Urine fertilizer could save energy and water

A Brattleboro company has located itself at what one of its founders calls “the intersection of sanitation and agriculture” — where researchers are learning to manure with urine.

Using methods still under development, members of the Rich Earth Institute are growing crops with “a local and abundant source of fertilizer,” said co-founder Kim Nace, speaking at a conference on water quality held Wednesday at Vermont Technical College.

Humans produce enough of the aurulent liquid each day to fertilize a loaf of bread’s worth of wheat, Nace said. That amounts to between 100 and 150 gallons per year, she said.

Diverting the fluid to crops saves water and energy, and forestalls carbon dioxide pollution, according to Nace.

Ordinary toilets require one to three gallons of potable water to carry away less than a liter of urine, Nace said. The resources needed to produce and distribute potable water mean that “every time we save energy, we save water, and every time we save water, we save energy,” she said.

The water and energy savings are one reason to recycle number one, Nace said. But spreading it on crops also reduces the volume of carbon dioxide released into the atmosphere, she said.

One percent of worldwide atmospheric carbon pollution can be attributed to chemical fertilizers, Nace said. Replacing those fertilizers with one humans produce every day would eliminate a significant source of pollution, she added.

Although urine typically emerges pathogen-free into the world, the Rich Earth Institute pasteurizes the roughly 5,000 gallons used each year for their research efforts, she said. The organization uses solar energy to heat the effluent to 158 degrees for half an hour, voiding it of harmful microorganisms, she said.

Urine contains significant concentrations of both nitrogen and phosphorus, which are the two most common nutrients plants require, Nace said.

Wastewater treatment plants would ideally remove those nutrients, as in large enough concentrations they pollute surface water, she said. But the technology to do so, once they enter the septage stream, is costly enough to prevent such efforts outside very large cities.

For example, current wastewater treatment methods require costs of between $200 to $275 to remove a pound of nitrogen from sewage. By diverting urine before it enters wastewater systems, the cost of producing nitrogen from liquid human excreta falls to around $20 per pound, Nace said.

Each person eliminates around eight pounds of nitrogen per year, meaning that costs associated with pulling these nutrients from wastewater aren’t insignificant, she said. Diversion of urine to cropland would also save almost a trillion gallons of water each year, she said.

The Rich Earth Institute is currently soliciting urine donations with which to conduct further research. Additional information may be found at richearthinstitute.org.

Mike Polhamus

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  • Moshe Braner

    It doesn’t require high tech. Mix 10:1 with water and apply in your garden.

  • Considering urea is a component of urine, I don’t think this is a new concept but the targeting of municipal waste costs may be where the game is. Is this just liquid urine or is it pelleted or crystallized? What about pharmaceuticals?

    Would the harvest of a algae or some other green manure as the end product using urine to create the bloom give a better public fuzzy? I would just worry about run off but maybe I am missing something.

    • Davis Moquin

      This isn’t the 19th century. Pharmaceutical risks are a definite show stopper here imho. For the home gardener, particularly non-edibles, human urine has potential.

    • Jan van Eck

      Urea is commercially synthesized by the millions of tons and not sourced from natural sources by industry. Urea in crystal form and containing other components will result from the evaporation of water containing mammalian urine; converting the stuff to a commercial use is problematic as there are a number of steps involved and it does not appear cost-competitive to synthesis from non-biologic chemical sources. Urea is a critical component in diesel exhaust after-treatment systems and this is the big market for the stuff; if it can be manufactured from mammalian urine cheaply then you have a real winner. So far, nobody has figured it out. So urine is typically left dissolved in water and simply spread on farm fields, where large amounts leach off and pollute streams and, eventually, Lake Champlain (together with manure, of course).

      It is entirely possible to de-water cow manure and urine mixes, converting the output to a solid, and then processing the solid into either a form of burn fuel or to fertilized loam. I have developed the machinery design to do that on a commercial scale and plan to build it soon enough, once I find the capital. By dumping the manure stream into the converter it is removed from the streams, and you remove the component that causes those algae blooms in Lake Champlain (and Carmi, and Magog). Finding commercial buyers for the converted solids is the real trick, of course.

      • Jan van Eck

        Impressive that there is somebody out there that actually votes “thumbs-down” to descriptions of processes to remove urine and manure from the waters of the State. What this demonstrates is that Digger has institutionalized anonymous passive-aggressive behavior by disturbed, dysfunctional persons, so psychologically warped that they are not prepared to make an identifiable post.

        • Urea probably has saved lives by replacing ammonium nitrate out of the commercial fert industry.

        • It is also very lightweight which brings down cost for farmers and has also helped in terms of emissions for diesels that would not have been possible otherwise.

  • In the sentence fragment “…once they enter the septage stream,” above the author appears to be mixing terms and concepts. “Septage stream” refers to liquids and solids that comprise the wastewater stream in a water-based system that utilizes a decentralized septic system. It appears that what the author meant to say was “sewage stream” which refers to everything that ends up in a centralized sewer system; which, at least in this context, refers to the material that is routed from streets (usually) and homes & businesses via pipes to a wastewater treatment plant(s).

    Also, the title of the article, “Urine fertilizer could save energy and water,” implies that there is some question about whether source-separating dry toilet technologies are more efficient in their use of water and energy. In reality, and proven time and time again across the globe, there is absolutely no doubt about this. Removing water and energy intensive treatment techniques from the equation absolutely results in a system that saves water and energy. It’s unfortunate, then, that a fact-based title didn’t make the cut.

    These minor critiques aside, the point of the story (and of REI’s innovative work) is well taken. The practices we as a society currently follow in the management of human excreta (and, for that matter, washwater, stormwater and the direct and indirect disposal of industrial toxics) are outdated, ineffective and unnecessarily costly. The time to rethink our methods is now. Approaches like that which s being researched by REI are well known in other parts of the world. In fact, dry ecological toilet technology is being relied on by growing numbers of people the world over. We in “the West”, however, need to stop thinking that our energy and capital intensive “legacy” systems are the gold standard. Instead, and for the sake of resiliency and effectiveness, we must adopt proven, low-cost sanitation approaches; particularly those that eliminate the use of precious water. This isn’t rocket science. These technologies are available right now. All that is missing is the political and grassroots will to implement them.

    As for the question about pharmaceutical residues in urine: it’s true that a sizeable percentage of the pharmaceuticals (both legal and illicit) that we ingest end up in our urine. This is why the focus of REI’s research is on examining what happens to these chemicals and compounds as they make their way to the terrestrial environment. I would argue that no system that includes inputs like these is perfect. However, when compared to legacy systems – which act to concentrate most of society’s toxic detritus and which end up dumping toxic-laden effluent either directly into aquatic environments (which are less able to cope with the onslaught and which are many times also used a sources of drinking water) or into failure-prone leach fields AND which also increasingly dump toxic-laden sludge or septage onto open land and/or agricultural land – a sanitation system that relies instead on dry, ecological, source-separating toilets (and, ideally, also on onsite greywater systems) is a far more intelligent and effective approach. The fact is that we need to stop polluting water in the first place. REI’s approach goes a long way toward achieving this necessary goal AND it produces a free and renewable supply of plant nutrients. I look forward to this becoming commonplace. The flush toilet is dead.

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