Re: [compost_tea] Re: Getting Oxygen into Tea and Preserving Fungi At The Same Time

From: David Loring <dloring3_at_cox.net>
Date: Sat, 1 Nov 2003 10:54:47 -0800

Elaine - I thought all the talk about bubble size was to get a handle on wh=
at the best diffusers when designing brewers. A lot more companies are goi=
ng to be making brewers here in the USA and in countries where brewers are =
not now available and I hope they are getting useful information from these=
 discussions.

Thanks for the info on respiration of microbes, we definitely need to know =
when news like that on N2 concentration from deep bubbling, is not relevent=
 to tea brewing.
  ----- Original Message -----
  From: soilfoodweb_at_aol.com
  To: compost_tea_at_yahoogroups.com
  Sent: Saturday, November 01, 2003 10:09 AM
  Subject: Re: [compost_tea] Re: Getting Oxygen into Tea and Preserving Fun=
gi At The Same Time


  Ah, we aren't talking mammlian respiration systems in compost tea. As fa=
r as I know, we aren't trying to send divers to live in the bottom of the c=
ompost tea machine.

  Could we stick trying to understand microbial respiration?

  The thing of concern is transfer of oxygen into the water. Oxygen is bein=
g used up in the water so rapidly by the microbes that oxygen concentration=
 is dropping to below 5.5 to 6 ppm.

  Unless I am mis-remembering my courses on microbial respiration, high con=
centrations of N2 gas don't really affect microbes much until you get to ab=
ove 85% N2 in the atmosphere.

  N2 gas is at 75% in the total atmosphere, so you have to pressurize air b=
ubbles a great deal more than we are, even with 20 foot deep, or 200 foot d=
eep, tanks, to cause a problem for the microbes.

  It is the use of oxygen by the microbes, and then diffusion of oxygen fro=
m bubbles into the water that is the important balance. Since we are deple=
ting oxygen in the water, the movement of oxygen from the bubble into the w=
ater will be more dependent on the diffusion co-efficient based on the grad=
ient between oxygen concentration in the water versus the air bubble.

  The more rapid the growth of the microbes, the more rapid the diffusion o=
f oxygen from the bubble into the water. The whole concern about the maxim=
um movement of oxygen from the bubble into the water requiring at least 3 o=
r 4 feet depth of water just went out the window.

  I think many of you still are hung up on the fact that you just can't bel=
ieve that bacteria and fungi can be growing so fast that they can use up 3 =
CFM of air being bubbled into water fast enough that the water can still be=
 dropping in oxygen content.

  But they do. It's what your oxygen probes are telling you.

  So, what do you do to solve the problem? Bigger and bigger pumps?

  Hum, the engineering approach to life. Get a bigger hammer. Doesn't wor=
k with living systems. Bigger hammer? Bigger problems......

  How about considering LESS FOOD?! MATURE compost?!

  Comprende?

  Elaine Ingham
  President, Soil Foodweb Inc.
  SFI Corvallis, OR
  SFI Port Jefferson, NY
  SFI Lismore, NSW, Australia
  SFI Hilversum, The Netherlands
  SFI Cambridge, New Zealand
  www.soilfoodweb.com

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Received on Sat Nov 01 2003 - 14:22:29 EST

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