A Study On Waste Water Treatment Of Heavy Mentals Combining Porous Material And Microorganism

With the rapid development of China’s industry, the heavy metal pollution has been getting more and more serious. For instance, the heavy metal ions such as Cd2+, Hg2+ and Pb2+ have relative biological toxicity, and they can keep stable under normal environment that can not degrade in a short time. The heavy metal ions can accumulate in living creatures in a long time and will be further transferred to human bodies through the food chain. Therefore, how to effective address the industrial wastewater with rich heavy metal ions is becoming an urgent problem for environmental engineering studies. On the basis of the overview on the heavy metal ions adsorption of the organisms, this thesis has studied multiple experiments on the absorption ability analysis.of porous material and engineering yeast strain on such heavy metal ions (e.g., Cd2+, Hg2+ and Pb2+).Firstly, the thesis has conducted adsorption experiments to analyze the adsorption results of porous material (such as activated carbon, natural zeolite and montmorillonite) on the wastewater with different concentrations of heavy metal irons. Based on the adsorption results, one can conclude that the activated carbon has the best Pb2+ adsorption ability, the natural zeolite has a better Hg2+ ability, and montmorillonite has the best adsorption performance with Cd2+. Alternatively, in a suitable concentration of the ions, the Cd2+, Hg2+ and Pb2+ adsorption results of the porous material can satisfy the Langmuir and Freundlich’s isothermal adsorption equations with a good fitting result.Moreover, the proposed experiment adopted the engineering yeast strain which has a good absorption performance on heavy metal ions. Through the experiments, it can determine the best conditional parameters in the absorption of the engineering yeast strain dealing with the wastewater with rich Cd2+, Hg2+ and Pb2+. The parameters include the initial pH value, adsorption time, the initial concentration of the heavy metal ions, the amount of the engineering yeast strain. The experimental results indicate that pH value of 4.0 for the removal of Cd+, Hg2+ and Pb2+ of the best heavy metalions, he adsorption process can reach the stable status in about 30 minutes, and 4g of the engineering yeast strain is the best amount for absorbing heavy-metal wastewater.And the adsorption process engineering yeast steain the pseudo-second-order kinetic model,there is a good fit results.Since the dissociative strains have a bad stability in addressing heavy-metal wastewater, the adsorption performance is not acceptable. Thus, this thesis adopted the immobilized microorganism technique to clean the heavy-metal wastewater with combining engineering yeast strain and porous material. After some experiments, one can find that the combination of montmorillonite and strain show the best adsorption behavior of the heavy-metal irons in the wastewater, and the adsorption efficiency of Hg2+ and Pb2+ is more than 95%. The adsorption efficiency has been increased compared to the single adoption of engineering yeast strain and porous material. The secondary kinetics model is used to analyze the combining adsorption process. The experimental results verify that this model can meet the requirements of simulated prediction of the heavy-metal irons elimination under the combination of montmorillonite and engineering yeast strain.