This project aims to quantify particulate matter (PM) emissions in Spain.

The project “Atmospheric impact of the uncontrolled burning of residual biomass: Proposal for sustainable corrective measures”, developed by the Ceramic Industries Research Association (AICE), aimed to quantify particulate matter (PM) emissions in Spain more accurately. The aim is to control the emissions associated with the uncontrolled burning of residual biomass, in order to propose corrective measures to reduce this impact.

The latest inventories of particulate matter (PM) emissions in Spain carried out by the European Commission establish the need to reduce PM2.5 emissions by more than 50% by 2030. According to these inventories (carried out by IIASA), the activity that has the greatest potential for reduction is the uncontrolled burning of residual biomass. In this scenario, it is considered necessary to quantify more accurately the emissions of PM2.5, associated with the uncontrolled burning of residual biomass, as well as to propose corrective measures to reduce this impact.

The main objective of this project is the determination of emission factors and chemical profiles of PM2.5 associated with the burning of different types of residual biomass, which will be selected based on the volume generated at the national level. These determinations were made for both uncontrolled burning (in the open air without purification systems) and controlled burning (combustion plants equipped with purification systems).

The IAEC carried out an inventory and selection of biomass, considering different bibliographic sources to select the biomass to be studied: almond, orange and olive trees. The selection of the areas in which the campaigns are subsequently carried out has been made thanks to the information from the national biomass inventory and the priorities identified by MAPAMA. Finally, the entity reviewed the regulatory framework that regulates the management of permits for the open burning of pruning waste of agro-forestry origin in the different Autonomous Communities.

Once the type of biomass had been selected, the entity visited different areas in which the burns were subsequently carried out, in order to design the experimental campaigns and outline the test protocol. Due to the requirements that must be met to carry out open-air burns (prevalence of a specific wind direction, the existence of physical space in the lee of the fountain and the absence of sources foreign to the one studied) they are finally carried out on a plot of land belonging to the Jaume I University of Castellón, after obtaining its permission. Before carrying out the burning, the entity carries out the necessary procedures for the transport and conditioning of the biomass to be studied.

The entity analyzed several methods to measure the dispersion of pollutants. Finally, the Reverse Dispersion Modeling (RDM) method is selected, which measures the concentrations of pollutants at strategic points around the emission source. In addition, a model developed by the ITC-AICE has been considered, in which the geometry of the source and the exact duration of the emission are faithfully reproduced.

The AICE, within the framework of the project, carried out experimental campaigns in scenarios with controlled and uncontrolled burning, determining chemical profiles of the PM emitted during the burns and carrying out a complete characterization of the ash obtained in both campaigns.

To determine the efficiency of corrective measures, the efficiency of a bag filter as a system for purifying the PM emitted during the combustion of residual agricultural biomass has been determined by comparing the gross and net concentration of the PM emitted in the controlled burning tests. From the evaluation of the chemical profiles of PM, the efficiency for certain metals and PAHs has been determined. The results for determining the effectiveness of the baghouse filter show a performance of over 99% for practically all the elements/compounds analyzed.

Finally, and in order to mitigate the environmental impact associated with open-air burning, the energy recovery of splinters from orange and almond tree pruning remains has been evaluated, showing great technical feasibility.

The development of the project has made it possible to adapt a pollutant dispersion model to obtain PM2.5 emission factors for the open burning of orange, olive and almond tree pruning, giving an average factor significantly lower than those proposed in the EMEP/EEA 2013 Guide and by GAINS. Similarly, the study of chemical profiles of PM2.5 shows a clear influence of elements associated with phytosanitary treatments (pesticides, herbicides,…) and crop fertilization, as well as the composition of the biomass and the soil where the crops are located.