The main control parameters defined by the state environmental agency are TRS (Total Reduced Sulfur), SO2 and suspended particulate matter (PM) generated by the production process’ stationary sources.
TRS values are related to the Kraft pulp process and they give an estimate of mercaptan concentration, which is associated to odor perception events. Considering the existing stationary sources, the emission values are lower than the international standard of 5 ppm, which is the level proposed and adopted by the Company in its environmental licensing since 2001.
The OPN (Odor Perception Network) is made up of analyzing instruments located at the main stationary emission sources, an automated meteorological station, hardware and software for atmospheric odor dispersion modeling, and a group of volunteers, spread over a radius of 42 km around the plant. Such network provides the basis for managerial actions related to odorous emissions generation and control. Odor events reported by the participants are subsequently computer modeled, in order to give a deeper understanding of the phenomenon and orient future reduction and control strategies.
SO2 emissions have historically been below the current limit of 2,500 mg SO2/Nm3, since the main processes linked to the Kraft pulp production are typically based on chemical reduction with TRS emission. The most relevant emissions provide from the central stack, which flows out the gases from the two biomass boilers, the auxiliary oil boiler and the recovery boiler no. 2 (combustion processes). The remaining sources answer for SO2 emissions lower than 10 mg/Nm³.