We have to rethink human waste and we are running out of time to get over the uncomfortable nature of the discussion and come up with real solutions. It’s an understatement to say humans produce a lot of waste. Adult humans produce 1-2 liters of urine a day; if you live to be 70 that’s around 10,000 gallons. Each of us also produces 13 gallons of feces annually - lovely. This overflow of excreta causes big problems. In countries like Zimbabwe lack of basic sanitary facilities leads to massive cholera epidemics. In developed nations like the United States, the aging infrastructure and wasteful sewage treatment system that uses clean water to remove waste is unsustainable.  A few brave individuals and organizations are moving through the muck and trying to find positive uses for one of our most abundant…products. Most of the promising waste solutions lie in the separation of components so here’s a look at each element individually.

Uses for Human Urine

Human waste has been used for thousands of years as a fertilizer with varying degrees of success. Problems generally occur when the “products” of human digestion are not separated resulting in a fertilizer generally referred to as “human sludge”. Urine, an almost sterile product, is easily converted to fertilizer. Unfortunately, feces is not unless it is allowed to sit for a very long time to kill any potential pathogens.

Urine in the ecosystem causes eutrophication or algae blooms, which suffocates fish and kills aquatic ecosystems. Urine is so effective at helping algae grow because it is rich in nitrogen, potassium, and phosphorus; these are the three main ingredients found in commercially produced fertilizers. Instead of flushing away this abundant resource many scientists, citizens, and organizations are encouraging the use of urine as a plant fertilizer.  A study in Finland showed very positive result when urine was used to fertilize a crop of cabbage. If poor countries and communities were instructed on the proper use of human urine as fertilizer it could prove a valuable resource and a substitution for increasingly expensive commercial fertilizers.

Urine diversion toilets would make it easier to separate liquid from solid and thus produce a viable, energy efficient fertilizer. The battle to make urine diversion toilets acceptable is going to be a tough one though, as the use of the toilet requires a new skill set (like men sitting down to pee).

Those in the pro pee fertilizer group are trying to break the stigma of using urine. At the Eyebeam Art Show in New York two artists Rebecca Bray and Britta Riley’s DrinkPeeDrinkPeeDrinkPee exhibit made quite a splash when they displayed a urine recycling circuit and also introduced DIY Urine to Fertilizer Kits for $15 a piece. The kit actually worked, producing 2 tablespoons of the common fertilizer struvite crystals.

Uses for Human Feces

The more difficult resource to utilize is human feces because of its ability to carry multiple pathogens. Two potential uses for this resource, energy and fertilizer, are being explored with the help of both new and old technologies.  

Companies like Enertech have developed a process to remove the water from waste producing a biosolid, which they call “E-fuel,” that is a substitute for coal. You can also harvest the natural gas from fecal matter. In 2008 San Antonio, TX unveiled plans to become the first city to make energy from methane derived from human waste.   Massachusetts-based Ameresco Inc. will spearhead the project to convert the cities biosolids into natural gas.

Using solid human waste as fertilizer requires delicacy and patients as it must be allowed to sit for a time before application. In some developing countries the “Arborloo” system has proved very successful. The “Arborloo” is a simple pit latrine where soil, wood ash, and leaves are added as well as human excreta. The latrine is eventually covered and planted with a fruit tree. It’s a simple and ingenious solution that is solving sanitary and hunger problems in countries like Malawi, Kenya and South Africa.

Currently, the majority of the world flushes away a valuable resource and lets it pollute both land and water. Western sanitation practices are mostly wasteful and crumbling infrastructures will leave many populations vulnerable to disease. The world must utilize human waste instead of trying to hide it because a growing population promises to make lots more of it in the future.