Equipment that removes particulate matter from a gas stream may also remove or create some gaseous contaminants; on the other hand, equipment that is primarily intended for removal of gaseous pollutants might also remove or create objectionable particulate matter to some degree. In all cases, gas-cleaning equipment changes the process stream, and it is therefore essential that the engineer evaluate the consequences of those changes to the plant’s overall operation. In this chapter, each generic type of equipment is discussed on the basis of its primary method for gas or particulate abatement. The development of systems that incorporate several of the devices discussed here for specific industrial processes is left to the engineer. Regulations and Standards PARTICULATE CONTAMINANT CONTROL Mechanical Collectors Centrifugal Collectors Electrostatic Precipitators Fabric Filters Mist Collectors Particulate Scrubbers (Wet Collectors) GASEOUS CONTAMINANT CONTROL Spray Dry Scrubbing Wet-Packed Scrubbers Adsorption of Gaseous Contaminants Incineration of Gases and Vapors AUXILIARY EQUIPMENT Ducts Dust- and Slurry-Handling Equipment OPERATION AND MAINTENANCE