A pirólise como tecnologia para redução de emissões de gases de efeito estufa e sequestro de carbono: um estudo de caso do tratamento de resíduos de couro wet-blue

Abstract

The objective of this research is to asset the potential of pyrolysis treatment of biogenic solid residues in terms of greenhouse gases (GHG) emissions reductions. These reductions are possible in two ways: (I) by methane avoidance, since the biogenic residues would not be sent to a landfill and it would not decay in anaerobic conditions, so methane would not be emitted and (II) by carbon storage, since the pyrolysed residue is rich in fix carbon and it is stable. This residue can be considered as Black Carbon (BC), which is not susceptible to chemical or biological degradation. Therefore, when the BC is storage in a dedicated landfill it is avoided that all the carbon present in the BC is released again to the atmosphere. Two methodologies were developed to quantify these reductions and sent to the United Nations Framework Convention on Climate Chance for approval, following the Clean Development Mechanism (CDM) rules. The residue analyzed was wet blue leather tanning solid wastes from a tanning industry in Ipatinga city, in Minas Gerais/Brazil. It is a residue classified by the Brazilian legislation as dangerous since it has chrome. It was built a pyrolytic reactor with a 200 liters cylinder capacity and a flaring system of the produced gases to generate thermal energy for the reactor. But it was also necessary external energy input. For that, it was used thermal processed wood chips as fuel, which can be considered carbon neutral. The average temperature during the pyrolysis treatment was 500ºC. Fix and volatile carbon were analyzed in residues before and after the treatment. There was a increase of 40,92% of fix carbon and a decrease of 49,33% of volatile carbon in the pyrolysed residues. Both mass and volume of residues were also reduced after the thermal treatment: around 80% and 85% respectively. The GHG reduction emission index found was 0.996 tones of CO2e per ton of residues treated by pyrolysis. Following this approach, it could be possible to achieve financial resources by selling carbon credits (CERs and/or VERs), which could help the economical feasibility of this technology implementation.