Screening of High-performance Flocculant-producing Bacteria and Optimization of the Conditions for Flocculation of Wheat Distillery Wastewater

Abstract

This study aimed to screen high-performance flocculant-producing bacteria for flocculating suspended matter in wheat distillery wastewater. After the preliminary and secondary screening, a high-performance flocculant-producing bacteria strain was screened from the activated sludge of wheat distillery wastewater. Single factor and orthogonal experiments were used to optimize the culture and flocculent conditions for the flocculant-producing bacteria. A superior strain of Klebsiella M1 was screened and identified by 16S rDNA. The initial flocculating degree was up to 72%. Based on single-factor tests, the optimum flocculent conditions were a resting time of 30 min, 8%(v/v) culture medium dosage, and 3%(v/v) CaCl2. The optimum culture conditions were an incubation temperature of 30 °C for 48 h at pH 4.5 and rotation speed of 150 rpm. Under the optimum conditions, the flocculating degree was up to 82%. The best fermentation medium components were 15 g/L glucose, 2 g/L peptone, 1 g/L KH2PO4, and 2.5 g/L K2HPO4. A high flocculating degree was also achieved with the low-cost medium. The Klebsiella M1 bacteria strain can be used as a good bioflocculant produced bacteria for wheat distillery wastewater.