Micro-organismos eficientes (EM’s) na compostagem de palha de cana-de-açúcar e esterco bovino

Abstract

Due to increasing demand of goods and products, agricultural systems are responsible for the generation of large quantities of solid waste, they represent a problem of social, economic and environmental. In order to evaluate the composting process of straw sugar cane and cattle manure were compared different concentrations of Effective Microorganisms (EM 's) using benchtop reactors ( 15 L capacity ). To this end, four treatments were tested with respect to the waste mixture C / N ratio of 30:1, adding the following concentrations : B (without addition of EM 's), T25 (100 mL EM's + 300 ml water), T50 (200 mL EM's + 200 ml water) and T100 (400 mL EM's). The composting process was conducted over 50 days and monitored for their physical - chemical characteristics (pH, electrical conductivity, solids, total carbon, nitrogen content (NTK), weight reduction, temperature and humidity) and microbiological (count Bacteria Heterotrophic, Bacteria Fermenting Lactose and Actinomycetes). For physico- chemical analysis, was observed reductions in C/N 35 to 47% weight and 36 to 47% of all treatments, highlighting the treatment T100 with the largest reductions. Obtained constant values of pH for all treatments on track of pH 8.5 and significant increase in electrical conductivity 700 to 1450 mS cm-1. It was not possible to observe high temperatures in all treatments, with highs of 33°C, possibly because of the humidity of the compounds that remained in the range of 70% and the small size of the reactors that did not favor the retention of heat. For microbiological analysis, was determined the prevalence of Bacteria Heterotrophic in all treatments, and the treatment T100 who had greatest score, compared with the other treatments, 1.8 x 106 CFU g-1 for Bacteria Heterotrophic and 4.0 x 105 CFU g-1 for Actinomycetes. For Bacteria Fermenting Lactose treatment T50 had the highest population count being 8.1 x 105 CFU / g-1. In general it can be seen that the addition of micro-organisms results in benefit to composting, treatment and T100, with the addition of higher concentrations of EM's one that showed the best results for all parameters evaluated.