An Optimal Flush

Faithful readers of the SOIL blog will know that we spend a lot of time thinking about cover material at SOIL. Cover material is basically the “flush” that keeps the toilet from getting gross as covering the waste with some kind of dry material prevents it from smelling and deters flies from visiting.

Here at SOIL, we call it bonzodè (pronounced bon-zo-deh, literally “good smell” in Haitian 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.

Julie and I, as Konseye for the Composting, EkoLakay, and EkoMobil programs, have been working on a way to facilitate communication and logistics for our bonzodè inventory. As you can imagine, bonzodè is central to our sanitation services – you can’t use an EkoLakay or EkoMobil toilet without bonzodè! – and it’s currently the responsibility of the Composting team to source peanut shells and sugarcane bagasse, process and mix the carbon material, and fill up buckets and drums for distribution.

In order to assure we have a steady supply of bonzodè, we’re currently working on two key systems to optimize communication and operations for bonzodè production and use.

The first is a calendar tool that inputs operational data like number of households per collection zone and outputs the quantity of bonzodè that needs to be prepared every day, as well as how many trips need to be made to the sites where we source our inputs (peanut shells and sugarcane bagasse) in order to produce the required quantity of bonzodè. This calendar tool will allow us to streamline communication between programs as well as improve management of bonzodè production and preparation at our composting facility. Additionally, we’re hoping to use the calendar tool to project how much bonzodè the Composting team will need to produce on a weekly basis in the future based on our strategic objectives for EkoLakay and EkoMobil. Having a clear picture of our projected inputs will also enable us to start exploring longer-term bonzodè procurement strategies. Perhaps we could outsource bonzodè production, and if so, what is a fair and reasonable price to pay for this service? Can our current suppliers even provide us with the amount of bonzodè material we’ll need in the future?

Bonzodè Optimization

The first table allows the EkoLakay Coordinator to update the number of clients per zone, while the second is a recap of how many buckets are needed for collection each day. Depending on how early the buckets need to be made (1, 2 or 3 days before) the third table tells the Composting team when they have to prepare the bonzodè. The next step to improve the tool is to include EkoMobil and Humanitarian toilets, as well as the treatment process (we also use bagasse for Composting!)

These tables (shown here) calculate how much material is needed per week and how many trips to the provider will be necessary to cover production for the month.

The second optimization system we’re working on is designed to improve how we process bonzodè. Previously, three workers would spend one day mixing sugarcane bagasse with ground peanut shells in order to fill 350 buckets of bonzodè. Recently, we experimented with a new system where four daily workers spend one day mixing a large quantity of sugarcane bagasse and ground peanut shells (like a whole Poopmobile’s worth of sugarcane bagasse!), which then later could be used to fill buckets by teams of 2-3 workers. We found this change resulted in a net reduction in costs from around 3 HTG per bucket of bonzodè filled to 1.5 HTG per bucket of bonzodè. Talk about optimization!

As a major input to our growing sanitation services in Haiti, we expect the production and use logistics of bonzodè to continue to occupy a lot of our thoughts. That said, we’re excited that these optimization tools are already helping us better achieve our ultimate goal of reducing the cost of providing dignified, affordable sanitation services in Haiti.

3 Replies to "An Optimal Flush"

  • Rex Cowan
    April 1, 2017 (2:36 pm)

    Cool (!), and I am learning a little bit of Creole along the way ! At minimal expense, you might consider posting these signs (charts) in three languages: Creole, French and English. It would provide a cheap/non-invasive and convenient way for persons working in the program to pick up a bit of each others language, should they choose to do so (or not). Somewhere down the line this cross-culturalization will reap big, and unexpected, benefits both for the persons choosing to take advantage of it, as well as SOIL.

    February 9, 2018 (8:07 pm)

    I am with Engineers Without Borders and we have a Eco-Banos project in Bolivia.
    We would like to know what naturally available additive we could use to reduce the odor and
    increase the composting rate.
    thaNK YOU

    • SOIL Haiti
      February 12, 2018 (7:55 pm)

      Hi Stephen, thanks for a great question! SOIL’s bonzodè carbon cover material effectively manages smells (learn more here!). Our current blend is a mix of sugar cane husks and peanut shells, though we’re in the early stages of testing adding compost to the blend as well and the results are promising. Our friends at x-runner might be worth reaching out to for other ideas, too!

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