Co-digestion of sewage sludge and microalgae – Biogas production investigations

Eva Thorin, Jesper Olsson, Sebastian Schwede and Emma Nehrenheim

Applied Energy, 2018, vol. 227, issue C, 64-72

Abstract: In municipal wastewater treatment plants (WWTPs), algae could be utilised for cleaning the water and, at the same time, produce a biomass that can be used for energy. Through anaerobic digestion, microalgae can contribute to biogas production when co-digested with sewage sludge. In this paper, previous published results on the co-digestion of sewage sludge and microalgae are summarised and reviewed, and any remaining knowledge gaps are identified. The batch tests currently documented in literature mostly concern digestion under mesophilic conditions, and studies investigating thermophilic conditions are less common. The average biochemical methane potential (BMP) for 29 different mixtures co-digested under mesophilic conditions is 317±101Ncm3 CH4 gVS−1 while the result for 12 different mixtures investigated under thermophilic conditions is a BMP of 318±60Ncm3 CH4gVS−1. An evaluation of the heat required for increasing the temperature from mesophilic to thermophilic conditions shows that increased methane production under thermophilic conditions can be enough to create a positive energy balance. For a full-scale WWTP, using thermophilic digestion on sludge, or a combination of sludge and microalgae could therefore be of interest. This is dependent on the demands on sanitation of the sludge and the possibilities for heat recovery.

Keywords: Biomass; Wastewater treatment; Batch; Continuous; BMP; Anaerobic digestion (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (8)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:appene:v:227:y:2018:i:c:p:64-72

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DOI: 10.1016/j.apenergy.2017.08.085

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