Experimental Study On Immobilization Of Efficient Manganese Removal Bacteria

In the view of the current situation that manganese concentration in groundwaterexceeds national drinking water standard. In this thesis, a strain of highly effectiveiron and manganese removal bacteria which is isolated from mature bio-filter isoffered as target bacteria for immobilization. Polyvinyl Alcohol (PVA) as well as asmall amount of Sodium Alginate (SA), powder activated carbon and sepiolite ischosen as the encapsulating carrier. Based on the water sample of the laboratory ofHunan University and by the aid of model experiment, embedment immobilizedmethods is used to prepare immobilized bacteria and bio-oxide manganese iron.Through the single-factor experiments and orthogonal tests, the optimizedconditions for bacteria immobilizing are ascertained as9%of PVA,0.8%of SA,0.5%of activated carbon,0.5%of sepiolite,15%of high-efficiency bacteria in volume, and24h of cross-linking time. It is included that the volume ratio for high-efficiencybacteria has the most remarkable influence on the effect of manganese removal. AndSEM performance of the selected optimal immobilized cells is characterized, resultsshow that there is a dense layer on the micro-sphere surface which can effectivelyprevent the outflow of the bacteria, and the internal reticular formation is helpful totransfer substrates products and dissolved oxygen.The removal performance of immobilized cells is apparently superior to that offree cells，and the best conditions for immobilized microorganism are determined as25℃of temperature,7.0of pH value,15%of the volume ratio for high-efficiencybacteria. Under these conditions, the removal rate of manganese iron with the massconcentration of1mg/L in aqueous solution can reach94.09%after48hours,25.34%higher than that of free cells.In different empty bed contact time (EBCT) conditions, the start-up time ofmanganese removal filter column is not the same. When the influent concentration ofMn changes from1.09to0.97mg/L, and the initial empty bed contact time is20minutes, after filtering column operated steadily for44days, manganeseconcentration in the effluent remains below0.1mg/L. when the initial empty bedcontact time is60min, only after the filtering column works steadily27days,manganese concentration in the effluent reaches national drinking water standard. Thecultivation carries on when the filtration empty bed contact time gradually is shortened, manganese concentration in the effluent changes fiercely. After a period oftime to adapt, the elimination rate of manganese reaches above90%again. Based onMonod equation, author analyses kinetics of manganese removal in filter and provedthat the biological removal of manganese follows different kinetics within differentinlet concentrations. The experiments indicate that kinetics of manganese removalrepresents mode of high food concentration under the condition of manganeseconcentration of about3.0859mg/L, and kinetics of manganese removal represents oflow food concentration under the condition of manganese concentration of about0.5mg/L, and kinetics of manganese removal represents of two order polynomial reactionrelationship under the condition of manganese concentration of about0.9587mg/L.