Bacterial cellulose as an oleaginous yeast cell carrier for soybean oil refinery effluent treatment and pyrolysis oil production.

Bacterial cellulose produced from soybean oil refinery effluent is a good immobilization carrier because of the large pores in its fiber network, its high water-holding capacity, and its good biocompatibility. In this study, it was applied to immobilization of oleaginous yeasts for treating soybean oil refinery effluent. The immobilization percentage reached 50%, and the removal of chemical oxygen demand and oil content reached 92.1% and 93.1%, respectively, during dynamic immobilization using a mass percentage of bacterial cellulose of 30% and an immobilization time of 24 h, which were significantly higher than those of free oleaginous yeasts or yeasts immobilized by bacterial cellulose from rich medium. The immobilized oleaginous yeasts facilitated the recovery of the yeasts and effectively treated three batches of soybean oil refinery effluent. The immobilized oleaginous yeasts recovered after soybean oil refinery effluent treatment were pyrolyzed to produce bio-oil, which contributed to more alkanes and a higher calorific value of bio-oil in the pyrolysis products as compared to those of free oleaginous yeasts. As bacterial cellulose used as an oleaginous yeast cell carrier is produced from soybean oil refinery effluent, no waste of immobilization materials is involved and an efficient waste-into-oil bioprocess is developed.

Trichosporon fermentans biomass flocculation from soybean oil refinery wastewater using bioflocculant produced from Paecilomyces sp. M2-1.

The soybean oil refinery (SOR) wastewater contains a high concentration of chemical oxygen demand (COD) and lipid, so the direct emissions of SOR wastewater will result in environmental pollution and waste of resources. Oleaginous yeast Trichosporon fermentans can consume organic materials in SOR wastewater to synthesize microbial oil, which achieves the purpose of SOR wastewater resource utilization. The effective harvesting technology of oleaginous yeasts can improve the utilization efficiency. In this study, Paecilomyces sp. M2-1 with high flocculating activity was isolated. The flocculants produced by M2-1 (MBF2-1) include 75% (w/w) polysaccharides, rely on cations, and display the flocculation percentage of above 77% in the range of pH 2-11. Especially under alkaline conditions, the flocculation percentage can be kept above 97%. The results of scanning electron microscope observation and zeta potential measurements suggested that the bridging, net trapping, and sweeping were the main flocculation mechanism of MBF2-1. MBF2-1 could flocculate T. fermentans that was used to reduce the organic matter in SOR wastewater and to produce microbial oil. Under the optimum conditions, the flocculation percentage of MBF2-1 against T. fermentans from SOR wastewater can reach 95%. Fatty acid content percent in microbial oil from T. fermentans was not almost affected by flocculation of MBF2-1. Moreover, MBF2-1 can further remove 55% and 53% of COD and oil content in the fermented SOR wastewater, respectively. The properties and high flocculating percentage displayed by MBF2-1 indicated its potential application prospect in oleaginous yeast harvest and food industry wastewater treatment.