There are several types of biological treatment for wastewater at 1h2o3. We will explain them to you one by one below.

Activated mud

What is it used for?

Activated mud technology is a process for treating wastewater and industrial wastewater. This technology was developed at the beginning of the last century and remains effective today.

The designs are different from other types of biological treatment, but the model often remains the same:

  • We can find an activation pond which acts as a biological reactor;
  • A settling tank will allow the separation of solids, activated mud and treated wastewater;
  • Activated wastewater return equipment to transfer activated mudto the aeration tank inlet

Operation process

The process of using activated mud is quite simple. Atmospheric air is introduced into the wastewater mixture. This wastewater contains organisms capable of producing a biological floc. These flocs are future activated mud.

The effectiveness of the removal process depends on several factors:

  • The hydraulic residence time in the aeration tank. It is calculated by dividing the volume of the aeration tank by the flow rate.
  • Influencer’s charge. This means its characteristics, such as COD, nitrogen concentration, carbon content, etc.
  • Aeration tank conditions (food/microorganism ratio)
  • Ventilation conditions
  • temperature
  • Etc…

After this operation, the floc, the treated wastewater, and the microorganisms present will all settle. The floc will sediment in the settling tank. While the supernatant, i.e. the treated wastewater, will either undergo further treatment or be directly reinjected into a natural source, if it meets the standards.

The settled TSS will be returned to the aeration tank inlet. Thus, they will be able to carry out a wastewater treatment cycle again. However, during this phase, due to the biological growth, this surplus, called residual activated sludge, causes an imbalance between the biomass and the food supplied. This is why it is removed before reinstating the TSS in the cycle.

Residual activated mud is stored in tanks away from other facilities. They will be treated there by aerobic or anaerobic processes, before entering one of the different elimination routes.

There are several types of facilities using activated mud technology, with a variety of techniques.


A screen to remove sand and grease is part of the upstream equipment to prevent clogging of the membrane. Only particles smaller than 3 mm are allowed to pass. We also accept theManual screenings. Pour réaliser la décomposition des impuretés. MBBR only uses bacteria.

The MBBR technology is based on the use of particles on which will proliferate sets of bacteria. These bacteria form a biofilm on free and moving particles. At the end of this water purification process, we will find treated water, but also mud that must be treated. It is therefore necessary to settle the mud using a bioreactor in the form of lamella technology. The big advantage of this technology is that spare parts are durable and less expensive, which gives MBBR a certain economic advantage over MBR.


Adding a fixed growth medium to an activated mud tank facilitates biomass growth and enhances the treatment process. This is the basis for the IFAS principle. This technology is still new, but can be easily integrated into existing activated mud plants by simply updating them.

The strength of IFAS is that it is the refinement of the advanced mud method. It can therefore be easily integrated into existing installations. In addition, adding a crib that can be either fixed or mobile provides many advantages:

  • This setup provides two different biological populations that act in synergy.
  • The mixed liquor (containing the wastewater to be treated and the biological treatment agents) will degrade the majority of the organic load. This action will then be completed by the biofilm which has a nitrifying population and will therefore treat the nitrogen present in the wastewater.
  • Biofilm processes allow anaerobic, aerobic, and anoxic zones to exist together in one step and IFAS systems allow the additional biological population to be on a fixed surface. This way, activated mud no longer needs to be disposed of, which means that it is no longer necessary to increase the growth of suspended populations.
  • The investment cost will also be lower than using a conventional activated mud plant. This is because the fixed-bed wastewater treatment system generally requires less volume than conventional systems. In addition, integrating the IFAS system into your activated mud system will increase your efficiency, saving you the expense of expanding your facility.

IFAS Technology

Integrated fixed-film activated mud (IFAS) is a relatively new wastewater treatment technology with many advantages. It is inspired by activated mud technologies, but more efficient. There is a big difference between IFAS and MBBR technology. It is linked to the reuse of activated mud.

IFAS is a technology adapted to existing activated mud installations in biological treatment. It allows for smaller pond sizes, and these ponds must be designed for the incorporation of dispersed or fixed media. For dispersed media, additional screens will be required.

This IFAS technology has many advantages over existing technologies. However, before installing an IFAS system in an existing station, it is important to make a few observations:

  • Evaluate its aeration capacity to ensure that it can handle the removal of biochemical oxygen demand (BOD) and its increase. In addition, it is important not to overlook the additional biomass respiration that will be added during the transition to IFAS ;
  • Media installation also requires careful planning to ensure that ponds can properly accommodate the chosen media.


The MBR or Membrane Bio Reactor is an extremely sensitive process especially when compared to other types of biological treatment.

The upstream mud buffer allows this system to:

  • produce less mud and therefore avoid having to treat them
  • also have a high space saving

While more efficient for the filtration process than FBBR or MBBR, it quickly becomes disadvantageous due to maintenance costs that are too high. The MBR system is a membrane-based bacterial filtration system with a concentration five times higher than that found in other systems. If the pore size is sufficient, even the germs that can be found in the water will be filtered out.

However, such results require negative pressure to sustain the wastewater flow. It is this process of maintaining negative pressure that is extremely energy intensive and makes this system so expensive, plus the membrane must also be changed and backwashed at regular intervals. All these operations require a qualified workforce.


FBBR or Fix Bed Biofilm Reactor is more similar to MBBR than to MBR. The only difference is that the FBBR has a fixed substrate that lines the walls of the tank. This difference in the configuration of the crib results in savings in operating and maintenance costs. This makes it the most economical unit.

The purpose of the biological layer is to transform the organic contaminants contained in the wastewater into sedimentary and mineral substances. This role will be played by aerobic organisms, consumers of oxygen. This comes from a layer underneath the substrate that allows for the supply of airflow. The second advantage of this airflow is that it is self-regulating, so it is very efficient, and the parts are always less expensive than for MBRs. The mud must still be treated like for the MBBR.


SBRs (sequential batch reactors) use a separate pretreatment section to mechanically retain the solids. Together with this, there is an aeration and biological settling tank.

Small SBR wastewater treatment systems clean the wastewater. This is a few sentences explaining how the SBR technology works.

The wastewater first undergoes a mechanical or chemical treatment to filter out solids. Following this operation, the wastewater will flow into the 2nd tank. They will be processed by the SBR method.

An aeration phase is necessary to guarantee the efficiency of the biological purification. It is carried out by means of specialized microorganisms. In SBR, there is an alternation between short phases of ventilation and phases of rest. This is how activated mud is formed.

The cycle of resting and ventilating will end with a prolonged resting phase. During this time, the mud will settle at the bottom of the tank, leaving a purified water as a supernatant. The purified wastewater is then extracted from the mixture and the mud will be reinjected into the first tank. The supernatant can be directly re-emitted in a natural environment or undergo an additional treatment according to the standards in force.

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