Bioremediation Of Acid Coal Mine Drainage Using Immobilized SRB Sludge With Modified Maifan Stone

In this paper,aimed at the characteristics of acid coal mine drainage（ACMD）with strong corrosive,high content of sulfur and manganese in our country,based on microbial immobilization technology,an immobilized microorganism particle was made to deal with ACMD,which main componen was the combination of modified maifan stone and sulfate reducing bacteria（SRB）activated sludge.First of all,through response surface and orthogonal experiments,optimizing content and analysising composition correlation of the particles;Second,the particles’ion response and dynamic characteristics were analysised by static batch experiments;Finally,dynamic continuous column experiment was carried on for analyzing the removal efficiency and the ability to resist pollution load change of particles.The main conclusions are as follows:（1）The study on the influence of maifan stone and optimization preparation of the particles indicates that,the maifan stone immobilized particles have a certain ability to resist acid,alkali and salt,which produced by polyving akohol（PVA）+boric acid embedding crosslinking method.Maifan stone have a certain role in promoting the physical stability and biological activity of the particles.To determine optimum dosage ratios of the particles,an orthogonal test was conducted which result was as follows:SRB sludge of 30%,corn cobs of 5%and scrap iron of 5%on the content.Response surface method was used to determine the optimal conditions for maifan stone,the result was as follows:modified maifan stone of 15%on the content,diameter from 200 to300 mesh.（2）The study on response regular of particles to ACMD with different ion concentration indicates that:the particles have a better treatment effect on the pollution load of low concentration SO₄^2-,with more stable metabolic performance affected by Mn²⁺concentration and good resistance to pH impact.Through measuring phase by X-ray diffraction（XRD）and analysising structure by scanning electron microscope（SEM）,the results shows that changes in the composition and structure of the particles between before and after the reaction is large.（3）The kinetics study of the particles indicates that,the SO₄^2-reduction curve by particles could be fitted by first order kinetics model,and the absorption behavior of Mn²⁺on the particles’surface could be described by pseudo secondary dynamic model well.Particle adsorption capacity research shows that the absorption curve of Mn²⁺could be fitted by both Langmuir model and Frundlich model well,which belongs to typeⅠadsorption isotherms.The maximum absorption quantity of Mn²⁺by particles was 1.094 mg/g.The particles have the ability to fast adsorp Mn²⁺in the solution,meanwhile the influence of the competitive adsorption between cationic in modified maifan stone,less than ordinary maifan stone.（4）Dynamic test of the particle indicates that,Mn²⁺could inhibit the activity of SRB,which affected SO₄^2-reduction rate,while COD/SO₄^2-is one of the main influence factors of SO₄^2-reduction rate.SO₄^2-reduction rate and Mn²⁺removal rate can reach 79%and 67.9%respectively.Hydraulic retention time are positively correlated with pH value,which keeps in the range of6.24⁷.45.Turbidity was susceptible to hydraulic loading and hydraulic retention time.COD,TFe and turbidity’s release quantities were low in the later period,less than 100 mg/L,10.28mg/L and 30 NTU respectively,and does not produce new pollution.In conclusion,adding the modified maifan stone can improve the basic characteristics and performance of immobilized microorganism particle,and promote the treatment effect to ACMD better.