Sludge expansion

- Jul 12, 2019-

In the activated sludge system, sometimes the sedimentation performance of the sludge deteriorates, the specific gravity is reduced, and the volume is increased. The sedimentation of the sludge in the sedimentation tank is difficult. When the sludge is overflowed and lost in a serious situation, the treatment effect is drastically reduced. This phenomenon is sludge. Swell. Sludge expansion is the most difficult problem to solve in an activated sludge system, and there is still no good solution.


The following table is a summary of the operational countermeasures summarized during the actual operation:


Method for controlling sludge expansion by adjusting process operation measures


Adjusting the operation process control measures is very effective for sludge expansion caused by improper control of process conditions.


The specific methods are:


1 Adding clay, slaked lime, raw sludge or digested sludge at the inlet of the aeration tank to improve the sedimentation and compactness of the activated sludge;


2 to make the wastewater entering the aeration tank in a fresh state, such as taking pre-aeration measures to make the wastewater in an aerobic state;


3 Strengthen the aeration intensity, increase the DO concentration of the mixture, and prevent partial hypoxia or anaerobic mixture;


4 supplement nutrients such as nitrogen and phosphorus to maintain the balance of nutrients such as C, N and P in the mixture;


5 increase the sludge reflux ratio and reduce the residence time of the sludge in the secondary settling tank;


6 pre-aeration of the wastewater to remove acid gas or alkali adjustment to increase the pH of the aeration tank inlet water;


7 play the role of the adjustment tank to ensure that the sludge load of the aeration tank is relatively stable;


8 controlling the inlet water temperature of the aeration tank;


Add a bio selector in front of the aeration tank. The aerobic bioselector performs regenerative aeration before returning sludge into the aeration tank, reducing the content of viscous substances in the return sludge, allowing the microorganisms to enter the endogenous respiration stage, and improving the ability of the bacteria micelles to take up organic matter and Competitive ability with filamentous microorganisms. In order to enhance the effect of the bio-selector, a sufficient amount of nitrogen, phosphorus and other nutrients can be added during the aeration process to increase the activity of the sludge.