MBBR (Moving Bed Biofilm Reactor)

A moving bed biofilm reactor (MBBR) is a biological wastewater treatment system in which microorganisms grow as a dense biofilm on the surface of small, buoyant plastic carrier media that move freely throughout an aerated reactor. The media provide a protected, high-surface-area substrate for biofilm growth, supporting high concentrations of active biomass within a compact reactor volume. The MBBR process removes organic carbon, performs nitrification and denitrification and provides stable biological treatment without the need for sludge recycle, making it one of the most operationally straightforward biofilm treatment technologies available.

In conventional activated sludge, the active biomass is maintained in suspension in the reactor and a portion of the settled sludge is recycled from the secondary clarifier back to the reactor to maintain the required mixed liquor concentration. MBBR retains all active biomass on the carrier media within the reactor, eliminating the need for sludge recycle entirely. This simplifies operation, removes a critical control variable and makes the MBBR process more resilient to load variations. MBBR also achieves higher volumetric treatment rates due to the high biomass concentrations achievable on the media surface.

MBBR systems can achieve BOD removal greater than 90 percent and effective nitrification and denitrification in appropriately configured multi-stage arrangements. Effluent from an MBBR combined with secondary clarification typically achieves BOD below 20 mg/L and TSS below 30 mg/L, meeting standard secondary treatment discharge standards. For applications requiring higher effluent quality, MBBR effluent can be polished by downstream membrane filtration, sand filtration or cloth media filtration before disinfection.

Yes. MBBR systems are widely used for nitrification and total nitrogen removal. Nitrification occurs in aerobic MBBR stages where ammonia-oxidising and nitrite-oxidising bacteria develop as specialised biofilm communities on the carrier media, converting ammonia to nitrate. Denitrification occurs in anoxic stages where heterotrophic bacteria use nitrate as an electron acceptor in the absence of dissolved oxygen. Multi-stage MBBR configurations combining aerobic and anoxic reactors achieve total nitrogen removal of up to 85 percent from municipal and industrial effluents.

MBBR is one of the most cost-effective technologies for upgrading overloaded or underperforming activated sludge plants without building new tanks. Carrier media can be added directly to existing aeration tanks, converting them from suspended growth to combined attached and suspended growth (IFAS) or pure biofilm MBBR operation. This increases the active biomass concentration in the reactor, improving BOD removal and nitrification capacity within the existing tank footprint. IWTE provides MBBR retrofit design and supply for existing plant upgrades, including media selection, aeration modification and outlet screen installation.

MBBR (moving bed biofilm reactor) relies entirely on biofilm attached to the carrier media for biological treatment, with no intentional suspended biomass maintained by sludge recycle. IFAS (integrated fixed film activated sludge) combines carrier media biofilm with a suspended activated sludge population maintained by sludge recycle, effectively combining the benefits of both biofilm and suspended growth processes within the same reactor. IWTE designs both MBBR and IFAS configurations depending on the treatment objectives, site constraints and the extent of the existing treatment infrastructure.

High-density polyethylene MBBR carrier media are chemically inert and mechanically robust, with service lives typically exceeding 10 to 15 years under normal operating conditions. Media degradation can occur through exposure to certain industrial chemicals, excessively high temperatures or mechanical abrasion from abrasive solids in the feed. IWTE selects media materials matched to the wastewater characteristics of the application and provides media condition assessment as part of ongoing service visits.

Yes. IWTE provides complete MBBR system design and supply encompassing biological process design, reactor sizing, carrier media selection and supply, aeration system design, outlet screen specification, downstream clarification or membrane separation design, PLC and SCADA control, effluent quality monitoring and commissioning. The entire system is engineered as an integrated scope. IWTE also provides operator training, process optimisation support and ongoing service for all MBBR systems we supply.