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ePaper created 2017-03-14, 10:25:37 | version 1.49.03
ENVIRONMENT AND ENERGY wastewater treatment water recircula- tion Circular Economy metal recovery energy recovery 1 2 electrical energy hydrogen recovery chemical nickel pre- treatment electro- oxidation electro- coagulation desalination pure water electro- winning nickel-free sludge nickel IMPROVEMENT OF PRODUCTION EFFICIENCY IN ELECTROPLATING FACILITIES BY ELECTRO- CHEMICAL TREATMENT OF PROCESS WATER M a x imilian Kot zur Initial situation ECOWAMA pilot plant The metalworking industry is of great importance for the Ger- The core of the pilot plant built for the project consists of the man and European economy, and in this sector of industry, electroplating plays a key role [1]. A signiicant use of resourc- es is required at the same time combined with release of large quantities of hazardous wastewater and waste material to maintain this position. In Europe alone the surface treatment industry consumes more than 100 million m3 of fresh water annually and, in doing so, produces more than 300,000 tons of toxic waste [2]. This indicates the need for clearly deined economic and eco- logical objectives in the electroplating sector [1]: Reduced need for chemicals Efluent-eficient mode of plating operation Total return of recyclable materials to the production process Minimization of energy consumption Reduction of the disposal costs and avoidance of waste, thus increasing production eficiency The ECOWAMA concept The EU-funded project ECOWAMA addresses these aims and combines the energy- and cost-eficient treatment of waste- water with the recovery of recyclable materials (metal) as well as the recirculation of treated process water into operation of the electroplating facility. By the eficient use of resources this closed-loop approach, which goes beyond the state-of-the-art processes of electrooxidation and electrocoagulation based on electrochemical and electrophysical principles, and also a new thermal multistage humidiication-dehumidiication process. These are used for the oxidation and precipitation of the components that are relevant both for disposal and for desalination (Fig. 2). These process steps are supplemented by the electrolytic recovery of nickel (electrowinning) and a preliminary cleaning of the process water by means of pulsed electric ields to remove fats and oils. Within the scope of ECOWAMA it was possible to show that hydrogen, which is a by-product of the electrochemical process water treatment, can be fed into a fuel cell via a suitable gas cleaning step and converted into electrical energy. Demonstration The ECOWAMA pilot plant was demonstrated in a facility for plastic electroplating. The chemical (electroless) nickel plat- ing of plastic parts is a widespread application in this area. These nickel-phosphorus layers are characterized by high corrosion resistance, very good wear and hardness properties, and above all they can also be used for geometrically highly sophisticated parts. The coating layers are mainly used in the automotive, telecommunications and plastics sectors and also in the chemical industry [1]. technology used at many electroplating facilities, the develop- However, due to the formation of undesirable by-products the ment supports the efforts of the European Union to achieve a circular economy (Fig. 1). treatment of the depleted chemical nickel baths and the rinse water associated with them presents a major challenge. The 9 6