Microalgal biofilms grown to evaluate potential nutrient removal options for wastewaters and feedstock for biofuels production were studied to determine the influence of bicarbonate amendment on their growth, nutrient uptake capacity, and lipid accumulation after nitrogen starvation. No significant differences in growth rates, nutrient removal, or lipid accumulation were observed in the algal biofilms with or without bicarbonate amendment. The biofilms possibly did not experience carbon-limited conditions because of the large reservoir of dissolved inorganic carbon in the medium. However, an increase in photosynthetic rates was observed in algal biofilms amended with bicarbonate. The influence of bicarbonate on photosynthetic and respiration rates was especially noticeable in biofilms that experienced nitrogen stress. Medium nitrogen depletion was not a suitable stimulant for lipid production in the algal biofilms and as such, focus should be directed toward optimizing growth and biomass productivities to compensate for the low lipid yields and increase nutrient uptake.
Bibliographical noteFunding Information:
The authors would like to acknowledge the Utah Science Technology and Research Initiative ( USTAR ), Utah Water Research Laboratory ( UWRL ), Church and Dwight Co., Inc., National Science Foundation ( NSF ) CHE-1230632, and the U.S. Department of Energy ( DOE ) Office of Energy Efficiency and Renewable Energy ( EERE ) Biomass Program under Contract No. DE-EE0005993 for financial support, as well as Montana State University, Center for Biofilm Engineering ( CBE ) for technical support. Also special thanks to Katie Davis, Luke Halverson, and Todd Pedersen for help and assistance in the CBE laboratories.
- Dissolved inorganic carbon