In the process of sewage treatment, aerobic tank is a crucial link. Microorganisms in aerobic tanks decompose organic pollutants in wastewater by consuming oxygen, thereby achieving the goal of purifying water quality. However, did you know? The concentration of dissolved oxygen (DO) in an aerobic tank is not necessarily better as it increases. If the dissolved oxygen is too high for a long time, it can actually cause a series of problems and affect the effectiveness of sewage treatment. Today, we will discuss this issue in detail.
01 Aerobic sludge undergoes self oxidation and turns white in color. The sludge in the aerobic tank is formed by the aggregation of a large number of microorganisms, forming microbial flocs. These microorganisms require an appropriate amount of oxygen for metabolism and decomposition of organic matter in wastewater. However, if the dissolved oxygen concentration is too high for a long time, microorganisms will excessively consume oxygen, leading to self oxidation of the sludge. In this case, the color of the sludge will gradually turn white and lose its normal brown color. This not only affects the activity of the sludge, but also reduces its ability to treat wastewater.
02 Aerobic sludge is gradually aging, and the loose structure and long-term high concentration of dissolved oxygen can also lead to the gradual aging of aerobic sludge. The aging sludge structure becomes loose, and the bacterial flocs become thin and small, unable to effectively adsorb and decompose organic matter in wastewater. In addition, a high dissolved oxygen environment can promote the massive reproduction of filamentous bacteria. The excessive growth of filamentous bacteria can further damage the structure of sludge, leading to a decrease in sludge settling performance and affecting subsequent sedimentation and separation processes.
03 Rotifers reproduce massively, and the amount of fine sludge in the supernatant increases. In a high dissolved oxygen environment, rotifers and other protozoa will reproduce massively. Rotifers feed on bacteria, and although it can help control the number of bacteria to some extent, excessive rotifers can consume a large amount of bacteria, affecting the activity of sludge. In addition, high dissolved oxygen can also lead to an increase in fine sludge in the supernatant, which is difficult to precipitate and makes the effluent turbid, resulting in poor treatment efficiency.
The treatment effect of 04 deteriorates and the effluent becomes turbid. In summary, long-term high dissolved oxygen in the aerobic tank can lead to the oxidation and aging of the sludge itself, the proliferation of filamentous bacteria and rotifers, the increase of fine sludge in the supernatant, and ultimately the deterioration of the sewage treatment effect and the turbidity of the effluent. This not only increases the difficulty of subsequent treatment, but may also lead to substandard effluent quality, affecting the stable operation of the entire sewage treatment system.
In order to avoid long-term high dissolved oxygen in aerobic tanks, sewage treatment plants need to strictly control the aeration rate of aerobic tanks. By monitoring the dissolved oxygen concentration in real-time and adjusting the operating parameters of the aeration equipment, it is ensured that the dissolved oxygen concentration is maintained within an appropriate range (usually 2-4 mg/L). In addition, regularly checking the activity, structure, and settling performance of sludge, and adjusting operational strategies in a timely manner, are also key to ensuring the effectiveness of sewage treatment. The concentration of dissolved oxygen in aerobic tanks is an important factor affecting the effectiveness of wastewater treatment. Excessive or insufficient dissolved oxygen can have adverse effects on sludge activity and treatment efficiency. Therefore, sewage treatment plants need to control the dissolved oxygen concentration reasonably according to the actual situation to ensure the stable operation of the sewage treatment system. I hope that through the introduction in this article, everyone has gained a deeper understanding of the importance of dissolved oxygen in aerobic tanks. If you have any questions or suggestions, please feel free to leave a comment in the comment section for discussion!
