초록
<P><B>Abstract</B></P><P>Outdoor cultivation of microalgae was carried out in 20‐L tanks using sewage influent or effluent, at an actual sewage treatment plant. The microalgae could be cultured by supplying only sewage influent or effluent without additional microalgal stock or nutrient salts. Adding air and CO<SUB>2</SUB> to the culture water promoted not only the cultivation of green algae but also the consumption of nitrogen. Increasing the hydraulic retention time also promoted consumption and cultivation. In particular, adding CO<SUB>2</SUB> to the sewage influent achieved a 59‐fold increase in the cell number of specific <I>Scenedesmus</I> species useful as components for fuel. The microalgae culture progressed even in the autumn/winter. The major organic components eluted by <I>n</I>‐hexane were fatty acids such as palmitic and 11‐hexadecenoic acid. The applicability of sewage culture microalgae as biofuel was demonstrated.</P>