The Screening And Application Of Microbial Flocculant

Flocculants are widely used in wastewater treatment. The flocculating activity has big deal with the type of flocculants. Micorbial flocculants are newly developed natural macromolecular organic substance, which have the ability to flocculate various wastewater. For their biodegradability, high performance and harmlessness to the environment, microbial flocculants have drowned more and more attention, and become the front line of investigation. This paper summarized a series of basic research and development om preparation of microbial flocculants. This isolation of flocculant-producing bacterium from active sludge and soil, optimization of culture condition for flocculant production, pilot-scale, the composition, characteristic and flocculation mechanism of the microbial flocculants were studied and discussed systematically. The main centents of research and the results are as follows:(1) For the screening of microbial flocculant-producing microorganism, suspensions from sludge and soil solution were cultivated in given media with Kaolin clay suspension as the test sample for flocculating activity. A flocculant-producinbg bacterium isolated from soil was identified as Bacillus BC—11.(2) Culture medium and conditions for flocculant production were optimized on the basis of original screening culture medium. Under the optimal culture conditions, Bacillus BC—11 synthesized intracellularly and excreted extracellularly viscous flocculant immediately.(3) Under the research of growth curve of Bacillus BC—11, the flocculating substances synthesized intracellularly which mainly existed in ferment liquid.(4) In order to reduce the cost of media, the strain Bacillus BC—11 was cultured in wastewater of yam samponin. The results showed that the strain Bacillus BC—11 could grow and reproduce well, which provided technical and economic feasibility for further production of microbial flocculant on pilot-scale.(5) The results of application studies indicated that the microbial flocculant produced by Bacillus BC—11 had the ability to flocculate various simulating wastewater and practical wastewater well, especially on the reflex blue wastewater.