Co-treatment Of Acid Mine Drainage And Domestic Sewage Based On SRB Remediation And Microbial Community Characteristics

With the continuous growth of the population,the demand for mineral resources and the production of domestic sewage is also increasing,resulting in a large amount of acid mine drainage and domestic sewage.acid mine drainage has a low p H value and high heavy metal content,which is very harmful to the environment.The environmental hazards of domestic sewage containing a large number of pathogenic microorganisms such as parasite eggs and intestinal infectious viruses and organic pollutants such as ammonia nitrogen,protein and carbohydrates should not be underestimated.The direct discharge of a large amount of domestic sewage is prone to foul smell and the proliferation of bacteria and pathogens,which may lead to the spread of infectious diseases.The use of sulfate-reducing bacteria for the microbial treatment of acid mine drainage is a research hotspot at home and abroad at this stage.This study built a new multi-unit continuous co-processing system based on sulfate-reducing bacteria treatment technology and combined with surface flow constructed wetlands to study the changes in the effluent water quality of each unit after the system co-treated acid mine drainage and domestic sewage.Batch experiments verified the optimal ratio of domestic sewage and acid mine drainage and the possibility of silage as a carbon source.This study reached the following conclusions:（1）Acid mine drainage and domestic sewage mixed in a ratio of 1:2 had the best purification effect on water quality.Domestic sewage was used as a neutralizer to buffer acid mine drainage with a p H of 2.5 to neutral（p H=7.03）,and the reducing substances contained in the domestic sewage caused the mixture to appear reduced.The organic matter contained can be used as part of the nutrient source and energy for microorganisms,which are more conducive to the growth and reproduction of sulfate-reducing bacteria.The removal rate of Cu²⁺,Cd²⁺,Fe²⁺,and total Fe in the supernatant was approaching 100%on the first 1,2,3,and 4 days,respectively.Zn²⁺reached a 95.9%removal rate on the sixth day.Mn²⁺and sulfate ions removal rate inferior,it is only diluted to cause the concentration to drop.（2）Domestic sewage as a single carbon source could not meet the long-term growth and development requirements of sulfate-reducing bacteria,and the residual concentration of sulfate was only reduced from 2014mg/L to 1841mg/L.The residual sulfate concentration of sulfate-reducing bacteria in Postgate C medium was stabilized to about 353mg/L.But the expensive cost is not suitable for practical applications.Silage was used as a single carbon source,and the residual concentration of sulfate continued to decrease to 633mg/L.The sulfate removal efficiency was better,and sulfate-reducing bacteria grew actively,which has the possibility of replacing Postgate C medium.（3）The effluent quality of the multi-unit continuous co-treatment system was gradually improved after three units were treated,a good co-treatment effect of the two types of wastewater was achieved.Acid mine drainage with a p H of 2.5 was weakly alkaline（p H stabilized at about 8）in the final constructed wetland,which successfully solved the problem of acid pollution.The five heavy metal ions of Cu²⁺,Cd²⁺,total Fe,Zn²⁺and Mn²⁺were well removed.The heavy metal influent concentration was doubled and still maintained a good removal efficiency,which solved the problem of high heavy metals in acid mine wastewater.At the end of the experiment,the final effluent of the residual concentration of ammonia nitrogen,nitrate nitrogen,sulfate ion,total phosphorus,and COD was kept within 5mg/L,15mg/L,285mg/L,2mg/L,100mg/L,and reached a good water purification effect.Desulfobacterota was the dominant bacteria in the multi-unit continuous co-treatment system.There were nitrifying and denitrifying bacteria in the constructed wetland,which played a great role in the removal of ammonia nitrogen and nitrate nitrogen.