What is MBBR?

The MBBR process is the basic principle of the biofilm method. By adding a certain amount of suspension carrier to the reactor, it improves the biomass and biological types in the reactor, thereby improving the processing efficiency of the reactor. Because the density of the filler is close to water, when the aeration is exposed, the water is completely mixed with water. The environment of microorganisms grows the three phases of gas, liquid, and solidarity.

The collision and shear effect of the carrier in the water make the air bubble smaller and increase the utilization rate of oxygen. In addition, each carrier has different types of biological types. Some anaerobic or oxygen bacteria grow inside, and the outside is a good oxygen bacteria, so that each carrier is a miniature reactor, which makes the nitrification reaction and nitrification reaction at the same time exist at the same time existing , Thereby improving the processing effect.

How does MBBR synchronize nitrification and nitrification?

Synchronous concept of nitrifying nitride (SND)

Synchronous nitrification nitrification removal technology (SND) produces nitrification, nitrification and carbon removal reactions at the same time in the same reactor. It breaks through the traditional perspective that nitrification and nitrification cannot occur at the same time, especially under the conditions of oxygen, and can also occur with nitrification reactions, making synchronization nitrification and nitrification possible.

The nitrification process consumes alkali degrees, and the alkali degree of nitrification process is generated. Therefore, SND can effectively maintain the pH value in the reactor stable, no acid and alkali neutrality, no need to add carbon sources; save the volume of the reactor, shorten the reaction time, reduce the nitric state by reducing the nitric state. Nitrogen concentration can reduce the floating of the secondary sinking pool, so SND has become a research hotspot for biological nitrogen dehydration. For the feasibility of SND biological nitrogen dehydration, there are currently three major views from different perspectives:

Macro environmental angle: This view is considered to be completely uniform mixed state. The unexplained DO distribution in the reactor can form good oxygen, hypoxic, anaerobic areas. Nitrotation reaction, the nitrification of organic matter in the oxygen environment in the combined area, SND can be realized.

Micro -environment angle: This view believes that the hypoxic micro -environment in the microbial floccope is the main cause of SND, that is, due to the limitation of oxygen diffusion (transmission), there is a dissolved oxygen gradient in the microbial floc. Microenvironment.

Biology perspective: This view is considered to be the main cause of SND in the existence of special microorganisms. Some nitrifying bacteria can also be nitrified in addition to the normal nitrification effect. It can also perform pantococcus that can be performed well. There are also some bacteria cooperating with each other to perform sequence reactions, converting ammonia into nitrogen, which provides possible biological nitrogen dehydration under the same conditions under the same conditions.

At present, there are many research and interpretation of microbiology of biological nitrogen dehydration, but they are not perfect. The understanding of SND phenomena is still under development and exploration. Microcycles theory is generally accepted. Due to the existence of dissolving oxygen gradient, the ingredients of microbial floccope or biofilm are highly dissolved in oxygen concentration, mainly based on good oxygenized bacteria and ammonia. A large amount of dissolved oxygen is consumed to produce hypoxia areas, and nitrifying bacteria are dominant bacteria, so it can cause synchronous nitrification and nitrification. The theory explains the problems of different types of bacteria in the same reactor, but there is also a defect, that is, the problem of organic carbon source. Organic carbon sources are both electronic donors with heterotransmidization and nitrification, but also the inhibitory substances of the nitrification process. When the organic carbon source in the sewage passes through the good oxygen layer, it is first good oxidized. The nitrification rate is reduced to not get the electronic donor, which may affect the nitrogen loss efficiency of SND. Therefore, the mechanism of synchronized nitrification and nitrification still needs to be further improved.

MBBR biological mobile bed synchronization nitrification nitrification and nitrating dehydration mechanism

MBBR is an efficient new type of reactor combining the active sludge method that combines suspended growth and the biofilm method that is attached to the biofilm. The basic design principle is to add the proportion of the suspended fillers that can be suspended in the water. The carrier, the suspension fillers can contact frequent contact with the sewage frequently, and gradually grow on the surface of the filling surface (hanging membrane), which strengthens the quality of pollutants, dissolved oxygen and biofilms, that is, MBBR is called “moving organisms that move the organisms membrane”. Based on the research of SND mechanisms so far, comprehensive micro -environment and biological theory, the possible response mode that may exist in the SND in the MBBR biofilm is the good oxygen oxidative bacteria, nitrite oxidation, and good oxidation nitrification distributed in the good oxygen layer of the biofilm. Bacteria and anaerobic ammonia oxidative bacteria, self -cultivated nitrite bacteria, and nitrifying bacteria that are distributed in the biochemical layer cooperate with each other, and finally achieve the purpose of nitrogen dehydration.

MBBR relies on the aeration of the aeration tank and the improvement of the water flow to make the carrier in a fluidization state, which in turn forms the active sludge and the biofosed biofilm that is attached to it. It not only provides a macro and micro aerobic and anaerobic environment, but also solves the dispute between the DO and carbon source of self -cultivation of nitrate nitrifying bacteria, heterogeneous nitrifying bacteria and heterogeneous bacteria. Therefore, MBBR can achieve dynamic balance between nitrification and nitrification, and has very good conditions for synchronized nitrification and nitrification, which can achieve MBBR synchronized nitrification nitrification and nitrating removal.

Third, MBBR synchronizes nitrification and nitrification factors

The key technology of realizing MBBR synchronized nitrification and nitrification is to control the reaction dynamic balance of MBBR endoorization and nitrification, and solve the dispute between the DO of self -nitrifying bacteria and the DO of heterotransmid Therefore, its main control factors are: carbon nitrogen ratio, dissolved oxygen concentration, temperature and pH.

The effect of filler on the MBBR method

The key to the MBBR method is that the proportion is close to water and slightly mixed with water. Generally, the fillers are made of polyethylene plastic. The shape of each carrier is a small cylinder with a diameter of 10mm and a high 8mm high. The cylindrical body is supported by the cross, the outer wall has prominent vertical fin wings, and the hollow part of the filler accounts for 0.95 of the entire volume of 0.95 In a container full of water and fillers, the volume of water in each filler is 95%. Considering the rotation of the filler and the volume of the total container, the fill ratio of the filler is defined as the vacancy of the carrier. In order to achieve the best mixed effect, the fill ratio of the filler is 0.7. In theory, the total comparison surface area is defined according to the number of surface area of ​​each unit volume biological carrier, generally 700m2/m3. When the biofilm grows inside the carrier, the actual effective use of the surface area is about 500m2/m3.

This type of biological fillers are conducive to the growth of microorganisms on the inside of the filler, forming a more stable biofilm, and easy to form a fluidization state. When pre -treatment requirements are low or sewage contains a large amount of fiber substances, for example, when primary sinking ponds are not used in municipal sewage treatment, or in processing papermaking wastewater containing a large amount of fiber, they use smaller surface area and larger biological fillers. When there is a good pre -processing or for nitrification, a biological filler larger than the surface area is used.

The effect of dissolving oxygen (do) on the MBBR method

The DO concentration is a major restrictions that affect the synchronous nitrification and nitrification. By controlling the DO concentration, the different parts of the biological film can form an oxygen or hypoxia areas. Physical conditions.

In theory, when the DO quality concentration is too high, the DO can penetrate the interior of the biofilm, making it difficult to form a hypoxic area inside. A large amount of ammonia nitrogen is oxidized to nitrate and nitrite On the contrary, if the DO concentration is very low, it will cause a large proportion of anaerobic areas inside the biofilm. The biofilm nitrification capacity is enhanced (the concentration of nitrate nitrate nitrate and nitrite is low), but due to the insufficient supply of DO, MBBR supply is insufficient, MBBR supply is insufficient, and MBBR is MBBR. The decline in the effect of the craftsmanship has increased the concentration of ammonia nitrogen, which leads to the rise of the water out of the water, which affects the final processing effect.

By researching the best value of MBBR law to deal with urban sewage DO: when the DO quality concentration is above 2 mg/L, the effect of DO on MBBR nitrification has little effect. The removal rate of ammonia nitrogen can reach 97%-99 -99 %, Water ammonia nitrogen can be maintained below 1.0mg/L; when the DO quality concentration is about 1.0mg/L, the removal rate of ammonia nitrogen is about 84%, and the concentration of ammonia nitrogen is significantly increased. In addition, the DO in the aeration tank should not be too high. Excessive dissolving oxygen can cause the decomposition of organic pollutants too quickly, so that microorganisms lack nutrition, active sludge is easy to aging, and the structure is loose. In addition, DO is too high, excessive energy consumption is not suitable for economical.

Because the MBBR method is mainly to achieve the final sewage treatment through suspension fillers, the impact of DO on suspension fillers is also the key to affecting the entire processing results. Studies have shown that the oxygen capacity of the reactor increases with the increase in the fill rate of the floating fillers within a certain range. Under the action of aeration, the water flows with the filler, and the degree of water flow is larger than the filler. It accelerates the update of the gas liquid interface and the transfer of oxygen to increase the transfer rate of oxygen. As the number of fillers increases, this cutting effect and turbulent effect between fillers, airflow and water flow have been continuously strengthened. However, when the amount of filler is added to 60%, the fluidization effect of the filler in the water is poor, and the degree of dynamics of the water body also decreases, which reduces the transmission rate of oxygen and the utilization rate of oxygen is reduced. Therefore, for different types of water quality, the amount of control of Do is essential for the final process of the entire process.

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