The Study Of Construction, Capability, And Mechanism On Genic Engineering Strains Used In Chromium-containing Wastewater Adsorption

The biosorption of chromium-containing wastewater was researched in this study. The electricity-fusion technology and the molecule biological technology were used to breed the engineering strains, which could not only resist the high concentration of heavy metal solution but also absorb heavy metal efficiently. The capability and mechanism of Cr biosorption have been discussed. It made the further advanced research possible.The adsorptive capabilities of Candida tropicalis with high Cr-resistance, Candida lipolytica with high Cr removal efficiency and the yeast fused strain RHJ-004, in addition to Bacillus subtilis, E.coli JM109, E.coli DH5 α and E.coli BL21^- were compared respectively. The results showed that RHJ-004 was better than two parent strains, and B.subtilis was superior to three E.coli strains.The effect of reaction time, pH, biomass concentration, dissolved oxygen, etc on biosorption of Cr by the yeast fused strain RHJ-004 and activated sludge in aeration was studied. When 10g/L strain and 6g/L activated sludge were used to adsorb 50 mg/L Cr-containing wastewater, the reduction and removal ratios of Cr were 83.26% and 72.04%, respectively. Both the Langmuir and Freundlich adsorption models were suitable for describing this biosorption, and the latter was better.The results of mechanism research showed that the removal ratio and the biosorption capacity of chromium by the cell wall were much higher than those by the integrated cell, and the capacity of the cell inclusion was only 43.88% of the integrated cell. The maximum biosorption capacity and the affinity of the cell wall for Cr⁶⁺ all exceeded those of the integrated cell, demonstrating that the cell wall was the major site for adsorbing metal ions.The constructed methods of genic engineering strains for absorbing Cr were probed elementarily. The expressed product of stronger Cr-resistance was obtained in E.coli BL21^- by means of selecting in the circles that have a Cr patch to restrain microorganisms from growing. It built the foundation for developing highly effective treatment of heavy metal-containing wastewater.