Experimental Study On Biological Permeable Reactive Barrier Repairing Contaminated Groundwater From Triphenylmethane Dyes

Due to the reasons of leakage and unreasonable emissions,a large number of triphenylmethane dyes have been discharged into the environment,contaminating groundwater through multiple ways such as atmospheric precipitation,soil leaching and surface water infiltration.This kind of dyes has been demonstrated to have potential carcinogenic effects on mammals.Groundwater is the main source of fresh water for humans and other creatures,so research on remediation technology and degradation of contaminated groundwater from triphenylmethane dyes is of concern for human health and ecological security.Permeable Reactive Barrier(PRB)is a common technique to remediate contaminated groundwater,and environmental factors and filling media have a great influence on the remediation efficiency.In this dissertation,physical media and microbes have been combined through PRB to degradate triphenylmethane dyes in groundwater.By using crystal violet as the targeted dye and choosing an appropriate PRB in batch experiment,the degradation under different conditions was evaluated with a strain of dominant bacterium isolated from river sediment.Furthermore,the degradation effect and pathway of Biological Permeable Reactive Rarrier(BPRB)repairing as well as the practical application feasibility were also studied.The main contents are as follows:(1)By batch experiment,the basic properties of activated carbon,zero-valent iron and their adsorption on crystal violet have been analyzed respectively.The results showed that both them are stable and possess no biodegradability.Comparing the adsorption effect under different composite media with various proportions between activated carbon and zero-valent iron,a 95% degradation of crystal violet can be obtained after 10 days when the proportion is 3:1,which also was determined as the PRB filling medium.(2)Through preliminary screening,separation,purification,second screening and re-separation,a strain bacterium J1 was finally obtained from the the southlake campus of China University of Mining and Technoiogy.By cultivating,observation and Gram's staining,it was identified that the bacterium is non-strict aerobic Gram-negative avalible for degradation of crystal violet in ground water with BPRB,and the degradation can reach to 95% in 10 days.Results indicated that temperature,pH value and initial concentration all have great effect on the biodegradation of crystal violet,and the process followed first-order dynamical order reaction.(3)The degradation of crystal violet applying biological PRB has been investigated by simulating the groundwater environment with a 5 mL/min inlet water velocity under 25 ?.After 60 days,all the degradation percentage of the dye can reach to more than 80% as against to 60% applying composite PRB.In addition,pH value of the influent has a significant impact during the early operation and the degradation can reach to more than 80% at the best value of 7.(4)Based on analyses,it can be concluded that the products of crystal violet degradation mainly include hydroxy-acetone,p-aminophenol,benzene and thiophene ketone and 4,4 '-double(dimethyl amine)phenyl methanol.