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

Abstract

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 8.34ng I-TE/Nm3 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 3.59ng I-TE/Nm3. In order to reach compliance to the newly introduced emission limit value of 0.4ng I-TE/Nm3 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 1.97ng I-TE/Nm3, while in 2012 the observed range was 0.058 to 0.91ng I-TE/Nm3. 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 (3.4MNm3/h). Mass-flow was estimated to be as high as 165g I-TE/year for 2007 using yearly average concentrations or 248g I-TE/year using the peak-value of 8.34ng I-TE/Nm3.