| The sewage biological nitrogen removal has became an important research direction in the field aboout water pollution control, the process is mainly completed by the nitrification and denitrification process. The ammonia nitrogen was converted to nitrate by nitrification bacteria, and the nitrate nitrogen was converted to nitrogen from the water by denitrification bacteria. If the nutrient or environmental conditions change, it will affect the activity of nitrification and denitrification bacteria, and then affect the biological nitrogen removal effect in the process of biological nitrogen removal.The extracellular polymeric substances?EPS? is an important part of activated sludge, and it is a polymer material which has a great influence on the structure and performance of activated sludge. A large number of studies have indicated that the operating mode, temperature and C/N have great influence on the performance of biological nitrogen removal. Under the condition of high temperature, promoting activity of nitrifying sludge types changed quickly achieve shortcut nitrification; and C/N ratio is too high, the activated sludge system, heterotrophic bacteria will proliferate and can inhibit the growth of nitrifying bacteria, the effect of biological removal of nitrogen efficiency.In order to investigate the influence of SBR operation mode, temperature and C/N on nitrogen removal performance and extracellular polymeric substances components, this study adopts SBR technology, studied the system changes of the biological nitrogen removal performance and extracellular polymer components from the mode of operation, temperature and C/N three. The main conclusions were as follows:?1? By investigateing the effects of aerobic / anoxic?O/A? and aerobic / anoxic?A/O? operating modes on the biological nitrogen removal performance and the EPS components, the main conclusions were as follows:1) The average removal rate of NH+4-N is more than 97.2% in two operating modes, and the removal efficiency of NH+4-N with high efficiency and stability is obtained; 2) The content of EPS in sludge increased gradually, and the content of EPS in A/O system sludge was greater than that of EPS in O/A system under the two operating conditions; 3) The amount of EPS in the nitrification stage was significantly higher than that of the denitrification stage EPS; 4) The SVI value and the increase range of the O/A system were significantly higher than that of the A/O system, which showed that the O/A operation mode was more easy for the activated sludge;5) The content of EPS in sludge was positively correlated with the value of SVI in activated sludge, which indicated that EPS had an important influence on the settling performance in activated sludge.?2? The effects of temperature on the performance of SBR biological nitrogen removal and the composition of the EPS were investigated at 15?, 25? and 35? in the experiment. The main results were as follows:1) The systems of three SBRs has obtained the high efficiency and stable ammonia nitrogen removal effect in different temperature conditions. The influent NH+4-N concentration is 24.3 39.8mg/L, the effluent NH+4-N concentration is maintained below 1.5mg/L, the removal rate is maintained in the range of 88.9100%, the average value reaches 97.5%; 2) The temperature has significant effect on the transformation of nitrification type in SBR system. Under the high temperature of 35 C, SBR is easy to achieve stable short cut nitrification and denitrification; 3) The control parameters as DO and p H value can accurately grasp the end of nitrification and denitrification, saving energy consumption, and can control the aeration time in real time, to control the activity of NOB, in order to facilitate the realization of the transformation of nitrification type; 4) The temperature has an important influence on the settling performance of activated sludge. The activated sludge in SBR system with the experiment was carried out under the 3 temperature conditions; 5) The changes of DNA, PS and EPS of PN in sewage sludge showed that the nitrification stage was gradually increased, and the denitrification stage was decreased in different temperature conditions. With the increase of temperature, the content of EPS in sludge decreased gradually; 6) The main components of EPS in sludge were PS, the main components of EPS in the supernatant were PN, and DNA in the sludge and supernatant was very small, which indicated that PN was more easily separated from the supernatant than PS; 7) The effects of PN and PS in the supernatant of short range biological nitrogen removal system were influenced by aeration and carbon source. In the nitrification stage, the PN content in the supernatant was decreased and the content of PS was increased, and the content of EPS in the supernatant was recovered by denitrification stage.?3? The effects of C/N on the SBR biological nitrogen removal performance and the EPS components were studied under the condition of four kinds of C/N?0:1?5:1?10:1?15:1?. The main results were as follows:1) The SBR system achieved full nitrification under the 4 C/N conditions, and the removal efficiency of NH+4-N was obtained, and the average removal rate was above 90%; 2) The order of the nitration reaction rate?NR? in the reactor nder the condition of four C/Nwas: NRR5>NRR10>NRR0>NRR15; 3) When C/N was 0 and 5, the content of DNA, PN and PS in activated sludge EPS was significantly higher than that at the end of nitrification. When C/N was 15, the increment of DNA and PN in activated sludge was minimal, while C/N was 0, and PS was the smallest; 4) The total amount of EPS was increased gradually in the process of nitrification under the four C/N conditions. C/N was 5 at the end of the total amount of EPS at the end of the reaction was 190.2mg/?g VSS?. And when the C/N was 10, the total amount of EPS was the smallest at the end of the nitration reaction, 119.9mg/?g VSS?. |
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