Finding the right term: vermicomposting digester? Vermicomposting with filtering? Other options?

  • goeco
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Finding the right term: vermicomposting digester? Vermicomposting with filtering? Other options?

Hi Elizabeth,

The tiger toilet and biofil digester use the same process, only construction methods are different. (note by moderator: this part of the post refers to this thread: forum.susana.org/forum/categories/205-to...-ventures-limited-uk )

Some papers on the tiger toilet:
Processing of human faeces by wet vermifiltration for improved on-site sanitation
The development of an onsite sanitation system based on vermifiltration: the ‘tiger toilet’
The Tiger Toilet: From Concept to Reality
Processing of human faeces by wet vermifiltration for improved on-site sanitation

I'd suggest a name change for the parent topic "Toilet with combined vermicomposting and filtering (such as Biofil toilet)" because Biofil is only a brand of vermicomposting digester.

Not that "vermicomposting digester" is standard terminology for the process and technology, but that's what I call it.

I'd be happy to call the topic "Toilet with combined vermicomposting and filtering". Other names for the process include:

Vermicomposting toilet (...but "toilet" is not the process and the process can be applied to more than toilets... e.g. kitchen greywater)
Vermicomposting filter / Vermifiltration (not a good description in my mind, this describes only part of the mechanics and this is more than a filter)

Would be good to have a term that can be applied consistently by forum users, and thus searchable.

In my mind the term "digester" is most suitable because it describes the process of conversion. The compost and effluent are products of the conversion while the "filter" is only part of the mechanics of the digester. I'd rather describe the process of converting solid waste than the process of separating solids and liquids. Doesn't matter how the waste is digested, because this can be described: " Vermicomposting digesters : This system provides aerobic primary treatment by providing an enclosed environment in which worms transform solid effluent into humus."

Thinking about the logic further, the subject is categorised within the "Composting processes" topic area of the forum. Composting itself can be aerobic or anaerobic, but of course we tend to think of it as aerobic. A septic tank is a "digester", but anaerobic. Vermicomposting "digesters" do the same thing as a septic tank (i.e. digest the solids) but aerobically. Being aerobic is the key feature that gives the vermicomposting system an advantage. Although the term "digester" usually refers to anaerobic processes, the paradigm shift is to appreciate that now, with this technology, the same description can apply to both anaerobic and aerobic processes (i.e. "digesting" the solids). Thats my take anyway...

cheers
Dean

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  • JKMakowka
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Re: The Tiger Toilet which works with worms - like in-situ vermi-composting (field trials in India, Uganda and Burma) - Bear Valley Ventures Limited, UK

While I can (in theory) follow your line of reasoning regarding the term 'digester', I think it will cause a lot of confusion as indeed it is most commonly associated with microbial anaerobic processes.

'Composting' on the other hand is mostly referring to various aerobic processes, usually even involving worms, so I am not sure why you want to stop calling it a 'vermicomposting' based process.

Krischan Makowka
Microbiologist & emergency WASH specialist
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Re: The Tiger Toilet which works with worms - like in-situ vermi-composting (field trials in India, Uganda and Burma) - Bear Valley Ventures Limited, UK

Hi Krischan,

I use both "vermicomposting" and "digester".... "vermicomposting digester". Although some might see this as a juxtaposition, technically it isn't. Although the term "anaerobic digester" is used commonly, I note that "anaerobic" implies that a digester doesn't have to be anaerobic.

It could alternatively be called a "reactor".

This emerging technology (vermicomposting digester) seems to be unique in terms of being an aerobic digester that is wet composting, enclosed and not mechanical.

cheers
Dean

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  • muench
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Re: Finding the right term: vermicomposting digester? Vermicomposting with filtering? Other options?

Dear Dean,

Thanks for initiating this conversation and thanks Kris for your input! I have for now changed the sub-sub-section title to omit the brand name "Biofil" - now it is:
Vermicomposting digesters with filtering of effluent

Is that good? If not, let me know; sub-category titles are easy to change and the URLs of threads remain unaffected which is great.

I thought about alternatively substituting the word "digester" with "reactor" - would that be better?

Like Kris, I think of anaerobic process when I hear digester but I have to admit that this is wrong. E.g. there is a process called ATAD which stands for: autothermal thermophilic aerobic digestion.

I was going to add a Wikipedia link here but found no Wikipedia page exists on ATAD yet! Wow. Instead, I found an old forum thread here:
forum.susana.org/forum/categories/105-pr...inois-university-usa
That thread starts with a post by Arno saying:

Just to make sure people understand what "autothermal thermophilic aerobic digestion" is- there is another maybe more commmon term for this - and that is "wet composting". The whole trick in composting in wet systems is addition of air.


Anyhow, so I think I am getting used to "vermicomposting digester".

However, Dean you said:

Not that "vermicomposting digester" is standard terminology for the process and technology, but that's what I call it.

What is the standard terminology then? Or if there is none yet, what are the names that other researchers and practitioners have given it? Do you have a good overview of all the different name options?

And one thing I still don't understand: what's the difference then between just "vermicomposting" and "vermicomposting digester"? Do we really need two distinct sub-categories on the forum for this? Are two distinct Wikipedia articles needed or could they be merged? If not, what is the main difference?

By the way, I noticed that you started a SuSanA Wiki page on vermicomposting digesters here: akvopedia.org/SuSanA/Vermicomposting_digesters (one needs to login with one's forum login; actually, why does one need to login to read the page? Reading should not require a login, but only writing? Sorry, I am still confused about it all, but I guess it will be cleared up in this other thread soon: forum.susana.org/forum/categories/198-wi...e-between-them#16752 )

You described it as follows there:

Vermicomposting digesters

Vermicomposting digesters offer primary treatment of wet mixed blackwater

The effluent flushes from the toilet into the chamber and adds to a "heap" sitting on filtration media. The liquid drains away through the media and is discharged to land. The system is aerobic because the heap composts in an aerobic environment (i.e. ventilated) and the worms introduce air into the heap. They are very effective at reducing bulk and with sufficient worms present the heap grows only very slowly.

Vermicomposting digesters are used for municipal sewerage treatment and for domestic on-site sewage treatment. These systems incorporate flush toilets and filtered effluent disposal to land.


Regards,
Elisabeth

P.S. I've just completed a re-structuring job of the existing threads on vermicomposting digester topics (as in some cases the conversation deviated far from the original topic of the thread). I've placed cross-links in both directions where I split a thread in two). An overview of the new threads is here:
forum.susana.org/forum/categories/205-ve...iltering-of-effluent

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  • goeco
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Re: Finding the right term: vermicomposting digester? Vermicomposting with filtering? Other options?

Good work Elisabeth in rationalising these topics. I'm happy with the title "Vermicomposting digesters with filtering of effluent".

There isn't a standard terminology used yet... which adds to the confusion and is why I am trying to address this. Two systems were funded by BMGF grants for development, the Tiger Toilet and the Biofil digester. Biofilcom call theirs a "biofil digester" while the Tiger Toilet process is called "vermifiltration" or "wet vermifiltration". Biofilcom even call theirs a "RAB System" referring to:
Rapid separation of solids and liquids
Aerobic decomposition of solids and
Bio-filtration of waste water

Here in NZ they have been called anything from "Solid Waste Digester", "verma composting", "Eco-system", "Treatment system", "vermiculture", "vermiculture composting tanks", "biopod" etc, even "worm farm septic tank" but mostly they are referred to by brand names.

I'd like to see the terminology standardised so everyone knows what they are talking about.

They are a biological filtration system, but the term biological filtration (biofilter) usually refers to purifying liquids such as wastewater. Technically that would happen next, after the digester. The digester itself separates and digests the solids but doesn't process the liquid effluent to purify it.

The difference between "vermicomposting" and "vermicomposting digester" is that "vermicomposting digester" is one method of vermicomposting that involves water as the transport media for the influent, and thus is "wet composting", which vermicomposting doesn't have to be at all. Of course "wet composting" doesn't need to involve worms... I have memories of a personal nightmare involving a Sunmar rotating drum with low-flush toilet and the smelly anaerobic mud that created.

cheers
Dean

Dean Satchell, M For. Sc.
Go-Eco Sustainable Solutions
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