1) The document discusses a project from 2014-2016 that used dispersion modeling to assess air pollution impacts from steel plants in Aosta, Terni, and Vicenza, Italy. 2) It describes using a microscale model to better reproduce pollutant dispersion near buildings and emissions sources at the plants. 3) The modeling simulated particulate matter concentrations and depositions from plant chimneys and diffuse sources to validate monitoring points and estimate diffuse emissions.

1. Arianet Info Day - Milan, 31/01/2019
The application of dispersion modeling
to the dust emissions from steel plants
Giordano Pession e Tiziana Magri (ARPA VdA)

2. The «Steel Plants» Project (2014-2016)
The objective of the project is to define a method for assessing the impacts on air
pollution caused by the production plants of scrap steel with electric furnace.
The plants considered were those of Aosta, Terni and Vicenza.
Attention to the environmental impacts related to the airborne particulate matter and
to the micropollutants contained in it: metals, polycyclic aromatic hydrocarbons (PAH)
and dioxins and furans (PCDD/F). The overall emissions of the plants are considered,
both the conveyed and the diffusive ones.
The project is based on an integrated approach, which involves direct measurements of
airborne pollutants and depositions, monitoring of plants in the AIA-IPPC environment
and dispersion modeling.
Arianet Info Day - Milan, 31/01/2019

3. SPRAY
Utility of the microscale model
Better reproduction of the pollutant dispersion due to the obstacle of buildings located near the
emission source:
Micro SPRAY
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4. Localsation of the emissions sources
For chimneys it is necessary to know the following parameters to be inserted as input to
the model:
location of the chimney
height
diameter
temperature of the fumes
vertical speed of the fumes
For the evaluation, instead, of the emissions diffused by particular buildings present in
the perimeter of the steelworks, a second simulation is performed considering an area
emission in correspondence of the roof of the building, equal to 1 mg/s, as it is not
known or calculable the output flux of the emitted particulate as it is for the chimneys
instead.
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5. Industrial plants domains
Steel plant of AOSTA:
chimneys
diffusives sources
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Grid domain:
3 km x 1,75 km
Step 5 m
Period: 7 days
(meteorological
scenarios)

6. Industrial plants domains
Steel plant of TERNI:
waste hill
waste pit
chimneys
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Grid domain:
2,7 km x 2,5 km
Step 5 m
Period: 2 days
(meteorological scenarios)

7. Concentrations yearly averages (AOSTA)
Emissions from chimneys
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8. Concentrations yearly averages (AOSTA)
Emissions from diffusive sources
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9. Concentrations daily averages (TERNI)
Emissions from chimneys
Wind breeze Wind calm
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10. Concentrations daily averages (TERNI)
Emissions from diffusive sources: waste pit
Wind breeze Wind calm
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11. Concentrations daily averages (TERNI)
Emissions from diffusive sources: waste hill
Wind breeze Wind calm
Arianet Info Day - Milan, 31/01/2019

12. Comparisons - wind calm scenario
Town Monitoring station
Concentrations
[µg/m3
]
Em. from chimneys
Concentrations [µg/m3
]
Em. from diffusive sources
(1 mg/s)
Aosta Piazza Plouves 0,42 0
Aosta I Maggio 1,05 <0,01
Aosta Pepinière 1,95 0,03
Terni Prisciano 2,54 0,01
Terni Carrara 1,35 0
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13. Comparisons - wind breeze scenario
Town Monitoring station
Concentrations
[µg/m3
]
Em. from chimneys
Concentrations [µg/m3
]
Em. from diffusive sources
(1 mg/s)
Aosta Piazza Plouves 0,32 0
Aosta I Maggio 1,34 0,02
Aosta Pepinière 0,09 <0,01
Terni Prisciano 1,51 0,03
Terni Carrara 0 0
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14. Depositions yearly averages (AOSTA)
Emissions from chimneys
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15. Depositions yearly averages (AOSTA)
Emissions from diffusive sources
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16. Daily depositions (TERNI)
Emissions from chimneys
Wind breeze Wind calm
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17. Daily depositions(TERNI)
Emissions from diffusive sources: waste pit
Wind breeze Wind calm
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18. Daily depositions (TERNI)
Emissions from diffusive sources: waste hill
Wind breeze Wind calm
Arianet Info Day - Milan, 31/01/2019

19. «Backward» calculation of the diffusive sources emissions
The assumption of this calculus is:
Deposition measured near the steel plant =
Deposition by chimney +
Deposition Urban Background (monitoring station away from the steel plant)+
Deposition by diffusive sources
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mg/m2
/d Depo
meas.
Depo
chimney
Depo
Urban BG
Depo
Diffusive s.
Aosta 157 0,2 91 66
Terni 346 0,8 115 230

20. Simulations of the monthly depositions by diffusive sources ( 2018)
january february march
junemayapril
july august september

21. Conclusions and developments
Arianet Info Day - Milan, 31/01/2019
The results of the microscale particle dispersion modeling simulations have allowed us to
verify how the measurement points envisaged for the monitoring of the two steel plants
of Aosta and Terni effectively manage to monitor the concentrations in the air and the
ground depositions of PM10 emitted by the chimneys and diffused sources.
Despite the difference in extent and activity of the two plants, the concentrations and
depositions reproduced by the model are of the same order of magnitude.
The deposition modeling simulations allowed to carry out the "backward" calculation to
estimate the particulate emissions deriving from the diffuse sources.
From January 2018 we have implemented the monthly simulation of depositions from
diffused sources in the Aosta steelworks domain. On the first months of 2019 we will
have the "effective" annual mapping of dust deposition in the area of interest.