Efficient Strategy by a Newly Isolated <i>Aspergillus oryzae</i> to Harvest <i>Chlorella vulgaris</i> MBFJNU-1 from Original Swine Wastewater

Abstract

Biological approach is a promising method to efficiently harvest microalgal cells after the wastewater treatment by microalgae. This work aimed to develop an efficient bioflocculation process with a newly isolated filamentous fungus to harvest microalgal cells from the treatment of original swine wastewater (OSW) by Chlorella vulgaris MBFJNU-1 and primarily grope the individual mechanism for this bioflocculation. C. vulgaris MBFJNU-1 performed well growth and nutrient removal (total nitrogen, 72.29–90.98%; NH4+-N, 97.18–97.80%; and total phosphorus, 47.51–70.77%) after the OSW treatment. Among the isolated filamentous fungi, Aspergillus oryzae exhibited a superior feature to harvest microalgal cells in the OSW treatment by microalga. Under the optimized conditions, the fungal pellet-assisted method with the newly isolated A. oryzae to harvest C. vulgaris cells achieved the highest bioflocculation efficiency (>90%). Moreover, the obtained results suggested that specific components on fungal pellet-derived cell walls belonged to glycoprotein, playing vital roles in the attachment of Chlorella cells. Furthermore, the fungal–microalgal biomass had around 27% lipid with over 90% C16 + C18, which was the promising feedstock for sustainable and renewable biodiesel production. Taken together, the bioflocculation process mediated with the newly isolated A. oryzae was a promising approach to harvest algal cells from wastewater treatment for sustainable biofuels.