Long-term emission sampling validation for PCDD/Fs control of compliance to permitted Emission Limit Values at a large sinter plant.

Continuous sampling of emission into air of dioxins has been one of the targets of Directive 2010/75/EU Of The European Parliament And Of The Council on industrial emissions (Integrated Pollution Prevention and Control, IED Directive) since year 2010. The present research was aimed at verifying the applicability of a long-term sampling system at the sinter plant of a large steel works in Taranto, Southern Italy, and to perform its validation compared to the standard reference method. Automated long-term samplings of 15 and 30 d were performed in parallel with manual short-term sampling, the latter with a frequency of two per week. Concentrations range was 0.05-0.20 ng I-TEQ/N m3 thus ensuring good coverage around the level of interest of 0.1 ng I-TEQ/N m3, as a typical Emission Limit Value for combustion plants. In addition the long-term device was used for short-time sampling in parallel with manual sampling showing an external variability between ± 0.05 ng I-TEQ/N m3 thus proving to be acceptable. As a result of the successful validation trial the long term emission sampling was enforced as Emission Limit Value official control technique.

POP emissions from a large sinter plant in Taranto (Italy) over a five-year period following enforcement of new legislation.

PCDD/F in exhaust gas emission samples was determined by the Environmental Agency of Apulia for a sinter plant located in Taranto (Italy) starting from June 2007 following an Agreement Act between plant owners and the Regional Government with the aim to assess and improve the environmental performances of the plant. The first two sampling campaigns yielded results ranging between 3.42 and 8.34 ng I-TE/Nm(3) that were soon considered revelatory of a high potential impact on the surrounding environment and the public, prompting for immediate action. As a first outcome, a Regional Regulation (LR 44/2008) was enforced in order to reduce PCDD/F emissions by plants operating in the metal sector, including sinter plants. After installation of a urea addition plant to the sinter mix as a process-integrated abatement technique the emissions ranged from 0.86 to 3.59 ng I-TE/Nm(3). In order to reach compliance to the newly introduced emission limit value of 0.4 ng I-TE/Nm(3) the urea plant was removed in favour of active-carbon injection as an end-of-pipe technique. Subsequently, during year 2011 emission values ranged from 0.095 to 1.97 ng I-TE/Nm(3), while in 2012 the observed range was 0.058 to 0.91 ng I-TE/Nm(3). As a better evaluation of the potential impact of the sinter plant emissions, a yearly mass-flow was estimated using exhaust gas PCDD/F concentrations and plant operational parameters (3.4 M Nm(3)/h). Mass-flow was estimated to be as high as 165 g I-TE/year for 2007 using yearly average concentrations or 248 g I-TE/year using the peak-value of 8.34 ng I-TE/Nm(3).