Effectiveness of Reduction of Iron and Acidity Using Microbiology System on Treating Acid Mine Drainage
Through continuous monitoring,systematic sampling,and analysis,the variations in key physicochemical parameters such as pH,acidity,total iron(Fetot),and ferrous iron(Fe(Ⅱ))concentrations as well as the efficacy in reducing acidity and concentra-tions of Fetot,Fe(Ⅱ),SO42-,and select trace elements,of the Reduction of Iron and Acidity Using Microbiology(RIAUM)system for treating Acid Mine Drainage(AMD)was assessed.The potential Fe removal and acidity reduction mechanisms within each RIAUM unit was also explored.Results indicated stable operation of the RIAUM system with notable removal capacities for Feto,and acidity,achieving an average Fetot removal rate exceeding 94.00％and an average acidity removal rate of up to 70.29％.Effluent Fetot concen-trations met the limit requirements outlined in the Emission Standard for Pollutants from the Coal Industry of China(GB 20426-2006).Furthermore,RIAUM exhibited removal effects on Mn,Pb,Cr,Cd,and SO42-,with average removal rates of 37.34％,61.65％,86.82％,39.42％,and 28.56％,respectively.The primary purification mechanisms of RIAUM encompassed three aspects.Firstly,in the oxidation-precipitation reaction unit,Fe removal and acidity reduction occurred through natural chemical oxidation-pre-cipitation,as well as curtain adsorption and filtration.Secondly,the microbial reaction unit potentially employed a"binary"Fe purifi-cation mechanism.In surface water,besides chemical oxidation,microorganisms such as Fe-oxidizing bacteria facilitated the rapid oxi-dation and precipitation of Fe(Ⅱ),while in bottom water,S2-generated by the reduction of SO42-mediated by anaerobic bacteria such as sulfate-reducing bacteria(SRB)reacted with Fe to form iron sulfide precipitates with low solubility.However,further comprehen-sive research is required to validate this purification mechanism.Thirdly,the alkali neutralization reaction unit involved the neutraliza-tion of acidity and elevation of the water body's pH through the dissolution of carbonate rocks.The successful application of RIAUM holds promise in providing crucial theoretical insights and potential technical support for AMD treatment initiatives.
reduction of iron and acidity using microbiology(RIAUM)acid mine drainageironaciditymicroorganisms
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