Exergy analysis in the assessment of the sustainability of waste gas treatment systems.

This study focuses on the sustainability of different technological options for the treatment of waste gases from a waste water treatment plant loaded with volatile organic compounds. The options considered are biofiltration, active carbon adsorption and catalytic and thermal oxidation. The amount of resources and utilities to construct and operate each system have been investigated from the point of view of the Second Law of thermodynamics. The unit in which all resources are treated is Joules of exergy. It was concluded that biofiltration was the most exergetically efficient system. The cumulative exergy consumption of the resources and utilities for construction and operation have been quantified in exergy terms. Further on, the requirements for the abatement of emissions generated by operating the waste gas treatment systems and the amount of renewables have been taken into account in the assessment of the sustainability of the waste gas treatment technologies. Finally, a comparison between exergy analysis and life cycle analysis in assessing the sustainability of the waste gas treatment options, is presented.