Bioaugmentation with Rumen Fluid to Improve Acetic Acid Production from Kitchen Waste

Fermentative kitchen waste to produce high-value chemicals (e.g., acetic acid) has been investigated actively in the past decades. Creating an alkaline condition is widely used to improve the hydrolysis of polysaccharide and inhibit the methanogenesis, but this method significantly increases the overall cost. Herein, the present study investigated the bioaugmentation with rumen fluid to improve acetic acid production from kitchen waste at neutral condition via strengthening hydrolytic and acid-forming bacteria. Results showed that the highest acetic acid yield reached 1.52 g/L at rumen fluid and granular sludge ratio of 1:1. The proportion of acetic acid in volatile fatty acids (VFAs) has increased by 10% compared to control. Microbial community analysis revealed that bioaugmentation with rumen fluid increased the relative abundance of Prevotella and Rikenellaceae_RC9_gut_group which has the ability to degrade polysaccharides and produce acetic acid. Moreover, the proliferation of butyric acid producers (Clostridium_sensu_stricto_1 and Clostridium_sensu_stricto_7) were inhibited significantly, which was in agreement with high acetic acid proportion in VFAs. The bioaugmentation strategy and process optimization provided an energy and cost-saving method for acetic acid production from kitchen waste.