Anaerobic bio-processing of agricultural waste for the biotechnological production of lactic acid and volatile fatty acid by landfill soil inoculums

With the increase in the world population and the ensuing surge in organic waste, effective management strategies are crucial to prevent environmental pollution. This study aims to address this challenge by utilising organic waste (OW) as the substrate for the production of lactic acid (LA) and volatile fatty acids (VFAs) through anaerobic bioprocessing. The substrates used, included grass, starch, and fruit wastes inoculated with non-sterile inoculum landfill soil (LS). The anaerobic bioconversion was performed by varying the substrate to the inoculum. The results unveil that a digester loaded with 150 g.L-1 of fruit waste, exhibits the highest concentration of LA, reaching a significance of 25 mmol.L-1. A digester fed with 100 g.L-1 starch, also manifests significant LA production (18.50 mmol.L-1). A digester, supplied with 150 g.L-1 starch waste, showcases the highest VFA (92.5 mmol.L-1). Intriguingly, the anaerobic bioprocessing of the grass substrate did not produce LA at all, yet al. the substrates showcased VFA production, albeit with fluctuating and lower concentrations. This study highlights the potential of incorporating simple sugar for enhanced LA production and starch-based substrates for increased VFA production when utilising LS as the inoculum. The anaerobic bioprocessing shows promising outcomes for the future development in sustainable waste utilisation.