--- title: "Where aeration's electricity goes | Alchemal" url: "https://alchemal.com/field-notes/where-aeration-electricity-goes/" description: "Aeration is the largest power draw at most plants, and much of it buys oxygen that never dissolves. Transfer efficiency is the physics behind the bill." source: "Alchemal — alchemal.com" --- # Where aeration's electricity actually goes Alchemal Published July 12, 2026 At most wastewater treatment plants, one line on the power bill dwarfs the rest, and it is aeration. The blowers that push air into the basins run around the clock to keep the treatment culture, the suspended community of bacteria that does the work, supplied with dissolved oxygen (DO, the oxygen carried in the water). The number worth understanding is where inside the process that money goes, because much of it never reaches the water at all. ## Transfer efficiency, in one number The figure that governs the bill is oxygen transfer efficiency: the share of the oxygen you supply that actually dissolves into the water instead of escaping at the surface. Run a blower and you pay for every unit of oxygen it pushes in. When a large fraction of that oxygen leaves the top of the basin as off-gas, the bubbles surfacing and bursting before the culture can use them, you have paid for oxygen the water never received. A system with low transfer efficiency spends more electricity for every unit of oxygen delivered, whatever the blowers are rated at. ## Why a coarse bubble gives its oxygen back Oxygen crosses from a bubble into water across the bubble’s surface, and it can only do so while the bubble is still in the water. A coarse bubble from a diffuser is millimeters across, and buoyancy dominates it: it accelerates to the surface and bursts within seconds. Its entire working life in the water is the length of that ride up, which is why a coarse-bubble system hands so much of its oxygen straight back to the air. This is the same size-and-residence story that makes a [nanobubble behave nothing like a bubble](https://alchemal.com/field-notes/how-small-is-a-nanobubble/): the smaller the bubble, the longer it stays down and the more of its oxygen the water keeps. Fine-bubble diffusers improve on coarse ones for exactly this reason, and they still surrender oxygen at the surface and clog as the grid ages. ## The bill is a physics problem first This is why the power bill is a physics problem before it is an equipment problem. Adding blowers or running the existing ones harder buys more oxygen at the same poor transfer, so the meter climbs with the demand while the off-gas keeps leaving. The lever that actually moves the bill is transfer efficiency, how much of the supplied oxygen stays in the water, and that is set by the physics of the bubble rather than the size of the blower. Nanobubble aeration attacks that gap directly, holding the oxygen suspended in the water instead of racing it to the surface. ## What the gap measures The size of that gap has been measured. In a bench comparison against a conventional diffuser, nanobubble aeration roughly doubled the standard oxygen-transfer efficiency. 2× oxygen transfer In a bench comparison, nanobubble aeration roughly doubled the standard oxygen-transfer efficiency of a conventional diffuser under the same conditions. It is the mechanism, not a pond result. [Kizhisseri, Sakr, Maraqa and Mohamed, *Heliyon*, 2025](https://doi.org/10.1016/j.heliyon.2025.e41687) A 25 L bench test in clean water. It shows the headroom of the mechanism, not what an installed unit does to a real pond or lake. Harmful-algal-bloom outcomes are held back until a credited limnologist reviews them. These findings describe nanobubble oxygenation as a mechanism, not an Alchemal unit. Our own installations publish their records as case files as they go in. A bench figure is the headroom of the mechanism, not a plant’s power bill, which is why we baseline the oxygen a basin holds and the blower duty it takes to hold it before anything is claimed. If aeration is your largest line, [describe your plant](https://alchemal.com/assessment/) and a specialist will reply with what we would baseline first. The [energy cost of aeration](https://alchemal.com/problems/aeration-energy-cost/) page carries that measured approach, a basin whose [aeration cannot keep up under load](https://alchemal.com/problems/aeration-cant-keep-up-load/) is the same transfer gap under strain, the [comparison with conventional aeration](https://alchemal.com/technology/nanobubbles-vs-aeration/) sets the two side by side, and the [wastewater overview](https://alchemal.com/wastewater/) walks the whole picture. ## Related field notes - [Nanobubble science How small is a nanobubble, and why the size is the point Under 200 nanometers, a bubble stops behaving like a bubble: no rising, no bursting. The physics of why size changes what oxygen can reach.](https://alchemal.com/field-notes/how-small-is-a-nanobubble/) ## Tell us what your water is doing. A specialist reads your description and replies in writing: what it usually means and what we would measure first. [Get a free assessment](https://alchemal.com/assessment/)