Soybean oil refinery effluent treatment and its utilization for bacterial cellulose production by Gluconacetobacter xylinus

Gluconacetobacter xylinus was used to treat soybean oil refinery effluent (SORE), which is rich in fatty acids, to produce bacterial cellulose (BC) under static conditions. The chemical oxygen demand (COD) and oil content removed were over 50% and 65%, respectively, and the maximum BC production obtained reached 1.3 g/L. Feeding sodium soap from oil or fatty acids to G. xylinus further demonstrated that fatty acids could be utilized for BC production. Re-utilization of the treated SORE contributed to increased COD and oil content removal, and BC production. When the SORE was mixed with barm washing effluent at a ratio of 75:25 (v/v) or with 2% corn steep powder as a co-substrate, the BC production was 1.9 g/L and 2.2 g/L, respectively, and good wastewater treatment effects were seen. A series of characterization results indicated that there was no significant difference in the composition, microstructure, and characteristics of the BC produced from a rich medium and SORE. However, compared to BC from a rich medium, BC produced from the SORE displayed slender cellulose fibrils, larger pores in the fiber network, a looser structure, and good water-holding capacity. This study demonstrated that SORE could be utilized by G. xylinus for BC production, thus realizing resource utilization of wastewater.