Characteristics Of Dmf-Degrading Bacterium And Its Applicate In The Bioaugmentation Sbr System

A bacterial strain, capable of utilizing DMF (N, N-dimethylformamide) as sole carbon and nitrogen source was isolated from activated sludge collected from wastewater-treating system of a pharmaceutical enterprise. This strain was identified as Pseudomonas sp. according to its morphological, physiological and biochemical analysis and the analysis of its16S rRNA gene sequence, and named DMF-3.DMF-3could utilize glucose and maltose better of carbon source, and it could utilize beef extract and peptone better of nitrogen source. The optimal growth temperature and pH is30℃and7.0respectively. Ventilation had little impact on the growth of DMF-3. Strain could grow well in the NaCl solution with the concentration of0-15g·L-1, and the optimum concentration of NaCl was5g·L-1. DMF-3was resistant to ampicillin, kanamycin, chloramphenicol, erythromycin, but was sensitive to gentamicin.Strain DMF-3could degrade400mg·1-1DMF within72h. Release of ammonia-nitrogen was equivalent to90%of the theroretical value of that404mg·1-1DMF was completely degraded to ammonia. The optimal pH and temperature for the degradation were7.0-7.5and30℃, respectively. The degrading rate showed a positive correlation with the initial inoculum size. By the result of HPLC-MS analysis, we find that the intermediate material of DMF degradation is formamide and metabolic end product is NH4+. Diversity of degradable substrates showed that strain DMF-3growed best in formate, and growed better in formamide than dimethylamine.The biodegradation of DMF in different concentrations by strain DMF-3, and reaction dynamic equations, such as Monod equation and Haldane equation were adopted to fit the degradation process, with low organic compound concentration, which was in accordance with Monod equation; with high phenol mass concentration, which was in accordance with Haldane equation. In order to investigate the effectiveness of bioaugmentation strains and to solve the problem of the inefficient DMF wastewater treatment, the high efficient DMF degrading bacteria (DMF-3) screened in laboratory was selected as the study object. It was added into SBR system to observe if it could improve DMF wastewater treatmentability and its ability to degrade the bioaugmentation SBR system influent COD at the time of enhancing the COD load.