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Hello everyone, In winter, the weather is cold. Many aeration tanks have low dissolved oxygen. This causes problems in treating wastewater.
First, low oxygen makes it hard to remove COD and organic matter. Bacteria need oxygen to break down these things. If oxygen is not enough, COD becomes too high. The water is not clean.
The biggest problem is ammonia. Bacteria need more oxygen to change ammonia into nitrate. If oxygen is too low, this change is very slow. Ammonia becomes too much in the water.
If oxygen is very low, the system may become anaerobic. In this case, bacteria work badly or die. This hurts the whole system. Then, the water cannot be cleaned well.
Why It Is Hard to Increase Dissolved Oxygen in Winter
In winter, the air is cold. This makes it harder to increase dissolved oxygen. Here are some main reasons:
- Problem with aeration equipment If the machine is broken or works badly, it gives less air. This means less oxygen goes into the water. If the air blower is weak or the pipes are blocked, oxygen cannot go in well. If the air time is too short, the water also gets little oxygen.
- High load in the system Sometimes, the water coming in has more COD. This needs more oxygen to clean. The bacteria use more oxygen to break down dirty stuff. But oxygen comes in too slow. So the oxygen level drops fast.
- Too much sludge In winter, we remove sludge less often. So sludge becomes too much. More sludge means more bacteria. These bacteria use more oxygen. This makes oxygen go down fast and hard to bring back up.
- Too much return flow If the return flow is too big, water moves too fast. This makes the time in the tank too short. So there is not enough time for air to go in. This lowers oxygen efficiency.
- Surfactant or foam problem: foam interferes with oxygen transmission In winter, some surfactants or foam may also affect the transfer efficiency of dissolved oxygen. Foam on top of the water blocks the air. So oxygen cannot mix well into the water. If we use some cleaners, foam may get worse, and the oxygen problem becomes bigger.
How to Fix the Low Dissolved Oxygen Problem in Winter
In winter, it is hard to keep dissolved oxygen high. But we can try these ways to fix the problem:
- Optimizing the aeration system: ensuring stable oxygen supply Make sure the air machine works well. Check if the blower is strong enough. Check if the pipes or air holes are blocked. Give enough time for air. If possible, upgrade the system to give more oxygen.
- Control the load By adjusting the inflow load reasonably, high load impact caused by sudden increase in COD concentration in winter can be avoided. When necessary, the load can be alleviated by increasing the dosage or adjusting the system operation mode to ensure that microorganisms have sufficient dissolved oxygen supply.
- Adjusting sludge concentration: optimizing sludge discharge and retention time Take out extra sludge often. Do not let sludge stay too long. Too much sludge uses too much oxygen. We can also return some sludge or add nutrients to keep the level good.
- Control return flow Ensure that the reflux ratio is moderate to avoid excessive reflux, which may cause a short stay time and affect aeration time. Regularly check the reflux ratio of the system and make corresponding adjustments according to seasonal changes to optimize oxygen transfer efficiency.
- Solution to foam problem: reduce surfactant interference Reduce or avoid the use of detergents or treatment agents that can produce foam. If the foam problem is serious, the effect of foam on dissolved oxygen can be reduced by adjusting the aeration rate or using defoamer.
Summary: Act Early to Keep Wastewater Treatment Stable in Winter
Low dissolved oxygen in winter is a common problem. But we can fix it. We need to check the air system, control the load, watch the sludge, and adjust the return flow.
If we keep oxygen at a good level, we can remove COD and organic matter better. We can also remove ammonia well. This helps the whole system work better and stay stable.
If you find this helpful, please follow our website. You will get more easy and useful tips about wastewater treatment. Let’s work together for a cleaner and greener future!
