Acidogenic digestion of organic municipal solid waste in a pilot scale reactor: Effect of waste ratio and leachate recirculation and dilution on hydrolysis and medium chain fatty acid production

Abstract The purpose of this investigation is to study the effect of 1) leachate recirculation (LR) and dilution (LD), 2) the increment of the waste ratio, and 3) co-digestion using poultry waste as co-substrate for enhancing the acidogenesis process of the organic municipal solid waste (OMSW), thereby increasing the medium chain fatty acids (MCFAs) production. The results of the experiment carried in a batch pilot reactor show that LR increases hydrolysis as well as the OMSW conversion efficiency. Meanwhile, the highest total MCFA production of around 62,000 mg/L is shown for LR with a high OMSW ratio. Thus, a high concentration of hexanoic acid is shown in LR lysimeters (5475 mg/L, 6627 mg/L, and 10,889 mg/L respectively). However, a metabolic shift toward the production of heptanoic and octanoic acids is reported for LD samples. Nonetheless, the use of poultry waste as co-substrate in the co-digestion process multiplied the concentration of the produced MCFAs.