Potencialidades de resíduos de poda urbana como fonte de energia e de taninos condensados

Abstract

The objective of the present study was to evaluate the biomass generated from tree management in the city of Natal-RN through the evaluation of its use as a source of renewable energy, performing the characterization of the material, for the production of briquettes and quantification of the tannin content. Residues of 12 (twelve) species were collected in the field for the study of tannic potential through extraction and application in water and effluent, and 05 (five) with the highest number of vegetation suppression were selected to study the energy viability through the densification of the matter for briquette production. The material was crushed at the time of collection using a branch chopper and taken to dry in a covered place with good natural ventilation, they were placed on a canvas and turned over daily in order to allow drying homogeneously by heat exchange. After natural drying, the samples of the five species were sent to the UFES wood technology laboratory located in the city of Jerônimo Monteiro, in Espírito Santo, where in the laboratory the material was characterized in terms of chemical composition (lignin, extractives, ash content and holocellulose), superior calorific value (PCS), bulk density, moisture content and briquette making, which were evaluated in relation to height, diameter, volume, density and mechanical resistance. The tannins of the twelve species were extracted, quantified, cationized in order to verify their economic viability for commercialization, then the cationized tannins of the two species that presented the highest content of condensed tannins, Mangifera indica and Terminalia catappa, were applied in dairy effluent and supply water. The bulk density of the residues varied, with Licania tomentosa and Azadiractha indica presenting the highest densities. The lignin content was higher in the Anacardium occidentale, Licania tomentosa and Azadiractha indica residues, this is an important property for the agglutination of the particles during the compaction of the briquettes. All briquettes showed satisfactory PCS, Pseudobombax munguba had the lowest higher calorific value, however, the value is still above the minimum recommended by the Swedish standard (16.2 MJ/kg). The briquettes showed good resistance to parallel compression as a function of density. The results were satisfactory, pointing out that the residues can be auctioned for briquette factories, and have energy potential to promote the creation of factories managed by the municipality, in order to generate employment and income.