Reducing Effect Of Modified Biochar On Heavy Metal Stress Of Dye Wastewater For Antibiotic Resistance Genes

In recent years,global overuse of antibiotics in human medicine and agriculture has resulted in the proliferation and dissemination of antibiotic resistance genes（ARGs）.in various environmental media,and various environmental factors such as heavy metal ions have synergistic selection effects on ARGs in the environment.The heavy metals（HM）existed as selected pressure in dye wastewater on the formation of microbial communities in water treatment biounits,which led to the generation and migration of ARGs.After the sewage plant treated the printing and dyeing wastewater containing heavy metals for a long time,the ARBs were enriched and the ARGs were detected at high abundance.However,the existing water treatment process is not ideal for the removal of resistance genes.For the past few years,Biochar（BC）,as a functional material with special physicochemical properties that can be applied to different ecological environments,is low-cost,abundant raw materials,simple preparing,and has new functions for different situations.For the purpose of efficiently removing pollutants such as heavy metal ions in wastewater,the selection of modified materials was considered to be added to the biological system in the later stage.Therefore,the nontoxic and harmless modified materialβ-cyclodextrin was selected to prepare functional BC for the removal of contaminants and ARGs from the environment.Functional BC of contaminants and ARGs.It provides a feasible solution to solve the new environmental pollution caused by the generation and transmission of ARGs in the water treatment process.Therefore,this study prepared the functional biocharβ-BC on the basis of straw biochar,which had special physicochemical properties and high efficiency of pollutant removal.On this basis,a new ARGs pollution solution is established in order to reduce the antibiotic resistance genes in the environment by relieving the pressure of environmental factors in the environment.The research results obtained in this study mainly include the following aspects:The β-cyclodextrin is supported on the basis of the existing biochar,so that the modified BC has better pollutant removal ability and physical and chemical properties.Theβ-cyclodextrin was successfully supported on the original carbon material by using epichlorohydrin（EPI）as a crosslinking agent and optimized by orthogonal test.In view of the importance of modified biochar preparation condition,the molar ratio ofβ-CD and epichlorohydrin（EPI,employed as the crosslinking agent）,reaction time,and pristine biochar dosage were firstly optimized.Results showed that at the condition of molar ratio（β-CD:EPI）6:1,rice straw biochar dosage 4.00 g,and reaction time 24 h,theβ-CD modified biochar（β-BC）could gain the best performance of metal removal,and the maximum adsorption capacity of Pb²⁺byβ-BC was 118.39 mg/L,which is24.65%higher the pristine BC.The characterization results show that the surface ofβ-BC is rough and rich in irregular pore size,and the porosity and specific surface area are increased.The morphology of the material before and after the adsorption reaction has no obvious influence.β-BC plays an important role in both physical adsorption and chemisorption during the adsorption reaction,in which physical adsorption dominates and tends to monolayer adsorption.When β-BC was added to containing heavy metal wastewater and the dye treatment system under the heavy metal stress,the dye removal rate was over 96%,and the heavy metal content in the system was reduced to less than 0.05mg/L,and the ARGs removal rates were 51.31%and 88.17%,especially for tetracycline ARGs（tet-M,tet-M）,sulfonamide ARGs（sul-1）and class I integron（intI-1）had significant reductions.Addingβ-BC can increase the species richness of the sludge microbial community and significantly reduce the relative abundance of the antibiotic resistance bacteria（ARB）in the microbial community,and promote enrich the strains which had the negative correlation with the ARGs.It is concluded thatβ-BC can reduce the ARGs by removing pollutants from the environment,reducing the selection pressure of the ARGs,and affecting the structure of the sludge microbial community.