Anàlisi de la sostenibilitat mitjançant la petjada de carboni en la implantació d'un nou sistema de gestió dels fangs de depuradora

Abstract

The aim of this study is to evaluate the greenhouse gas emissions with the Life Cycle Analysis (LCA), in order to compare the carbon footprint of both management systems of sewage sludge in the region of Maresme. This evaluation driven by the Maresme Regional Council (hereinafter CCM). The first scenario that arises is what is done currently, which consists of the distribution of the sewage sludge to composting plants that don’t belong to the organization. The second scenario is intended to implement a new system in the near future and take care of the management of the new sludge anaerobic digestion plant Wastewater Treatment Plant (hereafter WWTP) at Alt Maresme Nord that has two anaerobic digesters with the sufficient capacity to process all the sludge in the region. The process that takes place is a sludge stabilization and transformation of organic matter into biogas, a gas with a high calorific value, which later on can be used to generate heat and electricity. In both treatments there is areduction of sludge volume, which will result in a section that can be used as fertilizer in agriculture as a final disposal for both cases. The scope of the study is based strictly on the transport and energy used in each of the scenarios, which means that there are many other important elements left out. The results show a large amount of CO2 emissions avoided for the new type of treatment and management due to savings in the itinerary of the distribution unification favoured by the final destination point. However, there should be a much more extensive study on the constraints that exist for each of the technologies and their benefits, because depending on the scope and type of emissions quantification methodology it could generate major changes. It is important to consider all categories of LCA to make an assessment of all environmental impacts not only on climate change as there may be other impacts that are not being detected. However, it can be concluded that the sludge could become in a near future a new beneficial resource to supply us with energy, especially with the new technologies’ improvement possibilities.