Mitigation of gypsum and silica scaling in membrane distillation by pulse flow operation

Abstract

The existing literature on scaling resistance in membrane distillation (MD) mainly focuses on membrane materials. However, the operation conditions can also have a significant effect on scaling, which is often overlooked. This paper reports the effects of pulse and steady flow on mineral scaling in MD using a commercial hydrophobic polyvinylidene fluoride (PVDF) membrane. The scaling behaviors of MD concentration were compared between pulse and steady flow conditions using supersaturated gypsum or silica solutions. The pulse flow creates a state of regular vibration of the membrane, which disrupts the aggregation and deposition of particles on the surface and reducing temperature and concentration polarization. Comparing to steady flow, the pulse flow resulted in lower scaling propensity and a slightly higher initial flux of the PVDF membrane for both scaling types. The exploration of flow dynamics has provided a strategy for mitigating mineral scaling in membrane distillation, indicating that operation process optimization can contribute significantly to a robust and durable MD process.