary clarifiers includes treated sewage sludge from secondary treatment bioreactors.