To make large-algae cultivation systems sustainable, commercial fertilizer inputs should be minimized. One means of achieving this is to maximize the recycle of nutrients used in algae cultivation. In addition to recycling nutrient-containing water from algae harvesting and dewatering, after harvesting algal biomass can be used as a substrate for anaerobic digestion, which can then generate mineralized nutrients to be used for further cultivation. In this study, the effect of recycling media and using mineralized nutrients during Scenedesmus cultivation was investigated. The recycled media proved to be able to support cell growth with nutrient replenishment, and it could be recycled for cultivation up to four times. Algae biomass was subjected to anaerobic digestion, and the liquid digestate and the total digestate were tested as nutrient sources. The digestate was rich in ammonium ions and proved to be a sufficient replacement for urea. When both urea and ammonium ions were available in the media, the assimilation of urea by algal cells slowed down compared to the case where urea was the only nitrogen source.

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Published in Journal of Renewable and Sustainable Energy, v. 8, issue 1, 013116, p. 1-14.

© Author(s) 2016.

All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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The authors would like to thank the Kentucky Department of Energy Development and Independence for funding and Dr. Jennifer Aurandt for supplying the anaerobic digestate.

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The information reported in this paper (16-05-017) is part of a project of the Kentucky Agricultural Experiment Station and is published with the approval of the Director.