Produção de metano através da co-digestão anaeróbia de soro de leite e resíduos caprinos

Abstract

In the current energy context, the search for renewable and clean energy sources is constantly growing. Thus, methane emerges as one of the alternative renewable energies, assuming an ecologically significant role, with one of the main reasons being its ability to generate only carbon dioxide and water during its complete combustion process. Therefore, the present study aimed to evaluate methane production from the mixture of whey and goat waste. In this study, methane was obtained through the anaerobic fermentation of whey and goat waste, reducing the environmental impacts caused by the improper disposal of these materials and adhering to the idea of sustainability and low cost. Whey and goat waste were used as nutrient sources. Batch reactors were used for the biological production of methane, in which operational conditions such as a temperature of 35ºC and an initial pH of 7.0 were adopted. The following values were used: 5g/L of COD (Chemical Oxygen Demand) without agitation and a composition of SL25/RC75 for reactor 1 (R1), 5g/L of COD with agitation at 120rpm and a composition of SL25/RC75 for reactor 2 (R2), 10g/L of COD without agitation and a composition of SL50/RC50 for reactor 3 (R3), and 10g/L of COD with agitation at 120rpm and a composition of SL50/RC50 for reactor 4 (R4). Additionally, different mass compositions of the waste were used in each reactor, following a pre-established model. Duplicate analyses were performed using a total of 4 reactors in the experiment. Equipment such as a gas chromatograph (GC) and a shaker incubator, as well as software such as Origin and MINITAB, were used to obtain the results, which were adjusted with a non-linear regression model represented by the Gompertz sigmoidal function. Based on the results obtained, it was found that in terms of specific methane production, reactor 3 (R3) achieved the best result compared to the others used, with an accumulated production of 1221.24 mL of CH4 (methane). Thus, these numbers prove that there is a solution to the problem of the large accumulation of waste and its improper disposal.