[Gasification] HomeBiogas

[Bruce Wilson Contracting]

Just a quick primer on methane digesters, it is a two part process, 
first is the acidification stage where bacteria turn the waste to acids. 
The bacteria do not have teeth or mobility, so putting what you put into 
the digester through a grinder helps break it down so the bacteria can 
access the nutrients. These acid producing bacteria produce CO2. After 
the acids are produced the methanogenic bacteria digest the acids and 
produce methane. Gentle mixing is called for because so that the 
bacteria can access the nutrients to be digested, the bacteria that 
produce the methane stop producing methane when agitated which is why 
gentle mixing is called for. There are two ideal temperatures for 
digesters, 120 degrees F, or thermophylic and 100 degrees F mesophylic. 
A ten degree drop in temperature leads to a twenty percent drop in gas 
output. Thermophylic produces more gas but is more finicky, mesophylic 
is much more forgiving. Bacterial seeding can help a digester get started.

On 5/4/2022 1:19 AM, hugh at austrop.org.au wrote:
>
> Hi
>
>  we have one of the original Israeli HomeBiogas systems. Living where 
> we do - we had problems
> getting fresh cow shit. It was a disaster - mostly CO2.  So we 
> emptied, flushed and sterilized
> it and a (not so local) dairy provided 60 litres of fresh cow shit. 
> Then Covid hit and our supply
> of local ex-restaurant waste stopped. (we didn't produce enough 
> ourselves). 2 years later (the system
> having been been totally ignored), it started to inflate. Evidently 
> the battle between the CO2
> producers and the methanogens had finished, and to our delight the gas 
> appears to be pure methane. So
> we have been using this now for months for a significant amount of our 
> cooking.
>
> However - we homogenise everything.that goes in - this speeds up the 
> digestion process greatly,
> and means that we are not getting a residue of indigestible material 
> in the digester tank
> (which was a major problem with the initial clean out).
>
> And yes - we should be using the copious liquid fertiliser that the 
> system produces - too much
> else going on and not enough hands available.
>
> Homogenising - we use a modified Kambrook Power-drive stick mixer - 
> with a modified end (cut the
> loops off). So long as there is little fibrous material, or any really 
> hard stuff (bottle tops etc)
> it is a quite amazing machine.
>
> (also HomeBiogas have developed a toilet system that feeds the 
> digester directly. Wish we had had one!)
>
> Worth the effort.
>
> Hugh
>
> www.austrop.org.au
>
>
> On 04.05.2022 2:22 pm, Anand Karve wrote:
>> Dear all,
>> I developed in 2003 the urban domestic biogas plant which works
>> without dung, but uses only domestic food waste as feedstock. The
>> effluent slurry of this biogas plant is watery. I applied it regularly
>> to an experimental plot of garlic. It was just a feeler trial to see
>> how the plants responded to the effluent. To my surprise, the plot
>> receiving the slurry gave higher yield of garlic bulbs than the plot
>> receiving the recommended dose of chemical fertilizers. The area of
>> both the plots was equal.
>> Yours Anand Karve
>>
>
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-- 
Bruce Wilson LEED AP, Project Developer at GEMMasterPlanning www.gemmasterplanning.com
Bruce Wilson Contracting, bwc at ptd.net, 610-282-0822
Environmentally Sustainable Renovation, Restoration and New Construction.
Energy Efficiency Improvement Contracting and Sustainable Consulting
PA Registered Contractor PA#10930,

  Celebrating 45 years in Business.
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