Abstract: A method is disclosed by which vapour is cleaned of gaseous impurities during evaporation of polluted liquids. Vapour is conducted via a boiler, a compressor to a heat exchanger (12) in which condensation takes place. In order to clean the vapour, a scrubber (14) is arranged between the boiler (3) and the heat exchanger (12), in which the vapour is scrubbed in several steps (17, 18) at different pH values. Thus, the step (17) is an acid step, whereas the step (18) is an alkaline step. In this manner, the vapour for condensation may be conducted into the heat exchanger and be condensed in order to remove a clean condensate without pollution of acid or alkaline substances.

Abstract: A flat structural element has a plurality of openings which are distributed according to a predetermined pattern for use in packings. Every opening is delimited by the edges, which extend at an angle to each other or are curved. The structural element is made from two or more adjacent strips of flat material which are connected to each other with butt or overlapping connections.

Abstract: Crystals of the Zeolite Analcime (Analcite) Na.sub.2 O.Al.sub.2 O.sub.3.4SiO.sub.2.2H.sub.2 O are provided having a largest dimension greater than 50 micron. A method for preparing such crystals by mixing aqueous solutions of aluminium sulphate and sodium metasilicate, allowing a gel to form then heating, is provided. The presence of an organic water-miscible base encourages an increased crystal size. The crystals retain water strongly and a use for them in long term immobilisation of tritiated waste water is provided.

Abstract: A system for removing contaminants from a solution is provided. A supply tank holds the contaminated solution and a reactor containing a catalyst receives the contaminated solution from the supply tank and further receives hydrogen for reacting with the catalyst and contaminants for removal thereof. The system is applicable to both aqueous and non-aqueous streams contaminated with chlorinated hydrocarbon and the like. Furthermore, the hydrogen for the system may be produced in situ.