Activated sludge SV30 does not settle, what's going on? what to do? Recently, some friends have encountered the problem of activated sludge SV30 not settling and the value is particularly high when treating sewage, and their heads are getting bigger. Today, let's talk about what's going on and how to solve it. 1, Cause analysis
1. Sludge swelling: This is the most common cause. The proliferation of filamentous bacteria can lead to loose sludge structure and difficulty in settling. For example, normal sludge is like tightly arranged small squares, but with more filamentous bacteria, it becomes like a pile of tangled mess, spreading the sludge apart and unable to settle naturally. For example, if the proportion of carbon, nitrogen, and phosphorus in sewage is imbalanced, BOD5 is generally required to be: N:P = 100: 5: If there is too little nitrogen and phosphorus, filamentous bacteria are prone to overgrowth. In addition, due to insufficient dissolved oxygen, filamentous bacteria have a better survival advantage than ordinary bacteria in low oxygen environments and can also reproduce in large numbers.
2. Water quality shock: Suddenly, a batch of sewage with significant changes in water quality and quantity arrived, and the activated sludge could not adapt. Just like when a person suddenly transitions from a warm room to a snowy and icy world, their body cannot bear it. For example, if the production process of the factory is adjusted, the discharge of heavy metal ions and toxic and harmful substances in the sewage will increase, which will inhibit microbial activity, damage the sludge structure, and increase SV30.
3. Temperature changes: Microorganisms are very sensitive to temperature, and the suitable temperature is generally between 15-35 ℃. If the temperature is too high or too low, the activity of microorganisms will be affected. In summer, when the temperature is too high, microbial metabolism accelerates, which may produce excessive viscous substances, causing sludge to clump together and difficult to settle; The low temperature in winter reduces microbial activity and the ability to decompose organic matter, which can also lead to a decrease in sludge settling performance.
4. Overaeration: Aeration is used to provide oxygen to microorganisms, but if it is overexposed, the sludge will be crushed too much and difficult to settle. It's like kneading dough, if you rub it too hard, the dough will fall apart. Excessive aeration can also rapidly deplete nutrients in sludge, leaving microorganisms in a hungry state and hindering sedimentation.
2, Improve processing methods
1. Regarding sludge expansion: - Adjust nutrient ratio: Check the carbon, nitrogen, and phosphorus content in the sewage, supplement nitrogen and phosphorus sources according to the actual situation, and restore the ratio to normal. For example, urea can be added to supplement nitrogen, and potassium dihydrogen phosphate can be added to supplement phosphorus. -Control dissolved oxygen: By adjusting the aeration rate, ensure that the dissolved oxygen in the aeration tank is between 2-4mg/L, so that filamentous bacteria no longer have growth advantages. -Add coagulants: Add appropriate amounts of coagulants such as polyaluminum chloride and polyacrylamide to help the sludge coagulate and settle. However, it should be noted that the dosage of flocculant should not be too large, otherwise it will affect microbial activity.
2. Response to water quality impact: - Strengthen pretreatment: Set up regulating tanks before sewage enters the treatment system to homogenize water quality and quantity. Additional pre-treatment facilities such as oil and slag removal can be added to remove substances that may be harmful to activated sludge. -Domestication of sludge: gradually increasing the proportion of impact water quality, allowing activated sludge to gradually adapt to new water quality conditions. It's like slowly adding complementary foods to a child to help their digestive system adapt.
3. Coping with temperature changes: - Summer cooling: Sunshade facilities can be installed in the aeration tank to reduce direct sunlight and lower water temperature. It is also possible to increase the inflow appropriately to dilute the temperature of the wastewater. -Winter insulation: Adding insulation layers to treatment facilities, such as wrapping insulation materials. It is also possible to appropriately reduce the load and workload of microorganisms, allowing them to function normally even at low temperatures.
4. Resolve excessive aeration:
-Optimize the aeration system: Install a dissolved oxygen meter to monitor dissolved oxygen in real-time and automatically adjust the aeration rate as needed. Intermittent aeration can also be used to avoid excessive aeration.
-Supplementing nutrition: Properly supplement some easily degradable organic matter, such as glucose, to provide sufficient food for microorganisms and restore their activity.
The non settling of activated sludge SV30 is a complex issue that requires us to carefully analyze the reasons and take targeted measures. I hope these methods can help everyone solve the problem and ensure the normal operation of the sewage treatment system!
