Boron removal and recovery via vacuum assisted air gap membrane distillation-crystallization (VAGMD-C): A pilot-scale study

Boron is an essential element that is widely used in many industries. Due to its importance, it is beneficial to recover boron from water streams. The concentrate stream contains high boron content and is the major obstacle for membrane processes, due to its high salinity and contaminant content. Since membrane distillation (MD) can be used successfully to treat highly concentrated waters, the pilot scale vacuum-assisted air gap MD (VAGMD) unit was investigated in this study and boron removal efficiency from raw water and RO concentrate was evaluated. This operation was carried out with different recovery ratios through flow rate, conductivity, pressure and removal efficiencies and presented in this study. After the VAGMD operation the crystallization process was applied and up to 43.9 % B2O3 concentrated boron crystals were obtained.