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MBBR

The MBBR (moving bed biofilm reactor) process is an attached growth process that utilize bio-media made of plastic to provide a surface on which biofilm grows.  The carrier media are kept suspended in the reactor tank by a diffused air aeration system or by a mechanical mixing system which will depend on the types of processes. The mixing is also serves to control the biofilm thickness on the plastic carrier media.

The microorganisms consume organic materials and nutrients from the wastewater. As the biomass becomes too thick and heavy to hold onto the media, it is sloughed off, suspended and drained from the reactor with the treated water. This reactor effluent is further treated in a clarifier system to separate the sludge from the treated water. No sludge will be returned in the process because adequate microorganism population is maintained attached to the media.

The reactor tank size for MBBR is much smaller than typical conventional waste treatment, or other types of treatment using attached growth processes such as RBC, trickling filter or fixed bed bioreactor. This is due to the very large surface area of the bio-media so that it can keep many microorganisms in the reactor. MBBR tank configurations are very flexible depending on the type of waste pollutant being treated with the aim of BOD, nitrogen and/or phosphorus removal.

Advantages MBBR :

  • MBBR technology can be installed in existing tanks (Efficiency upgrade in existing systems)
  • Self-cleaning biocarrier elements
  • Cost-effective and compact design
  • Stable and robust which can handle hydraulic and organic fluctuations
  •  best water quality

Biocarrier

Our MBBR system with high pore and paraboloic shape biocarrier can establish high amount of “active” biomass, therefore efficiency and removal rate can be attained. It is essential that the biomass is permanently fixed on the carrier media in order to provide an optimal habitat for the required microorganisms.

Summary of major benefits :


  • a large protected surface area to maximize the amount of biomass
  • a porous surface to strengthen the biomass’s adhesion;
  • an optimal substrate diffusion depth to ensure the metabolism;
  • wear-resistance for durability
  • smaller new plants or larger reserve capacities (reduction of reactor volume)
  • long lifetime due to flexible, abrasion-resistant material
  • low mixing energy requirement in the MBBR tank
  • optimal supply of substrate and oxygen to the microorganisms due to thin biofilms
  • economical benefits in the price comparison per m² of protected active surface area

Other types of biocarrier media that are widely sold in the market, either in the form of hollow body carriers, tube- or helical-shaped or sponge carrier configuration or others, have shown some weaknesses where organisms are not sufficiently supplied with substrates and die off consequently. As a result, the layer below the depth of 0.5 mm (0.019685’’) does not contribute to the metabolism process (removal rate) and in turn must not be considered for indicating the removal efficiency of the respective carrier. Biomass that dies due to lack of nutrients is useless and does not contribute to the desired metabolic processes. Actually, the died-off biomass can even have a negative impact on the active biomass/biofilms above it, due to fouling processes and H2S-generation.

The biomass must stringently be “active” to attain optimal biological removal rates. The designation “active biomass” shall mean that all microorganisms within the biomass are sufficiently supplied with essential nitrogen (N), phosphorus (P), with the wastewater pollutants to be metabolized, and with oxygen (if required). The so called supply channel of the aforementioned substrates and oxygen is the diffusion depth. For the supply of organisms inside of the biomass (or biofilms), the reaction time-dependent diffusion depth is limited to 0.2 – 0.5 mm.

The illustration above shows the O2 removal up to the anoxic zone

Nearly complete diffusio through the entire disc having a thickness of 1 mm thickness, from both sides

Carrier with active surface and disc thickness of approx. 1.1mm  to fulfill the requirements

During the plant operation, an optimal carrier geometry is a stringent requirement for appropriately meeting the biological demands and hence to ensure the optimal development of the biofilm.

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