A hetero-photoautotrophic algal growth model was studied for improved wastewater treatment and low cost algal biofuel feedstock production. The microalga, Auxenochlorella protothecoides UMN280, was grown heterotrophically on concentrated municipal wastewater and then autotrophically with CO 2 supplementation (air, 1% and 5%, respectively). Strain UMN280 was harvested by self-sedimentation after the heterotrophic stage and the supernatant was aerated with different levels of CO 2 to facilitate autotrophic growth in the second stage. The maximal biomass concentration and lipid content at the first and second stages reached 1.12g/L and 28.90%, and 1.16g/L and 33.22%, respectively. The nutrient removal efficiencies for total phosphorus, ammonia, nitrogen and chemical oxygen demand at the end of the two-stage cultivation were 98.48%, 100%, 90.60% and 79.10%, respectively. The above process can be used to treat organic-rich wastewaters (e.g. industrial and animal manure wastewaters) to achieve the dual purpose of low-cost wastewater treatment and biofuel feedstock production.
Bibliographical noteFunding Information:
The study was supported in part by grants from the University of Minnesota Initiative for Renewable Energy and the Environment (IREE), Metropolitan Council Environmental Services (MCES), Xcel Energy, the Legislative-Citizen Commission on Minnesota Resources (LCCMR). The authors are also grateful to Blanca C. Martinez for providing help in the labs and Adam Sealock of Saint Paul MCES Wastewater Treatment Plant for helping with the sample collection.
- Biofuel production
- Facultative heterotrophic microalgae
- Hetero-photoautotrophic cultivation
- Municipal wastewater