Since Membrane Distillation (MD) is an energy-intensive separation process, therefore, it is vital to consider a realistic measure of energy evaluation for the MD system. Exergy analysis of Xzero flat-plate air gap membrane distillation (AGMD) laboratory and pilot scale units for treatment of Chemical Mechanical Polishing (CMP) wastewater from Nano-electronics manufacturing is focused in this study. Experimental work has been performed using the bench scale AGMD system considering different operating conditions and chemical concentrations for obtaining the thermodynamic and physicochemical data for the exergy calculation. Moreover, previously reported performance of a pilot scale AGMD module is employed to evaluate the system operation in the terms of thermal energy in order to execute the exergy analysis. Exergy flow rates in the AGMD system, minimum work input required, total exergy gain by the system and by CMP wastewater, system’s component share for exergy destruction and exergy efficiencies were calculated. The exergy analysis outcomes show that higher amount of exergy flow rates are associated with the hot streams in the AGMD separation process. Minimum work input required was 0.5 kW at feed temperature of 358K and flow rate of 7.2 kg/min for bench scale unit whereas for pilot scale system, 1.5 kW minimum work input was required at the same feed temperature with flow rate of 20 kg/min. The exergy efficiency varied between 12-19% for bench scale AGMD system and 18-24% for pilot scale AGMD system. Moreover, it was found out that MD modules, hot water recirculation tank and cooling water tank are needed to be optimized for better performance.