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Desalination

Pre-treatment that keeps biofouling and organic load off reverse-osmosis membranes.

Desalination pretreatment is everything done to seawater before it reaches the reverse-osmosis membranes. NanoMAR does it with gas cavities under 200 nm carrying a negative zeta potential, which attach to the colloids and biopolymer a biofilm starts on and lift them out of the feed. NanoMAR systems remove 80 %+ of suspended matter and reduce turbidity by 50 %+. Nothing is dosed, so no residue can carry over onto a polyamide element.

Desalination

As a pre-treatment step, nanobubbles lift organic load and the fine solids biofouling builds on out of the feed before it reaches the reverse-osmosis membranes — 80 %+ suspended-matter removal, 50 %+ turbidity reduction. Nothing is dosed, so the ionic composition of the feed is unchanged and antiscalant is still required.

Where fouling rather than scaling is the limit, that means fewer cleaning cycles and less downtime. NanoMAR publishes no recovery percentage and no cleaning interval; both belong to your feed water, and normalised flux decline measured before and after is what establishes them.

Biofouling on RO membranes

An element never fails suddenly. Feed pressure creeps up, permeate flow drifts down, differential pressure at the lead vessels widens. By then the biofilm is mature.

What starts it

Bacteria are not the first arrivals. A conditioning layer of organic matter and biopolymer settles first, and cells colonise that. It is colloidal, passes a cartridge filter, and a silt density index barely sees it.

What it costs

Higher feed pressure is energy, billed every operating hour. Each clean-in-place costs production, chemicals, disposal and element life. Coagulant pushed up to hold turbidity carries iron onto the membrane.

Nanobubbles as pretreatment

A nanobubble is a gas cavity under 200 nm. Buoyancy scales with volume and stops mattering there, so it does not rise and burst; it stays suspended for days.

Two properties do the work. The negative zeta potential draws in the colloidal fraction filtration leaves behind and lifts it to a flotation surface. The interface is vast, so transfer runs near completion: 40 %+ higher oxygen transfer, which keeps an intake basin aerobic — more on nanobubble aeration.

What figures does NanoMAR publish?

Four, and no others. They describe the platform.

80 %+
Suspended-matter removal
Load the membrane never sees
50 %+
Turbidity reduction
On the treated stream
40 %+
Higher oxygen transfer
Against conventional aeration
Zero
Chemicals dosed
Nothing to carry over

Where does the stage sit in a seawater intake?

Atmospheric-side equipment. Placement decides whether it earns anything.

  1. 01

    After screening

    A side stream off the intake basin, or feeding the flotation stage, where bubbles gather colloids.

  2. 02

    Ahead of media filters

    Every kilogram floated off is a kilogram the beds never hold. Backwash frequency moves first.

  3. 03

    Ozone strictly upstream

    Polyamide is oxidant-sensitive, so ozone belongs where no free oxidant reaches the first vessel.

  4. 04

    Never at high pressure

    Not between cartridge filters and racks. Not on permeate.

How does it compare with chemical pretreatment?

Coagulation adds mass to water you are about to push through a membrane.

Coagulation and dosingNanobubble pretreatment
ConsumablesCoagulant, polymer, biocideWater and a gas
Carry-over riskIron or aluminium onto elementsNothing added, nothing to carry
During an algal bloomRe-optimise the dose, usually lateNo dose to re-optimise
Effect on scalingAntiscalant still requiredAntiscalant still required
On siteBulk tanks, bunding, dosing skidsNo chemical storage
Published removalDose-dependent80 %+ solids · 50 %+ turbidity

A nanobubble stage reduces what the chemical programme must do. It rarely deletes it.

Recovery and cleaning intervals

Recovery is capped by whichever arrives first: scaling at the tail, or fouling at the lead. Establish which you have before reading any supplier claim.

Fouling-limited plants

Here there is room. A lower colloidal load into the first element means differential pressure climbs more slowly, so the cleaning interval stops being set by biology. Fewer cleans is fewer hours off line.

Scaling-limited plants

Here there is none. Nanobubbles leave the ionic composition unchanged and tail saturation is identical. Spend it elsewhere.

NanoMAR publishes no recovery percentage and no cleaning interval; both belong to your feed. Measure normalised flux decline before and after — see the NanoMAR pilot method — then size on the result: that is how a nanobubble system is selected.

Which NanoMAR unit fits a desalination duty?

Bench first, pilot second, unit sized on the pilot data.

ModelFlowRole at a desalination plant
NanOxy S22–50 lpmBench trials on your own seawater
NanOxy M Pro10–100 m³/h (nominal 35–55)Side-stream pilot on the live intake
NanOxy S10.3–1 000 m³/hFull intake duty; compressed gas required, no electrical connection at the module
NanVANN Pro5–500 m³/hBackwash and reject water, where solids dominate

Sizing follows pilot data, never a brochure.

What should you measure to prove it worked?

Agree the list before the pilot, then sample the same points each time.

  • SDI and turbidity, feed and outlet of the stage.
  • Normalised permeate flow and salt passage; raw readings drift with temperature.
  • Differential pressure by stage — biofouling shows at the lead vessels.
  • TOC, plus the biopolymer fraction if your laboratory runs it.
  • Cartridge changes and backwash frequency, already in your logs.

When is nanobubble pretreatment the wrong tool?

Three cases where we would rather say no.

Scaling-limited recovery

If the ceiling is carbonate or sulphate saturation, nanobubbles do not move it.

Rejection and boron

Both belong to the membrane and the operating pH. No pretreatment improves them.

A clean beach well

An intake already holding a low, stable SDI has little foulant left.

FAQ

What is desalination pretreatment?

Desalination pretreatment is everything done to seawater before the reverse-osmosis membranes. NanoMAR does it with nanobubbles under 200 nm that lift colloids and organics out of the feed: 80 %+ suspended-matter removal, nothing dosed.

Can nanobubbles stop biofouling on RO membranes?

Nanobubbles reduce the load that feeds a biofilm; they do not sterilise it. NanoMAR bubbles carry a negative zeta potential that lifts the colloidal layer bacteria colonise. No pretreatment ends cleaning.

Does nanobubble pretreatment increase recovery?

Only where fouling, not scaling, is the limit. NanoMAR publishes no recovery figure. Nanobubbles leave the ionic composition unchanged, so antiscalant is still required.

Can ozone nanobubbles be used in a desalination plant?

At the intake, yes; at the membrane, never. NanoMAR generators run on oxygen, air or ozone, but polyamide elements are oxidant-sensitive, so ozone belongs well upstream.

Which NanoMAR system suits a seawater intake?

NanoMAR starts with the NanOxy S2 at 2–50 lpm for bench work, then a NanOxy M Pro pilot at 10–100 m³/h on the live intake. Full duty runs on the NanOxy S1.

Send us your intake data

Salinity, SDI, TOC, the flux-decline curve and your cleaning log. Our engineers in Bergen will say whether this is a fouling problem.

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