Effects of different forms of vegetable waste on biogas and methane production performances in a batch anaerobic digestion reactor

Abstract

ABSTRACT Vegetable waste has a high biodegradation ability and moisture content and causes soil and underground water pollution. High moisture vegetable waste could be separated into juice and residual material for efficient disposal and energy recovery by anaerobic digestion (AD). In this study, two kinds of vegetables (Chinese cabbage and mustard) wastes in three different forms (juice, residue, and their mixture) were used to determine their AD process performances and methane production potential. The results showed that the biogas production rate of the Chinese cabbage residue (CR) was the highest, reaching 800 ± 62 mL/g VS. The biogas production rate of mustard juice (MJ) was the lowest, as low as 498 ± 60 mL/g VS. The results also suggested that the biogas and methane production potential in the residue groups of both vegetable wastes treatments was higher than that in the juice groups. Furthermore, the results also showed that the average biogas and methane production rates of the residue treatments of both Chinese cabbage and mustard wastes were much higher than those of their mixtures. The concentrations of volatile fatty acids (VFAs) and total ammonia nitrogen (TAN) in the juice treatments groups were much higher than those in the residue treatments groups, resulting in the lowest biogas and methane production potential being in the juice treatments groups. With the modified Gompertz equation fitting analysis, the results also confirmed that the highest biogas and methane production ability in the CR treatment groups among all the six treatments, with a correlation coefficient (R2) above 0.992. The results of this study provide new insights into the efficient disposal and energy recovery of vegetable wastes with AD for further industrial biogas engineering applications.