Good concept, is it practical? 3

[jlmtl]

The concept of nanobubbling in the linked video sounds good, mass transfer efficiency should be higher comparing with regular gas bubbling/diffusing devices; did anyone see any real successful applications?

https://www.youtube.com/watch?v=HIGNdO_tIMs

Regards/Joe

 

[ashtree]

Mass transfer efficiency may be good. In theory the smaller the bubble the greater the surface area for a given total volume of air. This is why fine bubble diffusers in wastewater plants are more energy efficient than coarse bubble diffusers for a given oxygenation requirement.

However if you follow the nano bubble argument this cannot be true because the bubble decreases in size and pressure builds up with the gas being held in by the ions around the outside. Therefore the oxygen transfer is low or negligible. In fact they argue in some of their information that the bubbles stay in solution for days , weeks or longer. On oxygen transfer there then.

However i would hypothesize that the reason you cannot see the nano bubbles even with a microscope is that they no longer exist.
As the oxygen is absorbed by the water around it the partial pressure inside the bubble is reduced causing the bubble to shrink. Eventually it shrinks to a negligible size or totally collapses with whatever gas is left being fully dissolved into the water.

There is no build up of pressure in the bubble. There is no collapse of the bubble which generates super heat and free radicals etc.

Likewise if a bubble is generated below the water as it rises the bubble will actually expand because of the reduction in pressure. Pressure outside = pressure inside, so the bubble expands.

I am sure some people will tell me I am wrong though.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[moltenmetal]

Many of the claims in the video are rubbish. Ozonation for disinfection is nothing new- it results in less flavour but has no residual effect, i.e. it is fine for initial "shock" disinfection but useless for protecting water from recontamination once it has left the treatment plant. The anti-cancer claims made in that video are a distortion in my view- they made no claim nor did they provide any evidence that cancer cells are killed preferrentially to non-cancerous cells, which makes sense given that ozone is a GENERAL toxicant. Drinking freshly ozonated water (right out of the ozonation tank) which an idiot in the video was encouraged to so, is dangerous- ozone is toxic and damaging to tissues whether it is ingested in water or in air. But since ozone has a short half-life in water (generally on the order of minutes), ozonated water would soon contain no detectable ozone and hence would be safe to drink.

I didn't hear a claim in this video about making radicals from bubble collapse etc. Those claims are frequently made about cavitation generated by ultrasound or other means. I've seen lots of these claims over the years but very little evidence for the efficacy of these devices as efficient generators of free radicals for water treatment, relative to other catalytic or radiation-stimulated means (i.e. UV peroxide etc.).

Making very small bubbles doesn't matter much except if you have an extremely fast reaction taking up the dissolved species, especially when self-reaction can destroy your feed gas if it hangs around too long. That can be the case with ozonation, but isn't usually the case even with ozone and is rarely the case when air is used as a source of reagent oxygen. There are exceptions of course. In aerobic water treatment, there are several things going on at the same time- aeration provides both oxygen and liquid/solid mixing in those systems, and fouling is also potentially a big issue. When comparing the efficacy of a particular aerator, it is important to control for these factors so you can really understand what's going on.

If the bubbles have to hang around for a long time to give sufficient conversion of the feed gas before the gas leaves the tank, i.e. aeration in a deep tank, it doesn't matter much how fine you make the bubbles in the first place. Surface tension and bulk mixing will rapidly determine the average size of the bubbles. Small bubbles will coalesce into larger ones quickly if there is insufficient liquid shear to tear them back into small bubbles again. Gas-liquid contact agitators are designed to do that.

 

[zdas04]

moltenmetal,
That was an excellent review of the process. Do you know any reason that putting ozone in the water would (could?) create a habitat suitable for both freshwater and seawater fish to coexist for years? That fish tank was the only thing in the video that didn't make me think "there is not enough data here to make that claim"

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[moltenmetal]

Ozone doesn't do anything to either fresh or salt water itself. It reacts with organic species in the water. It cannot, and does not, make fresh water saline or saline water fresh, nor can I imagine a way it would reverse the osmotic balance problems encountered by fish put in a type of water they are not evolved to live in. The whole fish tank thing was just plain stupid in my opinion. Then again, I don't like fish- to look at them, eat them or catch them, so I'm the wrong person to ask:

http://www.livescience.com/32167-can-saltwater-fish-live-in-fresh-water.html

 

[ashtree]

Perhaps some of you may not have picked up on my sarcasm.
The reason i added the comment about the free radicals is because this is what the good Dr Takahashi claims in his "research". I have added the presentation below if you want to check it out for a laugh. If you want to Google his "research" you will find that they claim nano-bubbles can just about fix every so far unsolvable problem known to man.
The bottom line is that the rules of chemistry and physics do not support the claims being made and its about as useful as a bucket load of oil extracted from boiled down rattle snakes.
I suspect that you may find that a lot of fish including those in the video can if acclimatised live in water that is both fresher or saltier than their normal habitat. Certainly carp is pretty adaptable.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[moltenmetal]

As much as I despise fish, the fact that one of the test species was carp was a dead giveaway- those suckers can live anywhere. It certainly had nothing to do with bubbles, or ozone, nano or otherwise.

 

[jlmtl]

Hi all,
Glad to hear your comments. I recently got the introduction from a UK university about their invention for nanobubbling and wanted to apply in our company. Later, I googled more info about nano-bubbling and got the video made by Japanese institute, which I have posted here.

It is not suprising to me that vendors always think their inventions/products can solve all the problems in the universe. But seems to me, it is a new concept, still need a lot of development.

It seems to me that all your comments are not favoring its application. To me, qualitatively speaking, nano or micro-bubbling may have the potentials in certain applications, related to mass transfer, maybe oxidation reaction, gas absorption,etc. I guess; but not now, may be certain years later.
Glad to hear more from you guys.

 

[georgeverghese]

They keep flogging this "nano" horse to death to claim R&D tax rebates in many countries - there is no other use for it.