Studies On Resource Application Of Absorption Of Zinc And Lead By Ferment Pectic Enzyme Bacteria

With Lead-zinc mining spreadly, It is grim to control metal wastewater and threatens human health. The main problem faced by environmental biologists is to search cheap, efficient, and non-toxic biosorbents, based on world crisis and economical endurance in wastewater drainage industries. Currently, the kind of biosorbents is mainly waste yeasts from wine fermentation industry but absorption results are not ideal. However, as a biosorbent, the waste microbial biomass from enzyme ferment is rarely studied. Compared alkaline pectic enzyme with acid pectic enzyme, the former is more attracting in many fields such as medicine, foods, weaving and so on. We isolated two producing pectic enzyme strains of S-2 and S-4 with appearing certain resistant for heavy metal of Lead and Zinc from rich alkaline mine soil, which pectinase activity is 1560u/g and 1150u/g. The two strains were identified Bacillus through traditional and modern-molecule genetic method, which is named B. gibsonii and B. clausii respectively.We investigated absorption performance of B. gibsonii and B. clausii in order to make biomass applied fully. The result has shown that lead and zinc can be removed by B. gibsonii and B. clausii in ferment efficiently. We found that it is suitable to choose Lead absorbed by B. gibsonii and Zinc by B. clausii according to the electivity. The adsorption capacity of Lead is 333.3mg/g, and that of Zinc is 57.5 mg/g. Also, we studied the influential factor such as absorption optimal pH, absorption temperature, absorption balance time. The results are listed as following as below: The optimal pH is at 4.5 or so; The absorption capacity is ascended with different temperatures 20, 30 and 40 °C; The absorption balance time is 20 30 min; The absorption data is fit well with Pseudo-second-order equation in kinetics analysis; The absorption isotherms is fit well with Langmiur equation.Today, scientists still agree with on the systemic absorption mechanism. In order to further study the absorption mechanism of Lead by B. gibsonii and Zinc by B. clausii, we made many efforts through FTIR (Fourier transform infrared ray), EDX(Energy Dispersive X-ray analysis) and XRD(X-ray powder diffraction).Some changes the adsorption of bond groups and metal ions can be observed on the cell wall surface of B. gibsonii and Bacillusclausii ,such as -OH, -NH₄⁺> -COOH, (-CO-NH-), -C₆H₅, Mg²⁺, Na⁺, Ca²⁺and so on. The cell wall is main absorption site. The research shows that the process of absorption is very complex process including all kinds of physical and chemic reaction such as integrate, ions exchange and so on.Finally, we make a judgment of application prospects that S-2 and S-4 absorb Lead and Zinc. From experiments results of desorption and immobilition, the desorption efficiency of Lead and Zinc is 95.7, 83.2 percent under acidic conditions. Moreover, lead and zinc can be removed well by immobilized vector B. gibsonii and B. clausii with PVA-sodium-alginate and gelatin-sodium-alginate. The data tell us that biosorbents can be cycled in industries with very promising wastewater treatment application technology.In summary, Bacillus gibsonii and Bacillus clausii are excelent Lead-Zinc biosorbent materials, including producing pectic enzyme. All that have shown biomass can be reused.