The Study On Nitrogen Source Of Sulfate Reducing Bacteria Culture Medium And The Treatment Conditions Of Acid Mine Drainage

Acid mine drainage?AMD?is characterized by high acidity and rich in sulfate and heavy metal.If discharged directly,which would cause water acidification,contaminate water source,threaten human health.Sulfate Reducing Bacteria?SRB?was widely investigated mainly due to its low process cost and without farther pollution.The research group have studied the soybean fermentation as carbon source for SRB to treat AMD,in order to make SRB adapt to soybean as carbon source in advance,the soybean fermentation was used to replace the nitrogen in the SRB original culture medium.The main factors influencing the processes to treat the AMD and its interaction were studied by the Box-Behnken center and respond surface methodology?RSM?,the optimum experimental conditions for the treatment of AMD by SRB were determined.The soybean fermentation was designed as nitrogen source for SRB medium,enriched in this medium for one month,SRB?1%,2%,5%?were inoculated into 100 m L anaerobic flask while the original culture enrichment of SRB in parallel.Under the above two conditions,SRB were successfully propagated and the soybean fermentation as nitrogen source for SRB medium was successfully verified.By measuring the growth curve of SRB,it was determined that the best inoculation time was the third day.The enriched SRB under the conditions of two media inoculated into AMD on the third day,monitoring the ORP,p H,SO₄^2-and metal ion on the treatment of AMD.The experimental data showed that,under the two conditions SRB all have the ability to treat AMD,while in the soybean fermentation medium the p H higher,ORP descends faster,the final SO₄^2-and metal ion content lower.It can be seen that the soybean meal fermentation as the medium nitrogen source better.By measuring the removal ratio of SO₄^2-under different factors for the treatment of AMD with soybean fermentation as medium nitrogen source,the conditions are as follows:the p H is 6.50,the initial concentration of sulfate is 2500 mg/L,the ratio of COD/SO₄^2-is3.00.According to the above conditions we use the Design-Expert.8.06 software to set up seventeen groups experiments,it determine that the removal rate of SO₄^2-on eleventh day.The optimal level and interaction of the three main influencing factors in the process of wastewater treatment were studied by RSM,the contours and surface effects of the two factors were obtained,the best experimental conditions as follows:the p H is 6.50,the initial concentration of sulfate is 2500 mg/L,the ratio of COD/SO₄^2-is 3.00.On the basis of the above optimum conditions,we use the two conditions SRB to treat simulation AMD.In this experiment,the ORP,the initial concentration of SO₄^2-,COD,TN,metal ion decreased gradually,VFA increased first then decreased and the concentration of NH₄⁺-N and TP increased continuously.However,the SRB enrichment in soybean fermentation as nitrogen source more advantages.The indicators of the treated wastewater are compared with the wastewater discharge standard.It is known that the p H,SO₄^2-,Zn²⁺,Fe²⁺,Cu²⁺,Co²⁺,Ni²⁺ and other indicators can reach the standards.But the COD in the wastewater has not yet reached the discharge standard.Experiments attempt a variety of methods to treat COD,the results show that,the COD can be treated well by centrifuge or polymeric ferric sulfate?PFS?,and the effluent COD can reach the discharge standard.Through the above series of experimental results,the effect of using soybean fermentation as SRB medium nitrogen to treatment AMD was better and the preliminary process was designed to process AMD process microbial SRB method.