# Thermophilic microbiome acclimation for enhanced anaerobic digestion of food waste: Optimization and performance evaluation

## TL;DR

This study improves thermophilic anaerobic digestion of food waste by optimizing temperature shifts and organic loading rates to boost biogas production.

## Contribution

A two-stage temperature shift strategy is introduced to acclimate microbiomes for stable and efficient thermophilic digestion.

## Key findings

- Biogas yield peaked at 671.2 ml at 55°C, 60.8% higher than mesophilic digestion.
- Increasing organic loading rate to 4 g VS/(L·d) achieved a peak biogas yield of 2264.8 ml with stable methane concentration.
- Thermophilic digestion enriched hydrolytic bacteria and hydrogenotrophic methanogens like Defluviitoga and Methanoculleus.

## Abstract

Thermophilic anaerobic digestion (TAD) represents a promising approach for food waste (FW) treatment, offering significant advantages including accelerated reaction rates and increased volumetric biogas yield. However, the practical application of TAD is hindered by both the limited availability of thermophilic methanogenic consortia and heightened sensitivity to organic loading rate (OLR) fluctuations. In this study, a two-stage temperature shift strategy from mesophilic to thermophilic was implemented to establish a stable methanogenic community. The results showed that daily biogas yield increased steadily with rising fermentation temperature, reaching to a peak of 671.2 ml at 55 °C, which were 60.8% higher than that of mesophilic digestion. Microbial community analysis revealed that TAD increased the abundance of dominant hydrolytic bacteria (e.g., Defluviitoga) and hydrogenotrophic methanogen (e.g., Methanoculleus), consequently enhancing biogas production efficiency. Moreover, gradually increasing the OLR from 1.5 to 4 g VS/(L·d) significantly enhanced both biogas production and CH4 content, achieving a peak daily biogas yield of 2264.8 ml with sustained CH4 concentration stability (72–76%).