CHAPTER XV

SCREENING AND SEDIMENTATION

228. Purpose. 229. Types of Screens. 230. Sizes of Openings. 231. Design of Fixed and Movable Screens. PLAIN SEDIMENTATION. 232. Theory of Sedimentation. 233. Types of Sedimentation Basins. 234. Limiting Velocities. 235. Quantity and Character of Grit. 236. Dimensions of Grit Chambers. 237. Existing Grit Chambers. 238. Number of Grit Chambers. 239. Quantity and Characteristics of Sludge from Plain Sedimentation. 240. Dimensions of Sedimentation Basins. CHEMICAL PRECIPITATION. 241. The Process. 242. Chemicals. 243. Preparation and Addition of Chemicals. 244. Results. 383–409