Contamination levels in biomass and spent media from algal cultivation system contaminated with heavy metals

Abstract Sustainability assessments have shown that integrating CO 2 from power plants with microalgae production systems can reduce costs and greenhouse gas emissions. However, coal fired flue gases contain contaminants (heavy metals) that could have a deleterious effect on products derived from such systems. To address this concern, photobioreactors (PBRs) were designed to test the hypothesis that metals in a microalgae cultivation system at concentrations derived from flue gas will limit end uses of the biomass and spent medium. Scenedesmus obliquus were grown in PBRs spiked with 10 metals found in such flue gases at concentrations representing typical (1X) and high (5X and 10X) metal loading scenarios. Results show that contamination levels can be modulated by managing the harvesting time and by leaching, with EDTA being effective at early growth stage (approximately ≤ day 6) and acidified methanol effective afterwards. Although metals limit biomass and medium uses, some uses fall within regulatory limits (e.g., 1X spent medium is suitable for irrigation, and 1X biomass is suitable for bio-fertilizer and select animal feed uses). Results showed that uses of biomass and medium under higher loading scenarios from such integration will restrict end uses of both biomass and media.