The Research For Enhanced Biological Stabilization Of Heavy Metals In Sediment Using Immobilized Sulfate Reducing Bacteria Beads With Inner Cohesive Nutrient

Heavy metals contamination has become one of the serious environmental problems today.And sediment is an important carrier of heavy metals,which can cause harm to human health via food chain due to its special chemical properties and toxicity effect.So it is critical to deal with heavy metal pollution of sediment.A series of experiments were conducted for treating heavy metals contaminated sediments sampled from Xiangjiang River,which combined polyvinyl alcohol(PVA)and immobilized sulfate reducing bacteria(SRB)into beads.The sodium lactate was served as the inner cohesive nutrient.The optimal conditions for the preparation of immobilized beads were determined by stabilization experiment in terms of the ability of dealing with Cu?Zn?Pb?Cd:the mass fraction of PVA,SA and CaCl2 is 9%,3%and 2%,respectively.And the mechanical strength,difficulty of forming beads and mass transfer is stronger under the optimal conditions.In this paper,the speciation analysis results on the basis of BCR continuous extraction indicate inner nutrient beads have the ability of transforming metals into more stable form.The results revealed the performance of leaching toxicity was lower and the removal efficiencies of Cu,Zn,Pb and Cd were 76.3%,95.6%,100%and 91.2%,respectively.It shows stabilization effect is good and the result is confirmed by continuous extraction at the optimal conditions.Recycling experiments showed the beads could be reused 5 times with superbly efficiency.Coupling the activity of the SRB with PVA,along with the porous structure and huge specific surface area,provided a convenient channel for the transmission of matter and protected the cells against the toxicity of metals through SEM analysis.Furthermore,X-ray diffraction(XRD)and energy-dispersive spectra(EDS)analysis indicated the heavy metals could be transformed into stable crystal texture.Results presented that immobilized bacteria with inner nutrient were potentially and practically applied to multi-heavy-metal-contamination sediment.