The Experiment Study On Treating Mine Drainage With The Combined Effect Of Bentonite Adsorption And Microbial Reduction

Acid mine drainage contains lots of Fe2+, Mn2+and SO42-, the problem of wide pollution, low effective control and great difficulty are existed. the article through static test stduty on bentonite composite particles to remove acidity, Fe2+, Mn2+and microorganism reduction remove SO42-from AMD. On this basis, further research on adsorbing by bentonite composite particles combined with microorganism reduction to deal with AMD through dynamic test. The aim is to explore a complementary and high efficient, economic and environmental protection treatment technology.In order to solve the mine drainage’s acidity, little industrial waste is added to bentonite, then mixing with binder to be made of bentonite composite particles, they were used for removing the acidity, Fe2+and Mn2+in mine drainage. The comparative screening study on six kind of basic refractories which are steel slag, dolomite, fly ash, limestone, slag and volcanic, the result show steel slag is the best basic refractories; Bentonite-steel slag composite particles releases of total alkalinity is122.13mg/g, the removal of Mn2+is excellent, the removal efficiency Mn2+can reach99.31%, adsorptive capacity can reach130.15mg/g for313h,1g bentonite-steel slag composite particles can treat2.44L AMD which pH=3, C(Mn2+)=35mg/L, the lost ratios of the particles is very low and the granule is adamant.Based on previous research, to determine the best preparation conditions of bentonite-steel slag composite particles:calcination temperature is600℃, calcination time is60min. The particles treat AMD well:when the reaction occurred60min, the removal rate of Fe2+changed to be steady and up to99.28%; when100min, the removal rate of Mn2+changed to be steady and up to89.66%. The mechanism of bentonite-slag composite particles remove Fe2+, Mn2+is mainly adsorption, chemical precipitation, coagulation.Through static test research on SRB reduction to remove SO42-, looking for the fermentation broth of chicken manure and sawdust as new organic carbon to SRB. In the conditions of inoculation amount6%, C:S=1.5～2.0, pH=6.5～7.6, temperature35℃, when the reaction occurred14d, the removal rate of SO42-reach maximum is98.23%,the capability of SRB remove to SO42-is excellent. Respectively exploring the concentration of Fe2+, Mn2+to affect the growth of SRB, C(Fe2+)≤500mg/L, Fe2+promote the growth of SRB, C(Fe2+)>500mg/L, Fe2+inhibit the growth of SRB, C(Fe2+)≥700mg/L, SRB loss of activity; C(Mn2+)≤140mg/L, Mn2+promote the growth of SRB, C(Mn2+)>140mg/L, Mn2+inhibit the growth of SRB. Based on the static test research, research on adsorbing by bentonite-steel composite particles combined with microorganism reduction to deal with AMD through dynamic test. The two dynamic columns are filled with bentonite-steel composite particles and biological carrier, the one is stratification, the other is mixing, contrast two columns’ the removal effect of acidity, Fe2+, Mn2+, SO42-in AMD, to determine the stratification filling conducive to the treatment of AMD. Bentonite adsorption combined with microbial reduction is a synergistic process which is bentonite adsorption promote microbial reduction and microbial reduction perfect bentonite adsorption, it is an innovative and efficient water treatment method, it is worth to application and spreading.