In the process of sewage treatment, aeration is achieved by injecting oxygen into the water body, promoting the growth and reproduction of aerobic microorganisms, and accelerating the degradation of organic pollutants.
Excessive aeration
Excessive aeration refers to the phenomenon where the amount of oxygen injected into the water per unit time exceeds the actual demand of microorganisms during the water treatment process. Excessive aeration may lead to the following:
1. Dissolved oxygen (DO) concentration is too high
2. Sludge aging
3. Sludge expansion
4. Decreased processing effect
5. Waste of energy
The impact of excessive aeration in wastewater treatment
1. Accelerate sludge aging
Excessive aeration can lead to a high concentration of dissolved oxygen, causing microorganisms to be in a state of excessive oxidation. In this case, the metabolic rate of microorganisms accelerates, the sludge age shortens, and the activity decreases.
When the following phenomena occur, it indicates that the sludge may have aged:
(1) Elevated sludge volume index (SVI): SVI is an indicator of sludge settling performance, and the higher the SVI value, the worse the sludge settling performance. When excessive aeration leads to sludge aging, the SVI value will increase.
(2) The color of sludge becomes lighter: Under normal circumstances, activated sludge appears black or grayish brown. Excessive aeration causes sludge to age and gradually lighten in color.
(3) Loose floc structure of sludge: Excessive aeration leads to excessive oxidation of microorganisms in the flocs, resulting in loose floc structure and easy breakage.
The following measures can be taken to address the issue of sludge aging:
(1) Pay attention to sludge discharge: Regularly discharge aged sludge, reduce sludge age, and maintain sludge activity.
(2) Adjust load: When the load is too low, nutrients can be added or raw water can be introduced to increase the load, stimulate microbial growth, and slow down sludge aging.
(3) Reduce dissolved oxygen: By adjusting the aeration equipment and reducing the aeration amount, the dissolved oxygen concentration can be maintained within an appropriate range.
2. Sludge expansion
Excessive aeration can cause the dissolved oxygen concentration in the water to be too high, leading to the overgrowth of microorganisms and the formation of a large number of bubbles. These bubbles adhere to the sludge flocs, causing a decrease in sludge density and leading to sludge swelling. Sludge expansion can cause the following problems:
(1) The deterioration of sludge settling performance affects the effluent quality.
(2) Sludge loss increases the difficulty of subsequent treatment.
(3) The load of aeration equipment increases, resulting in an increase in energy consumption.
To prevent sludge expansion, the following measures can be taken:
(1) Adjust the aeration rate to maintain the dissolved oxygen concentration within an appropriate range.
(2) Strengthen sludge reflux and increase sludge concentration.
(3) Add coagulants to improve sludge settling performance.
3. Decreased processing effect
Excessive aeration can lead to the following problems, which in turn affect the treatment effect:
(1) Reduced sludge activity: Excessive aeration leads to excessive oxidation of microorganisms, resulting in decreased activity and affecting the degradation of organic pollutants.
(2) Destruction of sludge floc structure: Excessive aeration leads to the breakage of sludge flocs, affecting the adsorption and degradation ability of microorganisms.
(3) Fluctuations in dissolved oxygen concentration: Excessive aeration may cause fluctuations in dissolved oxygen concentration, affecting the growth environment of microorganisms.
The aeration process requires a significant amount of energy consumption. Excessive aeration not only fails to improve treatment efficiency, but sometimes the energy consumption in the aeration process accounts for more than 50% of the total energy consumption in the entire sewage treatment process.
How to avoid excessive aeration in sewage treatment
1. Optimize wastewater aeration equipment: Select efficient and energy-saving aeration equipment to improve oxygen transfer efficiency and reduce energy consumption. Energy efficiency submersible aerators are supplied by us, you can always check our product on our website, you just send us your requirements, Suitable models will be recommended.
2. Real time monitoring: By using online monitoring instruments, parameters such as dissolved oxygen and sludge concentration can be monitored in real time, and the aeration rate can be adjusted according to the actual situation.
3. Intelligent control: Using a computer control system to automatically adjust the aeration process and maintain dissolved oxygen concentration within an appropriate range.