Simultaneous chromium removal and lipid accumulation by microalgae under acidic and low temperature conditions for promising biodiesel production

Microalgae have become the hotspot of recent researches as heavy metals (HMs) adsorbent and biodiesel pro-duction feedstock. In this study, the cell growth, lipid production and Cr6+ removal of Parachlorella kessleri R-3 at pH 3.5 and 15 degrees C were investigated. It was found that low concentration of Cr6+ (0.5 to 2 mg/L) promoted the algal growth, whereas Cr6+ higher than 5 mg/L inhibited the growth of P. kessleri R-3. Biomass concentration (2.40 g/L) and lipid productivity (131.79 mg/L d-1) reached the highest at 2 mg/L Cr6+, and lipid content (61.03 %) reached the highest at 5 mg/L Cr6+. The maximum Cr6+ removal efficiency of 91 % was obtained at 0.5 mg/L Cr6+ treatment. Furthermore, fatty acid composition analysis showed that strain R-3 had a high C16-18 content of 74.88-89.21 %. This study provides new insight into the treatment of HMs and lipid production in cold regions.

Automated summary

This study investigated the cell growth, lipid production, and Cr6+ removal of Parachlorella kessleri R-3 at pH 3.5 and 15 degrees C. It was found that low concentration of Cr6+ promoted algal growth, while high concentrations inhibited growth. The highest biomass concentration (2.40 g/L) and lipid productivity (131.79 mg/L d-1) were achieved at 2 mg/L Cr6+, while the highest lipid content (61.03%) was achieved at 5 mg/L Cr6+. The maximum Cr6+ removal efficiency of 91% was obtained at 0.5 mg/L Cr6+. Fatty acid composition analysis showed a high content of C16-18 in strain R-3 (74.88-89.21%). This study provides new insights into the treatment of heavy metals and lipid production in cold regions.