Study On The Effect Of Functional Bacteria On The Distribution Of Heavy Metal Forms And Synergistic Plant Remediation In The Soil Of Electronic Waste Dismantling Site

With the acceleration of the upgrading of electronic products,a large amount of e-waste has been generated,driven by interests and the imperfect management system at the early stage,and the irregular dismantling has caused serious soil heavy metal pollution,posing a threat to the environment and humans.Plant remediation is easy to operate,low in cost,and will not cause secondary pollution,which is welcomed by people.During the implementation of phytoremediation,there are shortcomings such as slow growth of plants,small biomass and long repair time.Functional strains can promote plant growth and improve plant tolerance to heavy metals.The emergence of functional bacteria provides a new method for solving this problem.This thesis samples the soil of the e-waste dismantling site,determines the content of heavy metals in the soil,and screens the strains that tolerate high concentrations of heavy metals in the e-waste dismantling site soil,and compares the effects of different strains on the form of heavy metals in the e-waste dismantling site The effects of strains with better morphology of heavy metals in the soil combined with ryegrass on the form of heavy metals in the soil of the e-waste dismantling site were analyzed,and the forms of heavy metals in the root soil were analyzed,as well as the effects on ryegrass biomass and reabsorbed metals.The main findings are as follows:(1)By screening and isolating the strains in the soil from the e-waste dismantling site,8strains resistant to multiple heavy metals were obtained,4 of which were bacteria(b1,b2,b3,b4),and the other 4 were Fungi(f1,f2,f3,f4).All 8 strains have indoleacetic acid production and phosphorus solubility.B4,f3,and f4 bacteria were identified by molecular biology as Lysinibacillus sp,Fusarium oxysporum f sp,and Aspergillus sp.(2)The shake flask culture experiment was conducted to study the influence of 8 strains on the changes of the occurrence patterns of heavy metals in the soil of the electronic waste dismantling site.The results show that the site for dismantling e-waste is a compound contaminated soil with multiple heavy metals.Cu(5384mg · kg-1)exceeds the standard by approximately 53 times,Zn(24078mg · kg-1)exceeds the standard by approximately 80 times,and Cr(727mg · kg-1)Exceed the standard by about 2 times,Pb(302 mg · kg-1)exceeds the standard by about 18 times,and Cd(54.2 mg · kg-1)exceeds the standard by about 68 times.Inoculation treatment changed the form of heavy metals in the soil of the electronic waste dismantling site after 60Co-γ sterilization,and different strains had different effects on different heavy metal elements.Among them,b1 bacteria have activation effect on Zn,Pb,Cu,Cr,Cd in soil;b2 bacteria have immobilization effect on Zn,Pb,Cr in soil;b3 bacteria have activation effect on Cu,Cr in soil;b4 Bacteria have activation effects on Cu in the soil and immobilization effects on Zn and Cr;f1 bacteria have activation effects on Zn,Pb and Cd in soil;f2 bacteria have activation effects on Zn,Cu and Cd in soil and Cr It has an immobilization effect;f3bacteria have activation effects on Zn and Cu in soil,and have an immobilization effect on Cr;f4 bacteria have activation effects on Zn,Cu,Cr,Cd and Pb in soil.(3)B4,f4,f3,and Acidithiobacillus ferroxidans(Af),which have significant effects on the forms of heavy metals in the soil,were selected and inoculated into the soil of ryegrass roots to study the effect of this series of fungi on black Wheatgrass grows in the soil contaminated by heavy metals in the e-waste dismantling site and is affected by the absorption of multiple heavy metals.Through the pot experiment,the three stages of rye grass were harvested.Over time,the biomass of the upper part of the rye grass gradually decreased;inoculation treatment(f4,f3,b4,f4 + b4,f3 + b4,f4 + Af)There is a significant difference between the aboveground biomass and the non-inoculated treatment in the D2 stage,which increased the upper biomass of rye grassland by 43%,43%,26%,13%,85%,8%;inoculated treatment(f4,b4,Af,f4 + b4,f3 + b4)There is a significant difference in the biomass of the lower part of the rye grassland without inoculation treatment,which increased the biomass of the lower part of the rye grassland by 91%,48%,30%,76%.In the D3 stage,the transfer coefficient of Cu,Cd,Zn,Pb in non-inoculation treatment is greater than 1,indicating that at this stage,ryegrass is easy to transfer heavy metals(Cu,Cd,Zn,Pb)below the ground to the above ground;then f4 bacteria black The lower part of wheatgrass has a strong enrichment capacity for Cu,Cd,Zn,Pb,Cr.The inoculation treatment improves the ability of ryegrass to adsorb heavy metals through its influence on the biomass of ryegrass,thereby improving the repair efficiency of ryegrass to heavy metals.In summary,the soil of the e-waste dismantling site is contaminated with various heavy metals,and the functional bacteria affect the form of heavy metals in the soil of the e-waste dismantling site through the production of indoleacetic acid and phosphorus dissolution characteristics.Strengthen ryegrass to repair heavy metals in the soil of the e-waste dismantling site,and provide microbial germplasm resources for microorganisms or microorganisms combined with ryegrass to repair the heavy metals in the e-waste dismantling site.