Bioremediation Of Heavy Metal Pollution During Soiled Utilization Of Mine Tailings

The exploitation of iron ore mining not only caused emission and storage of a large amount of solid waste,the beneficiation used in mineral processing and remained heavy metals would diffuse into the atmosphere,water and soil through different ways,causing serious environmental pollution.Therefore,the resourceful utilization of iron tailings can not only solve the environmental problems in iron ore mining industry,but also can improve the amount of soil resources in the process of mine restoration.Therefore,this study can provide theoretical basis for microbial remediation of soil,which has extremely important theoretical value and application value.Traditional heavy metal pollution tailings repair method can be divided into chemical,physical and biological methods according to the principle.Chemical additives will cause secondary pollution,and the application of physical repair methods was always restricted for high cost and complex equipment.Bioremediation technology,which is environmental friendly and efficient,is showing a broad application prospect in the field of heavy metal pollution remediation.And has become a main technical strategy of in-situ remediation of heavy metal polluted soil in recent years.of means.Screening out bacteria with high resistance to heavy metals and enhancing the effect of in-situ repair,has been a major problem in the field of microbial remediation.In this paper,strains resistant to heavy metals were selected from the samples in Anshan tailings was studied,and the factors were optimized to improve the efficiency of remediation.Finally,the field experiment was carried out to improve the fertility and biodiversity of microorganisms in mine tailings.Strains with resistance to Pb,Mn and Zn were screened out from mine tailings after it was tailored.The strains were identified through ITS sequencing,and the phylogenetic trees were characterized.Mucor circinelloides,which is resistant to Pb,Actinomucor sp,resistant to Mn and Mortierella.sp,resistant to Zn were selected from mine tailings.The strains were in logarithmic growth phase after 12 h of incubation,with high resistance of heavy metals and can be well adapted to the environment.The results produced basis for repairing heavy metal pollution in mine tailingsThe adsorption experiment was carried out to study the absorbing effect of of Mucor circinelloides to Pb2+,Actinomucor sp to Mn2+ and Mortierella sp to Zn2+,respectively.The factors including temperature,pH and initial inoculation amount were modified to investigate the optimum condition of adsorbing process.The results showed that the optimal pH of Mucor circinelloides adsorbing Pb2+ and Actinomucor sp adsorbing Mn2+ was 6,the optimum pH of Mortierella sp adsorbing Zn2+ was 7,and the adsorption of Pb2+ and Zn2+.And the optimum temperature of the adsorption of heavy metal ions ranges from 26-28?,the adsorption rates of Pb2+ and Mn2+reached the maximum at the initial inoculation amount of 1.0ml,and the adsorption rate of Zn2+ was the highest when the initial inoculation amount was(?).2ml.The adsorption rate of Pb2+,Mn2+ and Zn2+ were 95.46%,92.78%and 86.89%,respectively under optimum adsorbing condition.The adsorbing ability of the 3 strains of heavy metal ions in the solution was efficient.The adsorption capacity are in the order Mucor circinelloides,Actinomucor sp and Mortierella sp.The adsorption thermodynamics and kinetic curves of adsorbing amount ofheavy metals(Pb2+,Mn2+ and Zn2+)under the optimum conditions were studied by adsorption experiments.It was found that the Langmuir isothermal adsorption model could be used to describe the adsorption of heavy metal ions by 3 strains,The maximum adsorption capacities of Mucor circinelloides to Pb2+,Actinomucor sp to Mn2+ and Mortierella sp to Zn2+were 79.76,76.42 and 78.16 mg/g,respectively,and R2 were 0.9932,0.9693 and 0.9759,respectively.It may be induced that the affinity of Mucor circinelloides to Pb2+ was greater than those of the other two strains.The adsorption kinetics was consistent with the pseudo-second-order kinetics model,which indicated that the main mechanism of adsorption was chemical reaction such as ion exchange and complexation.The maximum adsorption capacities of Mucor circinelloides to Pb2+,Actinomucor sp to Mn2+ and Mortierella sp to Zn2+were 77.42,75.00 and 68.57 mg/g,respectively,and R2 was 0.999,0.909 and 0.9844,respectively.The adsorption curve of Mucor circinelloides on Pb2+ fits the model than the other 2strains.The adsorption capacity of the 3 strains to heavy metal ions were high,indicating a high value of practical application in the heavy metal pollution remediation of tailings.The effects of mixed fungi on the availability of heavy metals,enzyme activity and microbial diversity in tailings were analyzed by field application.The microbial fungi were prepared by mixing the bacteria and then added to the mine tailings.The strains were mixed and cultured to prepare microbial agents and applied to the process of soil tailings utilization.The results showed that the microbial agents had good fixation effect on the heavy metals,and the removal rates were 74.98%(Zn),85.29%(Pb)and 79.41%(Mn)respectively.The addition of microbial agents increased the number of microorganisms(p<0.05).The number of bacteria,fungi and actinomycetes increased by 16.81%,34.62%and 27.63%,respectively.At the same time,the activity of enzymes were increased by 68.79%and 56.47%during bioremediation,which indicated that the decrease of heavy metal content reduced the inhibition effect on enzyme activity and increased the tailings fertility.The Shannon-Wiener index of the tailings sample increased from 3.7 to 4.05,indicating that the addition of microbial agents increased the diversity of microbes in tailings,effectively improved the biota structure of tailings and promoted the growth of microbes in tailings.