Research On Nonylphenol Biodegration

Nonylphenol (NP), as one kind of endocrine disrupting chemicals, its threat to environment and human had been paid more attention. Many researchers had monitored the content of NP in environment and organisms. The toxic of NP had also been researched. But there were fewer researches on the elimination of NP, especially using the biodegradation method. The purpose of this experiment was to research the Biodegradation of NP.The samples were fetched from the water where the content of Nonylphenol and Polyoxyethylene were large. After culturing in lab, a bacterium which could tolerate phenols and biodegrade NP was obtained. Then its gram character was determined by gram staining. By 16S rDNA analysis, the bacterium which had the best biodegradation ability was confirmed to be Pseudomonas putida.After the bacterium was separated, the effect of biodegradation was researched and the growth curves of the bacterium were made. According to the growth curves, the orthogonal test was carried out to optimize degradation conditions in logarithmic growth phase, considering the affection of temperature, pH, time and concentration. The optimum conditions of the degradation of NP were obtained by counting degradation rates. The results showed that the optimum degradation conditions of the bacterium from broth culture (B-01) were as follows: temperature of 30℃, pH value of 7.0, degradation time of 26h and the concentration of NP in culture of 26.91860ng/μL (26.91860 mg/L). Under the above conditions, the degradation rate could reach 68.32%. The results also showed that the optimum degradation conditions of the bacterium from carbamide medium(B-03) were as follows: temperature was 20℃; pH was 7.0; culture time was 26h and the NP concentration in medium was 5.15987ng/μL (5.15987 mg/L). Under the above conditions, the degradation rate could reach 55.28%.By GC-MS detecting method, under the optimal biodegradation conditions, Pseudomonas putida could degrade NP, and the degradation products were octylphenol and pentylphenol. So it could be inferred that the mechanism of biodegradating NP was that the fracturation of alkyl chain was prior to benzene's. The NP broke off an end carbon and became octylphenol, and then it broke off others carbon and became pentylphenol.The primary application research on Pseudomonas putida was carried out in lab condition, and the affection of photoperiods on the degradation of NP was also considered. The result showed that the degradation rate was high when there was photoperiod. When the simulated wastewater was treated with the strains, closer to truewastewater quality, the degradation effect was excellent, the removal rateof COD could reach 60%, and the quality of the water was evidentlychanged.