# Co-Degradation of Coal and Sawdust for Enhanced Microbial Methane Production

## TL;DR

Adding sawdust to coal helps microbes produce more methane, offering a cleaner way to convert coal into energy.

## Contribution

A novel co-degradation method using sawdust to enhance microbial methane production from coal.

## Key findings

- A 4:1 coal-to-sawdust ratio significantly increased methane yield compared to coal alone.
- Sawdust enriched the substrate with bioavailable compounds and improved degradation of complex coal components.
- Microbial communities became more specialized and interconnected with sawdust addition.

## Abstract

It is difficult to efficiently obtain methane from coal using microbes because coal’s hard structure resists breakdown. This study tested whether adding sawdust—a natural waste material—could help microbes break down coal more easily and produce more methane gas. We mixed different amounts of sawdust with coal and measured gas production. We found that adding sawdust greatly increased methane output, especially when the ratio of coal to sawdust in the degraded substrate is 4:1. Sawdust provided easier-to-digest food for the microbes, helping them thrive and work together more effectively. This approach offers a cleaner and more efficient way to turn coal into energy, which could help reduce waste and provide sustainable energy without requiring harsh chemicals or high energy inputs.

Microbial coal gasification is a highly promising bioenergy technology, yet its efficiency is often constrained by the highly polymeric structure of coal. This study explores a novel approach to enhance methane production from low-rank coal through anaerobic co-degradation with sawdust. Using Xilinguole lignite as the substrate, we systematically assessed how wood chip supplementation influences microbial degradation efficiency and community dynamics. Results demonstrated that co-degradation significantly increased methane yield—most notably at a coal-to-wood chip ratio of 4:1—far surpassing methane production from coal alone. The addition of sawdust enriched the substrate with bioavailable hydrocarbons and organic acids, and enhanced the degradation of complex compounds including aromatics and lipids. Microbial analysis revealed a marked shift in community structure, with increased abundance of key genera such as Bacillus, Clostridium, and Bathyarchaeia, indicative of enhanced functional specialization and metabolic cooperation. Network analysis further confirmed more tightly interconnected microbial communities in co-degradation systems. These findings underscore the potential of sawdust as a co-substrate to facilitate microbial coal conversion by improving utilization efficiency and promoting synergistic microbial interactions. This strategy offers a practical and efficient means to advance the bioenergy recovery from low-rank coal resources.