Final Report: Nanochromatography Monitoring of Urine FertilizersEPA Grant Number: SU836767
Title: Nanochromatography Monitoring of Urine Fertilizers
Investigators: Lahr, Rebecca H
Institution: Michigan State University
EPA Project Officer: Page, Angela
Project Period: September 1, 2016 through August 31, 2017
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2016) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources
The average American flushes urine down the toilet four times per day, rinsing approximately 300 mL of waste with several gallons of water purified to drinking standards. Not only are significant resources (money, energy, time, distance) invested in the potable water used to flush wastes, but the urine from one person in a day (1-1.5 L/day) contains an ideal mix of nitrogen and phosphorus to fertilize approximately 1 m2 of land. Urine diversion for fertilizer production could reduce water use by four flushes per person per day, reduce the extent of our reliance on mining for phosphorus and N2 for fertilizer production, reduce resource requirements at wastewater treatment plants, reduce nutrient loading to surface waters (by keeping them from wastewater treatment plant effluents), and shorten the urban nitrogen cycle; however, the “yuck” factor hinders implementation. Thus, there is a need for user friendly, reliable, fast, cost-effective, low-tech metrics for monitoring contaminants of public health concern in urine-derived fertilizer production systems worldwide.
A low-tech, cheap, fast, and user friendly method was developed by the student design team for monitoring concentrations of nutrients and contaminants through the fertilizer production process. This technique employs nanochromatographic separation of solutes in an aqueous sample through the phenomenon known as the “coffee ring” effect, in which wastewater samples leave distinguishable “fingerprint” signatures based on the solubility and size of chemical constituents. The student design team from MSU developed and tested the new nanochromatography method for monitoring wastewater contaminants, built a reactor to produce fertilizer from the diverted urine, and applied the new detection method to reactor monitoring. EcoWorks, a non-profit entity in Detroit, Michigan, built a composting, urine diverting toilet at an urban Detroit farm where the student design team will conduct a field study over the summer of 2017.
Outcomes of this work included 1) a library of nanochromatography fingerprints for nutrients and contaminants expected in urine and urine-derived products, 2) a field testing protocol to record nanochromatography fingerprints with a cell phone camera and a jeweler’s loupe, and 3) a fertilizer production system for an existing urine diverting toilet at EcoWorks, a non-profit entity in Detroit. Field tests of the reactor and detection protocol will be conducted over the summer of 2017. Nanochromatography offers a low-cost, low-tech, rapid, user friendly, disposable, and automatable protocol for identifying changes in water composition with minimal technology or equipment.
Detection is the first step to prevention and control of pollution. Development of a cheap, user friendly detection method such as nanochromatography would provide worldwide users with the tool to investigate water quality anywhere with a magnifying glass and smartphone/camera. It is not always practical to regularly quantify all potential contaminants in a water or wastewater sample, but nanochromatography allows a snapshot of the water fingerprint to be collected and compared to a database of fingerprints with similar features. Instead of monitoring urine diversion systems for one contaminant at a time or using conductivity for phosphorus content indicator pathogens, and representative pharmaceuticals, the “fingerprint” of the sample can be evaluated throughout treatment, thus ensuring process control.