MBBR system - Moving Bed Biofilm Reactor for wastewater treatment

MBBR system: Moving bed biofilm reactor with aerobic bacteria

An MBBR system is an aerobic biological process in which the degradation of organic matter is carried out by aerobic bacteria inside a moving bed biofilm reactor.

Moving bed MBBR reactors use biofilm-covered plastic carriers to break down organic waste. These carriers, also known as carriers, are submerged in the biological reactor and, through their movement, increase the performance and purification capacity of the MBBR system without having to increase the size of the reactor.

This type of system is commonly applied in places where the available space is limited, since it allows to reduce the required volume of the aeration chambers with respect to conventional activated sludge systems while maintaining the same treatment performance.

In most cases, the pollutant load has to undergo primary treatment before being incorporated into the MBBR reactor.

Efficiency of MBBR reactors

What makes our moving bed biofilm reactors an outstanding process is that all the microorganisms needed to remove the pollutant load are submerged in the reactor attached to the plastic carriers. Thanks to this system, the only biomass that needs to be removed from the system is that which has been detached from the carriers and that which is in suspension in the already treated waste effluent.

An MBBR system is based on the activity of microorganisms that attach to and grow on large surface porous solids called "CARRIERS", which float in the wastewater medium. The fundamental role of the carriers is to provide a protected surface for the growth of "biofilms".

By "biofilms" we mean complex colony structures composed of microorganisms and biomaterial secreted by them.

Carriers that have a density close to water, float and circulate freely inside the reactor by means of aeration bubbles (in aerobic chambers) or mechanical mixing (in anaerobic chambers).
The circulation of carriers in water regulates and stabilizes biofilm growth and reaction kinetics.

After the reactor, this biomass can be separated by a lamella clarifier, producing a clean effluent. In this way we ensure that the reactor always retains microorganisms necessary for its operation within it, guaranteeing the efficiency and performance of this treatment system.

Purification capacity

The compact Sigma MBBR systems are ideal for industrial waters with pre-treatment where space is limited. Each unit is designed according to the inlet conditions.

The following table shows the general operating conditions. The pollutant removal efficiency is optimal and the treated water has a constant quality. The pollutant removal efficiency is very high and the treated water has a constant quality.

Advantages of a moving bed biofilm reactor

The most outstanding advantages of our MBBR system are:

• Reduced space required for installation.
• Simple operation without the need for sludge recirculation or cell residence time control.
• Elimination of bulking problems in the secondary clarifier and its impact on effluent quality.
• Ability to withstand peak loads and flow variations.
• It is a continuous operation system that does not require constant attention or interruption of treatment.

Technical information

Operation of the moving bed biofilm reactor

As mentioned above, this process is an activated sludge system in which a floating polyethylene material is introduced to support biomass growth on its surface. This floating material provides an effective surface area for biofilm growth, increasing the effective volumetric concentration of biomass.

This type of forced biomass growth on a floating element has a number of special characteristics:

• The MLSS concentration (biomass concentration inside the reactor) can be 1.5 to 2 times higher than that achieved with conventional activated sludge systems and can be as high as 4000 - 8000 mg/L.
• Effective cell residence time is increased.
• The treatment capacity of the system is increased by the same volume.

Since the increase in MLSS is produced by the growth adhering to the carriers, there is no increase in the concentration of the sludge that reaches the secondary clarification, but it is reduced, so the dimensions of this clarification are smaller than in conventional systems.

Our MBBR reactor is composed of two aerobic chambers (with oxygen injection) in which two different types of carriers are introduced. The chambers are connected by a channel in which grids are installed to retain the carriers from each of the chambers.

MBBR equipment components

• Lamella pack: Lamellar modules increase the specific contact surface causing an increase in the separation rate of suspended particles and, therefore, accelerate the sedimentation process, creating a higher TSS separation capacity, larger surface per m², as well as a better resistance against UV radiation.
• Diffusers: Broadband diffusers work by creating an air reservoir that allows air to pass freely through it. With the help of the deflector plate at the bottom of the system, the diffuser prevents debris and sediment from entering or backing up the device's functions. Corrosion resistance and flexibility help this diffuser provide balanced air distribution to all piping systems.
• Carriers: The MBBR process is based on the activity of microorganisms that attach to and grow on large surface porous solids called carriers floating in the wastewater medium. The fundamental role of carriers is to provide a protected surface for the growth of "biofilms". Carriers that have a density close to water float and circulate freely in the wastewater through aeration bubbles (in aerobic chambers) or mechanical mixing (in anaerobic chambers).
• Biofilm: Complex colony structures composed of microorganisms and biomaterial secreted by them.

MBBR system diffusers

The air injection system is of high efficiency with wide band bubble diffusers made of high quality stainless steel and bolted to a PVC air distribution grid. Air generation is by side channel blowers with a capacity of 150 m3/h at 0.3 bar.

Clarification

The clarifier system is included in our MBBR equipment. It is an ideal lamella clarifier for this type of installation, where the suspended solids content is much lower than that generated in a conventional biological system.

Due to the special design of this type of reactor, recirculation is not included. This allows savings in the corresponding equipment and impulsion piping.

The lamellae are generally of the honeycomb type, with a 80 mm clearance and 60º discharge angle, with a surface area of 3.2m2/m3.

MBBR system applications

The applications of Sigma MBBR systems are varied, from industrial wastewater to more special applications. These systems are preferred when space requirements are very small and maximum simplicity of operation is demanded.

• Industrial processes.
• Municipal waters.
• Military camps and humanitarian missions.
• Hotels and resorts.
• Buildings: hospitals, shopping malls, etc.

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