# Methane Yield and Microbial Dynamics in Solid-State Anaerobic Codigestion of Sugar Cane Bagasse and Bovine Manure

## TL;DR

This study explores how to optimize methane production from sugar cane bagasse and bovine manure using solid-state anaerobic digestion.

## Contribution

The study identifies optimal conditions and microbial dynamics for efficient methane production from lignocellulosic biomass.

## Key findings

- Intermediate total solids and C/N ratios maximized methane yields.
- Codigestion with bovine manure allowed higher organic loading without inhibition.
- Microbial communities shifted with process conditions, impacting digestion efficiency.

## Abstract

Solid-state anaerobic
digestion (SS-AD) offers a sustainable route
for the valorization of agro-industrial residues, yet its efficiency
is often constrained by limited mass transfer and process instability.
This study investigated the codigestion of sugar cane bagasse (SCB)
and bovine manure (BM) under varying substrate-to-inoculum (S/I) ratios
(0.5–2.0), total solids (TS, 8.9–17.2%), and carbon-to-nitrogen
(C/N, 16–37) ratios to identify optimal operating conditions
for methane production. The highest volumetric methane yields (12.6
to 13.9 L CH4 L–1 reactor) occurred at
intermediate TS (11.6 to 12.5%) and C/N (19 to 26%) values (T1 and
T4). Monodigestion of SCB was feasible up to S/I = 1.0, while codigestion
with BM enabled higher organic loading (S/I = 1.5) without inhibition.
A shift in the microbiological profile was observed from T1 to T4,
with a predominance of Clostridium sensu stricto 1 and Solibacillus, both of which are
associated with the degradation of lignocellulosic compounds. In T4,
the presence of Pseudomonas stood out, indicating a greater microbial
diversity in this SCB monodigestion trial. The archaeal community
was dominated by Methanosarcina in
T4, with a higher diversity of genes associated with the hydrogenotrophic
pathway, followed by the acetoclastic pathway. By linking microbial
community dynamics to process performance, this study defines operational
thresholds that enhance SS-AD efficiency and resilience, supporting
the development of robust dry-digestion systems for lignocellulosic
biomass valorization.