Recycling of Spent Reverse Osmosis Membranes for Second Use in the Clarification of Wet-Process Phosphoric Acid

Abstract

Various techniques have been used to “clean-up” wet-process phosphoric acid such as precipitation, flotation and adsorption. To address the potential of membrane processes in the phosphoric acid clarification process, this study explores the benefits of membrane techniques as a green separation technique for phosphoric acid clarification in an eco-efficient way through the use of recycling spent reverse osmosis membrane. Regenerated membrane was used to study the phosphoric acid clarification at a laboratory scale. They were immersed in an oxidizer for at most seven days. The samples were characterized systematically before immersion in an oxidant media. In this study, the potential to regenerate spent membranes and application of this media to clarify the 29% P2O5 phosphoric acid was demonstrated. This study shows, through experiments, that the reverse osmosis (RO) membranes could achieve a rejection of 70% and 61% for suspended solid and organic matter, respectively. These promising results will pave the way for implementation of these membranes in phosphoric acid treatment. Moreover, besides being economically advantageous, the use of the spent membrane is likely an environmentally friendly route (no waste, no organic solvent and effluent to be regenerated later on).

Performance Evaluation of UF Membranes Derived from Recycled RO Membrane, a Step towards Circular Economy in Desalination

“…So, the whole conversion with all the same details has been repeated one more time. The same concentration of NaOCl was applied a second time, and a net total of 2400 mL was used to convert the spent RO into an R-RO membrane [ 21 ]. The conversion procedure details are given in Table 2 .…”

“…Jawad in 2021 converted the RO membrane and tested it on the gray water that showed higher water recovery % and removal of E. coli [ 19 ]. Khaless et al in 2021 observed the salt rejection percentage of the RO spent membrane and proposed to use it for phosphoric acid treatment [ 20 , 21 ]. Salinas et al in 2020 evaluated the life cycle assessment (LCA) and direct economic analysis of recycling of RO membranes that showed positive results, and it proved effective as an environmental benefit, and recycled modules can be sold at a competitive price of 80 euros in the market [ 22 , 23 ].…”

Environmental Problems Caused by the Use of Reverse Osmosis Membrane Elements, and Ways to Solve Them

“…This process was studied in detail during the study of aging of reverse osmosis membranes (Donose et al, 2013) or the impact on the web of various oxidants, namely chlorine compounds (hypochlorite, chlorine dioxide, chloramines, etc. ), hydrogen peroxide, ozone, potassium permanganate (Khaless et al, 2021;Kang et al, 2007;Moradia et al, 2019;Donose et al, 2013;Cran et al, 2011;Ling et al, 2019;Yu et al, 2019). As shown by several authors, in the latter case the polyamide layer changes its morphology, resulting in changes in its selectivity (Lawler et al, 2012;Goh et al, 2018;Paula et al, 2018;Pontie et al, 2017).…”

Sustainability in Membrane Technology: Membrane Recycling and Fabrication Using Recycled Waste

“…Subsequently, the transformed membrane could be utilized as an MF/UF element for pretreatment of the feed or for non-potable water reuse applications (Figure 3a). The primary approach involved in membrane downcycling is the partial or full destruction of the PA layer using oxidizing agents such as NaOCl [37], potassium permanganate (KMnO 4 ) [61], hydrogen peroxide (H 2 O 2 ) [62], and their mixture [63]. The utilization of NaOCl is perhaps more common for NF/RO membranes downcycling due to the susceptibility of PA to NaOCl, causing its degradation [22,[64][65][66].…”