微生物絮凝剂絮凝机理的研究概况及例证

Research on the flocculation mechanism of microbial flocculants

微生物絮凝剂是一类由微生物产生并分泌到细胞外具有絮凝活性的代谢产物。微生物絮凝剂的絮凝机理比传统絮凝理论更复杂,国内外学者对此进行了大量研究。总结近年来国内外研究的相关文献,归纳了关于微生物絮凝剂絮凝理论的各种学说及其例证,指出了现在研究中存在的问题,并对今后的研究方向进行了展望。

Microbial flocculants is a type of metabolites which possessing flocculating activity and secreted outside of cells of microbe,in general constituting of various polymer materials such as polysaccharide,protein,DNA,cellulose,glycosidoprotein,amino acids and etc.A variety of functional groups are contained in the molecules,which are able to unite colloidal suspensions in water with each other for coagulation and precipitation.In the traditional flocculation,the inorganic flocculating agent do not yield good results,even worse;it would bring a lot of metallic ions into the final products and cause the environmental pollution.The organic synthetic polymeric flocculating agents are difficult to be degraded.The residual monomers are poisonous,which may cause secondary pollution.Compared with the traditional flocculating agent,a prominent feature of microbial flocculants is biological degradability,and it also has the features of high efficiency,non toxicity,non secondary pollution and broad spectrum.Therefore,it has attracted extensive attentions and studies both at home and abroad.Currently,considerable numbers of research work on the flocculating mechanism of microbial flocculants.Many theories that can explain the flocculating process under specified conditions have been proposed,such as adsorbing and bridging theory,cellulose fibrils outside bacterium theory,exogenous agglutinin hypothesis,virus theory,chemical reaction theory,Crabtree＇s PHB ester combination theory and Butterfield＇s viscosity hypothesis.This paper has made a summarization and conclusion on the various flocculation theories of microbial flocculants in detail.Besides that,we point out the existing problems in the present research and propose an expectation on the development trend in the future.