Environmental Sustainability Assessment of an Innovative Cr (III) Passivation Process

Abstract

A life cycle assessment was conducted for the Zn-electroplating products passivated by different processes in a small and medium enterprise. The goal was to evaluate and to compare the environmental impact associated to the conventional and alternative passivation process from a “cradle to grave” analysis. The assessment was divided into “cradle to gate”, “gate to gate”, and “gate to grave” steps for natural resources usage and environmental burdens. The innovative process was based on the integration of emulsion pertraction technology to the passivation bath in order to extend its lifetime. Results showed that the transferred hazardous waste from the process to the landfill was the major contributor to the environmental impact of the conventional and innovative passivation. The manufacture of the sodium hydroxide needed in the wastewater treatment process had a main role in the impacts of the “cradle to gate” cycle. This work concluded that the innovative passivation decreased most of the generated waste (92%) during the manufacture cycle of the passivated product as a consequence of the extension of the lifetime of the passivation bath. A reduction of the total environmental burdens to air and to water and the resource usage during the whole manufacture cycle of the product was stated. The environmental burdens to air and to water were mainly connected to the environmental impacts: human health effects and ecotoxicity to aquatic life, respectively.