Anaerobic codigestion of bovine manure and banana tree leaf: the effect of temperature variability on biogas yield in different proportions of waste

Anaerobic digestion (AD) is an efficient process for the conversion of predominantly organic waste into biogas. However, when those wastes have a lignocellulosic composition, the process is slower with low rates of biogas production potential. In these cases, the increment with other wastes, known as anaerobic codigestion (AcoD), proves to be effective, especially when animal waste is included. The objective of the study is to obtain the best waste proportion (manure/agricultural waste) according to the volume of biogas produced during the biodegradability test under investigation of the effects of different temperatures (from 36 to 60 °C). The preliminary investigation consisted of sampling and drying the wastes with analytical tests (TS, VS, COD, TOC, N, P, pH, and moisture), what did allow to determine the proportions to be used in the experimental research. The biodegradability test was evaluated in different proportions of substrate (banana leaf) and inoculum (bovine manure) (1:1; 1:2; 1:9; 0:1) under mesophilic and thermophilic conditions. During the test, different temperatures were tested, starting from 36 up to 60 °C, gradually increasing from 2 to 2 °C, every 3 or 5 days, to adapt the anaerobic microorganisms. The investigated proportions presented production different from biogas (in volume), which can be explained by the composition of the proportions and variability of proposed temperatures. The 1:9 proportion was that one which obtained the highest cumulative biogas yield among the proportions, with 113.00 mL/g VS. The results show that the tested AcoD has adaptability when undergone to the variation of temperature, with better profit of biogas in thermophilic temperatures, mainly for the proportion 1:9; when the best condition was considered for the profit of biogas for the employed wastes, in the conditions of the research.