Metal surface cleaning by chlorinated HCs, HCs and water-based systems

The new 2nd Statutory Ordinance pursuant to the German Emission Control Act (2. BimSchV) compelles to substitute the traditional metal degreasing in open equipment by water-, hydrocarbon- or chlorinated hydrocarbon-equipment with low emissions. The study examines how far this substitution is combined with a relief of environmental impact or a shift of the ecological burden from air to waterpath. 38 cases of substitution (all branches of German metal industry) are studied in which the same cleaning task was performed, formerly by chlorinated hydrocarbons, and subsequently by water based cleaning systems (27 cases) or hydrocarbons (11 cases). For all cases the consumption of matter and energy, emissions and waste products from the equipment, running and wastemanagement, are quantitatively registered and qualitativly valued. The main results: All three variants of modern process engineering lighten the ecological burden but use more energy. The shift of ecological burden from air to waterpath is smaller than expected. Concerning environmental impact, the aqueous cleaning material is superior. The cost analysis speaks well for aqueous or hydrocarbon cleaning. At the moment it s not possible to treat all cases by substituting the chlorinated hydrocarbons. The aqueous and hydrocarbon-equipments will have to be optimized.