Study On Screening Identification And The Affecting Factors Of Efficient Fungus For Removal Of Cr~3+from Leather-making Effluent

Chromium can cause great harm to the environment. The current research on chromium removal mainly concentrated on Cr6+removal, the removal of trivalent chromium is less reported. Although the toxicity and harm of Cr3+less one percent than Cr6*, the harm of trivalent chromium can not be ignored. It is a kind of protein coagulant that harm to humans and animals, it can cause hoarseness, epistaxis, nasal septum perforation, nasal mucosa atrophy disease, even lung cancer if who have been inhaled chrome oxide concentration of0.015-0.033mg/m3.In the leather industry, the effective use of Cr3+was only about60%, while the remaining Cr3+residue in the form of wastewater and sludge, which affecting the ecological environment and human health causing it will remain in environment and organisms. Therefore, we have research to screening of the high efficient fungus for removal of Cr3+from tannery wastewater and sludge and the affecting factors of the high efficient fungus. The main results are as follows:1. A Penicillium janthinellum for removal of Cr3+have been isolated for the first time.12bacteria strains and15fungi strains which can resist the Cr3+have been isolated from Changsha jinjing tannery wastewater. Fungus which have been isolated from tannery wastewater are inoculated to different Cr3+concentration in the liquid culture medium. By gradually increasing the concentration of Cr3+in medium,4fungi strains which have Cr3+tolerance ability have been screened inl.Og/L concentration of Cr3+liquid medium,which were named B2, B5, F2, P1. The strain B5and F2were found to have a strong resistance to Cr3+from the experiments. It was also found that the B5was an efficient fungus for removal of Cr3+by with a removal rate of50%, the strain F2was32%. B5strain was determined to be Penicillium janthinellum by morphological identification and ITS sequence analysis. Nowadays the study of Penicillium janthinellum resists the heavy metal main focus on resist the Cu2+and Zn2+, there is still unreported about Penicillium janthinellum resist the Cr3+in China.2. The optimum conditions for the high efficient fungus which can resist the Cr3+were studied. The growth curves of the high efficient fungus which can resist the Cr3+shows that1-3days was the adjustment period of the strain B5,3-4days was logarithmic phase,4-6days was the stable phase, after6days was the attenuating phase, removal efficiency of Cr3+of the strain B5was inversely proportional to the initial concentration of Cr3+.25-30℃was the optimum temperature to removal of Cr3+and the optimum pH was 7-8. In optimal conditions removal efficiency of Cr3+of the strain B5higher than92%when the concentration of Cr3+was lower than0.4g/L.