Study On Sorption Of Heavy Metal Chromium Ions By Microorganism

The heavy metal is a kind of very harmful pollutant in ecological environment. Dealing with the low density (<50mg/l) heavy metal in the waste water, traditional treatment method, such as chemistry precipitates law, electrolysis, ion exchange law etc. exist some shortcomings of operate with complexity and high costs in various degree, and easy to cause secondary pollution. In recent years, the biological adsorption method arouses great concern from vast researchers because of its high efficiency and friendly character to environment. At present, the researches on biological adsorption focus on heavy metal cation. But a lot of virulent metals exist (such as Cr, V, Se, Mo) in the form of anion in the real waste water, so the research on biological adsorption of anion has important realistic meanings. The experiment mainly study the absorbing characteristic of aspergillus to Cr⁶⁺. The strain M-06, showing relatively strong ability of adsorbing Cr⁶⁺, was screened from 33 strains come from different sources, and was identified. By the analysis of adsorbing active distribution,the main body of adsorption was ascertained. The action of biosorption and bioaccumulation were compared. By comparing the adsorbing capability of aspergillus to Cr6+ in different incubation period, appropriate incubation time of aspergillus were obtained. During the adsorbing course of the strain M-06 to Cr⁶⁺, the effect of physical and chemic condition to adsorption was studied. In the experiment, the effect of pH value to adsorption is more remarkable. Other factors such as response time, temperature, biomass, metal ion concentration etc. can also affect the result of adsorption in various degree. Six method of immobilizing biomass were compared, in which the method of immobilizing M-06 with 5%PVA+1%SA as entrapnet material was considered to be the optional. The absorbing characteristic of immobilized strain M-06 and the influence of concomitant ion to adsorption of Cr6+ were investigated. During dealing with the remainder ion of Cr3+ in the solution, the results indicated that the strain M-06 can also get rid of Cr3+ effectively. The ions of Cr6+ and Cr3+ adsorbed on the immobilized strain M-06 could be desorbed, and the biosorption agent still have good characters in the course of reuse. Through the treatment of the immobilized strain M-06, the actual waste water containing Cr6+ could be let out legally. It is obvious that the treatment method has better applied prospects. In the end, through the study of the strain M-06 in the adsorbing course and the technology of TEM and FTIR, the mechanism adsorbing Cr6+ by the strain M-06 were discussed.