Abstract: A waste gas exhausted from a chlorination furnace during the manufacture of titanium tetrachloride or zirconium tetrachloride which contains larger quantities of CO.sub.2 and harmful substances such as chlorides and the like is subjected to treatment which comprises the sequential steps of scrubbing the waste gas in a water scrubbing column, removing moisture from the waste gas to allow the waste gas to have a dew point of no more that 5.degree. C., and adsorbing the waste gas in an activated carbon packed column. The process is capable of reducing the content of chlorides in the waste gas to a level of no more than 5 ppm in HCl equivalent.

Abstract: Apparatus operating at low pressure drop and low initial velocity for removing pollutants down to sub-micron sizes from gas streams comprising a nozzle means accelerating the gas flow to about four times its entering velocity into a large expansion chamber having an impinger area for removal of pollutants. This is a method of removing pollutants down to sub-micron size at high efficiency by passing the polluted gas through a nozzle having specific geometry into an expansion chamber and impinging the pollutants upon an impinging area and removing them from the system.

Abstract: An air filter apparatus comprising an inner sleeve having a number of small apertures, an externally tapered outer sleeve having a number of small apertures, said inner sleeve being inserted in said outer sleeve and fixed in position to form a double-wall cylinder, a funnel-shaped suction port disposed at the mouth edge of the inner sleeve on the side where the larger diameter of the outer sleeve exists and active carbon packed in a space between the inner and outer sleeves.