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Simultaneous Removal of Cr (Ⅵ) and Phenol in a Consortium Bacterial Culture

Author: PanCui
Tutor: LiuYunGuo
School: Hunan University
Course: Environmental Science and Engineering
Keywords: Cr(VI) reduction phenol degradation Bacillus sp Pseudomonas putida Migula
CLC: X703
Type: Master's thesis
Year: 2008
Downloads: 132
Quote: 4
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Abstract


With the quick development of industry, chromate and its compounds extensively apply in tannery, metallurgy industry, print and textile manufacturing industry and so on. Wastewaters from these industries result in serious pollution of chromate in water, and bring threat to human health and the development of society. As the priority control pollutant in all countries, chromate and its treatment have caught the society’s eyes. In the wastewaters contain Cr(VI) always accompany with the organic pollutants. It is not only make the transform of Cr(VI) in the environment become more complicated, but also increase the difficulty of polluted environment treatment. There are researchers have investigated the treatment of Cr(VI) and aroma compounds by bacterial, and offered important theories to Cr(VI) and organic pollution, but most of these researches were aim at the behavior of single pollution in the environment. The environment pollution is substantially a complex pollution system which composes of various pollutants. When applied to the actual pollution environment manage, the previous research which aim at the behavior of single pollutants in the environment was affected due to the presence of other company pollutants. So, it’s essential to study the disposal of wastewater contain Cr(VI) and organic compounds by microorganism. In this study, we chose the effective bacterial consortium (Bacillus sp. and Pseudomonas putida Migula CCTCC AB92019) which resist Cr(VI) and use aroma organic compounds as carbon source to study the characteristic and mechanism of simultaneous removal of Cr(VI) and phenol by the consortium bacterial culture.A novel Cr(VI)-reducing strain Bacillus sp. which isolated from Cr(VI)-contaminated environment was studied. The result found that the strain had effective resistance to Cr(VI) and could grow in the presence of 100mg/l Cr(VI). The cells growth was declined with increasing the initial Cr(VI) concentration. The parameters affecting Cr(VI) reduction by Bacillus sp. were thoroughly investigated, such as carbon source, initial pH value of liquid medium, initial Cr(VI) concentration and temperature. The results demonstrated that addition of carbon source (glucose) enhanced Cr(VI) reduction obviously. The initial pH value of liquid medium had important effect on Cr(VI) reduction, the efficiency of Cr(VI) reduction by Bacillus sp. was the highest when the pH value was 9.0, and the Cr(VI) concentration decreased from 20mg/l to 0mg/l after 42h. Cr(VI) was reduced by Bacillus sp. under three different temperature, and the rates of Cr(VI) under 37℃was higher than the other two conditions, the Cr(VI) reduction complete after 36h.The second step of the experiment was to study the biodegradation of phenol by a pure culture of Pseudomonas putida Migula (CCTCC AB92019) when the phenol was the only carbon and energy source. Experiments were conducted at an initial phenol concentration of 100-1000mg/l, pH value 4-10, temperature 20-50℃and an addition of carbon source (glucose) 0.5-1.0g/l respectively. The Monod kinetic model was applied to describe the biodegradation process. It was shown that the first-order kinetics could properly interpret the process with a correlation coefficient of 0.928, based on which the maximum degradation rate of phenol was estimated up to 95.5% within the range examined. The optimum values of pH, temperature and glucose concentration were found to be 7.07, 30℃and 0.5-0.6g/l respectively when the degradation of phenol obtain the maximum.At last, the paper studied the simultaneous removal of Cr(VI) and phenol in a consortium culture containing Cr(VI) reducer, Bacillus sp. and phenol degrader, Pseudomonas putida Migula (CCTCC AB92019). Phenol was used as the sole carbon and energy source. B.anthracis utilized metabolites formed from phenol degradation as electron donors and energy source for Cr(VI) reduction. Optimum Cr(VI) reduction was observed at a phenol concentration of 150mg/l at an initial Cr(VI) concentration of 15mg/l. Both the Cr(VI) reduction and phenol degradation were influenced by the cell composition of the culture,but the phenol degradation was not significantly affected by the content of B. anthracis. The experiments also found that the amount of phenol being degraded was more than the stoichiometrically required for Cr(VI) reduction.

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CLC: > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization
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