The Cover Story

A few weeks ago, I wrote about SOIL’s progress in developing a working model for a sustainable sanitation business in Haiti. As I mentioned, we’ve had some really exciting successes, but also some serious challenges – like our cover material.

If you’ve ever used a composting toilet, you know the importance of good cover material.  For the uninitiated, cover material is basically the “flush” that keeps the toilet from getting gross; covering the waste with some kind of dry material prevents it from smelling and deters flies from visiting.

Here at SOIL, we call it bonzode (prounced bon-zo-deh, literally “good smell” in Creole), and it’s a crucial piece of the SOIL business model. With thousands of customers each using a handful every time they poo in a SOIL toilet, we need a whole lot of it – and our demand will only increase as SOIL expands its services.

A SOIL employee sieves the bagasse to separate larger pieces (used at the waste treatment site) from the finer pieces (used in bonzode).

A SOIL employee sieves the bagasse to separate larger pieces (used at the waste treatment site) from the finer pieces (used in bonzode). Photo Credit: Jon Brack

You can use a variety of things for cover material, but SOIL has been using a mix of ground peanut shells and bagasse (the woody bits of sugarcane left over after processing cane for rum production) since these waste products are in plentiful supply in Haiti.  The materials are sifted to the consistency of sawdust, which not only covers well in the toilet but also composts easily during our waste treatment process.

On the one hand, this is a great way to re-purpose organic waste that is otherwise carted away and burned. On the other, it’s made SOIL reliant on the goodwill of huge businesses that are ever-conscious of the bottom line. Unfortunately, realizing that their waste has value to SOIL is changing the way these businesses are offering their bagasse to us.

To avoid skyrocketing costs and/or disruption in our supply, our team is experimenting with mixing our cover material with – you guessed it – soil! We’re testing out a 50% bonzode, 50% dirt blend in one of our office bathrooms, and so far it’s great! It’s working well in the toilet, and while we anticipate needing to add more carbon material for the composting process, nearly any kind of vegetable waste could be used at our waste treatment site.

A steady cover material supply is one of the biggest challenges of implementing ecological sanitation projects, so if SOIL can successfully use a substance as freely available as dirt, we’ll be well on our way to establishing a working model. And the bonus is that we can use poor quality soil and convert it into rich fertile compost, transforming our own namesake to realize our mission!

11 Replies to "The Cover Story"

  • Patricia Dillon
    July 12, 2014 (3:31 pm)

    Thanks for the idea of dirt as part of the cover. We will try it with our composting toilet at Lekol Jezi-Mari in Fon Ibo (Gros-Morne). Can some dirt be used with the solid waste that is decomposing? Also we have regular latrines for the younger children. Do you know anything we can use to control the smell which will not harm the environment and hopefully is not too expensive? Thank you.

    • Erica Lloyd
      July 22, 2014 (12:52 pm)

      Yes, you can use dirt, although for producing better compost you would want to add more carbon material. You can use many kinds of dry vegetation (we use a lot of sugar cane bagasse and ground peanut shells), ashes, sawdust, etc – ask around to see what’s readily available in your area and start experimenting!

  • Larry D. Hull, MD
    July 12, 2014 (5:15 pm)

    We are doing Urine Diversion Dehydration Toilets (UDDT) in Papua New Guinea in a rural region and would like to buy some of your toilet seats that provides separation of feces and urine and send them to PNG or take with me on my next visit.
    Do you sell those or are they available in USA? What is the cost? Are they stackable for ease of shipping? Do you have a brochure or instruction manual on use of and placing them on our own hand made toilets?
    We have a team going to PNG in 3 weeks and they could take some with them is they are available.
    If you have a USA representative or if you have a Skype we could talk directly.
    My USA phone is 360 269 4335 and my Skype name is larrydhull Thank you

  • John Sloan
    July 12, 2014 (6:05 pm)

    Have you considered using some type of shredded grass or landscape waste? If you could obtain something like a chipper/shredder, the type used to grind up yard waste in the U.S., you could convert almost any type of landscape vegetation into a carbon source. I realize this means purchasing and maintaining a piece of equipment that could and probably will break down, but if your operation continues to grow, you might need to have this capability. Alternatively, a few guys with machetes could chop up a stalky-type of grass pretty quickly.

    Also, regarding use of the finished compost, are you using any to revegetate hillsides? Perhaps some of the NGOs working with reforestation would consider buying some of the compost.

    I have been following SOIL’s progress over the past few years and I have been very impressed. You are all doing some really great work.

    • Erica Lloyd
      July 22, 2014 (12:29 pm)

      Hi John,
      Thanks for your comments! We have thought about a chipper and are researching options (and ways to fund the purchase). We have distributed seedlings and compost to various reforestation projects, but largely on a donation basis as many of them are small student groups. However, we are gearing up our marketing efforts and hope to attract some larger groups that could pay to purchase it.
      Thanks for your insight and your kind words! We appreciate the support!

  • Alan Marshall
    July 12, 2014 (7:19 pm)

    Bonjou Erica, everyone. This is a great project, congratulations on your Lateral Thinking.
    I visited you during December 2012.
    On the topic of cover material, I also have been thinking about this, and wonder if you have considered crushing dried leaves of various kinds. In Haiti there, I would be looking at banana leaf. You know how it accumulates at the base of each tree? It dries out there into a relatively brittle condition. Could it be crushed in some way?
    Here in southern Tasmania, Australia, I have a similar material that falls from our eucalyptus forest. The leaves dry out well and could be crushed in the same way if I can come up with a practical, low-tech method.
    It’s possible that I shall be re-visiting Haiti sometime within the next 6-12 months and would love to get involved, if that would be ok by you.

    • Erica Lloyd
      July 22, 2014 (12:09 pm)

      Hi Alan,
      Interesting idea! I’ll share it with our team. Please do let us know if you’ll be in Haiti – we’d love to have you come by for a visit.

  • Ron McCord
    July 26, 2014 (4:52 pm)

    Hello Erica,
    Have you guys looked into bokashi composting the hamanure? If you don’t know what bokashi is, it’s a method of adding an lacto inoculated medium onto food waste, which essentially ferments or pickles it. The inoculant is made with indigenous microorganisms that naturally occur everywhere. I have a startup business which recycles food waste from a local fish market and restaurant. I think the bran inoculant would work as a great “bonzode” for humanure because that is one of its intended purposes. The added benefit is that your compost making time would drastically decrease. My average composting time for a five gallon bucket of fish entrails, bodies and heads, veggie scraps and the ocassional chicken and beef scraps is 4 weeks. No matter the amount of waste (1 to 100 gallons or more) the timeline from the day of collection is 2 weeks in an airtight container, to ferment. Then two weeks in the compost heap to turn I to soil. Very little turning is needed and the process enhances the the thermophilic phase of composting. There is very little odor. I use spent brewery grains as my inoculant because they are free, but any dry high carbon material would work, even shredded paper or newsprint. If you want to discuss this further I can be reached a 619-798-6101 or [email protected]

    • Erica Lloyd
      August 7, 2014 (12:25 pm)

      Hi Ron, we do have some folks who experimented with bokashi a while back without much success, but it’s something we’ll keep in mind for the future. Thanks!

  • Bob Bond
    September 12, 2015 (2:35 pm)

    As a former science teacher I’m intrigued & fascinated by the Bonzode material, its use and creation and the ideas given above to continually improve and produce a low cost easily accessible product. What a great service SOIL provides the people of Haiti. There is no doubt that what you are creating will be shared with rest of the world eventually and improve the lives of many more people in need.

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