The power of microorganisms: Biophase observation experiments promote green development of the sewage treatment industry

When the control factors in the sewage treatment system change, the types, quantities and active functions of various biological phases in the activated sludge will also change accordingly. Therefore, by observing the changes in the number of biological phase populations and the number of activated sludge in the sewage treatment system, we can understand the operating status and quality of the treatment system, and adjust the operating conditions of the treatment system in time to ensure that the treatment system can continue to operate normally.

In the work related to sewage operation and commissioning, two experiments are often required, one is the SV30 experiment and the other is the biological phase observation experiment. Therefore, many scholars call these two experiments the "two knives" of on-site operation and commissioning.

 Sludge bulking changes

Today I will talk about the biological phase observation experiment；

In this experiment, we observe protozoa and metazoa. Why do we use them as indicator organisms of activated sludge system?

Because the main role in activated sludge is played by bacterial groups, and they grow up by eating bacteria, so their species, quantity and changes in living conditions can reflect the state of activated sludge in the system.

As indicator organisms of activated sludge system, the book "Process Control of Activated Sludge Process" divides protozoa and metazoa into three categories;

1. 1.Non-activated sludge

As the name implies, non-activated sludge refers to protozoa that are not seen in normal activated sludge. When they appear, it indicates that the activated sludge system has failed. Only protozoa appear in non-activated sludge. Common species are as follows;

This type of protozoa has the following 5 characteristics:

1. 1.Very small
2. 2.Generally do not have flagella
3. 3.Very fast
4. 4.Feed on free bacteria
5. 5.Amazing numbers

Why does the water quality deteriorate when non-activated sludge organisms appear in large numbers?

These protozoa feed on free bacteria. When the influent load is high, many free bacteria will appear. At this time, these protozoa will multiply in large numbers and actively obtain free bacteria by destroying the structure of bacterial flocs, which will deteriorate the sedimentation performance of activated sludge.

2. 2.Intermediate activated sludge

The appearance of this type of protozoa often indicates that the activated sludge system is in a transition period. There are three types of transition periods here;

1. 1.The activated sludge changes from normal to deteriorated
2. 2.The activated sludge changes from deteriorated to normal
3. 3.The initial bacterial culture stage of activated sludge

The frequency of this type of protozoa will not be too high, because your water quality cannot always be in a transition period. Protozoa will only appear in the intermediate activated sludge type. The common types are as follows;

Such protozoa can not only capture free bacteria, but also prey on bacterial micelles, but also release free bacteria by destroying bacterial micelles.

It usually has the following three characteristics;

1.soft body

2. 2.Macroflagellates and slow-moving ciliates coexist
3. 3.No bristles

3.Activated sludge

This kind of protometazoan is in the normal activated sludge state should appear, that is, to see this kind of protometazoan indicates that the activated sludge is mature, the effluent water quality is good, in the activated sludge protozoan and metazoan will appear.

Why do activated sludge protozoa exist

Does it indicate the maturity of activated sludge?

1.this kind of protozoa move slowly will not cause damage to the bacterial micelle;

2.In order to avoid being preyed on by such protozoa, the bacteria micelles strive to gather together, strengthening the flocculation of activated sludge

3.the attached protozoa feed on free bacterial micelles, purify the fine floc in the activated sludge system, and enhance the settling performance of activated sludge

4.Final summary

When the process parameters change, the behavior of proto-metazoan is as follows;