When selecting aeration equipment, stability is key. Ensure practicality rather than pursuing a single goal at the expense of equipment with low practical value but high cost. In practice, in bio-treatment pools filled with media, the oxygenation power of aeration equipment often experiences significant changes. Generally, equipment using microbubble aeration methods is chosen primarily for consideration. When the bubble diameter is small, the oxygen transfer and utilization efficiency improve; however, the issue is that during aeration, all bubbles are microbubbles, which lack disturbance to the water body and are thus unfavorable for the renewal of the biofilm on the media surface.
And micro-bubbles often show a tendency to aggregate rather than burst when they collide with the filling material during their ascent, thereby reducing the oxygen consumption rate. Aeration equipment that uses large and medium bubbles for illustration often demonstrates lower oxygen usage rates in blank experiments compared to micro-bubble equipment. However, due to the larger bubble sizes, these aeration devices frequently cause vigorous turbulence in the water. The lower surface tension of the bubbles causes them to be continuously cut and broken when colliding with the branches of the filling material during ascent. Therefore, in structures rich in filling material, the oxygen usage rate of this aeration equipment tends to show a relative increase.
Wastewater treatment facilities have reached the national discharge standards, but the sludge generated during the treatment process, which is subject to rewards and penalties, has not been properly disposed of, leading to secondary pollution of the environment. In some areas, sludge is not treated safely and is simply stacked outside the facility, with no trace of its whereabouts. In other regions, sludge is dried and used as agricultural fertilizer, with little consideration given to the heavy metal content and the potential harm to crops. Of course, treatment ponds filled with different types of fillings will show varying results under the same aeration conditions. Beijing University of Technology has designed and constructed seven experimental columns, each with a diameter of 150mm and identical volume and water level, to test this. They filled six representative types of fillings and one blank column, with the filling height at 3 meters. The fillings used were: honeycomb fillings, soft fiber fillings, composite fillings, plastic spherical fillings, semi-soft fillings, and elastic three-dimensional fillings.
Due to the high power of the blowers and the excellent three-dimensional aeration performance, blowers are currently widely used. The terminal key equipment for blowering is the aeration device, thus, the development status of the aeration technology represents the level of blowering technology. Because of the process theory calculation related to the aeration pond, the basic point is the oxygen utilization rate, which leads to the focus of the technical evaluation of aeration devices on the oxygen utilization rate, and also results in the phenomenon of pore dispersion—where exhaust pores become increasingly finer. For any equipment, its functional efficiency must be supported by reasonable technology, which is a general technical principle, and pore dispersion is entirely inconsistent with such a technical principle. In theory, higher functional efficiency is always better for equipment, but if this efficiency is achieved at the expense of reduced technical reliability, it is obviously problematic. Of course, the "oxygen utilization rate" of aeration devices should be as high as possible, but if achieving such power degrades technical reliability, it is clearly an issue.
