Computational fluid dynamics analysis of Trichosporon fermentans flocculation in refined soybean oil wastewater and flocculation rate prediction method.

Trichosporon fermentans can be used to treat refined soybean oil wastewater (RSOW) and produce microbial lipids. Bioflocculation is an effective method to recover Trichosporon fermentans which accumulates intracellular oils from wastewater. During the flocculation, the hydrodynamic distribution and parameters in the reactor are important limiting factors of yeast flocculation performance. In a 0.25 L flocculation device, it was found that the appropriate range of turbulence kinetic energy was within 0.00065-0.00073 m2/s2, the dissipation rate was within 0.119-0.317 m2/s3, and the shear force was less than 0.433 Pa by computational fluid dynamics. In this case, the flocculation rate (Fr) of Trichosporon fermentans could reach more than 90%. The empirical formula associated Fr of Trichosporon fermentans with hydrodynamic parameters was obtained by Matlab, and improved in the enlargement of flocculation device, displaying an error of less than 3.03%. A conical draft tube airlift circulating reactor for flocculation was designed based on the empirical formula, and the Fr reached 91.3%. The study shows that it is feasible to predict Fr of Trichosporon fermentans according to hydrodynamic parameters by numerical simulation, and design the industrial reactor for flocculation harvesting yeasts. It is also helpful for large-scale treatment of RSOW in a safe environment.

Computational fluid dynamics and factor analysis of a novel swirling demulsified airlift loop reactor for the treatment of refined soybean oil wastewater.

A swirling demulsified airlift loop reactor (SD-ALR) was developed for the treatment of oily wastewater with yeasts. Computational fluid dynamics simulations showed that the gas holdup and liquid velocity gradient in the SD-ALR were 2.9% and 0.37 m/s higher than those in the traditional airlift loop reactor. The optimization results of the swirling demulsifier showed that the optimal number and elevation angle of the blades were 8 and 45°, and the optimal installation position was 150 mm from the bottom of the draft tube. The results of treating refined soybean oil wastewater in the SD-ALR showed that the wastewater treatment time was decreased by 8 h, and the removals of chemical oxygen demand and oil content increased by 5.10% ±â€¯0.02% and 9.55% ±â€¯0.40%, respectively, compared with those in the traditional airlift loop reactor. A volumetric mass transfer coefficient model was established for SD-ALR and oily wastewater.

Refined soybean oil wastewater treatment and its utilization for lipid production by the oleaginous yeast Trichosporon fermentans.

BACKGROUND: The release of refined soybean oil wastewater (RSOW) with a high chemical oxygen demand (COD) and oil content burdens the environment. The conversion of RSOW into lipids by oleaginous yeasts may be a good way to turn this waste into usable products. RESULTS: The oleaginous yeast Trichosporon fermentans was used for treating the RSOW without sterilization, dilution, or nutrient supplementation. It was found that the COD and oil content of the RSOW were removed effectively; microbial oil was abundantly produced in 48 h; and the phospholipids in the RSOW tended to contribute to a higher biomass and microbial lipid content. With Plackett-Burman design and response surface design experiments, the optimal wastewater treatment conditions were determined: temperature 28.3 °C, amount of inoculum 5.9% (v/v), and initial pH 6.1. The optimized conditions were used in a 5-L bioreactor to treat the RSOW. The maximum COD degradation of 94.7% was obtained within 40 h, and the removal of the oil content was 89.9%. The biomass was 7.9 g/L, the lipid concentration was 3.4 g/L, and the lipid content was 43% (w/w). The microbial oil obtained, with a main component of unsaturated fatty acids, was similar to vegetable oils and was suggested as a potential raw material for biodiesel production. CONCLUSION: Trichosporon fermentans can be effectively used for RSOW treatment, and lipid production and can complete pretreatment and biochemical treatment simultaneously, allowing the utilization of RSOW, which both solves an environmental problem and positively impacts the use of resources. These results provide valuable information for developing and designing more efficient waste-into-lipid bioprocesses.

Dichlorido[N-(2-pyridylmethyl-idene)benzene-1,4-diamine]zinc(II).

In the title compound, [ZnCl(2)(C(12)H(11)N(3))], the Zn(II) atom is four-coordinated by two N atoms from an N-(2-pyridylmethyl-ene)benzene-1,4-diamine ligand and two Cl atoms in a distorted tetra-hedral geometry. In the crystal, the complex mol-ecules are connected by N-H⋯Cl and C-H⋯Cl hydrogen bonds into a two-dimensional layer structure parallel to (110).