I鈥檝e frequently tested my limits and my wife鈥檚 patience in my quest to be more sustainable.听 Pulling something out of the trash she鈥檚 just thrown away because it is recyclable always gets at least an eyeroll. Recent reporting prompted me to explore a new type of recycling. Reducing reliance on industrially produced fertilizers seemed like an idea worth exploring to me. Only half of my two-person household agreed. My investigation reaffirms that just because you can do something, it doesn鈥檛 mean you should.听
Reading about two University of Michigan professors 鈥溾€� urine diversion to fertilize plants struck me as impractical as I read it. Not one comfortable with rash decisions, I decided to do a little research before dooming the idea.听
Nitrogen, phosphate and potassium are necessary plant nutrients. The three numbers on the bags of fertilizer tell the percentages of nitrogen, phosphate as equivalent P2O5, and potassium as K2O. These three nutrients are also found in human urine. Urine contains most of the nutrients we excrete, and about . ,, and all 聽have natural cycles, cycles we鈥檝e disrupted. Modern agriculture depends on industrial inputs of all three key nutrients.听
Phosphorus is supplied to agriculture as phosphate from mining. Same for potassium or potash.听 Nitrogen is a chemical product, supplied as ammonia made from air. All three key nutrients are the products of energy intensive processing. By most accounts, ammonia production is the . The environmental concern doesn鈥檛 stop at production. Fertilizer lost to runoff damages ecosystems. Nitrogen oxides released to the air are . Modern waste water treatment lets nutrients escape. We end up literally pissing the key nutrients away. The result is .听
Fertilizers are globally traded commodities. Russia and Belarus are major suppliers, now subject to embargoes. Together the two countries account for about , about and about . They represent a larger , causing concerns about shortages in many countries.听 聽聽聽聽
Urine can, when recycled, address fertilizer production, supply chain issues, and damaging loss to the environment. Urea is the after water, making up to 2.5% by some accounts. Urea is an effective fertilizer, able to replace industrially produced ammonia. Other nutrients are at lower levels, with potassium being about 0.6% and phosphate at 0.1%. Life-cycle assessments of urine as fertilizer, but ignore the capital intensity and logistical issues.听
Urine comes with a bit of a . It isn鈥檛 completely warranted. Thanks to the osmotic filtering in the kidneys, urine from a healthy human, , doesn鈥檛 contain many dangerous micro-organisms. Collecting and fertilizing diluted urine is touted by many. Love and Wigginton, the intrepid Michigan professors, are not the first to recognize the potential in urine. Community collection was , as one example. 鈥淧ee for peonies鈥� uses , leveraging an existing program and highlighting the logistical challenges of local collection.
My testing was decidedly less involved. Urine diversion via a juice bottle proved easy enough, at least for half of my household. In round numbers, I produced about 1.7 L of urine a day. Focusing only on the urea, necessary for greening my lawn, I was , using one of the higher, peer reviewed concentration estimates. , known to damage plants, and human urine are similar in composition. To be safe, I diluted my urine 10:1 before using it around the yard. I can buy a 50-pound bag of urea for $35. At that price, my urine collecting efforts are worth about 4垄 a day in fertilizer. I avoid a couple of cents of water use through avoided flushing. I鈥檓 saving less than a dime a day.
My yard鈥檚 yearly fertilizer needs could be met if all household urine for a year were diverted. Storage for at least 500 liters during the winter is not a pleasant proposition, something necessary given year-round production and seasonal use. Urine releases ammonia when it degrades, causing a stink. Treatment with either acid or base stabilizes the urine. Some say sterilization is also required. Urine storage and stabilization, even at the household scale, just doesn鈥檛 make economic sense and it is a lot of unpleasant work.
Ideally, the nutrients in my urine would be recycled to produce food I consume. Those who have looked at the infrastructure requirements, from to the to concentrate the urine to an economically applied fertilizer, conclude it is impractical. Urine diversion can be done and is environmentally responsible, yet is difficult to implement economically at scale.
Recycle of urine, while certainly possible, has yet to reach the threshold of practical. I also can鈥檛 tell any difference in my yard. Fertilized and unfertilized areas are identical after my short test. I鈥檝e ceased peeing in bottles and returned to flushing. Eye-rolling is now back to pre-diversion levels.
Mark Jones is a frequent speaker at a variety of industry events on industry related topics. He is a long-time supporter of ACS Industry Member Programs providing both written and webinar content, supporting the CTO Summits, and as a former member of Corporation Associates. He currently serves on the ACS Committee on Public Relations and Communications and the Chemical Heritage Landmark Committee. He is a member and former chair of the Chemical Sciences Roundtable, a standing roundtable of the National Academies of Sciences, Engineering, and Medicine. Mark is the author of over a dozen U.S. patents and numerous publications.
The opinions expressed in this article are the author's own and do not necessarily reflect the view of their employer or the American Chemical 中国365bet中文官网.
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