Tratamento e recirculação de água por osmose inversa em processos de fabricação de lentes oftálmicas. Beneficios ambientais e financeiros

Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia

Due to increased environmental awareness and water costs, industries have increase the need to optimize the use of water by selecting production processes more efficient, with lower water consumption or through a treatment and recirculation of water. This study comes from the Essilor Portugal need to reduce the environmental impact and costs of a water consumption of the main processes for producing ophthalmic lenses, but also the need to improve the quality of the water process due the quality requirements. One of the processes of water treating with an increased use in industrial sector, particularly in processes that require water with very stringent quality characteristics, is reverse osmosis. This process, thanks to its numerous advantages, including the high capacity and effectiveness of treatment, occupying small areas, unnecessary regeneration and energy efficiency has proven to be an economically viable technology. The objectives of this study are based on the evaluation of the environmental and financial benefits due the implementation of water treatment and recirculation by reverse osmosis, in processes of manufacturing of ophthalmic lenses, and also the analysis and optimization of operating conditions. With this system, of water treatment and recirculation, there was a significant improvement in the quality of the water for cleaning of ophthalmic lenses in the coating process (the most demanding in terms of water quality) which serves to protect the surfaces of the lenses from knocks and scratches, giving them hardness and abrasion resistance. The water needs, to clean lenses in the coating process is crucial, to ensure the pre-cleaning of the lens surface before application of the coating and quality of the product, and after the treatment system implementation there were some improvements of the coating process quality service, in terms of non quality costs and process yield. From the analysis of the environmental benefits of the project, we can verifier that there is a reduction of consumption of resources and materials, which translate into a significant positive impact, combined with reduced consumption of water and energy. The present study showed that reverse osmosis is an technology treatment, economically and environmentally feasible for the specific conditions of the project in question, allowing rapid coverage of the initial investment, managing to generate a rate return much higher than the capital cost.