Impact assessment of mercury emissions from a waste-to-energy plant on local air quality.

The reduction in the application of mercury and the introduction of effective separate collection systems, particularly for batteries, has resulted in the progressive reduction of its presence in waste. Nevertheless, waste combustion is still considered a major source of anthropogenic emissions of mercury into the atmosphere because in the incineration process it evaporates almost entirely from the waste and is transferred into the flue gas as elemental mercury and mercury chlorides. In waste incineration plants, the commonly adopted techniques to meet the emission limit of 0.05 mg/m3 as an 8-hour average concentration [3] are wet scrubbing and adsorption on activated carbon. These techniques are indicated as best available techniques (BAT) to reduce mercury emissions to air (including emission peaks) from waste incineration in the EU Decision 2019/2010, that establishes the BAT conclusions for waste incineration. Studies investigating the actual impact on local air quality of mercury emissions from waste combustion plants are still rather limited. This work presents results of atmospheric dispersion modeling for mercury emissions from a municipal waste-to-energy (WtE) plant in northern Italy and their comparison with TGM (total gaseous mercury) values observed in the atmosphere around the plant. The work adopts the methodological approach of a previous study conducted for the same plant in 2018-2019 and provides new elements of knowledge on the impact of the WtE plant on local air quality.