Avaliação da biodigestão anaeróbia de resíduos orgânicos: ensaios de potencial bioquímico de metano (BMP) e projeto piloto de um biodigestor em escala real

Abstract

Due to the problem of inadequate disposal of organic wastes mainly in dumps, which unfortunately still exist all over Brazil, several technologies have been applied to promote the reuse of these wastes, because in their decomposition produces gases such as methane with high potential to increase the greenhouse effect . The objective of this research was to evaluate the performance of anaerobic biodigestion with organic residues (substrate) from the university restaurant of the Federal University of Ceará (UFC-PICI), in which it was divided into two experiments, methane (BMP) to evaluate the best inoculum / substrate (I / S) ratio in g / SV and the increase of the specific methane production with the use of lignocellulosic residue (pruning) as a co-substrate under the operating conditions that ensure stability of the anaerobic digestion process. The second experiment, a 1.3m3 biodigestor on a real scale for the production of methane in waste treatment. In this way, experiment 1 was carried out in two phases, the first one being performed with four I / S ratios, being 1: 1; 1: 2; 1: 3; 1: 4, with a constant temperature of 35 ° C, stirring at 150 revolutions per minute (rpm), with hydraulic detention time (TDH) of 60 days. It was observed that in the first phase the highest accumulated volumes of biogas and specific methane were obtained in the ratio 1: 1, with values ​​of 1208.06 NmL / biogas and 420.33 NmLCH4 / gSV, respectively. In the second phase, the pruning co-substrate was used at 5% and 10% of the 1: 1 ratio and obtained values ​​of biogas and methane-specific production respectively 1566.06 NmLbiogás, 536.04 NmLCH4 / gSV for residue of 5% (RP5%) and 1273.41 NmLbiogás and 466.09 NmLCH4 / gSV for 10% pruning residue (RP10%) with a methane percentage of approximately 52.60% and 62.59% of CH4, respectively, for samples containing 5% and 10% pruning. Experiment 2 was used the 1: 1 I / O ratio in which a biodigestor was operated during 150 effective days, with 30 days TDH. A methane yield of 150m3CH4 / tSV and 245m3CH4 / tSV was observed with VOCs of 1 and 2kgSV / m3.day, respectively, showing satisfactory results for low VOCs used in the biodigester. The study proved to be important as a sustainable option that encompasses both waste management, avoiding its inadequate disposal, reducing greenhouse gases, and consequently reducing the impacts of climate change.