On-site sanitation based on bio-additives and pit design (LSTH, UK and Tanzania, South Africa and Vietnam)

  • KimAndersson
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Re: AW: WG: Sanitation Updates

Dear all,
If you have been following this discussion and are interested in hearing more about the project on new concepts for on-site sanitation based on bio-additives and pit design led by London School of Hygiene and Tropical Medicine please join the upcoming live webinar.

The webinar, hosted by SEI, will take place on Tuesday 26 November 2013, 16:30 - 17:15 (CET – Sweden time), and will give you an opportunity to interact with Jeroen (and two other grantees). For more details how to participate (with or without microphone rights) please see here:
forum.susana.org/forum/categories/139-ge...nment-institute#6427

If you miss the live event, the recording will be provided a few days after the webinar.

Best regards,
Kim

Kim Andersson
Stockholm Environment Institute
Postbox 24218,104 51 Stockholm, Sweden
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  • muench
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Re: Write-up of presentation from webinar 4

Dear all,

I am writing this post to provide people who don't have access to Youtube videos with a quick overview of what Jeroen Ensink presented during the fourth webinar that SEI organised on 26 November (see Arno's post about it here: forum.susana.org/forum/categories/139-ge...mit=12&start=12#6564 ).

Jeroen’s presentation starts exactly here in the Youtube video:

(the total duration of presentation and Q&A session was 19 minutes)

New concepts for on-site sanitation based on bio-additives and pit design - the fundamentals of pit latrine research
by Jeroen Ensink who works at the London School of Hygiene and Tropical Medicine in London, UK

The powerpoint slides that he used:

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Notes that I took from his presentation:
  1. Their grant was a 5-year grant (ending next year) which included diverse work packages such as consumer demand studies, toilet designs, taking products to market, black solider fly work in South Africa, Tiger Toilet,.... In this presentation he focused on just one part of the research: the fundamentals of pit latrine research.
  2. The starting point for the research is: why do some pit latrines fill up fast (in 2-3 years) while others don’t fill up fast and rather last forever – if if all things are equal (i.e. same soil characteristics, same number of users, same diet, etc.)?
  3. They took the latrine fill-up rate (FUR) as the main indicator whether a pit latrine is performing “well” or not. This means a latrine that fills up fast is classified as not performing well. They found a variation in fill-up rate from around 0.25 L of faecal sludge per person per day to over 2 L/person/day.
  4. They selected 50 latrines in Vietnam and 50 in Tanzania (all in well draining soils) and followed them for 2 years (monitored use and management of the pit latrine). During this time they measured every 2 months with a laser reader the level in the pit.
  5. After 2 years, a core sample of the pit was taken and shipped to the UK. With this core sample many different parameters were analysed, for example the Sanger Institute in Cambridge did the microbial analyses (with 454 sequencing).



  • One parameter is the biological activity in the pit and this was measured by doing anaerobic digestion experiments in the lab, i.e. measuring how much biogas is produced.
  • Looking at the results, the pits can be roughly classified into 3 groups in terms of biodegradation (where biogas production was taken as an indicator for biological activity): those that perform well (= the sludge produces biogas automatically and fast) – these are the top 4 lines in the graph; those that perform not so well (=only after inoculum had been added biogas was produced; the inoculum was Dutch wastewater because the experiments were performed in the Netherlands at Wageningen University) – these are the middle lines in the graph. And those that never produce biogas (or only very little) even after an inoculum was added – there are the two lower lines in the graph.


  • They found that 60% of the organic matter in the pits (measured as COD) does not degrade at all (=inert organic matter). This material is probably lignin and complex polysaccharides (determined by NMR analysis). It is at a depth of 1.5 to 2 m in the pit.
  • Their idea is that if they understand this material better which is not degraded, they could find enzymes that would help to degrade it (as it said on his slide: "Through characterising this material we will be able to identify whether specific organisms, or enzymes exist which could break it down and be added to the latrine)".
  • They found different microbiota in the faecal sludges (pits that perform well, i.e. fill up slowly, have different microbiota than latrines that don’t perform well, i.e. fill up fast). Therefore, they think they can come up with bioadditives to “seed” the pits. Or it could also be possible to seed such low-performing pits with faecal sludge of well-performing pits? In any case, it seems that certain microbiota are missing in the poorly-performing pit latrines.
  • Right now they are still analyzing their data on Archaea – these are the methanogenic microorganisms.
  • [/ol]
    Questions from the audience:

    (1)
    Question by me: "I thought the most important parameter about a pit filling up fast or not are the soil characteristics and hydrogeological conditions. Is this not the case?"

    Answer by Jeroen:
    "We chose only latrines in free draining soils; we found that even if they are all in soils with the same characteristics, there are still signification differences in fill-up rates.”

    (2)
    Question by me: "There are many suppliers of pit additives. What questions would you ask them to find out if their product really works or not?"

    Answer by Jeroen:
    "We have tested all commercially available pit additives that we could get hold of together with the University of Kwa-Zulu Natal in South Africa (see also here on the forum: forum.susana.org/forum/categories/53-fae...dge-includes-em#1005 ). None of them worked! My question back to the supplier would be: what is in it? Most likely they won’t tell you though! (trade secret). Probably a mixture of different bacterial strains. The problem is that you first have to build up a large amount of bacteria before the biodegradation process can work; this will initially increase the biomass and make the pit fill up even faster initially. - We have worked with Novozyme in the US (a large enzyme company: www.novozymes.com/en/Pages/default.aspx ). In the lab, we found with some strains a 15% (or 50%?) more rapid decomposition rate. In any case we have found that there are certain microbiota in well-performing pits.”

    (3)
    Questions by Daniel Yeh and Dorothee Spuhler: "Do you have data on diets and on user behaviour?"

    Answer by Jeroen:
    "Yes, we have a large database which we are analyzing statistically with the help of some statisticians at the University of Glasgow (we have 50,000 different variables). Our data base is huge. We can look at every parameter and can control for any variable. We have data on use patterns, diet and so forth. Our problem is that the diet in rural Tanzania is so uniform (rice and beans all the time, with some maize), so we cannot look at different factors there. The data from Vietnam might give us more insight, as the diet is more varied there.”

    (4)
    Question by Marc Deshusses: "Have you looked at parameters such as pH, nitrogen content, ammonium and their correlation with biogas production?"

    Answer by Jeroen:
    "Yes and we have found that the key parameter for good performance is the moisture content, which needs to be in the right range (not too wet and not too dry). Also phosphates help in good performing pit latrines; pH and temperature also play a role.”

    (Alison Parker mentioned in the chat field: “We are about to publish a review which correlates diet and demographics to faeces characteristics.”)

    (5)
    Question by Laura Talsma: "Do you have data on calorific value of the pit content? Can we access all your data on faecal sludge characteristics, will you share it?"

    Answer by Jeroen:
    "No, we did not measure the calorific value. We will publish a paper in about 2 months with many of the results that I mentioned. “

    Alison Parker mentioned in the chat field: “We have data on calorific values from pits in Zambia (EPSRC funded)- EPSRC is the Engineering and Physical Sciences Research Council. The project is this one: transformingwasteproject.com/ .”

    Marc Deshusses was also interested in the calorific data and said they found a big spread in the values for faecal sludge in South Africa. They hope to find it to be above 12 MJ/kg. Laura Talsma said they are doing calorific tests of the waste collected by Sanergy in Kenya.

    In his closing statement, the moderator Nelson Ekane said: How do plastics and pads from menstrual hygiene management affect the biodegradability in the pits? Something we could discuss on the forum. (I would guess that plastic waste is probably a hindrance in biodegradation of the organic matter because it gets in the way, prevents mixing and moisture transfer and alike)

    If anyone has further questions or comments, then please put them here by replying to this post.
    Thank you again to Jeroen for giving this presentation and for answering our questions!

    Regards,
    Elisabeth

    P.S. Their project website is this: www.sanitationventures.com (currently not very up to date but Jeroen said he is in the process of updating it).

    Community manager and chief moderator of this forum via SEI project ( www.susana.org/en/resources/projects/details/127 )

    Dr. Elisabeth von Muench
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    • muench
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    Re: Write-up of presentation from webinar 4

    After listening to the recording a second time so that I could do the write-up above, I have a few more small questions for you, Jeroen:
    1. You said “we are looking at Archaea data” – what do you mean exactly? I know that Archaea = methanogens but would did you mean with this statement?
    2. You said that papers will come out in the next couple of months – where will they be published? Could you pay extra to have them available online?
    3. You said all your latrines in Tanzania (and also in Vietnam?) were in well-draining soils – how did you measure whether the soil was well draining or not? Which of the soil characteristics were measured? How about rainfall data and level of groundwater, was that all taken into consideration?
    4. With those Novozyme enzymes from the US: when you did the lab work, did you see a 15% or a 50% increase in decomposition rates? What kind of enzymes are these? Do you happen to know if they are mentioned on their website, i.e. here: www.novozymes.com/en/Pages/default.aspx
    5. You mentioned that phosphate helps in the good performing pit latrines – what do you mean by this and what is your explanation for this observation?
    6. Is your assumption that the degradation processes in pit latrines is primarily of an anaerobic nature?
    7. When you took your core samples from the pit latrines how did you cope with the solid waste issue (normally lots of solid waste in the pits, like rags, plastic bags and so forth).
    I never realised the content of pit latrines could be so interesting and have so many aspects for fundemental research. This is really a very comprehensive study that you did. Thanks for sharing.

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    Re: AW: a few more questions

    Dear Elisabeth,

    Here are my answers to your questions:

    You mentioned the Sanger Institute like one should know what this is? Where and what is it? Oh, I guess it must be this one: www.sanger.ac.uk/

    The Sanger institute as you point out in the link is a world class institute doing work on genomics a.o. and is doing the 454 sequencing for us on the latrine samples, to identify what kind of bacteria and archea families are there.

    You said “we are looking at Archea data” – what do you mean exactly? I know that Archea = methanogens but would did you mean with this statement?

    We have looked in our samples for the type of bacteria present, but also which Archea are there, several Archae are methanogenic and as a result their presence or absence might be associated with better performance.

    You said you are in the process of updating your website ( www.sanitationventures.com ) – I had a look and I can’t see any new information on there yet?

    We will start in the new year, we have moved the website to our server now and hope to update it from January onwards.

    You said that papers will come out in the next couple of months – where will they be published? I think you mentioned in the past that you will pay extra to have them available online, is this still the case?

    Well it will depend if the journals we have in mind accept our papers, but yes we intend to publish open access.

    You mentioned that the inoculum added was Dutch wastewater – is this really true or was it rather Dutch activated sludge from a WWTP?

    The work was done in Wageningen and to my knowledge it was wastewater, but could as well have been sludge.

    You said all your latrines in Tanzania (and also in Vietnam?) were in well-draining soils – how did you measure whether the soil was well draining or not? Which of the soil characteristics were measured? How about rainfall data and level of groundwater, was that all taken into consideration?

    We selected latrines where the groundwater table was at least 5 meters away, we installed piezometers and did soil type and soil moisture analysis. Climate data was also collected.

    With those Novozyme enzymes from the US: when you did the lab work, did you see a 15% or a 50% increase in decomposition rates? What kind of enzymes are these? Do you happen to know if they are mentioned on their website, i.e. here: www.novozymes.com/en/Pages/default.aspx

    I cannot tell you what kind of enzymes were used, and the increase was 12-15%.

    You mentioned that phosphate helps in the good performing pit latrines – what do you mean by this and what is your explanation for this observation?

    Better performing latrines had higher contents of phophates but at the moment I do not yet have an explanation for this.

    Is your assumption that the degradation processes in pit latrines is primarily of an anaerobic nature?

    I think in a pit latrine we have an initial aerobic process breaking material down but think that the dominant processes are anaerobic.

    When you took your core samples from the pit latrines how did you cope with the solid waste issue (normally lots of solid waste in the pits, like rags, plastic bags and so forth)?

    We did not encounter huge amounts of other waste. A few latrines (<10%) had rags in them, this is rural Tanzania, not urban Dar es Salaam or South Africa.


    Hope these answers make things a bit clearer.

    Regards,
    Jeroen

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    • JKMakowka
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    Re: On-site sanitation based on bio-additives and pit design (LSTH, UK and Tanzania, South Africa and Vietnam)

    Is there any "rule of thumb" in regards to optimal moisture content? Might be interesting to add some water in certain cases or change the surface to volume content of some pits to allow for higher evaporation.

    Microbiologist & emergency WASH specialist
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    Re: On-site sanitation based on bio-additives and pit design (LSTH, UK and Tanzania, South Africa and Vietnam)

    I agree moisture seems to be key, too much and too little and all degradation processes stop. What exactly the upper and lower moisture contents are, i can't say yet...the analysis is ongoing

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    • AParker
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    Re: On-site sanitation based on bio-additives and pit design (LSTH, UK and Tanzania, South Africa and Vietnam)

    Hi,

    Dooes anyone know if there is a final report for this project (bio-additives generally rather than tiger worms specifically)? I can't immediately find it anywhere but I may not be looking in the right places!

    Alison

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    • muench
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    Re: On-site sanitation based on bio-additives and pit design (LSTH, UK and Tanzania, South Africa and Vietnam)

    Good question, let's see what Jeroen answers. Meanwhile, you might like to look at these two threads:

    forum.susana.org/forum/categories/53-fae...it=12&start=24#11976

    --> I wrote here about research results that Katja Grolle from Wageningen Uni presented in Hanoi which were done as part of this project. I think she was also busy submitting a journal paper about this work, perhaps it is out by now?

    And this thread where I talked about updating the Wikipedia article on pit additives with results from Katja's research (plus older research by WRC in South Africa):
    forum.susana.org/forum/categories/53-fae...ve-microorganisms-em

    Hope this helps a little bit.

    Regards,
    Elisabeth

    Community manager and chief moderator of this forum via SEI project ( www.susana.org/en/resources/projects/details/127 )

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    • AParker
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    Re: On-site sanitation based on bio-additives and pit design (LSTH, UK and Tanzania, South Africa and Vietnam)

    Thanks Elisabeth. I have done some review on this topic before but wanted the most up to date information. I have found Katja Grolle's presentation now and the SusanA factsheet so will work with them for now!

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    Re: [SuSanA forum] On-site sanitation based on bio-additives and pit design (LSTH, UK and Tanzania, South Africa and Vietnam) (Processing technologies for excreta or faecal sludge)

    Dear Alison,

    Wageningen University is working on a final document, hopefully we will have it soon

    best regards jeroen

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