Abstract: A scrubber having a housing and a pair of replaceable and removable perforated casings within the housing. Preferably, the casings are cylindrical and concentric forming an inner corespace inside the innermost casing and an annular fillspace between the casings. A central, conical feeder at the top of the housing permits uniform distribution of treatment media into the annular fillspace. Circulation of exhaust gas through the scrubber is provided by a removable inlet pipe and removable outlet pipe. Contaminant-laden exhaust gas that is fed into the core, percolates through the treatment media and is discharged out through the housing. The stream of exhaust gas can be reversed without any modification to the internal or external parts of the scrubber. A plurality of removable horizontally extending cylindrical pipes secured to the lower end of the housing are used to remove the exhausted treatment media without disturbing surrounding piping through discharge ports secured to the lower end of the housing.