The Research On The Preparation And Characterization Of Microbial Flocculant To Seawater Purification

In this paper, the screening of microbial bacteria with flocculating activity wascarried out. The bacteria were identified, then the genetic background was determined.The optimum culture conditions and growth characteristics were studied. Theseparation, purification and chemical characterization of the bacleria and the use ofthe bacleria as flocculant for seawater treadment were explored.Effective strains were isolated from the samples of Bohai Bay. Five effectivestrains were isolated from the samples. According to their morphology, culturalcharacteristics,16S rDNA and18S rDNA sequences, they were identified as two ofAspergillus niger, one of Penicillium purpurogenum, one of Pseudomonas sp. and oneof Bacillus licheniformis, respectively.In order to study effects of carbon and nitrogen sources, initial pH and aerationrate on the flocculating activity, Penicillium purpurogenum and Bacillus licheniformiswere studied respectively. The best culture conditions of Penicillium purpurogenumand Bacillus licheniformis were obtained.With the qualitative experiment of carbohydrates,proteins, lipids, nucleic acidsand the analysis of UV absorption spectroscopy and infrared spectroscopy, it showedthat the flocculation active ingredient of Penicillium purpurogenum was presented inthe culture supernatant,it was identified as polysaccharides．The flocculation activeingredient of Bacillus licheniformis was presented in the cell detritus and the culturesupernatant, it was identified as glycoproteins with a large amounts of hydroxyl andcarboxyl functional groups．Penicillium purpurogenum extracts molecular weight ofmicrobial flocculant was approximately1.4×10~5Da．Bacillus licheniformis extractsmolecular weight of microbial flocculant was approximately1.1×10~5Da．In order to study the practical application, Penicillium purpurogenum andBacillus licheniformis were used as flocculant for seawater treatment. The resultsindicated that the flocculation effect was batter than combined with other inorganicflocculant, the turbidity of seawater after the flocculantion was maintained at below4NTU and the flocculation rate was93.5%．...