What Is A MBBR Coarse Bubble Diffuser

A MBBR (Moving Bed Biofilm Reactor) coarse bubble diffuser is a device used in the MBBR wastewater treatment process to introduce air into the reactor tank. Its primary purpose is to provide oxygen to the microorganisms present in the biofilm on the moving carriers. In an aerobic MBBR system, the availability of oxygen is crucial for the biological degradation of organic matter and other pollutants in the wastewater.

Structure and Design
Material: Coarse bubble diffusers are typically made of durable materials such as polyethylene or rubber. These materials are chosen for their resistance to corrosion, chemical attack from the wastewater, and mechanical wear and tear.

Shape and Configuration: They usually have a simple tubular or disc - shaped design. The diffuser body has small holes or pores through which air is released. The size of the holes is relatively large compared to fine bubble diffusers, which is why they produce coarse bubbles. For example, the hole diameter might range from 2 - 5 mm, depending on the specific design and application.

Connection Mechanism: Coarse bubble diffusers are connected to an air supply system through pipes and fittings. The air supply system consists of an air blower or compressor that provides the necessary air pressure to force the air through the diffuser and into the wastewater.

Function in the MBBR System
Aeration: When air is forced through the coarse bubble diffuser into the MBBR reactor tank, it creates a stream of large bubbles. As these bubbles rise through the wastewater, they transfer oxygen to the liquid phase. The rising bubbles also play a role in keeping the MBBR carriers (the small plastic carriers with biofilm) in motion. The agitation caused by the bubbles helps to prevent the carriers from settling and ensures that they are evenly distributed throughout the reactor tank, maximizing the contact between the biofilm - covered carriers and the wastewater.

Mixing and Circulation: The coarse bubbles contribute to the mixing of the wastewater within the tank. This mixing helps to distribute the pollutants more evenly, ensuring that the microorganisms on the biofilm have equal access to the organic matter and nutrients present in the wastewater. It also helps to prevent the formation of stagnant zones where the treatment efficiency might be reduced.

Advantages
Low Maintenance: Coarse bubble diffusers are generally less prone to clogging compared to fine bubble diffusers. The larger pore size allows for the passage of air even if there is some particulate matter in the air supply or the wastewater. This makes them a more reliable option in applications where the wastewater contains a relatively high amount of solids or debris.

High - Flow Capacity: They can handle a relatively high - volume of air flow. This makes them suitable for larger MBBR reactors or systems where a significant amount of oxygen needs to be supplied quickly, such as in cases where the influent wastewater has a high organic load.

Cost - Effective: Coarse bubble diffusers are usually less expensive to purchase and install than fine bubble diffusers. They also have a simpler design, which means that the associated air supply equipment (such as blowers) can be of a lower cost and power rating.

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