Study Of Chromium, Nickel-containing Wastewater Biosorption Treatment

Mechanism of biosorption on heavy metal and genetic strains construction were discussed in this research, including heavy metal-contained wastewater treatment craft, ion exchange, substance metabolism, functional group, cells microstructure in the process of biosorption and genetic strains construction.Nickel-contained wastewater was treated by yeast fused strain and activated sludge together with aeration and the results showed that the strain could accumulate nickel effectively from aqueous solution and when the strain dosage is 10g/L the removal ratio of 20mg/L nickel is 70.10%. With 6g/L activated sludge added in the solution the ratio has increased to 80.73%, which is owed to steady and favored environment for biosorption created by activated sludge. Dissolved oxygen (DO) was important factor for aeration biosorption with optical DO 2.5⁴.5mg/L.Modern analysis technology, including inductively-coupled plasma spectrometer, ultraviolet spectrum, infra-red spectrum, energy-dispersive X-ray spectra, atomic force microscopy, scanning electron microscopy and so on were used to probe into the mechanisms of biosorption. Cations transportation experiment certificated that the transportation of heavy metal, H ion was coupled with the release of intracellular K⁺ Mg²⁺ Na⁺ Ca²⁺ in the process of biosorption and in 30min the biosorption approached saturation and the exchange between heavy metal and cations reached balance. Cell surface-microprecepitation and intracellular accumulation together played important role in the accumulation of heavy mental and amide and protein were vital carriers for biosorption. SEM and AFM observed that after heavy metal biosorption the microstructure of cells were destroyed and the retraction, empty and fission of cells appeared because of microprecepitation of chromium on cell surface, increasing permeability of cell membrane, chelation of Cr and organic high molecule in cells and release of cations from cells.The DNA library of Cr-resistance Bacillus subtilis was constructed to study the resistance gene.