Experimental assessment of a zero liquid discharge system driven by a micro gas turbine

This study presents an experimental proof of concept for a zero liquid discharge (ZLD) system applied to seawater desalination. The system concentrates brine through direct-contact heat exchange using the exhaust gases of a solar micro gas turbine, bubbling them through the brine from a reverse osmosis (RO) unit until a dry residue is obtained. The design phase initially involved a hydraulic evaluation to assess gas stream-brine interactions, using a cold air stream to test different configurations and define the working region. Once hot exhaust gases were introduced, preliminary findings guided the correct sizing and internal arrangement of the ZLD system. Initial tests employed low-cost materials to successfully achieve zero liquid discharge. To fully characterise the thermo-chemical performance, experiments were conducted in batches, even though the process would operate continuously in real applications. After validating the proof of concept, the setup was refined, addressing key aspects such as material selection and optimised geometries to enhance durability and performance.