Diagnosis and treatment of common abnormalities in sludge II

- Apr 25, 2019-

5, the aeration tank produces brown or gray foam


The sludge is aged, the mud age is too high, and the sludge after deflocation is attached to the foam.


Increase mud discharge and gradually update the new sludge in the system. The sludge renewal process needs to last for several days. During the period, the operating environment should be controlled to ensure that the new sludge has strong activity.

6. The sedimentation tank has a large black sludge floating up.


The sedimentation tank has a dead angle, and the local mud is anaerobic, producing CH4 and CO2, and the bubbles are attached to the sludge particles to float upward, and the ammonia nitrogen of the effluent is often higher;

The reflux ratio is too small, and the sludge reflux is not anaerobic in time.


If the sedimentation tank has a dead angle, the problem that the system can maintain a high dissolved oxygen state can be alleviated, and the fundamental solution needs to be structurally modified to achieve the dead angle;

Increase the reflux ratio to prevent the sludge from staying in the sedimentation tank for too long.

7, the sedimentation tank mud surface is too high, and the effluent suspended solids rise


If the load is too high, the decomposition of organic matter does not completely affect the sludge sedimentation performance, and the sedimentation effect is deteriorated;

The load is too low, the sludge lacks nutrition, and the low-nutrient bacteria increase the flocculation performance.

The sludge is older, the sludge concentration in the system is too high and the sludge structure is loose and not easy to settle;

When the water temperature is too high, the small molecules of organic matter increase, and the bacterial gum group adsorbs too much organic matter to cause sludge deflocmentation.


Reduce the load to reduce the total amount of influent COD, and increase the dissolved oxygen to gradually restore the sludge performance;

Increase the amount of water in the appropriate range, maintain a high dissolved oxygen state for a period of time to inhibit the continued increase of low-nutrient bacteria;

Increase the excess sludge discharge and control the system sludge concentration to a reasonable range;

Reduce the water temperature in the aeration tank, control the dissolved oxygen level, and the sludge can return to normal after a period of time.

8. Sludge expansion

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;

③Strengthen 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;

⑦play 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.