Correlação entre os três métodos de quantificação de matéria orgânica: demanda bioquímica de oxigênio, demanda química de oxigênio e carbono orgânico total, para análise de biofertilizantes derivado da biodigestão anaeróbica

Abstract

Anaerobic biodigestion is a process where organic residue undergoes biological decomposition with the aid of microorganisms, under anaerobic and thermophilic conditions in order to obtain by-products such as biogas and biofertilizers. Therefore, this work aims to quantify the organic matter from biofertilizer from the anaerobic biodigestion of two different reactors available by the Laboratory of Solid Waste and Effluents (LARSE), using the methods of Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) and seeking correlations between these parameters. The samples were analyzed by 5-day BOD test, colorimetric method in closed reflux and high temperature combustion method, according to the methodology proposed by Standard Methods 23º edition, with the aid of calibration curves, an average of 1,533.92 mg O2/L, 49,750 mg O2/L and 2,791.67 mg C/L, respectively, for Reactor 4 and an average of 1,764 mg O2/L, 67,128 mg O2/L and 2,403 mg C/L, respectively, for Reactor 5. The result presented of the relationship between BOD and COD demonstrate scans of sufficiently high biodegradable organic matter and promising ability to act as liquid organic fertilizer in crops. The correlation coefficients between the parameters of BOD, COD with comparison of TOC was 0.37 and -0.57, respectively, so it is not possible to consider the existence of correlations between these factors, consequently, substitutions between the techniques are not recommended.