Wang X.W., Huang L., Ji P.Y., Chen C.P., Li X.S., Gao Y.H. and Liang J.R.. 2019. Bioresource Technology, 289: 121681.

This study was conducted to evaluate the potential of the marine diatom Phaeodactylum tricornutum in nutrient removal coupled with biodiesel production using different ratios of mixed municipal wastewater (MW) and seawater (SW) as the growth medium. The results indicated that P. tricornutum exhibited high nutrient removal efficiency with the ratios of MW : SW = 1:1 and MW : SW = 2:1, e.g. 87.7–89.9% for chemical oxygen demand (COD), 82.2–86.7% for total nitrogen (TN), 96.0–97.0% for total phosphorus, and 76.9–84.2% for ammonium (NH₃-N). Significantly higher biomass and lipid productivity were obtained with aeration. The highest lipid productivity of P. tricornutum was 54.76 mg/L/day, which was obtained with a two-step cultivation using the ratio of MW : SW = 1:1 by diluting half of the mixture and bubbling with 5% CO₂ during the second step. These results suggested that the marine diatom P. tricornutum exhibited great potential for using mixed wastewater for wastewater treatment and biodiesel production.

Figure 1. Biomass growth curves (A) and biomass, lipid productivity and lipid contents (B) of P. tricornutum cultured in mixed wastewater medium MW : SW = 1:1 at Phase I (8 day) and followed by different treatments for Phase II. MW: municipal wastewater; SW: seawater; 1/2SW + 5% CO₂: diluted by half with seawater with 5% CO₂ aeration; 1/2MIXTURE + 5% CO₂: diluted by half with municipal wastewater with 5% CO₂ aeration; 1/2SW + AIR: diluted by half with seawater with air aeration; 1/2MIXTURE + AIR: diluted by half with municipal wastewater with air aeration. Values with the same letter (a, b or A, B, C) show no significant difference of lipid content or lipid productivity between groups, respectively (p > 0.05, Duncan’s multiple range test).