ANAEROBIC DIGESTION OF BREWER'S SPENT GRAIN WITH BIOCHAR - BIOGAS PRODUCTION KINETICS AND PROCESS EFFICIENCY

Biochars made from brewer's spent grain were added to the anaerobic digestion of brewer's spent grain to enhance the methane fermentation process and improve biogas production. In research, the effect of biochars made at 300, 450, and 600 degrees C and doses of 1-8% added to anaerobic digestion was tested. The biochemical biogas potential tests in mesophilic conditions were performed. The tests took 28 days, the biogas yield for each reactor varied from 500-650 mlxg (-1)(VS), and around 60% substrate degradation was obtained. For each test, the kinetics parameters using the first-order model were determined. The constant biogas production rate (k), and the biogas production rate (r) varied from 0.05-0.08 d(-1), and 42-60 mlx(g (VS)xd)(-1) respectively. Though the differences in biogas production turned out to be statistically insignificant (p<0.05) due to the high disappearance in obtained data and conflicting effects, the response surface area analysis showed that biochar made at 450 degrees C at the share of 1-4% could be used to maximize biogas production. Nevertheless, supplementation with biochar needs to be done carefully since in many cases, a reduction in biogas production was observed.