The Study Of Exploitation, Application, And Mechanism On Biosorbent Of Heavy Metal

The biosorption of heavy metal-containing wastewater was studied comprehensively in the research, including selection of biosorbents, capability of sorption, treatment of simulated and practical chromium-containing wastewater, mechanism of biosorption, on-site experiment, and toxicity of chromium and strains of biosorption.Many samples of wastewater and sludge from plating plants and hardware plants were collected. Ten strains cultured by these samples were determined to have high-efficiency of chromium accumulation, including a strain of bacteria, Sporobolomycetaceae sp. YJS, Candida utilis, Candida FOLA, and six strains of mold.The study of culture conditions of biosorbent showed that different ingredients of the medium had distinctive effects on the growth of strains. The optimal cultivation condition of Sporobolomycetaceae sp. YJS was glucose 20g/L, peptone 5g/L, yeast extract 2g/L, and pH5. After cultivated by this medium for 60h, the ceil of S. sp. YJS had reduction and removal ratios of 68.9%, 61.6% to the 30mg/L chromium-containing wastewater after 8hr biosorption. When cultivated by monosodium glutamate wastewater, the ratios were 68.8% ^ 63.1%, respectively.The capability of the biosorbent would be promoted greatly after some rational pretreatments. Among the general compounds, NH4C1, NH4NO3, NaOH, Na2MoO4, especially NH4Cl, NH4NO3, could boost the biosorption effectively. The ratios of reduction were 87.1%, 84.4% respectively, and the removal ratios were 83.9%, 80.7% accordingly, after pretreated the cell by NH4Cl,NH4NO3 severally.There were a lot of ions and compounds in the chromium-containing wastewater, each of them would impact the practice of biosorption accordingly. When ranged from proper concentration, the ions of Na+, K+ , NH4+, -NH2, Cl- would increase the ratios of removal.PH was one of the most crucial factors for the removal of heavy metal by biosorbent. Different strains had dissimilar optimal pH. The appropriate pH of S. sp. YJS, Candida utilis, and Candida FOLA were 2.5-6.5, 3-5, 3-7, the optimal cultivation time were 50~65h, 35~48h, and 20~60h respectively. The reduction and removal ratios to the 30~35mg/Lchromium-containing wastewater by these three strains after 8 hours biosorption were 85%~95%, 65%~80%; 70%~80%, 65%~70%; and 95%~100%, 85%~98% respectively.The efficiency of biosorption would heighten markedly when the suitable conditions for the treatment were reached. When treating plating waste water in which the total content of chromium was 34.4mg/L and the Cr(VI) was 30mg/L, the reduction and removal ratios were exceeded 92% after treated by Sporobolomycetaceae sp. YJS undergoing the optimal condition for 8 hours.The study of aerobic treatment of practical plating wastewater was discussed. The removal ratio to the 30.9-68.6 mg/L chromium-containing wastewater was reached 94%~100% after treated by 10g/L Candida FOLA for 8 hours within the pH range of 5.4-5.8. The combination treatment of heavy metal and organic waste water was proposed for the first time. The toxic experiment showed that the biosorbent were safe.