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Talking about the common problems of the second settling pond

Time : 2020-04-15

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Talking about the common problems of the second settling pond


In the daily operation of the sewage system, the abnormality of the second settling tank is the most common phenomenon. For example, there may be increased suspended solids in the secondary sedimentation tank and floating mud in the secondary sedimentation tank, which everyone may have experienced.


Today we will talk about the analysis and solution of two common anomalies in the second sink pool.
1. Increased suspended solids in the secondary sedimentation tank
(1) The swelling of activated sludge deteriorates the sludge settling performance. The sludge-water interface is close to the water surface, and some sludge debris overflows through the weir. The countermeasure is to eliminate one by one by analyzing the cause of sludge expansion.
(2) The concentration of activated sludge in the aeration tank is relatively high, the mud-water interface of the secondary settling tank is close to the water surface, and some sludge fragments overflow through the weir. The countermeasure is to increase the discharge of excess sludge.
(3) The disintegration of activated sludge causes the flocculation of sludge to decrease or disappear, and sludge fragments flow out with the water. The countermeasure is to find the cause of sludge disintegration and eliminate and solve them one by one.
(4) The residence time of activated sludge in the secondary sedimentation tank is too long, and the sludge overflows with the water flow after decomposing due to anoxic decay. The countermeasure is to increase the amount of return sludge and shorten the residence time in the secondary settling tank.
(5) When the water temperature is high and the nitrate content in the water is high, the denitrification denitrification phenomenon occurs in the sludge in the secondary settling tank. A large amount of sludge wrapped with nitrogen floats to the water surface and overflows with the water flow. The countermeasure is to increase the amount of return sludge and shorten the residence time of the sludge in the secondary settling tank.
  
2. Sludge floating in the second settling tank
Sludge floating in the secondary sedimentation tank refers to the phenomenon that the sludge acidifies or denitrifies in the secondary sedimentation tank, causing the sludge to float to the surface of the secondary sedimentation tank. The floating sludge itself has no quality problems, and its biological activity and settling performance are normal.

The main reason for floating is that these normal sludges stay in the secondary sedimentation tank for too long. Acidification occurs due to the gradual consumption of dissolved oxygen, resulting in H2S and other gases attached to the sludge flocs, causing the sludge to float. When the mixed liquid entering the secondary sedimentation tank contains a large amount of nitrate, the sludge denitrification occurs in the secondary sedimentation tank due to lack of sufficient dissolved oxygen (DO <0.5mg / L), and the nitrogen generated by the denitrification will also adhere to the sewage On the sludge body, its density is reduced, causing the sludge to float.


Measures to control the floating of sludge, one is to discharge excess sludge in a timely manner and increase the amount of sludge to return, so that the residence time of the sludge in the secondary settling tank is not too long; The dissolved oxygen content in the mixed solution of the secondary settling tank ensures that the sludge in the secondary settling tank is not in an anaerobic or anoxic state. For the upward movement of sludge caused by denitrification, the discharge of remaining sludge can also be increased, the age of sludge can be reduced, and the purpose of denitrification can be controlled by controlling the degree of nitrification.
   
The Bio Target Floc series is a highly efficient and environmentally friendly biological coagulant product developed to target the problem of sludge activity and swelling in sewage biological systems. Bio Target Floc is made by bio-fermentation technology under specific conditions. It contains microbial secondary metabolite-biological flocculant and several exclusive enzymes (amylase, cellulase, protease, etc.), surfactant, Buffer. This product has a small amount of high efficiency, the targeting effect is environmentally friendly and safe for microorganisms, it can improve activated sludge, improve sedimentation performance, and reduce COD, total phosphorus, SS and other characteristics.

Benefits:
Bio Target Floc can:
Increase SV30;
Improve system impact resistance;
Does not affect microbial activity;
Increase COD and total phosphorus removal.