[Digestion] Alkalinity

[Anand Karve]

Dear Mr. Eaton,
Is this a newly constructed biogas plant? Please check the biogas holder
for a possible leak. Has the biogas output been satisfactory in the
beginning and become low now, or has it been low right from the beginning?
Please check what the high pH of water is due to. At our own farm, we have
water with high calcium bicarbonate content. We get good biogas production
in spite of having such water. In fact, all cells, except the
methanogens, produce acetic acid as the end product of intracellular
catabolism. If the non-methanogenic organisms in the dung produced
enough acetic acid, it should neutralize the alkalinity.
Yours
A.D.Karve

On Fri, Aug 31, 2012 at 7:33 PM, Alexander Eaton
<alex at sistemabiobolsa.com>wrote:

> Dear List,
>
> Yesterday I was visiting a handful of "problem" digesters to help get them
> back on track.  The issues is almost always acidity due to overloading
> (either stemming from too much waste, not enough water, or dropping
> temperatures), and a big dilution, some bicarbonate, and a new "seeding"
> from another nearby system is almost always the fix.
>
> However, yesterday I went to a system that had a pH of 7.2 (in the range
> of OK), but was producing almost no gas.  I checked everything before I
> decided to check the pH of the irrigation water from a deep well they used
> with the waste.  It had a pH of 8.6.  That was the most alkaline reading I
> had seen in input water, which must indicate it is highly mineralized.
>  This pH seems out of a healthy range for AD, but there is no other water
> source.  So, two questions:
> 1.  Please confirm that input water with such high alkalinity could be
> inhibiting the AD process, and;
> 2.  What could be done to cost effectively (eg no cost) lower the
> alkalinity, or at least the impact on the AD process.
>
> I had them start using less water, arriving at the lowest possible
> dilution levels for the cow manure, hoping that less water would mean less
> inhibition of the process.  Thought?
>
> Best
>
> --
> Alexander Eaton
> Sistema Biobolsa
> IRRI-Mexico
> RedBioLAC
>
> Mex cel: (55) 11522786
> US cel: 970 275 4505
>
> alex at irrimexico.org
> alex at sistemabiobolsa.com
>
> sistemabiobolsa.com
> www.irrimexico.org
> www.redbiolac.org
>
>
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>
>
>


-- 
***
Dr. A.D. Karve
Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)
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