Reference
Nanobubble glossary: size, terms and definitions
Bubble size classes, water-quality parameters, process equipment and aquaculture terms — defined in engineering language.
A nanobubble is a gas-filled cavity under 200 nm across. At that size the bubble is effectively neutrally buoyant, so instead of rising and bursting it stays suspended for days to weeks. Nanobubbles carry a strong negative zeta potential, and that charge is what lifts contaminants out of the water. Ultrafine bubble is the same object under a different name.
Nanobubble
A gas-filled cavity in water, under 200 nm in diameter. Buoyancy scales with volume and drag with radius, so below that scale the bubble travels with the water instead of rising through it.
Contact time then runs to days or weeks, and the combined gas–liquid interface becomes enormous — the quantity mass transfer is proportional to. For the mechanism, see how NanoMAR generates nanobubbles.
Ultrafine bubble
The same object under the name most bubble-science literature uses. Nanobubble is the water-treatment term; NanoMAR uses it throughout, and the two are interchangeable.
“Micro-nano bubble” is a different claim — a mixed distribution still containing bubbles large enough to rise. Ask for a size distribution and a zeta potential, not an adjective.
Microbubble
Three size classes, three behaviours. Which one a machine really produces is the first thing to settle.
| Coarse bubble | Microbubble | Nanobubble | |
|---|---|---|---|
| Diameter | Millimetres | Tens of micrometres | Under 200 nm |
| Visible | Individually | As a white cloud | No |
| In the water | Rises and bursts in seconds | Rises slowly, breaks | Suspended for days to weeks |
| Charge | Negligible | Weak | Strong negative zeta potential |
| Usual duty | Diffused aeration | Dissolved air flotation | Gas transfer and separation |
A bubble count says nothing about the distribution behind it.
Zeta potential
The surface charge an object carries in water, measured at the shear plane and reported in millivolts. Sign and magnitude both matter.
Nanobubbles carry a strong negative zeta potential. Like charges repel, so they never merge into bubbles large enough to rise — the source of days-to-weeks stability. The same charge draws in fine and colloidal solids, the route to 80 %+ suspended-matter removal with no coagulant. High ionic strength lowers the reading, so seawater and fresh water differ.
Nanobubble science terms
The rest of the physics vocabulary, and why each term reaches a specification.
| Term | Definition | Why it matters |
|---|---|---|
| Bulk nanobubble | Suspended in the liquid, not on a surface | The population that does the work |
| Surface nanobubble | A gas cavity resting on a solid surface | A laboratory subject, not a product |
| Brownian motion | Random movement from molecular collisions | Beats buoyancy below 200 nm, so bubbles stay put |
| Coalescence | Small bubbles merging into larger ones | The failure mode; surface charge prevents it |
| Supersaturation | More dissolved gas than equilibrium allows | Reachable with nanobubbles, but design for it |
| Gas–liquid interface | Total bubble surface gas can cross | Transfer scales with it, so size sets the rate |
Oxygen transfer efficiency
The share of supplied gas that dissolves rather than leaving at the surface — a percentage, or kilograms of oxygen per kilowatt-hour.
Datasheet values are clean-water values; field efficiency is lower, and the ratio between them is the alpha factor. Two proposals compare in one unit only: kilowatt-hours per kilogram actually transferred. NanoMAR publishes 40 %+ higher oxygen transfer and lower energy operation, with no energy percentage, because the honest figure depends on the plant. The oxygen budget calculator works the demand side.
Dissolved oxygen
Dissolved oxygen (DO) is the mass of oxygen in solution, in milligrams per litre. Four terms travel with it.
- DO saturation the reading as a percentage of what the water holds at that temperature and salinity.
- Oxygen deficit target minus current concentration; multiplied by flow it gives the duty in kilograms per hour.
- Oxygen uptake rate how fast fish or biology consume it. Design against the peak after feeding.
- Off-gassing gas escaping at the surface — oxygen bought and not delivered.
BOD and COD
Two measures of how much oxidisable material the water carries. They are not interchangeable.
| BOD | COD | |
|---|---|---|
| Full name | Biochemical oxygen demand | Chemical oxygen demand |
| Measures | Oxygen bacteria use oxidising organics | Oxygen equivalent of what a strong oxidant attacks |
| Result timing | Days — the sample incubates | Hours |
| Refractory load | Excluded | Included, whether biology reaches it or not |
| Nanobubble route | Oxygen held across the tank, so no floc starves | Flotation takes the solids, ozone the soluble rest |
The gap between them is the fraction biology cannot reach inside your retention time.
Water-quality parameters
The lines on a water analysis, and what each one decides.
| Term | Definition | Why it matters |
|---|---|---|
| TSS | Total suspended solids, dry mass filtered from a sample | What charged bubbles float out — 80 %+ removal published |
| Turbidity | How strongly the water scatters light, in NTU | A live proxy for TSS — 50 %+ reduction published |
| TOC | Total organic carbon held in the water | Feeds biofilm and eats oxidant; the NanVANN Pro targets it |
| ORP | Oxidation–reduction potential, in millivolts | The control signal for ozone, and a fast anoxia check |
| DO saturation | Dissolved oxygen against the equilibrium value | Comparable between sites, where a raw mg/L reading is not |
| Dissolved CO₂ | Carbon dioxide held in solution | Depresses pH; stripped out, never fixed with oxygen |
TAN
Total ammonia nitrogen: un-ionised ammonia plus ammonium in one sample. Only one is acutely toxic, and pH decides the split.
-
01
Fish and feed produce it
Ammonia crosses the gill; feed and faeces release more as they break down. TAN tracks feed load.
-
02
pH sets the toxicity
The equilibrium shifts to un-ionised ammonia as pH and temperature rise. Equal readings are not equal risk.
-
03
The biofilter oxidises it
Bacteria convert ammonia to nitrite, then nitrate — consuming oxygen and alkalinity, failing first in patchy aeration.
-
04
Nitrate leaves the loop
Removed by water exchange or an anoxic stage. NanoMAR specifies the NanVANN Pro for TAN management.
RAS
A recirculating aquaculture system treats its water and returns it. Makeup water covers losses only, so equipment has to remove everything the fish produce.
The loop
Water leaves the tank, passes the train and returns. Nothing is diluted away, so each stage holds its own.
Solids removal
Drum filter and settling take out faeces and feed before they dissolve. Colloidal solids pass through.
Biofilter
Media colonised by nitrifying bacteria — the slowest stage to recover once starved of oxygen.
Degas, then oxygenate
Stripping removes carbon dioxide and surplus nitrogen; oxygen goes back in before the water re-enters.
Process equipment terms
What the hardware names mean on a flow diagram or a quotation.
| Term | Definition | Why it matters |
|---|---|---|
| Venturi injector | A constriction that drops pressure and draws gas in | One of three NanoMAR generation stages |
| Membrane diffuser | Gas pushed through a porous membrane into moving water | The NanOxy S1 platform; no electrics at the module |
| Ceramic diffuser | A rigid porous element shearing gas into the flow | For abrasive water that shortens polymer life |
| Side-stream | A branch treating part of the flow and returning it | Sized on gas duty; serviceable while the plant runs |
| Oxygen cone | A tapered vessel holding bubbles against downflow | The conventional route to high oxygen in RAS |
| Biofilter | Media carrying bacteria that oxidise ammonia | Oxygen-limited, so upstream transfer caps it |
| Degasser | A column stripping carbon dioxide and nitrogen out | Adding oxygen does not remove CO₂ |
Aquaculture terms
Farming vocabulary that ends up in water-treatment specifications.
| Term | Definition | Why it matters |
|---|---|---|
| Smolt | A juvenile salmon adapted to seawater | Water quality here reports later as survival after transfer |
| Post-smolt | Fish grown on land after smoltification | A longer land phase raises oxygen and solids duty |
| Biomass density | Standing fish mass per cubic metre | Limited by oxygen delivery and CO₂ removal, not tank volume |
| Off-flavour | Earthy taint from compounds such as geosmin | Fish must be purged before harvest, which costs tank time |
| Biosecurity | Keeping pathogens out and contained | Ozone nanobubbles suit the intake: ozone reverts to oxygen |
Froth flotation
Separation by attaching particles to bubbles and skimming the froth on top. Mineral processing named it; water treatment runs the same physics as dissolved air flotation.
Conventional cells arrange the attachment chemically — collectors, frothers, coagulant, polymer — and all of it ends up in the float, paid for on purchase and again on disposal. Nanobubble flotation arranges it electrostatically, so the colloidal fraction those cells capture worst is the fraction it targets. See it applied to effluent and sludge or mineral processing water.
A supplier who cannot give you a size distribution and a zeta potential is describing half the object. Those two measurements decide whether what reaches your water behaves like a nanobubble.
Where these terms are explained properly
FAQ
- How big is a nanobubble?
A nanobubble is a gas-filled cavity under 200 nm in diameter — invisible, and effectively neutrally buoyant. Because it does not rise and burst, a NanoMAR nanobubble stays in the water for days to weeks, still transferring gas.
- What is the difference between a nanobubble and a microbubble?
Size, and everything that follows. A microbubble is micrometre-scale, visible as a white cloud, and rises. A nanobubble is under 200 nm and stays suspended. NanoMAR builds nanobubble generators; micro-nano equipment behaves like its coarsest fraction.
- Are ultrafine bubbles and nanobubbles the same thing?
Yes. Ultrafine bubble is the term most bubble-science literature uses for the sub-micron gas cavity the water industry calls a nanobubble. NanoMAR says nanobubble throughout; the object, the physics and the equipment are identical.
- Why does zeta potential matter in water treatment?
Zeta potential is the surface charge a bubble carries in water. NanoMAR nanobubbles carry a strong negative one, which stops them merging into rising bubbles and pulls fine solids onto the bubble surface — the mechanism behind 80 %+ suspended-matter removal with nothing dosed.
- What oxygen transfer efficiency does NanoMAR publish?
NanoMAR publishes 40 %+ higher oxygen transfer than conventional bubble aeration, plus lower energy operation. No energy-saving percentage exists, because the honest figure depends on tank geometry, temperature and diffuser condition. Compare suppliers in kilowatt-hours per kilogram transferred.
Need these terms applied to your water?
Send the analysis — flow, dissolved oxygen, suspended solids, ammonia, temperature. Our engineers in Bergen will tell you which parameter is binding.
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