Effect of continuous low-concentration ammonia aeration on growth and nitrogen uptake in microalga <i>Botryococcus braunii</i>

In this study, semi-continuous cultivation of microalga (Botryococcus braunii) was conducted by aeration with a mixture of ammonia (NH3) and carbon dioxide (CO2), which simulates the waste gas generated during the composting of livestock waste, to investigate the possibility of using NH3, an odorant substance, as a nitrogen source for microalgal cultivation.By using NH3 as a nitrogen source, more than 1.3 times more nitrogen could be fixed as organic nitrogen while maintaining a higher algal density than when potassium nitrate (KNO3) was used as the nitrogen source.In addition, a comparison of three different nitrogen sources, namely, KNO3, ammonium sulfate ((NH4)2SO4), and NH3, revealed that the use of NH3 as a nitrogen source resulted in higher nitrogen absorption by the alga.