Biogas production from low-organic-content sludge using a high-solids anaerobic digester with improved agitation

Xiaocong Liao and Huan Li

Applied Energy, 2015, vol. 148, issue C, 252-259

Abstract: Sludge with a low organic content has poor biochemical methane potential. High-solids digestion is a possible method to recover bioenergy economically from this kind of sludge, but the blocked mass transfer is a major obstacle. A pilot scale high-solids anaerobic digester equipped with an enhanced stirring system was designed and operated continuously for 9.5months to evaluate the feasibility of bioenergy recovery from low-organic-content sludge. The results showed that high-solids anaerobic digestion can evolve successfully from low-solids status. Although the system once suffered slight inhibition derived from ammonia, it then stabilized with volatile fatty acids concentration of 200–400mg/L and free ammonia concentration less than 250mg/L, exhibiting similar removal rates of organic solids and biogas yields as achieved using low-solids digestion. Statistical analyses proved that the organic removal rate was almost proportional to the organic content of feed sludge. The organic removal rate was nearly 35% when the organic content of feed sludge was 50%, while the system tended to failure when the organic content of feed sludge was less than 38%. High-solids anaerobic digestion, when combined with improved agitation, is an effective method for bioenergy recovery from sludge with organic content of 40–50%.

Keywords: Sludge; Anaerobic digestion; Biogas; Ammonia; Volatile fatty acids (search for similar items in EconPapers)
Date: 2015
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Citations: View citations in EconPapers (14)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:appene:v:148:y:2015:i:c:p:252-259

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DOI: 10.1016/j.apenergy.2015.03.082

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