ACTIVITY OF DECOMPOSING MICROORGANISMS IN THE COMPOSTING OF POULTRY PRODUCTION CHAIN RESIDUES ASSOCIATED WITH CRUDE GLYCERIN

In composting, the intensity of the activity of the decomposing microorganisms is related to the diversification and concentration of nutrients. These microorganisms realized most of the chemical and physical modifications of the material, being possible in this way, to determine the speed rate of the process. The basal respiration rate is one of the parameters applied to quantify the level of microbial activity in the composting process, since it allows to make inferences about the content and stage of the organic matter decomposition, being influenced mainly by temperature, nutrients and carbon. Therefore, the objective of this study was to evaluate the activity of the microorganisms involved in the process of composting organic residues from poultry production associated with crude glycerin. The experiment was developed in the Federal University of Paraná (UFPR/ Palotina), being conducted in composites built with pallets. The residues used in composting as carbon sources were urban tree trimmings, sugarcane bagasse and crude glycerin and nitrogen sources were poultry litter, flotation sludge and hatchery waste. The treatments consisted of the organic residues and concentrations of crude glycerin in the natural mass (0.0; 1.5; 3.0; 4.5 and 6.0%) and were defined according to the carbon and nitrogen composition of the residues, setting the C:N ratio of approximately 26:1. During composting, the basal respiration rate, temperature and total organic carbon (TOC) were monitored biweekly. Data were submitted to analysis of variance and Tukey's test at 5% probability for comparison of the means, using the statistical software R and later the Spearman correlation matrix was calculated with the variables time, temperature, TOC and basal respiration. There was no significant difference between TOC concentration and basal respiration, however the correlation was high, suggesting that the addition of crude glycerin did not interfere in the ambiance and performance of the microorganisms on the organic matter. TOC and time (biweekly) presented a significant correlation (p <0.05) for all treatments. The accentuated decline in TOC is due to the accelerated consumption of the more labile forms of carbon by the microorganisms present at the beginning of composting. During the most active phase of the process, the C-organic decreases in the material due to the decomposition of the organic matter, which reduces the weight of the pile and consequently decreases the C:N ratio, because microorganisms eliminate part of the TOC as carbon dioxide.