Membranas de osmose inversa em final de ciclo de vida recicladas e recuperadas aplicadas ao tratamento de lixiviado de aterro sanitário

Abstract

Membrane technologies have shown promise in the treatment of landfill leachate due to their high pollutant removal capacity. At the same time, due to the fact that reverse osmosis (RO) membranes have a limited life cycle, the reuse and recycling of membranes at the end of their life cycle have received significant attention in academic and industrial contexts. These practices contribute to reducing the impacts caused by the disposal of membranes in landfills and allow the use of recycled membranes in less restrictive separation processes. In this context, the present study sought to develop, from end-of-life OI membranes, recycled (via oxidative treatment with commercial sodium hypochlorite) and recovered (via chemical cleaning) membranes, applied to the treatment of landfill leachate. In the first part of the study, 6 contact intensities (MR1-30,000, MR2-20,000, MR3-15,000, MR4-10,000, MR5-8,000 and MR6-6,000 ppm/h) were investigated in order to obtain membranes with good performance in leachate treatment. In the second part of the study, different chemical cleaning protocols were applied, with membranes from two sources (demineralization and desalination of water), with the aim of recovering the permeate flux of the membranes at least 85% of that specified for new commercial membranes. Among the recycled membranes produced, the MR4 membrane, with hydraulic permeability of 21.14 ± 0.06 L-h-1-m-2-bar-1 and salt rejection of 17.7%, therefore with characteristics similar to UF membranes, showed higher removal efficiency when all monitored parameters were evaluated: color: 86.1%, COD: 64.1%, and electrical conductivity: 21.1%, ammonia nitrogen: 11%. For the membranes recovered with chemical cleaning, used for demineralization, hydraulic permeability values of 4.61 (BW30-400), 5.14 (B400 LE ASD), 4.90 (BW30-XFR) were obtained, with color removal greater than 97% and COD removal ranging from 91 to 95%. Despite the modest performance of the recycled membranes in leachate treatment, none of the evaluated parameters met the federal and state legislations regarding effluent discharge standards. For the recovered membranes used in desalination, permeabilities of 6.45 (AG4040FM-1), 5.87 (AG4040FM-2) and 4.45 (AG4040FM- 3) L-h-1-m-2-bar-1 were obtained, with color removal between 86 and 99.5%. Total dissolved solids removals were higher than 99% for all recovered membranes. The permeates obtained using recovered membranes presented COD removal in accordance with the state legislation of Minas Gerais (minimum removal of 70% for landfill leachate). It is concluded that the recovered membranes represent high efficiency in leachate treatment, while the recycled membranes have the potential to be used for other less restrictive treatment processes, as well as applied as pre-treatment or post-treatment of leachate.