Practical experiences with the implementation of the concept of zero emissions in the surface treatment industry in Austria

The authors have developed the approach of the “Zero emission retrofitting method for existing galvanizing plants” (ZERMEG). The goal of this approach is to take existing galvanizing plants as far as possible towards zero emissions. The development was supported by the Austrian ministry for science and technology within the programme “Factory of the Future”. The method consists first of an analytical step to describe the existing performance of the plant in terms of production, water input and input of chemicals, a second step is designed to characterize the theoretically possible minimum consumption using the present equipment and the third step is the comparison of the present to the ideal situation to identify optimisation options (improved draining, dosage of chemicals, control of rinsing water, mixing in the tanks, etc.). To facilitate the calculations, a Microsoft-Excel-programme was developed (Zero Emission Program Analysis, ZEPRA), which allows to calculate the ideal water consumption of different configurations of rin ses, drag out for different shapes and surface conditions of parts, and changes in concentrations of active baths. A technology data bank was developed that includes information on different technologies to enlarge the useful time of galvanizing baths or to recycle spent solutions and rinsing water. This paper describes case studies in five galvanizing plants. The measures which were implemented include changing the rinsing cascades in three plants at the wire producer Pengg (reduction of the water consumption in the batch pickling plant by 50%), the use of spent caustics to preneutralise spent process baths and the implementation of an electrolysis plant to recover copper at the printed circuit board manufacturer AT&S (recovery of 20 kg/day of copper), optimising the pickling baths of the hot dip galvanizer Mosdorfer (50% reduction of consumption of acids) and the optimisation of the spray rinses in the automatic copper plating plants of the producer of printing cyclinders Rotoform (reduction of water consumption by 50%, reduction of acid consumption by 40%). The work showed, that in three of the five plants it was possible to fully avoid the discharge of spent process baths. One plant now operates at zero emissions. In one plant it would be technically feasible to do so, however, it is not economically feasible, at this time.