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Topics in Category: Vermifilters (or vermi-digesters) - SuSanA Forum Fri, 26 May 2017 03:35:38 +0200 Joomla! - Open Source Content Management /media/kunena/images/icons/rss.png Topics in Category: Vermifilters (or vermi-digesters) - SuSanA Forum en-gb What can we reliably say about pathogen removal with vermifilters? - by: muench
In response to your post just before this one, I would like to contribute this:

The grant applications are not in the public domain but the level of funding is. You can find it in this public database on the Gates Foundation website:

I think it's nice and useful that they are making this information public.
The grant to Bear Valley Venture you won't find in there as it is a sub-grant from this grant to USAID:

(8.5 Million USD "to support a collaboration with the U.S. Agency for International Development to support the identification, testing, and sustained uptake of evidence-based approaches to delivering water, sanitation and hygiene services to the poor ")

I tried last year to assemble outcomes from that grant to USAID and what I was able to gather is available here (I would have liked to gather more but some of the grantees had no time to respond):

Secondly you said:

Despite lots of grant money spent on "development" of the technology, we appear to still know nothing about helminth content of the humus fraction that is removed from the vermifilter, or how this changes over time.

From what I gather, indeed, the grantees did NOT focus on the solids/fecal/humus fraction of these "tiger worm toilets" but rather on other aspects. I can understand why that decision was taken. Whilst it would have been interesting from a research point of view, it may not be critical from an upscaling and commercialisation point of view. Why do I say that? Because firstly, the solids accumulation is so slow that it takes years before anyone has to empty that out. When it's being emptied out, it can be done safely so that nobody comes in touch with the stuff and could get infected with the helminths. It might indeed be best to have a service provider rather than let the household people do it themselves? Either way, if we can empty out pit latrines safely (with the right service provider, personal protectic equipment etc.), then we can also empty out these vermifilter digesters.

It's all about risk management and a multiple barrier approach, i.e. what do you do with the stuff aftewards? I would say burying or at least covering under some soil to prevent direct content.

The multiple barrier approach is key here, it is the one propagated in the WHO Guidelines from 2006. You can also read up about it on Wikipedia here:

Now I want to reply to your points in your earlier post from 17 May:

You said:

Firstly, lets not call the solid phase sludge please. In a vermifilter there is fecal material and there is humus, but no sludge.

Point taken although doesn't the material look like sludge to a lay person? I agree we shouldn't call it fecal sludge but it is a type of sludge, isn't it? Could you post a photo to remind us what it looks like?
Or perhaps the first photo here is a good example?:

Then you said:

Secondly, yes for helminth eggs, but no for pathogens.

Not sure if this wording was a slip of tongue or on purpose, but helminth eggs are part of the pathogens!

You said:

Well, again, we do know that over time helminth eggs break down. Seems that nobody has studied the rate of helminth reduction for resting humus in a vermifilter.

Those helminth eggs are actually extremely hardy. E.g. they can survive in soils for years, even at low moisture level. They just go into some kind of dormant state...
I was involved in summarising information on Wikipedia here (although reading it again, it still needs to be made easier to understand):
Would love it if a helminth egg expert could help with editing that article!

You said:

The research paper (2016) that preceded the hurried commercialisation phase in India stated "vermicompost is a valuable product" and "The next challenge is to make a scalable and economically viable prototype for this market." Cart before the horse? What is the vermicompost used for? I trust not for food crops...

I semi agree with you. I think the users should not be given a false sense of security: the vermicompost should not be marketed as "pathogen free" unless we know that it is. Until then, the toilet owners should be advised to treat that product with considerable care. As I said above, it is probably best if certified service providers empty the vermidigesters. But as emptying is only needed so rarely, I don't see this as a big drawback. Although maybe we'll run into the same problem as we did with filled pit latrines: users abandon them rather than getting them emptied (?).

So I guess it's a fine line: you want toilet owners to be aware that there are likely still helminth eggs in that humus and you want them to be careful but you don't want them to be so scared that they wouldn't dare to empty the digester themselves if needed (like if no service provider is available or too expensive or not convenient).

I would like to hear from those who are operating or selling these kinds of toilets, what are their experiences with the humus/solids/sludge? Or is it taking so long to accumulate that there are no emptying experiences yet?

Lastly about that wording for the Wikipedia article, you said:

It is possible to eliminate fecal coliforms to 2.0 Log10 of Most Probable Number (MPN) per 100 mL−1 - If the reduction in fecal coliforms is not to be expressed this way in the wikipedia article, then how should it be expressed?

I would say this kind of sentence says pretty much the same thing but is more easily understood by a lay person and therefore better:
"In the effluent there was a 99% reduction in fecal coliforms."

Don't you agree? (I am in two minds if it's better to discuss this Wikipedia issue here in this thread or rather in this thread: I suppose it's fine to keep it together with the pathogen removal topic, i.e. this thread)

I always enjoy discussing vermifilters with you, Dean, and I hope that others who are reading our posts also get inspired to write in this thread, too - i.e. to the silent members, I would like to say: "please don't just read but also write!" :)

Vermifilters (or vermi-digesters) Tue, 23 May 2017 14:30:04 +0200
Vermi-Trickling Filters (or vermifilters) for Sewage Treatment (looking for help to design) - by: BPopov
Look what I have done with the crates!

Vermifilters (or vermi-digesters) Sat, 13 May 2017 09:03:26 +0200
Composting system by Human Endeavors (USA and in future Costa Rica) - formerly AlasCan system - by: Ecowaters
Three or four design teams were selected. I haven't seen their solutions yet.]]>
Vermifilters (or vermi-digesters) Wed, 04 Jan 2017 03:46:09 +0100
Composting system by Human Endeavors (USA and in future Costa Rica) - by: clint
I totally agree with you concerning forgetting about the fertilizer aspects. If 85 - 99% of all organic materials, including human excrement, urine and food scraps is H2O, the remaining %, if composted correctly, is so insignificant that it could be buried or burned for economically total stupidity safety.

My procedure for the recycle of the compost tea and the composted finished soil is the following.

The excess compost tea is float switch controlled and pumped into a polyethylene holding tank of any size to match the occupancy. It is stored for at least 30 days before I would recommend that it only be utilized for non-edible animal crops or landscapes removed from the site and applied by certified maintenance/service professionals.

The finished compost from our tanks is primarily wet redworm castings and broken down pine bedding, our carbon source. It is always wet because of the flush water and urine from the toilets. Therefore, ANY compost that is removed from any correctly operating composting mass will contain fecal coliform because of the transport of the liquid through the fresh material on top to the bottom, which is constant.

My recommendation is that any compost, tea and/or solid, which is removed from a functioning human composting system be re-introduced into another similar mobile composting tank to be further composted for at least 30 days to eliminate the continuous injection of fecal in the first and primary tank. This mobile composting tank would be just the same as the septic pumper pumping the compost into another composting tank on his truck to be composted further until safe.

Nor am I an engineer! My knowledge has been strictly hands-on trial and error. I approached the wastewater industry with no preconceptions and after reading about the Clivus Multrum composting toilet invention from Sweden I jumped into it up to my elbows.

This is the first Forum I found regarding sanitation and water and I agree that maybe I need to ask you for additional suggestions of Forums that my and your comments may be more appreciated.

Thanks for your extremely valid comments.

Vermifilters (or vermi-digesters) Wed, 27 Apr 2016 00:03:18 +0200
Finding the right term: vermicomposting digester? Vermicomposting with filtering? Other options? - by: goeco
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.

Vermifilters (or vermi-digesters) Fri, 05 Feb 2016 22:59:01 +0100
Discussion about pros and cons of vermicomposting digesters, including groundwater pollution aspects - by: goeco
Vermifilters (or vermi-digesters) Wed, 20 Jan 2016 23:49:04 +0100