Microalgae Culture with Digestate from Methane Fermentation

－ Effects of Digestate Concentrations and pH on the Growth of Euglena gracilis

抄録

In order to determine the suitable combination of concentrations of digestate from methane fermentation sludge and pH levels for culturing microalgae, Euglena gracilis was cultured in an aqueous solution containing digestate at 5, 10, 20, 25, 40 and 100% concentrations and at pH 3.4, 6.8, and 8.7. The pH of the aqueous digestate solution was adjusted with 10% HCl solution. Photosynthetic photon flux density (PPFD) was 150 µmol m^-2 s^-1 with continuous illumination at 30℃. The number of cells was monitored daily and specific growth rate (µ) was calculated. The highest µ (0.05 h^-1) was obtained at pH 3.4 in 20 – 25% digestate concentrations. This result demonstrates that E. gracilis could be produced at a high growth rate with diluted methane fermentation sludge adjusted to a low pH.