Feasibility study of biogas upgrading coupled with nutrient removal from anaerobic effluents using microalgae-based processes

• Published in: Journal of applied phycology 2016-08, Vol.28 (4), p.2147-2157
• Main Authors: Posadas, E., Szpak, D., Lombó, F., Domínguez, A., Díaz, I., Blanco, S., García-Encina, P. A., Muñoz, R.
• Format: Article
• Language: English
• Subjects: Absorption; Algae harvesting; Biogas; Biomass; Biomedical and Life Sciences; Carbon dioxide removal; Ecology; Feasibility studies; Freshwater & Marine Ecology; Life Sciences; Microalgae; Nutrient removal; Phosphorus removal; Plant Physiology; Plant Sciences; Retention time
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-015-0758-3

The present research was conducted to simultaneously optimize biogas upgrading and carbon and nutrient removal from centrates in a 180-L high-rate algal pond interconnected to an external CO 2 absorption unit. Different biogas and centrate supply strategies were assessed to increase biomass lipid content. Results showed 99 % CO 2 removal efficiencies from simulated biogas at liquid recirculation rates in the absorption column of 9.9 m 3  m −2  h −1 , concomitant with nitrogen and phosphorus removal efficiencies of 100 and 82 %, respectively, using a 1:70 diluted centrate at a hydraulic retention time of 7 days. The lipid content of the harvested algal–bacterial biomass remained low (2.9–11.2 %) regardless of the operational conditions, with no particular trend over time. The good settling characteristics of the algal–bacterial flocs resulted in harvesting efficiencies over 95 %, which represents a cost-effective alternative for algal biomass reutilization compared to conventional physical–chemical techniques. Finally, high microalgae biodiversity was found regardless of the operational conditions.