Lipid production by a mixed culture of oleaginous yeast and microalga from distillery and domestic mixed wastewater.

Lipid productivity by mixed culture of Rhodosporidium toruloides and Chlorella pyrenoidosa was studied using 1:1 mixed real wastewater from distillery and local municipal wastewater treatment plant with initial soluble chemical oxygen demand (SCOD) around 25,000 mg/L, initial cell density of 2×10(7) cells/mL (yeast) and 5×10(6) cells/mL (microalga), at 30 °C and 2.93 W/m2 (2000 lux, 12:12 h light and dark cycles). Lipid content and lipid yield achieved were 63.45±2.58% and 4.60±0.36 g/L with the associated removal efficiencies for SCOD, total nitrogen (TN), and total phosphorus (TP) at 95.34±0.07%, 51.18±2.17%, and 89.29±4.91%, respectively, after 5 days of cultivation without the pH adjustment. Inoculation of microalgae at 40 h of the initial yeast cultivation and harvesting part of inactive biomass at 72 h by sedimentation could improve both lipid production and wastewater treatment efficiency under non-sterile conditions.

Enhancement of lipid productivity of Rhodosporidium toruloides in distillery wastewater by increasing cell density.

This study is to improve the process of producing lipid convertible to biodiesel, from distillery wastewater while simultaneously removing organics and nutrients efficiently by inoculating oleaginous yeast Rhodosporidium toruloides in the presence of indigenous microorganisms. The lipid productivity of R. toruloides was studied using real wastewater obtained from distillery and local municipal wastewater treatment plants. Under the conditions of mix rate of 1:1 with domestic wastewater, initial soluble chemical oxygen demand (SCOD) over 20,000 mg/L and initial cell density of 2×10(7) cells/mL at 30 °C, lipid content and lipid yield achieved were 43.65±1.74% and 3.54±0.04 g/L, with the associated removal efficiencies for COD, total nitrogen (TN), and total phosphorus (TP), 86.11±0.41%, 57.81±0.29%, and 67.69±0.73%, respectively, after three days of cultivation in real distillery wastewater without pH adjustment. The pH of wastewater increased from 3.71 to over 8 in 7 days of cultivation.