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Causes and Countermeasures of Sludge Bulking in The Sewage Treatment Industry
2024-08-20 15:43:28
With the continuous improvement and development of the activated sludge process, the operational management experience has been greatly improved. However, in the actual operation of the sewage treatment industry, sludge bulking often occurs, seriously affecting the amount and quality of treated water. Therefore, it is essential to understand the causes of sludge bulking and the corresponding countermeasures to solve it in advance.
Sludge bulking is one of the abnormal phenomena that occur during the operation of the activated sludge system. Due to some reasons, the sedimentation performance of the activated sludge deteriorates, resulting in poor mud-water separation, abnormal suspended solids in the effluent, and the destruction of the treatment process. This phenomenon is usually related to the growth and metabolism of microorganisms. Specifically, it can be divided into two main types: filamentous sludge bulking and non-filamentous sludge bulking. Filamentous sludge bulking is mainly caused by the extreme growth of filamentous bacteria, which leads to extremely loose sludge structure, increased volume, floating, and difficulty in sedimentation and separation, affecting the effluent water quality. Non-filamentous sludge bulking is caused by the accumulation of metabolites (high-viscosity polysaccharides). This high-viscosity substance covers the microorganisms in the activated sludge, generally in the form of a gel, which makes the sedimentation and concentration performance of the sludge worse.
1. Causes of Sludge Bulking
There are many reasons for sludge expansion: it is affected by factors such as changes in the water quality components of the influent, changes in pH value, changes in temperature, changes in nutrients, and changes like pollutants. In the early stage of expansion, the sludge index (SVI) will continue to rise, the sludge structure will be loose and a large amount of sludge will float, the mud-water separation effect will be poor, and the effluent water will be turbid. At this time, attention should be paid and investigation should be carried out immediately to find out the cause of the expansion.
Fig.1: Sludge bulking state
Fig.2: Normal state
2. Countermeasures to Solve Sludge Bulking
Emergency measures include strengthening the monitoring of influent and effluent quality, adjusting the operating process, adding chemical agents, increasing the amount of sludge discharged, and reducing the sludge concentration:
(1)Regularly monitor various parameters in the sewage process: such as the sludge index (SVI), dissolved oxygen, pH value, etc.;
(2) According to the monitoring results, adjust the operating conditions such as aeration and nutrient addition to create an environment conducive to the growth of microorganisms.
(3) Add appropriate amounts of chemical agents, such as flocculants and bactericides, to control the growth of filamentous bacteria or improve the sedimentation performance of sludge;
(4) By increasing the amount of sludge discharged, and removing excessive filamentous bacteria, it helps to restore the normal sedimentation performance of sludge.
Through the above countermeasures, the sludge bulking problem can be effectively solved and the effect and efficiency of sewage treatment can be ensured.