The secondary sedimentation tank was filled with turbid sludge, and a large amount of fine suspended particles could be seen at the water outlet

Low load, self-oxidation and decomposition of sludge

What are the causes and influencing factors of sludge leakage from the secondary sedimentation tank? 1. The effluent is clear but contains sludge particles; this is what is referred to as \"sludge floating\"“； •Low F/M ratio, insufficient bacterial nutrition ； •The DO level is too high, indicating excessive depth of reaction ； •Slight aging of sludge ； •The c/n/p ratio is not appropriate. 2. The effluent is clear, with sludge forming layers that overflow; the overflow becomes more severe when the water volume is high ； •The surface load on the secondary sedimentation tank is too high ； •Filamentous sludge bulking occurs in the aerobic tank ； •The sludge level in the secondary sedimentation tank is too high ； •Sludge poisoning. • The P H fluctuates too much. 3. The effluent is turbid, containing sludge particles ； •Incomplete degradation of organic matter in the aerobic tank, with an excessive organic load ； •Too high or too low DO in the aerobic tank ； •Excessive aeration or abnormal pH ； •Decomposition of aged sludge ； •The aerobic tank has an excessively high level of mineral oil ； •Sludge poisoning ； •Severe C/N/P imbalance ； •The temperature in the aerobic tank is below 5°C or above 38°C. 4. The effluent is turbid, with both the effluent and fine sludge particles overflowing outward ； •The sludge poisoning is quite severe ； •The high mineral oil content in the aerobic tank severely affects sludge flocculation ； •Denitrification occurs in the secondary sedimentation tank. • The pH is greater than 10 or less than 5.5. Lumps of sludge rise from below the water surface in the secondary sedimentation tank; after being stirred, some of this sludge sinks while another part flows away with the water. The color of this sludge is the same as that of biochemical sludge ； Denitrification or partial denitrification occurs in the secondary sedimentation tank. 6. In the secondary sedimentation tank, lumps of sludge rise from beneath the water surface; after being stirred, some of this sludge sinks while another part flows away with the water, and the sludge is dark in color ； Anoxic conditions occur in the secondary sedimentation tank, or there are local anoxic zones. 7. The scum on the surface of the secondary sedimentation tank flows away with the water ； A malfunction in the aerobic tank causes foam or scum to flow into the secondary sedimentation tank, where it forms scum and is carried away with the effluent. 8. Foam on the surface of the secondary sedimentation tank; sludge particles attached to the foam flow away with the water ； Failure in the aerobic tank; foam flows into the secondary sedimentation tank. 9. In some areas of the secondary sedimentation tank, sludge flows out with the water, and this phenomenon becomes more severe when the water volume is high ； a. The mud surface is too high ； •The load on the secondary sedimentation tank exceeds the designed load by a significant amount ； •Filamentous fungus swelling ； •The outlet weir is uneven or there is misalignment in the secondary sedimentation tank. 10. The deposits attached to the weir of the secondary sedimentation tank enter the effluent stream from the secondary sedimentation tank. The effluent from the secondary sedimentation tank is rich in N, P, etc., which causes algae and other deposits to form at the weir opening, and these are carried away by the flow of the effluent. 11 Effects of the secondary sedimentation tank itself on sludge migration: • Scraper malfunction; • Uneven water outlet weir; • Deviation in flow within the inlet tank with water entering from the center and exiting around the edges, as well as uneven distribution of water flow; • Delayed sludge removal leading to an excessively high sludge level in the secondary sedimentation tank ； •The inlet water flow velocity and volume are momentarily high or exceed the design capacity ； •Local dead zones or prolonged sludge retention lead to anaerobic fermentation or denitrification ； •The sludge scraper is rotating too fast.