Effect of Different Parameters on Membrane Concentrate Treatment by using Vacuum Assisted Air Gap Membrane Distillation Crystallization (VAGMD-C)

The concentration problem represents a significant challenge for membrane processes, necessitating supplementary treatment and management strategies. This study assesses the efficiency of a vacuum-assisted air gap membrane distillation/crystallization (VAGMD-C) system to addressing this issue, specifically focusing on the removal and recovery of boron, a critical raw material. Synthetic boron solutions were employed to optimize key parameters such as concentration, pH, and membrane type. Following this, real reverse osmosis (RO) concentrate was treated under optimized conditions using both commercial and custom-fabricated membranes. The experimental analyses included flux measurements, boron concentration assessments, and boron rejection rates, along with scanning electron microscope-energy dispersive spectrometry (SEM–EDS) and X-ray fluorescence (XRF) analysis of the resulting crystals. The results demonstrated that achieving up to 44.6% boron content in the crystals is feasible by utilizing the fabricated nanofiber membrane (NF) within the VAGMD-C system.