40 Treatment of wastewater, water, gases or air flows; Decolourization, filtration and purification of waste water, water,gasses and airstreams, as well as absorption of impurities from waste water, water, gasses and airstreams; Rental of installations and apparatus for decolouration, filtering and/or purifying of waste water, water, gases or airstreams, and installations and apparatus for absorbing impurities from waste water, water, gases and airstreams