The Chromium (Cadmium) Detoxification Of Lotus Seed Pods And Lotus Seed Pods-immobilized Sulfate-reducing Bacteria WH16-1

With the industry and agriculture rapid developing,heavy metal pollution,such as chromium and cadmium in large area of water and soil,is becoming a serious problem,which leads to the decline of water quality and crop production.Therefore,it is concerned that how to efficiently remove chromium and cadmium from wastewater and contaminated soil.This research used a kind of cheap and available agricultural wastes-lotus seed pods to dispose the wastewater containing Cr???,then prepared the immobilized.sulfate-reducing bacterial WH16-1 using lotus seed pods,and applied the immobilized WH16-1 to detoxify the wastewater containing Cd²⁺and Cr???and the Cd²⁺-contaminated soil.The main results were as follows:1.The maximum removal of Cr???by louts seed pods in the solution was 150.71mg/g and the removal process fitted to the pseudo-second-order kinetic model.The optimum pH for the removal of Cr???was 2,and the removal rate decreased with the increase of the initial concentration of Cr???.Considering the results of SEM-EDS,FTIR,XRD and XPS characterization and removal experiment,an�Adsorption-oxidation�reduction-re-adsorption process�was put forward about the removal process of Cr???by lotus seed pods.Louts seed pods after removal of Cr???was collected and carbonized to prepare a kind of new materials,which contained 16.70%chromium.2.Through the orthogonal experiment,the optimum conditions of preparing the immobilized WH16-1 strain were found,which was 0.5 g for lotus seed pods,1 g for sodium alginate,2%of calcium chloride and crosslinking for 24 h.The removal rates of immobilized WH16-1 on 9 mg/L and 50 mg/L Cd²⁺solution were 92.96%and 81.09%,respectively,which were 24.53%and 76.09%higher than that of free WH16-1 strain.The removal rates of immobilized WH16-1 on 300 mg/L and 500 mg/L Cr???were 100%and 82.43%,respectively,which were 19.87%and 19.22%higher than that of free WH16-1 strain.The removal rates of Cd²⁺and Cr???in the solution containing 9 mg/L cadmium and 300 mg/L Cr???mixed were 83.19%and 97.46%,respectively,which were 31.51%and 12.37%higher than those of free bacteria WH16-1,respectively.3.In rice pot experiment,compared with the control,the paddy soil exchangeable and carbonate bound cadmium in the immobilized WH16-1 treatment group decreased by33.6%?P<0.05?and 17.36%,respectively.The Fe-Mn oxides-bound,organic matter-bound and the residue cadmium significantly increased by 56.51%,67.14%and17.48%?P<0.05?.The cadmium concentration in rice decreased significantly by 78.31%?P<0.05?.This study found a biomaterial which can effectively deal with environmental wastewater and was a kind of good materials for microbial immobilization.Lotus seed pods and lotus seed pods-immobilized sulfate-reducing bacterial WH16-1 has certain application prospects in wastewater treatment and soil detoxification.