초록
<P><B>Abstract</B></P> <P>Anaerobic digestion produces biogas and digestate containing CO<SUB>2</SUB> and volatile fatty acids, respectively that might need to be removed if they are to be used or discharged. Algae cultivation would remove the carbon in biogas and digestate. The present work used a textile desizing wastewater digester's biogas and digestate effluent to cultivate microalgae <I>Scenedesmus</I> sp. The tested biogas CO<SUB>2</SUB> and digestate chemical oxygen demand (COD) concentrations were 22% and 3–7 g L<SUP>−1</SUP>, respectively. It is shown that <I>Scenedesmus</I> sp. could simultaneously assimilate biogas CO<SUB>2</SUB> and organic carbon in the digestate. A digestate concentration of 5 g COD L<SUP>−1</SUP> resulted in peak algal biomass concentration, COD removal and bio-CO<SUB>2</SUB> fixation efficiency with values of 1.79 g L<SUP>−1</SUP>, 69.1% and 98.2%, respectively in 10 day algae cultivation. Based on the experimental results, a diagram was proposed to show a wastewater treatment to give an algae and methane bioenergy production concept as an example of circular economy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Scenedesmus</I> sp. could assimilate biogas CO<SUB>2</SUB> and digestate carbon. </LI> <LI> Digestate concentration affected algal biomass growth. </LI> <LI> Digestate 5 g COD L<SUP>−1</SUP> had peak algal biomass concentration and COD removal. </LI> <LI> A diagram of algae and methane bioenergy production concept is proposed. </LI> <LI> Simultaneous biogas up-grading and reduction of digestate pollutant. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>