How to address oxygen consumption and foaming in wastewater treatment
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Our company has been experiencing severe foam formation due to oxygen consumption these past few days, and it’s very difficult to get rid of this foam. One of the tanks produces white foam, while another produces brown foam. We’re not sure how to resolve this issue; could it be related to temperature? It’s winter now and it’s quite cold
You can consider adding an antifoaming agent; that will solve the problem. Consider whether the reason for foaming is poor oxygen treatment – if the treatment is done properly, the foam will be fragile
OP, I think you can consider whether the following 4 points apply: 1. Whether the wastewater contains substances such as surfactants； 2. Is there excessive aeration? ； 3. Has sludge bulking occurred? ； 4. Is there any overloading?
Generally, the formation of foam in the aerobic tank is an indicator of whether the system is improving or deteriorating. Based on your description, the tank that produces brown foam has deteriorated; I assume it must have initially produced white foam, which gradually turned brown. If the situation worsens further, a large amount of dead sludge will float to the surface. The analysis indicates that the cause is related to low water temperature and high inflow load, which leads to the death of some of the activated sludge and the formation of foam.
It is recommended to check the pH level of the aerobic tank immediately, as sludge is very sensitive to changes in pH; especially when the pH level drops, a large amount of foam will form in the aerobic tank.
I checked some more information; there is a high likelihood of overloading or deterioration of operating conditions. The person in question should take samples from the aeration tank and test their pH value, and also conduct a microscopic examination to see if there are any abnormalities in the microorganisms. In addition, it is also possible to check whether the water inflow volume and COD load have already exceeded the design values ； You can also get a test to see if you are indeed well-nourished!
I think the handling can be carried out from the following aspects: 1. Check the incoming water to identify the causes of foaming (pH, water temperature, sludge). 2. Control the water inflow. 3. Add active bacteria. 4. Adjust the aeration volume. 5. Foam can be removed using a water pipe.
The reasons for foam formation are: ① Sludge retention time. ②pH value. ③Dissolved oxygen (DO). ④Temperature. ⑤Hydrophobic substances. ⑥Aeration method. ⑦The alternating changes in temperature, air pressure, and water temperature.
- An abnormally increased amount of foam can be an indication that the system is operating better, or it can also indicate that it is operating worse. - The reasons for an increase in foam may be: – increased microbial activity, higher metabolic rates, and thus a faster treatment speed. - Microbial activity decreases or even ceases, and a large amount of foam appears. - The entire processing system improves or worsens. - Backflowing sludge may cause foaming. - Abnormal wastewater has entered the aeration tank. - There is little foam during normal operation. - When abnormal foam appears, it is necessary to promptly assess the condition of system operation. - For foam caused by an improved system, no further action is necessary; simply using an appropriate amount of defoamer to eliminate the foam is sufficient. - Foam caused by poor system performance should have its causes identified promptly; if necessary, the amount of water fed into the system can be reduced, and the flow rate can be increased again once the system improves.