Production Of B-megaterium Bioflocculant And Its Experimental Study On Heavy Metal Wastewater Treatment

Many toxic metal ions in heavy metals wastewater are easy to accumulate in the food chain, and a large amount of discharge of the wastewater can not only endanger human body health, but also lose the rare and precious metals.Therefore,the treatment of heavy metals wastewater and the recycling of precious metal resources have become a focus in the ecological environment governance. Microbial flocculants are now widely used in the field of the treatment of heavy metals wastewater, because of its wide source, good treatment effect, strong applicability, easy to recycle, etc.In view of the treatment of wastewater containing lead,zinc and copper, this paper studied the production of a kind of microbial flocculant,which is high efficiency, high flocculating activity and easy storage.Screening strains with high flocculating activity from the sludge of a sewage plant in Kunming, and identified by the 16s rDNA as B-megaterium.In order to improve the flocculating activity of the microbial flocculation, optimizing the screening culture medium composition and culture conditions, the following results:the best carbon source and carbon source concentration of media are sucrose,20 g/L respectively, and the best nitrogen source and nitrogen source concentration of media are yeast extract,2 g/L respectively, metal ions Na+ and Cu2+ have little influence of flocculating activity of the bacteria,and the appropriate concentration of Mg2+ ions is helpful of improving flocculating activity of the bacteria, and Fe2+ ions have inhibition of the flocculating activity of the bacteria.Under the condition of the optimal culture medium,when the initial pH value of medium is 7,inoculated quantity is 2.0% ,the training temperature is 30℃, the table speed is 100rpm,the bacteria has the highest flocculating activity.After the optimization of culture medium and culture conditions,the flocculating activity of the bacteria is from 78.76% to 90.78%,and 2.31022g of flocculant dry products are extracted by the best culture in 1LWith the flocculant dry products to remove the wastewater containing lead,zinc and copper, the following results:when the initial pH value of flocculation system is 7,the flocculant dosing quantity is 100 mg/L, the time of flocculation reaction is 20 min,the flocculation temperature is 30癈,the removal of Pb2+, Zn2+, Cu2+ ions has the best removal rate of 99.72% ,76.78% and 95.96% respectively.The experiment found that the removal rate of Pb2+ and Cu2+ ions can reach more than 90% , and the removal rate of Zn2+ ions is maintained at 70% - 80%.The removal of Pb2+ and Cu2+ is superior to the removal of Zn2+ by the flocculant.To delve into the flocculant for heavy metal ions removal,the flocculant before and after the reaction were analyzed by SEM、FT-IR and XPS.The results showed that Cu(Ⅱ) and Pb(Ⅱ) replaced the hydrogen in-OH or-COOH,and they were formed colloidal substance such as (C2H3O2)2-Pb-(C2H3O2)2 and CH2CHNH2COOCu which could condensed lead and copper through adsorption bridging.The zinc(Ⅱ) in wastewater was mainly removed through the adsorption of combination of ionic bonding which formed ZnO and ZnS.