Low-Energy Method for Water-Mineral Recovery from Acid Mine Drainage Based on Membrane Technology: Evaluation of Inorganic Salts as Draw Solutions

Abstract

In this work, a novel study for acid mine drainage remediation and reutilization by means of a forward osmosis technology is addressed. The proposed process is a potential alternative path, which allows to recover high-quality water and to concentrate metals for its possible reutilization as synthetic minerals. This novel process will help in the mining industry evolving toward more sustainable processes and favors circular economy policies. Four inorganic salts (NaCl, KCl, CaCl 2 , and MgCl 2 ) were evaluated as draw solutions from 1 to 5 M concentrations, in terms of water flux, water recovery, and metal rejection, using a thin-film composite (TFC) membrane. Water flux obtained was in the range of 14−53 L/(m 2 h). The highest water flux was found for MgCl 2 , whereas the lowest correspond to KCl. The metal rejection obtained was greater than 99%. After a discussion and comparison of the results, MgCl 2 was chosen for evaluating long-term assay performance. Scanning electron microscope images of the thin-film composite membrane after long-term assays were taken. The tendency of Mg−Ca and Al−Fe fouling was observed over the membrane surface. The energy consumption was estimated from 4.84−22.3 kWh e /m 3 , assuming that osmotically assisted reverse osmosis is used to regenerate the draw solution.

Relevance of membrane biological reactor in heavy metals recovery: Diminutive review

“…It is a separation of supernatant (sludge) from treated wastewater/permeates/by the application vacuum suction force that draws the water through the membrane. It involves the application of the suction force and the flow permeates across a membrane into a separate channel for recovery, while the supernatant is retained on the membrane surface (Baena‐Moreno et al., 2020). After settling of sludge, trans‐membrane suction pressure −25 to −300 mbar is applied to separate the liquid wastewater from the solid sludge through Micro‐ or Ultrafiltration (MF/UF) membrane openings which provide perfect retention of microscopic solid particles (Robles et al., 2012).…”

Potential for water and metal recovery from acid mine drainage by combining hybrid membrane processes with selective metal precipitation

“…Other active treatments applied to AMD and wastewater effluents and to recover water are based on the use of membranes. Membrane technologies have significant advantages; their operation is simple; they can be integrated with other processes to improve the yield of the recovery; and they presents low energy consumption (Cho et al, 2012;Rodríguez-Galán et al, 2019;Baena-Moreno et al 2020). In addition, membranes allow for obtaining high-quality water recovery.…”

“…Selection of the draw solute is one of the most important factors in the regeneration process (López et al, 2021;Chekli et al, 2012;Ge et al, 2013;Achilli et al, 2010;Hamdan et al, 2015). Baena-Moreno et al (2020) have studied the use of different inorganic salts with ultrapure water and acid mine drainage as feed solution (Baena-Moreno et al, 2020). Through experimental tests, they have demonstrated that magnesium chloride and calcium chloride afford the highest water fluxes and thus the highest water recovery per unit of area with the same molarity.…”

Forward Osmosis Membranes: The Significant Roles of Selective Layer

“…Compared with traditional pressure-driven processes, FO has been proposed for treating complex wastewaters, including saline wastewater [ 45 , 46 ], industrial wastewater with high salt concentrations from oil and gas [ 2 ], mining and metallurgy [ 47 ], and cooling tower blowdown [ 48 ], streams that need to be concentrated such as liquid food [ 34 , 49 ], sludge [ 50 ], and nuclear wastewaters [ 51 ]. In general, they can be summarized into two types of applications: general applications that require draw solutes regeneration and special applications without the need for draw solutes recovery ( Figure 3 ).…”