Aiming at the problem of low oxygen transfer rate in the process of continuous aeration in biochemical tank, combining with the actual situation of sewage treatment, the pulse aeration method of disc microporous aerator was put forward to improve the oxygen transfer rate. By comparing the experiments of four groups of different types of disc microporous aerators under pulsed and continuous aeration, it is found that the bubble clusters are produced by pulsed aeration. The analysis of experimental data shows that the time needed for pulse aeration to reach oxygen saturation is about 10% longer than that of continuous aeration, but the utilization rate of oxygen is increased by more than 50% and the dynamic efficiency is increased by more than 28%. Pulse aeration greatly improves the utilization rate of oxygen, saves energy consumption and has better aeration effect. It provides a new research idea for the aerobic biochemical treatment system of activated sludge.

Fine bubble membrane diffuser is the core equipment of activated sludge water treatment aeration system. It can increase the oxygen content in sewage through aerator, which is used for microbial growth and biochemical reaction, and improve the water environment. Statistical data show that the energy consumption of the aeration system accounts for more than 60% of the total energy consumption of the sewage treatment system, and the power consumption of the aeration system accounts for about 40% of the total operation cost of the sewage treatment system. The traditional aeration system has been paid close attention by experts at home and abroad because of its low utilization rate of oxygen, which leads to large energy consumption. However, these problems have not been substantially improved. Therefore, improving aeration equipment to improve its efficiency and reduce energy consumption has become an important research topic of environmental protection industry.

1. Aeration experiment phenomena: continuous microporous aeration produces a steady bubble flow, and the diaphragm of the aeration disk has been in a bubbling state; pulse microporous aeration produces a stream of bubbles, the turbulence of the water is greater, and periodic bubbling and contraction of the diaphragm of the aeration disk can be observed. The angle is generated from the surface of the diaphragm and dissolved into the water body.

2. Effect of pulse aeration on bubble formation

According to the theoretical analysis of bubble formation, bubble diameter decreases under pulse aeration. In order to verify the correctness of the above theoretical analysis, the image of bubble formation process is analyzed and processed. Because there are many and dense bubbles at the orifice of the aeration pan and it is difficult to distinguish them, the bubbles sampled are 80 cm away from the bottom of the tank, as shown in Figure 4. The high-pixel digital camera (VW-600 optical microscopy system) was used to take multiple pictures at the same location, and then the image analysis software Image profession plus 6.0 was used to analyze and count the bubble number in the selected range. Value. 2 of the pictures are shown in Figure 5, and the results are shown in Table 1. As can be seen from Fig. 5, the number of bubbles generated by pulse aeration is large and the area of single bubble is small. Image-ProPlus 6.0 statistical function is used for data analysis, and the data is arranged as shown in Table 1. As can be seen from Table 1, the number of bubbles produced by pulsed aeration is nearly 46% more than that by continuous aeration in the same region; the average diameter of bubbles produced by pulsed aeration is smaller than that by continuous aeration, and the average area of bubbles produced by pulsed aeration is smaller than that by continuous aeration. In the same region, the bubble diameter generated by pulse aeration is smaller, the total bubble area generated by pulse aeration is larger than that by continuous aeration, and the contact area between gas and liquid is increased, which is more conducive to the transfer of oxygen.

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