This waste-to-resource project not only produces a less smoky and long-burning fire, but could also help improve health and sanitation outcomes.
Wherever people are, poop happens. It's quite possibly one of the most abundant and widely available human resources, useful as a biodigester feedstock for producing methane, as well as a soil-builder in the form of compost, and yet when this human waste goes untreated or is disposed of improperly, it can lead to massive local health issues, such as cholera outbreaks or other sanitation-related diseases.
One common aspect of rural life in the developing world is the lack of adequate waste infrastructure, whether it's a municipal sewer system or a properly-built pit latrine, and for those without access to any form of human waste disposal, the 'night soil' often gets dumped anywhere that's handy, which can contaminate local water or food sources. Pit latrines can also leak into groundwater, leading to drinking water contamination. And even the treatment of sewage from pit latrines, septic systems, and existing sewer systems has a cost and a potential environmental toll to it, adding to the residents' impact on local groundwater and surface waters.
However, one project that addresses both the human waste issue and the cooking fuel issue in Kenya, where some 80% rely on charcoal or wood, leading to deforestation from fuel-cutting activities and "enormous health risks" from cookstove air pollution, has proven to be a success so far, as it turns sewage sludge into cleaner-burning charcoal briquettes. We already know that both urine and feces are useful human 'products' for things like fertilizer, but the sewage-based charcoal balls represent a new kind of table-to-toilet-to-kitchen cycle that could lessen the health impacts of cooking while also being economically desirable.
In Nakura, Kenya, the Nakuru Water and Sanitation Services Company’s processing plant takes in truckloads of sewage from septic systems and pit latrines, which is slowly sun-dried, then treated at a high temperature (300 Celsius / (572 Fahrenheit) in a kiln in a carbonizing process where sawdust is added to it. The resulting product is then pulverized in a hammer mill, after which it is mixed with a little molasses to act as a binder, rolled into balls, and dried. A kilo of the briquettes cost "about 50 US cents," and according to reports, not only is the charcoal free of odor, and can burn cleaner than charcoal, but it also burns longer, which effectively saves every user money each week.
"Carbonisation basically is a process whereby we increase the carbon content of your materials. In this case we are using the drum kiln whereby the sludge is fed, the drum has some holes at the bottom, these holes allows the oxygen to come in, in a controlled manner, that oxygen will only support combustion but to a certain level so that it doesn’t burn completely into ash. In this way, you are able to eliminate all the volatile matters, all the harmful gasses, and it is at this point that you ensure that your sludge doesn’t smell it is safe for handling when you are carrying out the other processes which is milling and briquette production." - John Irungu, site manager at Nakuru Water and Sanitation Services Company
As you might expect, overcoming the taboo of using poop for anything related to food was challenging at first, but current users report favorably for both the product's effectiveness and its cost.
Nakuru Water and Sanitation Services Company, or Nawasso, can currently produce about two tons of the human waste briquettes per month, with the goal of ramping up to 10 tons per month by the end of the year. Once the company has procured additional de-watering and carbonization equipment to scale up and optimize its production methods, it is targeting a goal of producing "at least 10 tons per day." As part of the project, support is being provided for the construction of more than 6,000 toilets that can collect the waste, while also serving as a necessary and convenient sanitation solution in poorer parts of the city, and plans are being made to initiate similar projects in other parts of Kenya.
I, for one, think this poop briquette model could work here in the US, although it might take some time to break into the BBQ bro market. "Do you want me to pick up mesquite or hickory charcoal for tonight?" "Well, actually, I've been hearing great things about this new local brand... " Or maybe a hipster restaurant that uses artisanal briquettes made from the guests' own waste?