Experimental Study On Treatment Of Acid Mine Wastewater By Immobilized Sulfate Reducing Bacteria

With the rapid development of China's economy,the demand for mineral resources is increasing,but it also brings serious environmental problems.The acid mine wastewater produced in the mineral exploitation has the characteristics of strong harm and long duration,which seriously threatens the survival of human beings and many natural organisms.Therefore,effective measures must be taken to treat it.Biological treatment is an efficient and promising technology for mine wastewater.Its principle to remove heavy metal ions from wastewater is through the interaction between organisms or their metabolites and metal ions.In this thesis,the treatment of simulated acid mine wastewater was studied.The effects of free sulfate reducing bacteria(SRB) solution,immobilized SRB spherical particles and SRB sludge on the treatment of acid mine wastewater containing zinc(200 mg/L,400 mg/L),Cd(15 mg/L,30 mg/L) were discussed.Batch treatment experiments showed that the effect of immobilized SRB spherical particles was better than that of SRB sludge and SRB suspension.This was due to the fact that immobilized SRB spherical particles avoided direct contact between SRB bacteria and wastewater,which made SRB react with sufficient nutrients and improved the activity of SRB.Based on batch experiments,a series of dynamic experiments were carried out to treat acidic mine wastewater by immobilized SRB spherical particles,SRB suspension and SRB sludge.The results showed that the effluent pH of the three treatments increased to a certain extent,and the three treatments had certain reactivity to acid mine wastewater.Among them,the effluent pH of immobilized SRB granular group was the most stable and the highest,followed by SRB sludge,while the pH value of SRB suspension was the lowest and fluctuated greatly.With the increasing concentration of sulfate ion in influent,the sulfate radical in effluent was removed.In general,the order of sulfate removal rate is as follows: immobilized SRB pellets > SRB sludge > SRB suspension.Immobilized SRB pellets were the most stable,followed by SRB sludge and SRB bacterial solution treatment.During the experiment,the sulfate ion in the effluent of SRB suspension bacteria fluctuates greatly,which is due to the unstable effluent of the reactor because the experimental bacteria easily flush out with the water flow.After immobilized SRB pellets,the concentration of heavy metal ions was the lowest,indicating that the reactor had the highest removal rate of heavy metals and the best tolerance.In conclusion,immobilized SRB technology is more effective in treating acidic mine wastewater,and has a certain advantage in treating wastewater with high concentration of heavy metals.