[Digestion] Biogas concentration sensors - technical question

[Paul Harris]

G'day All,

I have a paper (packed in a box in my office - I had to move offices in
January) that found that bubbling biogas through sodium bicarbonate
solution and monitoring pH gave a good indication of quality. It's
something I have been wanting to try for a long time.

Hawkes, F. R., A. J. Guwy, et al. (1994). "On-Line Monitoring Of
Anaerobic Digestion - Application Of a Device For Continuous Measurement
Of Bicarbonate Alkalinity." Water Science & Technology 30(12): 1-10.
	Alkalinity or pH buffering capacity in anaerobic digesters is chiefly a
function of bicarbonate levels, and should be within 10 to 50 mM for
stable operation. A novel on-line instrument for measuring bicarbonate
alkalinity has been developed, independent of titration techniques.


Happy digesting,
HOOROO

"alastair ward (IGER-NW)" wrote:
> 
> I have been using a Crowcon triple plus + IR gas sensor that will measure up to 4 gases. I don't think they do CO2, at least not at the concentration expected in AD but they can measure H2S up to about 200ppm I think. I was only interested in the methane part, and as standard it comes with a 0-100% LEL IR sensor, but can be bought with a dual range IR that will also measure 0-100% volume. It is of course designed for safety around landfill sites, so I advise the purchase of  the hand operated bulb which will allow you to channel gas from a digester across the sensors rather than constructing a channel from plastic as I did. The H2S sensor would be catalytic but I have no real pressure in my biogas: a couple of PSI is a lot when you ask to have a large tank manufactured. I just vent off the gas through the sensor for a minute or two, then flush it out with air. I think the dual range unit alone (with charger) would be less than 2000 euros.
> 
> Alastair Ward
-- 
Mr. Paul Harris
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