Study On Treatment Of Acid Mine Wastewater Reaction Kinetics By Sulfate-reducing Bacteria Based On Permeable Reaction Wall

Acid mine drainage(AMD for short)is formed in the process of high sulfur coal and mental mine mining.In this process the reductive environment changed into oxidative environment,under the action of water vapor,air and bacteria Pyrite was oxidized.Finally,it forms the wastewater with low pH,strong corrosion,high concentrations of heavy metal content and sulfate.This subject adopts permeable reactive barrier with immobilized sulpHate reducing bacteria to treat acid mine drainage in situ treatment.With computational Fluid Dynamic to simulate the distribution of water conditions in PRB and based on the result to the study the model of degradation of acid mine drainage by immobilized sulfate-reducing bacteria.By model the research can elaborate the process of biodegradation pathway and the reaction mechanism of pollutants and accurately simulate the internal mass transfer and macroscopic reaction kinetics in the reactor.This is an in-depth study of principle of AMD treatment of microbial process,to optimize the treatment effect and achieve technological innovation and improvement of premise.This experiment mainly research results are as follows:1)Using the RTD test got the distribution curve of hydraulic residence time,according to the distribution curve and experimental data for the hydraulic residence time of two days.The reactor has a dead zone,which accounts for 4%of the volume of the reactor.Through the study on characteristics of filling medium of PRB got the relevant data of PRB,including the total porosity,n=0.38,K=1.1mm/s,?=0.14*10-9.To simulate the internal flow regime of PRB system by FLUENT,the result show that when the fluid flows through the PRB,fluid suffered from the resistance of porous medium inside the wall,energy loss occurring.When fluid flow through porous medium,the velocity in porous medium increased obviously compared with inlet velocity,the ratio of maximum flow is higher about 4 times than inlet velocity,the maximum velocity was in gap center and decrease from the center of gap to the surface of carrier.This suggests that the carrier surface is suitable for sulfate reducing bacteria to immobilize.The fluid in the gap in the compression,to make the width of PRB greater than the pollutant plume region,or pollutants in flowing through the reactor wall will not be treated effectively.2)The adsorption kinetics test of immobilized SRB bacteria on ceramic suggests that the equation of adsorption kinetics model is:mt = mte(1-e-at),mte =35.74g,a=0.19,the correlation coefficient of test curve and the fitting curve is R2=0.93137,reliable is 0.93,thus the theory equation and experimental data fitting is very high.According to the growth of SRB biofilm dynamics test SRB growth dynamics model is established,the model equation is obtained as follows:m=0.9942t+9.6229,R2=0.9981.3)The slow release law of carbon source in PRB:the proportion of filler and corn cob,temperature and pH as corncob release rules influencing factors found that when the filler and corn cob ratio of 1:3,the reducing sugar of the release of carbon source can meet the demand of biological growth and relative economic,low proportion has a inhibitory effect on corncob hydrolysis;when the pH is equal to 4,corn cob hydrolysis rate is the fastest,too low and too high pH value both has a inhibitory effect on corncob hydrolysis;the temperature test shows that corncob can easily hydrolysis under middle and low temperature which can satisfy the conditions in situ remediation of groundwater.4)The mathematical model of the relationship between sulfate reduction and COD was established and the model equation:Q(Si-Se)=2?Se/?Se+?,or ?=Q(Si-Se)(?Se+?)/2Se.And the reliability of the equation was analyzed.The results showed that the model could be a good response to the relationship between COD degradation and SRB sulfate reduction.5)According to the degradation rate of sulfate in the reactor,the reaction kinetics equation was established,and the maximum reaction rate constant Rmax0.5872(mg SO42-/mg SRB/h)was measured,and the half reaction rate constant Kr=485.7 mg/L.The model equation is established,and the accuracy of the equation is tested.The results show that the model has good prediction and high precision.According to results of the efficiency of treatment of heavy metal by PRB,the effluent and effluent suggest that SRB biofilm treatment system based on PRB can be very good in situ treatment of groundwater and the operation is stable and cost is saving.