Study of the bubble membrane crystallization process for zero-brine discharge

Zero-brine discharge technology is being closely followed because it can help address water scarcity. Crystallizers show the promise of zero discharge because of their ability to recover resources from concentrated brine. However, traditional industrial metal crystallizers corrode easily and are bulky. Membrane distillation is favored because of its large evaporation area and high efficiency. However, membrane fouling is an inevitable problem in membrane distillation. To address these issues, this study designed a new type of membrane crystallization process, namely bubble membrane crystallization (BMC). In this process, a hollow fiber hydrophobic membrane was used to aerate a feed solution to accelerate the evaporation of the feed solution, which helped crystallize the concentrated brine, and avoided corrosion and membrane fouling. In this study, NaCl crystals with uniform distribution (80.0-110.0 µm) were produced. The results showed that the membrane aeration treatment made BMC possesses excellent anti-pollution and long-term stability. This process advances all-plastic crystallizer technology to achieve zero-brine discharge.