Avaliação do potencial de geração de biogás a partir do dejeto bovino por meio da Bioaumentação

Abstract

It is increasingly necessary to search for alternatives that allow treating animal production waste efficiently and that do not result in an increase in the cost of the final product. Among them is anaerobic digestion (AD), which consists of a technique that allows recycling organic waste and generating energy in the form of methane. One of the alternatives to increase the efficiency of biogas production is to enhance the stages of the anaerobic process. In these systems, the technique of bioremediation or bioaugmentation can be used, which is achieved through the application of a bioaugmentator composed of environmental facultative bacteria. Therefore, the objective was to evaluate the potential for biogas production from AD of bovine manure using bioaugmentation, optimizing the operating parameters in a batch-type bioreactor system. A completely randomized design was used, with four treatments and three replications. The treatments were different compositions of substrate and addition of bioremediator, in anaerobic digestion, in batch-type biodigesters, as follows: DB (Bovine manure only, control); DBI (Bovine manure + inoculum); DBI3 (Bovine manure + inoculum + 3 mL of bioremediation additive); DBI9 (Bovine manure + inoculum + 9 mL of bioremediation additive). The inoculum from a UASB reactor (Upflow Anaerobic Sludge Blanket) from a food industry effluent treatment unit was used. The bioremediator formulation was in gel, containing environmental bacterial spores, being composed of different concentrations of Bacillus megaterium, Bacillus mycoides, Bacillus amyloliquefaciens and Bacillus thermoglucosidasius. The substrates were characterized in terms of pH, Dry Mass (DM), Organic Dry Mass (MSO) and Inorganic Dry Mass (MSI), total organic carbonate/total inorganic carbonate ratio (FOS/TAC) and nutrient concentration. To evaluate the efficiency of the system, the quantification of the volume of biogas was carried out, as well as the characteristics and concentrations of the gases generated in the ix biodigesters. Data were submitted to analysis of variance, using the F test, and when significant, the means were compared using Tukey's test, at 5% significance level. With regard to DM of bovine manure and inoculum, averages of 13.07 and 8.49% were found, respectively. Regarding MSO, bovine manure and inoculum showed averages of 11.59 and 5.95%, respectively. With regard to MSI, inoculum had the highest average, 2.54% compared to bovine manure (1.48%). The biodigestion process lasted for a total period of 65 days, with maximum production ranging from 0.19 to 5.21 LN g-1 of MSO. The use of the inoculum, as well as the inoculum together with the bioremediator provided better performance in the production of biogas throughout the experimental period. The evaluations carried out with a view to increasing the production of biogas from batch reactors demonstrated that the inclusion of inoculum in the AD process was efficient in increasing the production of biogas and the dose of 9 mL of bioremediator showed better results.