What is nanobubble aeration?
Nanobubble aeration is the latest leap forward in water aeration technology. Nanobubble aerators produce microscopic bubbles called nanobubbles, which are 500 times smaller than typical microbubbles and 10,000+ times smaller than regular bubbles. The bubbles are so tiny they’re around the same size as a viral particle. In fact, a typical nanobubble (80nm) is equal in size to a COVID-19 particle (80-120nm).
The benefits of nanobubble aeration
Due to their size and structure, nanobubbles are far more effective at improving water quality and enhancing water treatment processes than regular bubbles. While conventional aerators typically transfer around 1-3% oxygen per foot of water, nanobubble aerators can achieve greater than 85% oxygen transfer (as tested in two feet of water). This means far more oxygen is dissolved into the water body than typical aeration, requiring less overall oxygen.
(i) Faster to add oxygen to water
Nanobubbles not only dissolve at a higher rate than conventional bubbles, but they also tend to dissolve faster when first added to water. This is because nanobubbles are so small that they act much more rapidly and randomly (brownian motion) than regular bubbles, meaning they collide and break apart more often when first ejected from the aerator. These collisions break the bubbles apart so more oxygen enters the water, faster. And we’re not just talking about a few more collisions—with around 64 million nanobubbles fitting into one microbubble, there are millions more collisions early on.
(ii) Oxygenate deeper waters
Unlike regular bubbles, nanobubbles have almost zero buoyancy. This means they don’t travel straight for the surface like their larger counterparts. Instead, they tend to follow currents and end up in deeper parts of dams, lakes and wastewater lagoons. This unique characteristic of nanobubbles means you can create a homogenous column of oxygen throughout your entire body of water without having stratified layers.
(iii) Bubbles last longer
Those nanobubbles that don’t collide and break apart when first leaving the aerator also tend to stick around for longer periods than conventional bubbles. This isn’t just because nanobubbles don’t head straight for the surface like conventional bubbles, although (as explained above) this is true, it’s also because nanobubbles have a higher structural integrity than regular bubbles, meaning they are less likely to break apart under pressure.
The easiest way to think about structural integrity is imagining a balloon that has barely any air in it compared to a balloon that is full of air. The wall of the balloon that is full of air has a much weaker structural integrity than the balloon with very little air in it, therefore it is more likely to rupture under pressure.
(iv) Attracted to organic matter
Due to their structural make-up, nanobubbles also have a much stronger negative surface charge than regular bubbles. This makes them more attracted to positively charged organic matter like precipitated metals, pollutants and dangerous cyanotoxins. Bringing oxygen to these compounds, in many cases nanobubbles can render them inactive and stop them from causing undesirable water quality conditions.
This strong negative surface charge also makes nanobubbles more stable than conventional bubbles allowing them to participate in physical and chemical reactions for longer periods than regular bubbles.
(v) Higher levels of oxidation
Oxidation is one of the most common methods for treating water without the use of chemicals. It occurs when an electron is removed from a molecule, making the molecule less stable and therefore more reactive with other compounds (e.g. pathogens like bacteria and viruses). Because of their size and structure, nanobubbles oxidise at a much higher rate than regular bubbles.
Nanobubbles have also been shown to release the hydroxyl radical, one of the strongest known oxidants, when they destabilise and collapse. These radicals are ideal for commercial water treatment because they scour surfaces and prevent biofilm growth on submerged surfaces in wastewater lagoons, irrigation pipes, drip lines and swimming pools. This reduces the need for harsh chemicals that can damage pipes and filtration systems. In fact, these hydroxyl radicals are so effective at cleaning water and breaking down toxins that earlier this year Virginia Tech proved “nanobubbles can eliminate pathogens like E. Coli and Listeria on surfaces within five minutes of exposure”.
Commercial uses of nanobubble aeration
While nanobubble aerators can be used to replace conventional aerators in just about any environment (e.g. residential, mining etc), the three industries below are benefiting enormously from the technology.
Wastewater treatment
The unique oxidising properties of nanobubbles make them ideal for commercial wastewater treatment plants looking to reduce their need for chemicals. As explained above, nanobubbles release the hydroxyl radical, one of the strongest known oxidants, when they destabilise and collapse. These hydroxyl radicals are extremely effective at removing toxic and corrosive compounds like ammonia and hydrogen sulfide.
Nanobubbles also improve the flotation ability of fats, oils, greases, and floatable solids, making it easier to separate unwanted compounds from wastewater. And because nanobubbles have almost zero buoyancy and thus can travel to deeper pockets of water bodies, they are ideal for penetrating flocs of biomass that have settled at the bottom of wastewater lagoons. Encouraging more aerobic biomass, this speeds up the breakdown of toxins to improve the treatment capacity of wastewater plants.
Aquaculture / Aquafarming
With oxygen transfer rates over 85%, nanobubbles are by far the most efficient way to add oxygen to water. For fisheries this means significantly less oxygen needs to be added to the water, reducing total energy costs. And with improved feed conversion ratios and better treatment of parasites and aerobic bacteria, nanobubbles can lower operational costs for fisheries too.
Nanobubbles also help to uniformly add oxygen to your water, preventing stratification of layers. This provides a more stable, oxygen-rich environment for your fish and gives them access to more of the water body, reducing mortality rates and permitting farmers to grow fish in higher densities without jeopardising quality. Nanobubble aeration can also be used for targeted, chemical-free treatments. For instance, salmon farmers are using nanobubbles to reduce sea lice in their stocks.
Agriculture and Horticulture
Nanobubble aeration is also being used more and more in agriculture and horticulture to improve plant health and ultimately boost levels of harvest. By increasing the amount of dissolved oxygen in the water, plants utilising nanobubble aeration can uptake higher levels of key nutrients like calcium and potassium, and gain greater root mass. These same plants have also proven to be more robust, weathering environmental stresses like heat spells and radical shifts in atmospheric conditions.
Plus extra oxygen in the growing ecosystem means less pathogens, which reduces biofilm, algae and toxic pathogens like pythium and phytophthora. It also means a lower power bill for farmers because more efficient oxygen transfer means less oxygen is needed.