Why should activated sludge be refluxed?

Because activated sludge contains a large number of microorganisms and organic matter, activated sludge culture takes a long time, and the reflux mainly plays the role of inoculation. Without reflux, the treatment capacity of new sludge is limited, and reflux is also a process that accelerates the growth of microorganisms.

Activated sludge can be divided into aerobic activated sludge and anaerobic granular activated sludge, and activated sludge is mainly used to treat wastewater. Activated sludge method.

It is a kind of aerobic treatment method for the treatment of organic sewage by using microbial floc grown in suspension.

Because activated sludge contains a large number of microorganisms and organic matter, because this sludge is to be cultivated, activated sludge culture is a long time, reflux is mainly to play the role of inoculation, and if it is not refluxed, the treatment capacity of new sludge is limited, and reflux itself is also a process that accelerates the reproduction of microorganisms.

The activated sludge method relies on the removal of BOD by biological sludge, and the biomass carried by the influent is limited, so it should be refluxed from the sludge separated from the secondary sedimentation tank, and part of it should be refluxed into the aeration tank. The magnitude of the reflux ratio depends on the sludge concentration x in the aeration tank x and the reflux sludge concentration xr, according to the sludge balance r = (xr-x) x.

The first thing we need to know is: the concentration of sludge in the aeration tank (MLSS) is actually the amount of sludge, so if you don't return the sludge, is the sludge in the aeration tank less and less when you discharge the sludge? In this case, the MLSS of the aeration tank is getting lower and lower, and the COD concentration of our influent water remains the same, so the sludge load will be higher and higher, and the best result is sludge poisoning.

Finally, even if we don't consider sludge poisoning, there are many disadvantages once we put all the sludge in the aeration tank and not backflow into the sedimentation tank. 1: The mud surface of the sedimentation tank rises, and the mud runs.

The effluent SS exceeds the standard. 2: The MLSS of the aeration tank is getting lower and lower, and eventually there may be no mud directly.

There are no microorganisms to participate in aerobic.

Activated sludge contains a large number of microorganisms and organic matter, which can be used to treat organic wastewater, and biological treatment is the best choice, so it should be recycled, because this sludge is to be cultivated, and the heavy metal content of sewage is too high, or the oxidation is too strong, and the sludge will be damaged. It is a good medium in water treatment, and if it is not refluxed, the new sludge will not work, and the reflux itself is also a process that accelerates the reproduction of microorganisms.

Reflux can be reused!

Sludge backflow and flow is an important elimination measure in the sewage treatment process, which can improve the efficiency and stability of the biological treatment system. However, if the sludge backflow is too large, it will have the following effects:

1.Excessive sludge load: Excessive sludge backflow will lead to too high sludge concentration in the treatment system, which will cause the sludge load to be too large and affect the treatment effect.

2.Insufficient dissolved oxygen: Excessive sludge reflux will lead to insufficient dissolved oxygen in the system, thereby inhibiting the growth and metabolic activities of aerobic microorganisms and affecting the treatment effect.

3.Increased ammonia nitrogen concentration: Excessive sludge reflux will lead to an increase in ammonia nitrogen concentration in the system, which will inhibit the growth and metabolic activities of aerobic microorganisms and affect the treatment effect.

4.Increased energy consumption: Excessive sludge backflow can lead to an increase in mixing energy consumption in the treatment system, which increases the operating costs of the treatment system.

Therefore, in the process of sewage treatment, it is necessary to reasonably control the sludge return flow to avoid excessive backflow from adversely affecting the treatment effect and operating cost.

Sludge reflux can promote clarification, which is mainly reflected in two aspects:

Contact flocculation in the reaction process section – Alum particles in the sludge are an adsorbent that can adsorb suspended solids in water and the precipitate formed by the reaction, separating them from water. At the same time, the precipitate generated by the reaction plays a crystallization core role, which promotes the gradual growth of the sediment and accelerates the sedimentation and separation.

Sludge reflux of purified water.

Bridging filtration and collision coagulation in the pre-sedimentation - clarification process section - because the sludge contains more alum flowers, the alum flowers form many meshes in the formation process, and the sludge layer at this time seems to be a layer of filter screen, which can block the passage of small suspended solids and sediments, thus producing a bridging filtration effect.

The sludge reflux of sewage has the following points:

1. First of all, the difference between the activated sludge method and the biofilm method is clarified, the biofilm method relies on the filler as the biological carrier, while the activated sludge method relies on the activated sludge colloids as the biological carrier. Because the biofilm method has a fixed filler as a biological carrier, the biological bacteria are not easy to lose. On the other hand, it is also possible to recover part of the lost activated sludge colonies to replenish the lost carbon source, and the excess sludge can be discharged.

2. The mud age of the sludge is not 20 days, but also very short or very long, although the mud age is shorter and has become sludge, it does not affect the sludge to continue to act as a carrier and supplement the lost carbon source.

3. For the activated sludge method, it is very important to properly maintain a certain amount of sludge, because it can maintain the conditions for the implantation of biological bacteria. It can also be observed and judged according to the shape of the sufficient amount of sludge in the pool water.

4. The biofilm method generally does not need to be used for sludge reflux, because the biological bacteria have a stable implantation condition, and the activated sludge is not easy to be lost. However, there are also exceptions, once the implanted biological bacteria accidentally fall off due to improper operation, sludge reflux must be carried out, and external activated sludge can also be re-added.

5. There is a more important point of sludge reflux, which is the removal of ammonia nitrogen, which has a non-negligible effect.

Sludge reflux can act as a biological carrier, refluxing some of the lost activated sludge bacteria, maintaining the microbial mass in the system, and also removing ammonia nitrogen. Specific questions about sewage treatment you can go to the ring. Baotong asked, there are many experienced people there, I hope I can help you.

Maintain the microbial biomass of the bioreactor system.

The new type discloses a surface sludge reflux device in sewage treatment, which mainly solves the problem that the prior art occupies a large space and needs high power, the reflux device has an air compressor, a reflux pipeline, one end of the reflux pipeline is a negative pressure suction inlet, the other end is a sludge discharge outlet, the negative pressure suction inlet is located in the surface layer of the water body, there is an air inlet end that makes the pressure air only run to the sludge discharge port on the reflux pipeline, and the air inlet end is connected to an air compressor through a pipeline. It has the characteristics of low equipment investment and energy saving.

It is characterized in that: described device has air compressor, return pipeline, one end of return pipeline is negative pressure suction inlet, the other end is sludge discharge outlet, negative pressure suction inlet is located in the surface layer of water body, there is an air inlet that makes pressure air only run to sludge discharge port on the reflux pipeline, and this air inlet end is connected with air compressor by pipeline.

Because activated sludge contains a large number of microorganisms and organic matter, because this sludge is to be cultivated, activated sludge culture is a long time, reflux is mainly to play the role of inoculation, and if it is not refluxed, the treatment capacity of new sludge is limited, and reflux itself is also a process that accelerates the reproduction of microorganisms.

The activated sludge method is based on the removal of BOD by biological sludge, and the biomass carried by the influent is limited, so it should be refluxed from the sludge separated from the secondary sedimentation tank, and a lead mold is divided into the aeration tank. The magnitude of the reflux ratio depends on the sludge concentration x in the aeration tank x and the reflux sludge concentration xr, according to the sludge balance r = (xr-x) x in and out of the collapse hood aeration tank.

Sewage treatment, right?

Sludge is the "corpse" of fungal bacteria within the water treatment after metabolizing and dying

But it also contains bacteria that have not yet died when the water reaches the sedimentation tank, which is the "alive" sludge. Activated sludge contains the bacteria and fungi required for this water treatment, so in order to avoid waste and make the water treatment system work efficiently, these live bacteria can be returned to the anaerobic-aerobic pond to speed up the reproduction and treatment.

Because activated sludge contains a large number of micro-collapse cover and organic matter, because this sludge is to be cultivated, activated sludge culture is to take a long time, the most important thing is to play the role of agitation, and if it is not refluxed, the treatment capacity of new sludge is limited, and the reflux itself is also a process that accelerates the reproduction of microorganisms.

The activated sludge method relies on biological sludge to remove BOD, and the biomass lead mold carried by the influent is limited, so it should be refluxed from the sludge separated from the secondary sedimentation tank, and part of it should be refluxed into the aeration tank. The magnitude of the reflux ratio depends on the sludge concentration x in the aeration tank x and the reflux sludge concentration xr, according to the sludge balance r = (xr-x) x.

Sludge aging should be related to the low concentration of your influent water and the activity of the sludge, while the sludge reflux is to supplement the sludge concentration of the previous aerobic stage.

The common reasons for sludge aging are: 1. Sludge discharge is not timely; 2. The inlet water is in a low-load state for a long time; 3. Activated sludge aging caused by excessive aeration; 4. The concentration of activated sludge is too high. Recommendations:

1. Control the sludge concentration through the food-to-micro-ratio, and the food-to-micrometer ratio is controlled around the right; 2. Pay attention to controlling the uniformity of aeration and preventing over-aeration (DO should not be greater than 4mg L); 3. To avoid low-load operation, it is necessary to supplement the external carbon source. Sludge aging is mainly caused by the lack of nutrients in microorganisms for a long time, that is, the imbalance between nutrition and microbial mass, and microorganisms can not grow normally, but the situation of the treatment device in actual operation is more complicated, and the activity of sludge is also related to factors such as operation control conditions and nutrient ratio.

The aging of activated sludge is common in most of the aerobic biochemical systems currently in operation, and the aging of activated sludge will not only lead to the increase of the main pollution index of the effluent, but also the waste of energy. This is because the ageing of activated sludge is often associated with over-aeration, underloading, and these operational problems consume excessive energy.