Powering change at the molecular level

A nanobubble is a gas-filled cavity in water with a diameter under 200 nanometres. That is the whole definition, and everything else follows from it — because below roughly that threshold, the forces acting on a bubble stop being dominated by buoyancy.

Consider what a conventional bubble does. Gas is released through a diffuser, the bubble forms at a few millimetres across, buoyancy overwhelms drag, and it travels to the surface in seconds. Along the way some gas dissolves; the rest is delivered to the atmosphere above the tank, where it is of no use to anyone. That is the fundamental inefficiency of bubble-based aeration, and no amount of pump pressure fixes it.

Now shrink the bubble by three orders of magnitude. Buoyant force scales with volume — the cube of the radius — while viscous drag scales roughly with radius. Take a bubble down to 200 nm and buoyancy loses. The bubble no longer rises in any practical sense; it goes wherever the water goes, and it stays there for days or weeks rather than seconds.

What that persistence is actually worth

A bubble that does not leave is a bubble that is still transferring gas an hour later, a shift later, sometimes a week later. It is also a bubble that reaches parts of a system a rising bubble never touches: the underside of a surface, the inside of a pipe run, the far corner of a tank away from the diffuser grid. Persistence is not a curiosity of the physics — it is the reason one nanobubble system can oxygenate a fish tank and strip biofilm from a membrane.

Gas transfer across a bubble wall is governed by three things: the concentration difference driving it, the interfacial area available, and the time the two phases stay in contact. Nanobubbles improve two of the three, dramatically.

Interfacial area. Divide one bubble into a thousand smaller ones and the volume is unchanged while the total surface area rises sharply. Take that division far enough — to sub-200 nm — and a modest volume of gas presents an interface area that a diffuser cannot approach at any pressure.

Contact time. A coarse bubble has the few seconds of its ascent. A nanobubble has as long as it remains in the water, which is days. In practice this converts what was a race against buoyancy into a process that simply runs to completion.

Driving force. The internal pressure of a bubble rises as its radius falls, which keeps the concentration gradient pushing gas into the liquid rather than letting it equilibrate early.

The measurable outcome, in NanoMAR's published figures, is 40 %+ higher oxygen transfer. The number that matters operationally, though, is not transfer efficiency in isolation — it is energy per kilogram of gas actually dissolved. Gas that leaves at the surface was bought and never used, whatever the motor rating says.

Two questions follow naturally from the physics above. If nanobubbles do not rise, why do they not simply merge into larger bubbles that do? And if they are only gas and water, why do they interact with contaminants at all?

Both answers are the same: surface charge. A nanobubble in water carries a strong negative zeta potential at the gas–liquid interface. Because every bubble in the cloud carries the same charge, they repel one another electrostatically, and that repulsion is what prevents coalescence. It is the mechanism behind the days-to-weeks stability, not an incidental property.

That same charge is what makes nanobubbles useful beyond oxygenation. Many contaminants of interest — suspended solids, oils, organic films, biofilm precursors — carry their own surface charge. A charged interface moving through the water attaches to them, and once attached, a cloud of bubbles will lift a particle that would otherwise stay in suspension or bound to a surface. That is the basis of NanoMAR's published 80 %+ suspended-matter removal and 50 %+ turbidity reduction, and it is also why the same platform is used for surface cleaning and degreasing without a detergent.

NanoMAR AS was founded in Bergen in 2023 out of the University of Bergen's water-purification research, and the technology is patented. The scientific basis for the behaviour described on this page — sub-micron stability, zeta potential at the gas–liquid interface, and enhanced mass transfer — is established in the peer-reviewed literature on bulk nanobubbles rather than proprietary to any one supplier.

What differs between suppliers is engineering: how the bubbles are generated, how consistently, at what energy cost, and how the equipment behaves in the water it will actually see. That is the part worth testing on your own site, which is why NanoMAR's portable laboratory unit and pilot-scale platform exist as products rather than as demonstrations.

If you are evaluating the technology, the practical route is on the pilot and validation page, and the equipment choices are set out in our guide to nanobubble generators.