Combining Desulfuromonas alkenivorans S-7 with rice husk to treat acid heavy metal wastewater

To study the role and mechanism of sulfate-reducing bacteria and rice husk combined bioreactor in heavy metal wastewater treatment,the sulfate-reducing bacteria Desulfuromonas alkenivorans S-7 isolated and identified in the laboratory was combined with a rice husk column bioreactor to deal with the synthetic acid heavy metal ( Fe3+ ,Mn2+ ,Cr6+ ) wastewater. The physicochemical characteristics ( pH,Eh ,Ec ) and changes of three heavy metal ions in wastewater treatment process were compared. Then the removal characteristics of heavy metal ions under the combined treatment of microorganism and rice husk were analyzed by FT-IR spectrometer. The results showed that S-7 could sig-nificantly increase the pH of acidic wastewater,and the pH was finally stabilized at about 6. 20 after 20 days. It could also maintain the reaction system in a high reduction environment and reduce the conductivity of the system. S-7 strain had a certain treatment effect on three representative ions,and the removal efficiency of Fe,Mn and Cr metal ions was Fe>Mn>Cr,respectively. At the early stage,the removal rate of metal ions in the wastewater treated by the reactor was relatively fast,but at the later stage,due to the influence of metal ions coexistence on the wastewater treatment,the concentration of them in the wastewater tended to balance,and a dynamic restriction balance appeared. The removal mechanism of the three heavy metal ions in the S-7 strain may be different. In the later stage of treatment,the concen-tration of Cr6+ increased significantly,which increased the heavy metal content in SRB reactor and significantly affected the stability of SRB reactor. Rice husk filling could maintain the stable anaerobic environment of SRB reactor for the growth of S-7 strain,and the rice husk also had a certain degree of physical adsorption effect on the removal of metal ions. FT-IR analysis showed that S-7 bacteria adsorbed Fe,Mn and Cr ions when treating wastewater,and the hydrox-yl,amine,amide and carboxyl groups were important functional groups for adsorption. The Si—O—Si and carbonyl groups of rice hull may play a role in the treatment of heavy metal wastewater.