Dear Gregg:

"Gregg" wrote in message
...
....
Hi Dave,
I have a friend who has designed some very high
efficiency bubble diffusers (originally designed for
O2 transfer). Since the diffusers are ceramic

I've seen and used porous teflon membranes too...

and can be easily fitted with ozone resistant fittings,
I was wondering if you thought there would be a good market for
bubble diffusers as a replacement for
injectors. (90% O2 transfer efficiency in 8' of water
IIRC) They have an incredible turn down ratio. ( I
can't remember the exact operating pressure ~20"
water IIRC) When I worked on the diffusers, I
noticed there was a lot of reluctance to try an
unproven technology esp in water treatment.

Diffusers have been used in municipal water treatment since the
early 1900s.

Turndown ratios for diffusers are on the order of 50%, which is
fine for some applications. If the growing bubble is filled too
slowly, it doesn't distribute over the whole surface... just on
the "high spots".

Some were sold for special applications and proved
very effective. I know he has some ideas for
improving transfer efficiency even further - but could
this be a solution to a problem nobody wants to solve?

Thanks in advance for any input,

There is a great lot of competition in diffusers. If you can do
it without polymeric seals of any sort, you will have a leg up on
the competition.

I personally *hate* diffuser systems. The diffusers are
constantly requiring service, since ozone will cause iron (among
other things) to go insoluble right on the diffuser. This
requires a full shutdown of the process to remove / replace /
refurbish. Then you have to build huge tanks for contacting.
And you have to make sure the manifold is level and
self-draining. And you require high flow rates, or multi-tier
delivery manifolds for large gas turn-down ratios. Finally, with
large exposed volumes you get very high dissolved oxygen levels,
which pose serious corrosion problems in municipal systems.

I'll put my salesman's hat on for a second, even though the
company I used to work for doesn't work out of Arridzona any
more. Injector systems reside outside the contacting area,
allowing service on components without draining (or wearing a
wetsuit). Injector systems can be arranged to deliver ozone in
just a few tens of feet of pipe... even for huge flow rates, and
mixed to get (in most cases) better then 95% mass transfer.
Injector systems can even be made to keep DO levels close to
ambient saturation, so that you don't end up with air binding in
filtration systems downstream.

Salesman's hat comes off...

I added 100 ppd of ozone at 12 wt% to a 350 gpm semiconductor
wastewater flow stream, got about 99% mass transfer (very high
instantaneous demand), and only took about 60 sq feet of floor
space including contacting and destruction of excess gas.

Diffusers don't require additional power to contact. But that
really is their only benefit. Sorry.

David A. Smith