How green are environmental technologies? A new approach for a global evaluation: the case of WWTP effluents ozonation.

The research on the impact of chemical pollution is now increasingly attracted by the topic of organic micropollutants: as secondary biological treatment of wastewater does not provide the complete elimination of these substances, an advanced treatment downstream the biological process can be implemented. Notwithstanding, the benefits of improved effluent quality can be weakened by the negative effects on air quality, when energy consumption and related pollutants emissions deriving from the advanced treatment technologies are taken into account. It is the aim of this work to present an innovative methodology to judge the environmental compatibility of wastewater treatment processes on the basis of the damage on human health produced/avoided, expressed as an economic value. In particular, while for air pollution the established external costs were applied, for water pollution the rates of the impacts on human health have been evaluated in terms of Global Burden of Disease and measured in units of DALY (Disability-Adjusted Life Years), then converted into costs based on Gross Domestic Product. As a first application, this procedure was used for assessing environmental compatibility of a final ozonation: the results of this study showed that the reduction of water pollution achieved by means of ozonation might be beneficial for human health at an extent which is in the same order of magnitude of damage caused by air pollution, emphasizing that the question if the use of advanced (energy-intensive) treatments is a proper solution to remove organic micropollutants from wastewater remains still open.