Causes, hazards and control methods of sewage treatment bubble
In the process of sewage treatment, I believe that everyone often encounters a large amount of foam in the biochemical pool, and if it is restrained, it will overflow from the pool, causing severe pollution of the external pool wall of the external equipment, worsening the operating conditions, seriously, seriously It affects the surrounding environment.
1. Types of foam
1. Start the foam
1. In the early stage of the launch of the aeration tank, the sludge in the aeration tank did not adapt to the water quality of the sewage, and it was not adapted to the growth environment, and it was easy to form foam. With the adaptation of sludge to water quality, the foam will decrease.
2. At the beginning of the initial start of the aeration tank, the sludge was relatively small, the sludge load was high, and it was prone to foam. After the amount of sludge increases, the foam will gradually disappear.
3. In the early stages of active sludge process operation, because the sewage contains some surface active substances, it is easy to cause surface foam. However, with the maturity of active sludge, the phenomenon of foaming will gradually disappear through biodegradation.
2. Nitrification foam
When the active sludge treatment system is running at a low load, nitrogen will occur in places where the sedimentation tank or is insufficient aerated. The foam phenomenon, the suspended foam is usually not very stable.
3. Surface active foam
Surface active agents and starch, protein, oil and other surface active substances in the molecular structure of the molecular structure containing polarity-non-polar groups are so-called bilateral elements. Under the condition of theerated aeration, one end of the non -polar group stretched into the bubble, and the polar group was selectively adsorbed by hydrophilic substances, which transformed the surface of hydrophilic substances into hydrophobic substances and adhered to bubble water. On the membrane, float up with the air to the water.
4. Biological bubble
1. Most of the microorganisms related to foam contain lipophytes. Such microorganisms are lighter than water and easy to float to the surface.
2. Most of the microorganisms related to foam are silk or branches, which are easy to form nets. They can catch and sweep particles and bubbles, and float to the water. The bubble surrounded by the silk net increases its surface tension, making the bubbles not broken, and the foam is more stable.
3. The air floating effect produced by air bubbles is often the main driving force formed by foam. Granules use air bubbles to float, which must be small, light, and hydrophobic substances. Therefore, when there is oil, lipid substances and lipid -containing microorganisms in water, the surface foam is prone to.
2. The factors generated by foam
1. Small stay time
The growth rate of microorganisms that produce foam is generally low and the growth cycle is long, so long sludge stays are conducive to the growth of these microorganisms. Therefore, the active sludge method with delayed aeration method is more likely to produce foam. In addition, once the foam is formed, the biological stay time of the foam layer will be independent of the sludge stay in the aeration tank, which will easily form a stable and lasting bubble.
2. pH value
Different silk microorganisms have different requirements for pH. Amarae’s growth is extremely sensitive to the pH value. The most suitable pH value is 7.8. When the pH value drops from 7.0 to 5.0 to 5.6, it can effectively reduce the formation of foam. This is mainly because the low pH value exceeds the limit of the pH of the microbial community that produces foam. Therefore, when the pH value is 5.0, it can effectively control its growth. However, changes in the pH value can also cause uncomfortable adaptation of activated sludge, which causes foam phenomenon.
3. Solubbing oxygen
The Norcus flora in the biological foam is a strict oxygen microorganism. Under the condition of hypoliance or anaerobic, it cannot be used to grow, but it will not die. The root is the final electronic receptor. Therefore, even in the existing lack of oxygen or anaerobic section in the existing nitrogen dehydration system, it can still be produced smoothly. When the dissolved oxygen is insufficient and the system is running at a low load, it is prone to a nitrification foam.
4. Aeseum method
Different aeration methods have different air bubbles, while micro -air bubbles or small bubbles are more conducive to producing biological foam than atmospheric bubbles, and the foam layer is easy to concentrate in areas with low aeration intensity.
The bacteria related to the formation of biological bubbles have their own suitable growth temperature and best temperature. When the environment or water temperature is conducive to the growth of fungi, the phenomenon of foam may be produced. Not only that, the temperature will also affect the microbial community in the activated sludge system, leading to the generation of biological foam, which can be seen from the seasonal production of many biological foams.
3. Harm of foam
1. Normal display of the instrument
In particular, the sewage treatment plant that is automatically controlled by DCS will cause system error operation. For ultrasonic liquid levels, it will cause false liquid levels, causing the pump air to rotate in severe cases; if the total discharge of the sewage treatment station adopts a bright canal flow meter, it may cause errors in the total sewage flow of the oral discharge.
2. Affect the environment
After a large number of biomole is generated, it spreads to the aisle plate, affecting normal maintenance. Winter foam may be freezing in winter, and it is difficult to clean up; in summer, the wind will flutter, forming a bad smell, and seriously polluting the environment.
3. Decreased dissolving oxygen
The process of using surface aeration equipment, the biological foam has viscosity, which will prevent normal aeration oxygen and reduce the dissolved oxygen of the mixture.
4. Wave water quality out of water
Some biological bubbles may also enter the second sinking pool, resulting in increased pollutants such as SS and CODCR with external drainage.
4. The control method of foam
1. Spray water
High -speed sprayed water flow or water droplets can break the bubbles floating on the water. The dispersed part of the sludge particles resume the settlement performance, which can reduce the foam. By spraying water, the foam can be reduced. If it is sprayed with a good oxygen tank, the effect of long -term bubbles can be achieved. Although spraying water cannot be fundamentally bubble, it is the simplest and most commonly used physical method.
2. Increase chemicals
Increased chemicals can solve the foam problem in a short period of time, and the operation is simple. However, the investment and addition chemical agent will also have a great impact on the sludge while solving the foam problem. After using chemical agents, it will also have a large impact on the water quality and the treatment of the remaining substances.
Common voting agents:
1. Add chlorine and oxidant;
2. Increase the concrete;
3. Add foam and vegetable oil.
3. Shorten the time of sludge stay
Reduce the sludge stay of the aeration tank, that is, to reduce the average cell residence time, which can effectively control the biological foam during the active sludge process. To reduce the residence time of the sludge, it is essentially a kind of biological screening strategy, that is, the characteristics of the average period of the foam microbes to suppress the excessive proliferation of the foam microorganism in the analog pool or exclude it to control the biological bubbles to control the biological bubble Purpose.
4. Reading carrier in the aeration reactor
Incurred or fixed fillers in some active sludge systems, so that some microorganisms that are prone to expansion of sludge and foam grow in accordance with the growth of the biomass in the aeration tank, improved the treatment effect, but also reduce or control the foam. produce.
Disclaimer: The above content is reproduced from micro -link chemical, and the content issued does not represent the position of this platform. National Energy Information Platform Tel Tel 010-56002763, mailbox hz@pe partle-rgy.com.cn
Product Recommendation: foaming pump