10-45: Pre-treatment and anaerobic biodegradability of cashew bagasse

The cashew bagasse is a waste from industrial production of juice, which can be used for biogas production, as an alternative to add value to cashew production chain. However, cashew bagasse is mainly comprised of lignocellulosic material that is difficult for biodegradation. The objective of this paper is to improve the anaerobic digestion process and increase the biogas production potential from cashew bagasse. Experiments on thermochemical pre-treatment, using sulphuric acid solution (concentration between 0.17 and 1.20 M) at temperatures ranging from 100 to 120 °C, were conducted in order to make the fibers more accessible to the action of microorganisms, or to produce fermentable sugars (referred as Total Reduced Group - TRG). The results showed that the higher the temperature and time increased the concentration of TRG. Within the ranges studied, the conditions that maximize the concentration of TGR are temperature of 120 °C, sulphuric acid 0.66 M and a reaction time of 36 min. With these parameters, 12.0 g/L of TRG was produced, including 0.021 mg/L of furfural, and 0.225 mg/L of hydroxymethylfurfural. The results also showed that it is of no avails to apply this pre-treatment, as it led to an anaerobic biodegradability of 61%, which is lesser than the biodegradability of the raw material (74%).