| Denitrogen of the low C/N ratio wastewater has been one of the hotspots and difficulties in the research of sewage treatment. The application of normal denitrogen technologies in low C/N ratio wastewater has some limitation. Therefore, it is of great importance to develop new technologies for denitrogen of low C/N ratio wastewater. In this study, a novel Fe-C based biological carrier which combined the biodegradation function of biocarrier and the carrier chemistry was firstly created. Special attention were paid to the preparation technologies and methods of the composite biological denitrifying carrier, the performance of physicochemical properties, the application of the carrier for denitrification of low C/N ratio wastewater.(1) Iron powder and activated carbon powder, as the main materials of the composite biological denitrifying carrier, were mixed with different volume ratio, together with varies adhesives. The mixture were stirred fully, made into small balls, roasted under certain temperature and time and finally turned out to be the carrier with the size5-10mm. The index such as the changing of pH, ORP, NH3-N and NO3--N changing in water treatment, together with the material characteristics such as specific surface area, porosity and strength, were investigated as the optimizing objective of the carrier. According to the single factor analysis method, the best adhesive, the best volume ratio of Fe/C, the roast temperature and best duration could be calculated as a result.(2) The physicochemical properties of the carrier created in the experiment were: almost round ball shape; rough and porous on the surface; average grain size at8.47mm; true density, apparent density, bulk density were4.072g/cm3,2.621g/cm3,1.412g/cm3, respectively; void ratio46%; strength of single grain2.31MPa; angle of reposeθ23°; electric potential of Zeta-22.1mV; specific surface area of BET32.017m2/g. Besides, the carrier was mainly consist of mesoporous, including iron, carbon, oxygen, adhesive5, catalyst and so on, and the mass fraction for each of them were51.86%,36.97%,6.33%,3.53%,1.31%, respectively. Comparing with other carriers such as activitated carbon, ceramsite, zeollite and so on, the characteristic index of the composite biological denitrifying carrier is better.(3) The experiments were carried out to analyze the effects of pH and HRT on denitrifying of the carrier. According to the results, the carrier worked well in acidity, neutral, as well as alkalinity wastewater. However, the microorganism, such as nitrifying bacteria, autotrophic denitrifying bacteria, could only performence well in some neutral pH value. With the combination of the two aspects, the chosen theoptimal pH value of carrier is neutral around6.5-7.5. Besides, a longer hydraulic retention time, resulted in the better the denitrfying. Taking both the processing results and economical factors into consideration, optimal HRT was determined4h.(4) Continuous run experiment was cuducted in a reactor, investigating denitrifying of the coupling system of biofilm and the carrier for low C/N ratio wastewater. The results showed that, after51days’microculture in the reactor, the coupling system of biofilm and the carrier were gained and steable, and showed a good denitrifying result of the low C/N ratio wasterwater (C/N=2.5), with the remove rate of NH3-N, NO3--N, TN and COD at86.54%,85.68%,83.67%and91.65%without additional carbon resource. Comparing with other carriers such as activitated carbon, ceramsite, zeollite and so on, the characteristic index of the composite biological denitrifying carrier is better.It can be concluted that low C/N ratio can be efficiently treated by the self-developed carrier without extral carbon resource. This technology can solve the problem of the denitrifying for low C/N ratio wastewater, providing basis of theory and technology for the deep denitrogen of low C/N wastewater. |
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