Study On The Parameters Optimization Of Of ARUM Acid Drainage Treatment System And Its Pilot Test At Anabandoned Coal Mine

By aiming at a series of problems in the coal mining acid wastewater treatment system—Acid Reduction by Microbiology(ARUM)constructed for Dapo Waste Coal Mine,Huaxi District,Guizhou Province,such as insufficient existed shortages in the system,small water yield for treatment,insignificant pH improvement effect,relatively low SO₄^2-removal rate,and insufficient organic padding effect for the carbon source capacity,the research group combines the status of the research area to optimize the ARUM.By carrying out dynamic and static experiments in the lab,as well as indoor and outdoor small-scale simulation tests,the research optimizes key technical parameters of the ARUM,enlarges the wastewater handling capacity,improves coal mine acid wastewater,and increases SO₄^2-removal rate.Based on it,the research constructs the field pilot plant test handling system of Jinzhuchong Waste Coal Mining,Sunjiazhai,Kaili City,Guizhou Province and draws the following conclusions:(1)In the oxidation/sedimentation unit of the ARUM,the heavy curtain is hung to increase the unit handling effect,screening out the optimal heavy curtain to find that 12-pin sunshade net is the most economical and effective.The adsorbing capacity is up to 55.5g/m² per day;organic paddings are added in the acid-degradation unit of the ARUM,so as to provide the effective carbon source for microorganisms.The static screening experiment finds that No.5 organic fertilizer and mushroom bacteria stick belong to the optimal matrixes.At the same time,when the matrix input ratio is1:3,the handling effect is optimal;to improve acid wastewater pH of coal mining,carbonatite alkali reaction wall unit is added at the end of the ARUM.Two typical carbonatites in the research area(limestone and dolomite)are screened out for the static experiment,finding that the increase pH effect of limestone is better than that of dolomite.Moreover,with the increase of the grain size,the effect becomes worse.Rocks with the too small grain size not only are easy to flow away with water but also will block the system.In practical applications,limestone with 10cm grain size not only can satisfy the requirement of increasing pH but also will not cause rock drainage and system block.(2)To verify and improve feasibility of using the ARUM in the field applications,a small-scale improved and simulated field ARUM is constructed at the nearby water gushing point of Jinzhuchong Waste Coal Mining.The flow is 5L/h.It is supervised one month continuously,finding that except for the insufficiently ideal pH and SO₄^2-treatment effect,this system has the good handling effect as a whole(pH is increased to 4.90,DO is increased to 3.1mg/L,and total Fe and Fe²⁺concentration removal rates respectively reach 92%and 93%,and SO₄^2-removal rate is 54%).Moreover,the system operation is relatively stable,suitable for the changeable environment in the field.(3)To ensure stability of the ARUM in practical applications,the SAPS is expected to be integrated with the ARUM to improve the handling effect.Through the dynamic SAPS simulation experiment in the lab,total Fe and Fe²⁺removal rates in the SAPS after continuous operation of 70d respectively reach 82%and 88%.SO₄^2-removal rate is up to 50%.At the same time,pH is increased to 6.82 from 3.09 to effectively improve pH and handling effect of AMD.(4)The improved pilot plant test ARUM is constructed in Jinzhuchong Waste Coal Mining,including the catchment unit+oxidation/sedimentation unit+microorganism reduction unit+SAPS unit+carbonatite acid reaction wall unit for a total of 5 units.Through 4 months of continuous supervision,total Fe and Fe²⁺removal rates respectively 96%and 97%.SO₄^2-removal rate is relatively lower and only reaches 57%.The improved ARUM system has the good effect for dealing with acid coal mining wastewater and has the stable operation.Hence,this research can provide the technical support for the in-situ sustainable governance of acid wastewater in Chinese coal mining.