Biodiesel production and properties estimation from food waste and domestic wastewater by Rhodosporidium toruloides

Producing biodiesel from food waste (FW) would benefit both environment and economy. Current study investigated biodiesel production from food waste and domestic wastewater by utilizing the oleaginous yeast Rhodosporidium toruloides under non-sterile condition. The potential of biolipid production from the mixture of effluents of existing local FW treatment facilities and domestic wastewater was firstly evaluated. Then, to increase the nutrient recovery efficiency, FW hydrolysis process by crude enzymes produced from solid FWs by Aspergillus oryzae was introduced and the conditions were further optimized. The optimized hydrolysis process resulted in reducing sugar (RS) yield of 251.81 ± 8.09 mg g_dryFW^-1 and free amino nitrogen (FAN) yield of 7.70 ± 0.74 mg g_dryFW^-1 while waste oil with the RS yield of 93.54 ± 0.01 mg g_dryFW^-1 was easily separated without solvent usage. Compared to the hydrolysate only used, when mixed with domestic wastewater, the results showed obvious enhancement on biomass yield, biolipid yield, and wastewater treatment efficiency. The maximum biolipid yield was 29.80 ± 0.50 mg g_dryFW^-1 and the estimated quality of biodiesel produced from the biolipid met both EN 14214 and ASTM D6751 standards.