Treatment acid mine drainage by sulfate reducing bacteria using different biomass carbon sources

In terms of the serious pollution of multi-component Acid Mine Wastewater (AMD) and the high treat-ment cost,the treatment of AMD based on Sulfate-Reducing Bacteria (SRB) has many advantages such as low cost,applica- bility and environmental friendliness. A strain of SRB was purified and cultured for a long time from soil contaminated with coal gangue leaching water. Using cheap and easy-obtained corncob,bagasse and peanut shells as the carbon source for SRB growth,the dynamic columns 1,2 and 3 were constructed respectively and the simulation experiment of AMD was carried out. Each dynamic column was filled according to the optimal ratio of the orthogonal test. Column 1 filled with SRB biomass and 60 mesh corncob was loaded at a solid-liquid ratio of 106. 8 ∶ 100 (mg ∶ mL) and 3. 5 ∶ 100 (g ∶ mL). Column 2 filled with SRB biomass and 100 mesh bagasse was loaded at a solid-liquid ratio of 71. 2 ∶ 100 (mg ∶ mL) and 4. 5 ∶ 100 (g ∶ mL). Column 3 filled with SRB biomass and 100 mesh peanut shell was loaded at a solid-liquid ratio of 106. 8 ∶ 100 (mg ∶ mL) and 4. 5 ∶ 100 ( g ∶ mL). The results showed that Column 2 with the 100 mesh bagasse as the carbon source performed better in repairing AMD. The average removal rates of SO24- ,Fe3+ , Mn2+ ,Cr6+ and Cr3+ were 61. 63% ,99. 81% ,72. 35% ,96. 8% ,100% ,respectively. The pH and ORP values of the system effluent were 6. 38-7. 30 and -246 mV,respectively. Therefore,as a carbon source,the growth and metabolism activity of the bagasse was better than those of corncob and peanut shell. Bagasse could supply carbon source for a lon- ger time. The SEM and XRD analysis of the biomass material before and after the reaction showed that the element Fe was mainly removed by chemical adsorption of the biomass material,and the elements Mn and Cr were mainly removed by precipitation of metal sulfides formed by reaction with metabolites of sulfate-reducing bacteria. A small part of the metal element was removed by the physical adsorption of biomass material. The surface structure of the biomass materi- al before the reaction was complete,but,it was destroyed and the nano-scale metal sulfide precipitate was attached on it after the reaction.