Production of a Bioflocculant by Pseudomonas fluorescens C-2 and Its Application in Wastewater Treatment

摘要

Pseudomonas fluorescensC-2 was found to produce a novel bioflocculant PS-2 with high flocculating activity for Kaolin suspension and six wastewaters .Results showed that the carbon and nitrogen sources favorable for the production of the PS-2 were glucose and soybean flour, and an optimal condition of 30 °C, 5% of inoculum size (v/v), initial pH 8.0 and shaking speed of 150 rpm. The highest flocculating efficiency achieved for Kaolin suspension was 95.8%, after 72 h cultivation. The bioflocculant PS-2 was mainly composed of sugar (86.7%) and nucleic acid (7.8%), and an average molecular weight of 2.38×106. Fourier transform infrared (FTIR) spectra showed hydroxyl, C-H, carbonyl, C-N-H groups were present in the PS-2 molecule. The PS-2 was effective for removal of COD, chromaticity and turbidity of six wastewaters, in particular domestic sewage and riverwater with a turbidity removal efficiency of 95.80% and 95.26%, respectively. The flocculation process indicated negative groups (hydroxyl) in PS-2 molecules made flocculant molecules extend fully and played a role on bridging, it was concluded that the flocculation process was based on the bridging mechanism, the combination of organic particles with PS-2 by hydrogen bond at the active position of bioflocculant.