Effect of Hyper-Thermophilic Anaerobic Digestion on Microbial Health and Biogas Viability.
Author: Noah Christy
Year: 2023
Supervisors: Halldór Guðfinnur Svavarsson, Jean-Baptiste Joos
Abstract:
Anaerobic digestion (AD) is the decomposition of organic material by anaerobic bacteria. The process is often used to generate biogas, a renewable natural gas alternative, as well as digestate, a natural liquid fertilizer. AD is normally conducted in the mesophilic temper- ature range (35-38°C), the thermophilic range (50-56°C) is less common but still applied in industry. The process occurring beyond the thermophilic range is often dismissed as unstable and not a viable option for prolonged system health. The research denoted herein is conducted through side by side mini biogas reactors, the baseline being held at 52°C, while its counterpart is subjected to gradual temperature elevation beyond the thermophilic range until resting at 62°C or, the hyper-thermophilic range >60°C Both systems are fed an equivalent organic load of co-digested feedstock comprised of grain, onion skins, dog food, and manure. The experiment is conducted over a period of 188 days. The result shows both reactors maintained prolonged survival of single stage hyper-thermophilic AD. Greater instability in immediate reactions was apparent, but maintaining stable biogas output and microbial health is possible. Careful monitoring of the system and its inhibitor concentrations are required, but this advent of stability indicates the potential for further research into differing feedstocks and further potential of AD in the hyper-thermophilic range.