There are two common causes of clogging in Fine Bubble Air Diffuser: mechanical clogging (mostly in the inner side of the aerator) and Biological Clogging (mostly in the outer side of the aerator). Mechanical blockage is caused by too much dust (dust and oil) in the air. It can be solved by oil-free gas source (such as centrifuge), dust-free pipeline (such as plastic pipe, stainless steel pipe, etc.) and air filtration. The simple and economic method is to use electrostatic precipitator (according to the actual application). Biological blockage is caused by stop of gas supply or high organic load blocking the air hole, resulting in bubble coalescence and affecting the aeration efficiency.
According to foreign experience, biological blockage is the main reason for the decrease of oxygen transfer rate. In general, head blockage often occurs in aeration tank, which is obviously caused by too high F / M and too low dissolved oxygen.
The following measures shall be taken in the actual project:
1. If the blower is used, the air inlet must be filtered with dust content of & lt; 15mg / 1000m3. Electrostatic precipitator has the advantages of convenient management, small air resistance and low operating cost. Prevent oil mist from entering the air supply system;
2. If steel pipe is used for the main gas transmission pipe outside the aeration tank, the inner wall shall be strictly anti-corrosion treated, and other gas transmission and distribution pipes and accessories must be plastic pipes. Considering the different expansion coefficient of steel pipe and plastic pipe, expansion joint should be set;
3. Air pressure drainage pipe shall be set at the end of the gas distribution pipe to drain the water in the pipe;
4. During the operation, the temporary gas shutdown time shall not exceed 2-4 hours. When the aeration tank is out of service, the tank shall be filled with clean water with a depth of about 1.2m, or qualified secondary treatment water, and a small amount of air shall be introduced at the same time. According to the actual measurement, taking the φ 178 ~ 229mm aeration plate as an example, the air supply quantity of 1.1 ~ 1.13m3/h can meet the anti blocking requirements;
5. The aeration system shall be equipped with dual power supply. If there is no dual power supply, the diesel generator shall be standby. When the power is cut off, the air volume of 1 / 4 ~ 1 / 6 of the microporous aerator shall be kept in normal operation, so that the sludge will not be deposited on the surface of the aerator;
6. In order to ensure pipeline safety and avoid negative pressure generated by aeration head, the opening and closing of pipeline valve shall be slow.