PRODUÇÃO DE BIOGÁS A PARTIR DE DEJETOS SUÍNOS: EFEITOS SAZONAIS NO RENDIMENTO DE METANO E NO DESEMPENHO DO BIODIGESTOR

Abstract

This study evaluated the influence of seasonal conditions on the biogas profile generated from swine manure treated in a German-type biodigester. The research was conducted at a finishing pig farm located in the municipality of Rio Verde, Goiás, Brazil, consisting of three production units and totaling approximately 28,000 animals.The residues, composed of feces, urine, feed leftovers, and wash water from the facilities, were subjected to mechanical agitation and subsequently directed to a Continuous Stirred-Tank Reactor (CSTR). The monitoring of biogas production and composition was carried out over a twelve-month period, covering different seasonal conditions, in order to assess the influence of climatic and operational factors on anaerobic digestion efficiency.Measurements were performed three times a day (at 08:00, 11:00, and 16:00) at a fixed point in the pipeline, using a portable digital multigas analyzer capable of quantifying the concentrations of carbon dioxide (CO2), methane (CH4), oxygen (O2), and hydrogen sulfide (H2S).Statistical analyses were conducted in the R environment (R Core Team, 2024), using Pearson correlation, Generalized Additive Models (GAM), and cluster analysis.The results indicated that the observed correlations confirm the influence of oxygen (O2) and temperature on methanogenesis and sulfidogenesis processes. CH4 and CO2 production showed seasonal stability, while O2 and H2S concentrations varied significantly, indicating greater sensitivity to climatic conditions. Cluster analysis demonstrated that more strictly anaerobic environments favor higher methane production.Thus, the integrated monitoring of gases and environmental factors is essential to ensure bioreactor stability, demonstrating that the efficiency of anaerobic digestion depends on the balance between microbiological processes and the adopted operational practices.