Enhancing performance and stability of anaerobic digestion of chicken manure using thermally modified bentonite

In this study, anaerobic digestion was carried out along with bentonite addition to avoid ammonia accumulation, which significantly inhibits methane production. To make better use of bentonite, calcinations were applied for modification. Chicken manure was anaerobically digested for 75 days at 35 ± 1 °C in lab-scale sequencing batch reactors. Better performance in methane production and process stability was observed in reactors treated with bentonite, compared to those without bentonite. Among all treatments, the maximum increase of 41% in cumulative methane was found with the treatment where bentonite thermally modified at 300 °C was applied. The treatment also revealed stable variation of pH, total ammonia nitrogen (TAN), and free NH3 contents. In addition, adsorption capacity of bentonite to TAN was enhanced significantly with thermal modification as well, the TAN concentration reduction was improved by 5%-12% compared to natural bentonite.