The effect of acetate additives on inoculum on Vs, CoD and microbial communities on food waste anaerobic digestion

Abstract

The inoculum is a growth medium for microorganisms to optimize their growth and optimizes the performance of the Anaerobic Digestion (AD) reactor. Acetate additives on the inoculum are expected to optimize the formation of methanogenic microorganisms that can improve the performance of anaerobic fermentation. There are 2 types of inoculums used in this study, namely natural inoculum and modified inoculum. Natural inoculum is made from cow manure diluted with a ratio of 1:1. Meanwhile, modified inoculum is made of shrimp paste, granulated sugar, rotten banana tree trunks, milk, bran, yeast extract, Lactobacillus MRS Broth, rumen fluid, and acetate addition. The parameters tested in this study include microbial diversity, biogas production, Volatile Solids Destruction (VSD), and Chemical Oxygen Demand removal (CODr). The results showed that acetate additives are not proven to enrich the population of methanogenic microorganisms and biogas production. However, modified inoculums with acetate additives are shown to increase methane concentration, VSD up to 91%, and CODr up to 99.5%. This shows that the modified inoculum has great potential as a growth medium to treat food waste using Anaerobic Digestion (AD) with the help of pH control, which corresponds with the optimum pH range for the methanogenesis stage.