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Simultaneous Nitrification and Denitrification

The biofilm that forms on the membrane used in Fluence’s MABR technology allows nitrification and denitrification to take place simultaneously in the same tank.

Simultaneous nitrification and denitrification means wastewater treatment can take place in a single tank

A membrane aerated biofilm reactor (MABR) is a revolutionary wastewater treatment and reuse solution that cuts the energy requirements of the aeration cycle by as much as 90% compared to legacy activated sludge systems, for which aeration is by far the largest energy expense.

Its low energy requirement allows MABR to be operated by alternative energy sources, making it ideal for distributed, or decentralized, treatment. Because aeration is contained, MABR treatment is low-odor and low-noise, meaning plants can be sited close to neighbors. Additionally, MABR modules produce effluent that meets both the exacting California Title 22 and PRC Class 1A standards.

From the outside, an MABR module looks like a plain, black, plastic cylinder, but the simple appearance conceals something remarkable. Taking place within the MABR module is a process that creates and maintains simultaneous nitrification and denitrification (SND), which offers several benefits for wastewater treatment.

MABR technology packs both of these features into a smaller footprint than traditional wastewater treatment methods.

Benefits of SND

In both MABR and traditional activated sludge processes, denitrification is the final goal, and in both, aerobic microorganisms do much of the work. These organisms need air. In traditional activated sludge treatment, nitrification takes place in one step, then denitrification happens in deep-bed, mono-media filters, with methanol or another carbon source being added to nourish denitrifying bacteria in the filters. Compressed air is used to aerate the wastewater with bubbles to feed the microorganisms.

Air compression is a large energy expense, and adding chemicals to nourish bacteria creates another step and expense. Moreover, bubbles are inefficient at supplying microorganisms with air and are mostly wasted when they rise to the surface before beneficial bacteria can make use of them.

On the contrary, MABR is all about efficiency. The modules house a spirally wound membrane sleeve, with air on the inside and mixed liquor surrounding it. The membrane is semi-permeable, allowing efficient delivery of air into the wastewater without bubbles. Air is conveyed directly through the membrane at near atmospheric pressure, requiring no expensive air compression and creating an ideal environment for bacteria. Bacteria soon form a biofilm on the membrane that converts ammonia in the wastewater into nitrate.

Simultaneous Processes

Denitrification must occur just as in activated sludge processes. Although the membrane creates an air-rich environment within its spiral layers for aerobic bacteria, wastewater in the surrounding tank is anoxic enough to support a robust anaerobic culture that converts the nitrate into nitrogen gas, which can simply be released into the atmosphere with zero impact.

So, the steps of a process that previously required separate compartments now takes place simply, simultaneously, and efficiently in a single tank, allowing MABR to treat more effluent to a higher quality within a smaller footprint.

Retrofitting Existing Plants

MABR’s small modules can also be used in the tanks of legacy plants to reap the benefits of SND. Arrays of Fluence SUBRE MABR modules can be submerged in existing infrastructure to increase both capacity and the quality of effluent.

MABR’s small footprint also has the benefit of portability. The newly released Aspiral™ line of Smart Packaged MABR units has rolled out for use anywhere a standard shipping container can be shipped, from urban or industrial settings to Caribbean islands, along with Fluence’s other decentralized solutions. These packaged plants can be easily concealed, and installation can be accomplished with minimal ecological disturbance, making them ideal for resorts and tourist areas.

SND makes MABR modules one of the most efficient and compact wastewater treatment technologies available. Contact Fluence to learn how MABR can benefit your wastewater operation.