Nutrients from anaerobic digestion effluents for cultivation of the microalga Nannochloropsis sp. - Impact on growth, biochemical composition and the potential for cost and environmental impact savings
Journal article, 2017

Microalgal biotechnology has yielded a range of products for different consumer markets, but large scale production for bulk commodities is limited by the cost and environmental impact of production. Nutrient requirements for large-scale production contribute significantly to the cost and environmental impact of microalgal biomass production and should subsequently be addressed by more careful sourcing of nutrients. This study assessed the use of nitrogen and phosphorus contained in effluents from anaerobic digestion of food waste to cultivate the marine microalga Nannochloropsis sp. With suitable dilution, effluent could replace 100% of nitrogen demands and 16% of required phosphorus, without significant impacts on growth or biomass productivity. Additional phosphorus requirements could be decreased by increasing the N:P molar ratio of the media from 16:1 to 32:1. Nannochloropsis sp. accumulated lipid up to 50% of dry weight under N-stress, with significant increases in the content of saturated and mono-unsaturated fatty acids. Using empirical data generated in this study, the cost and environmental impact of nitrogen and phosphorus supply was assessed versus the use of fertilizers for biomass and biodiesel production. Nutrient requirements predicted by the Redfield Ratio overestimating impacts by as much as 140% compared to empirical data. By utilising residual nutrients and optimising nutrient supply, the cost and environmental impact of nitrogen and phosphorus were decreased by >90% versus the use of artificial fertilizers. This study demonstrates the importance of using empirical data for process evaluation and how anaerobic digestate effluent derived nutrients can contribute to the sustainability of algal biomass production.

Nutrient sustainability

Biodiesel

Microalgae

LCA

Anaerobic digestate effluents

Biomass

Author

Joshua Mayers

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Anna Nilsson-Ekman

RISE Research Institutes of Sweden

Eva Albers

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Kevin J. Flynn

Swansea University

Algal Research

2211-9264 (ISSN)

Vol. 26 275-286

Upgrading of renewable domestic raw materials to value-added bulk and fine chemicals for a biobased economy: technology development, systems integration and environmental impact assessment (BioBuF)

Formas, 2013-06-17 -- 2018-12-31.

Västra Götalandsregionen, Regional development committee, 2013-11-01 -- 2018-10-31.

Subject Categories

Bioremediation

Bioprocess Technology

Bioenergy

Microbiology

Areas of Advance

Energy

Life Science Engineering (2010-2018)

DOI

10.1016/j.algal.2017.08.007

More information

Latest update

7/12/2018