RESUMO
Recycling of end-of-life polyamide-based thin film composite (TFC) membranes is gaining interest in academic and industrial contexts. The effects of chlorine exposure on the performance of polyamide membranes result in an increase in membrane permeability, whereas the solute rejection decreases. Therefore, the controlled chemical conversion of old reverse osmosis (RO) membranes has been reported by some previous papers. The objectives of this study were to assess recycling of old nanofiltration (NF) membrane, to assess the performance of the recycled membranes for a river water treatment application, and to conduct preliminary cost evaluations. Recycling technique consisted of exposing the membrane to a sodium hypochlorite solution in order to remove its polyamide layer and conversion to a low-pressure membrane. The work conducted bench scale and long-time pilot tests, and the recycled membranes showed a low fouling tendency. The difference between some results in bench- and pilot scale underscores the importance of evaluating design parameters using pilot scale units. Based on the cost analysis, the total cost of chemical recycling end-of-line NF membranes for a river water treatment is approximately 1.1% of the cost of using a new UF membrane. There is a great potential in using recycled membranes for rivers water treatments.
Assuntos
Membranas Artificiais , Purificação da Água , Filtração , Osmose , ReciclagemRESUMO
The reverse osmosis (RO) technology for desalination and demineralization serves the global water crisis context, both technically and economically, and its market is growing. However, RO membranes have a limited life-cycle and are often disposed of in landfills. The impacts caused by the disposal of thousands of tonnes per annum of RO membranes have grown dramatically around the world. Waste prevention should have a high priority and take effect before the end-of-life phase of a product is reached. In this review, a summary is presented of the main advances in the performance of the RO technology and the membrane lifespan. Afterwards, this paper reviews the most important relevant literature and summarizes the key findings of the research on reusing and recycling the discarded modules for the purpose of extending the life-cycle of the RO membranes. In addtion, there are some recent researches that indicated recycling RO membranes for use by the microfiltration or ultrafiltration separation processes is a promising solution to the disposal problem. However, there are many gaps and differences in procedures and results. This article also discusses and brings to light key parameters involved and controversies about oxidative treatment of discarded RO membranes.