The shortage of drinking water and the limited availability of freshwater resources are driving the development of desalination technologies, among which membrane distillation is gaining increasing research interest. The main challenge remains membrane pore fouling, which reduces the long-term efficiency of the system, as a fouled membrane generally requires replacement. Using a single-stage membrane distillation experimental setup, the suitability of the operating conditions was first evaluated by analyzing the influence of the heat exchanger medium temperature and NaCl concentration on permeate flux. The central part of the study focused on ultrasonic cleaning methods for fouled PTFE membranes, specifically using an ultrasonic bath and a sonotrode. For comparison, two passive cleaning methods, rinsing and soaking, were also investigated. The results showed that a higher heat exchanger medium temperature reduces permeate flux, while a 25% NaCl mass fraction causes complete membrane fouling. Among the passive cleaning methods, soaking the membrane in water for 24h proved to be more effective than rinsing with water. The ultrasonic bath provided uniform cleaning; however, excessively high temperatures could damage the hydrophobic layer. The sonotrode was more effective at lower amplitudes, whereas higher amplitudes caused mechanical damage to the membrane.
|
