Impact of Heterogeneous Seeding on Membrane Distillation Crystallization

Description

The growing demand for clean water and sustainable wastewater management necessitates innovative technologies that address limitations of conventional methods, such as high energy consumption. Membrane Distillation Crystallization (MDC) emerges as a promising solution, combining membrane distillation with controlled crystallization to recover valuable salts from wastewater and high-salt solutions at moderate temperatures. Our research investigated the use of heterogeneous silica seed crystals to study the effects of various factors on crystallization efficiency in highly concentrated salt solutions, including supersaturation levels, temperature dependence, and seed crystal size. Initially, different salt solutions were prepared, and seeding crystals of varying concentrations (0.1 – 0.5wt%) and sizes (50 – 300 μm) were characterized using microscopy before being introduced into these solutions. The suspension was then transferred to the MDC plant, where it underwent treatment at various operating conditions.The process achieves salt precipitation within a metastable supersaturation range (S = 1.003 ± 0.02 for 210-300 μm seed crystals and S = 1.03 ± 0.1 for 50-125 μm seed crystals) at moderate temperatures (45-55°C) investigated in this study. This approach enables the selective recovery of various individual salts with high purities (92%) due to their differing solubility limits. A temperature increase of 5°C ± 1°C within the chosen operating range resulted in a 15% ± 2% increase in crystal size, suggesting a potential for temperature control to influence crystal growth. Additionally, the study highlights the potential for optimizing salt separation based on solubility products by adjusting key parameters like temperature, seed concentration, and crystal growth, as investigated here. These findings pave the way for developing efficient fractional crystallization techniques for diverse salt mixtures utilizing MDC.

Period	11 Sept 2024
Event title	EuroMembrane 2024
Event type	Conference
Location	Czech RepublicShow on map