ANUBIX™ – B Upflow Anaerobic Sludge Bed (UASB) System

Now in its seventh generation since 1979, the ANUBIX™ – B reactor has proven to be highly reliable (more than 200 plants are currently in operation) and capable of handling high loading rates (up to 25 kg COD / m3d). However, to allow for contingencies and to maximize the efficiency of COD removal, the ANUBIX™ -B reactor is usually designed for lower loading rates.


ANUBIX™ – B process is a form of Upflow Anaerobic Sludge Blanket (UASB) Reactor. It is suited for high-strength wastewaters with COD (Chemical Oxygen Demand) values of up to around 25,000 mg/L.

Advantages of the ANUBIX™ – B (UASB) system:

  • It achieves superior overall treatment with lower effluent COD/BOD/TSS concentrations with small aerobic polishing stage;
  • Can be used as a treatment step both with granular and flocculant sludge;
  • Superior separation of suspended matter ensures minimal risk of excessive sludge loss;
  • Additional sludge storage and gas holder are not required;
  • Solid, corrosion-resistant construction for long-term operations is easily accessible for inspection;
  • Operating interruptions are minimized due to lack of moving parts inside of the reactor;
  • For your convenience and optimal land development we offer steel or concrete construction, rectangular or round configurations;
  • Fast startup of the system.

How does ANUBIX™ – B work?

In a typical plant, wastewater is first screened and then collected in a buffer tank equipped with an agitator. This tank is designed to allow sufficient qualitative and quantitative equalization and to acidify the wastewater partially. This allows for more stable operation and better sludge quality in the next stage: the ANUBIX™ – B anaerobic reactor. Provisions will be made for pre-settling of solids, heating, cooling, CO2 degasification, and inline neutralization if required as part of the overall process.

Raw wastewater is fed into the ANUBIX™ – B reactor through an internal influent distribution system and rises from the bottom to the top part of the reactor at a predetermined speed, after passing through a bed of active anaerobic sludge. Anaerobic digestion of organic material takes place in the ANUBIX™ – B anaerobic reactor. Organic compounds (such as sugar) are primarily degraded by anaerobic bacteria (sludge) and converted into biogas (a mixture of methane and carbon dioxide). Only a small amount of sludge growth takes place at this stage.

At the bottom of the ANUBIX™ – B reactor, the sludge becomes highly concentrated (up to 10% DS) and develops a granular structure. At sufficient hydraulic stress and under the appropriate conditions, which are created by the ANUBIX™ – B reactor, the granular structure is achieved spontaneously, without the need for additives.

Unique three-phase separator – maximum biomass retention

Wastewater enters the reactor at the bottom via a unique distribution system and leaves through a built-in three-phase separator at the top, which diverts the biogas and retains even the smallest flocs of methanogenic sludge.

The modular separator units, built-in stainless steel and GRP (Glass Reinforced Plastic), are equipped with an extra crossflow type parallel plate separator so that even fine flocs can be retained and returned to the middle of the anaerobic reactor. This allows for a fast start-up, even when started with low quality, non-granular anaerobic sludge.

The effluent leaves the reactor through a collection pipe. The biogas is sent to conditioning and/or utilization or disposed of in a biogas flare.

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