Comparative Life Cycle Assessment of Urine Derived Fertilizer
This research developed an Excel-based tool to assess the environmental benefits of urine diversion and conversion to useful products (e.g., fertilizer) on a citywide basis to compare them to conventional wastewater management approaches. Using life cycle analysis, the tool considers several types of urine-derived fertilizers, models how urine diversion affects the wastewater treatment system, and includes the environmental benefits of reduced conventional fertilizer production. The tool’s flexibility allows users to input parameters related to water, wastewater, electricity production, and more. It is intended to be used as a first screening approach to assess the relative environmental impacts of these systems. Published by WRF. 96 pages. Online PDF. (2018)
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Originally funded as WERF project STAR_N1aR14T.
- Urine contains nitrogen, phosphorus, and potassium—nutrients that are essential for plants to grow. Nitrogen promotes leaf growth. Phosphorus grows roots, flowers, and seeds. Potassium encourages strong stems, flowers and fruits, and it helps move water within a plant. According to the International Plant Nutrition Institute, commercial fertilizers are used to augment 40-60% of world food production.
- Professor Nancy Love, principal investigator for UM's Urine Diversion research project, and her team have installed special toilets and urinals at a University of Michigan engineering building to divert urine, concentrate it, sanitize it, and prepare it for re-use as fertilizer.
- Funded by a $3 million dollar grant from the National Science Foundation, the project team is assessing if diverting urine will be a less energy intensive and more cost-effective way to reduce the nutrient loads in wastewater effluents and create fertilizer for agriculture.
- The hope is that on a large scale this sort of recycling might offset the need for commercial fertilizers, which are synthesized using fossil fuels, mined using strong acids that pollute the environment, and also deplete natural mineral resources. Researchers also hope “pee-cycled” fertilizer will be less energy intensive and more cost-effective way to reduce the nutrient loads in wastewater effluents. Removing the high concentrations of nutrients from urine is expensive and energy-intensive, and although many water treatment plants do what they can to lessen the nutrient load before releasing the “effluent” back into the environment, some do not. Excess nutrients (partially from attributed to wastewater effluents, but also to commercial fertilizer runoff) causes eutrophication of natural water bodies, leading to harmful algal overgrowths that kill fish and other aquatic life and poison waterways.
- The main roadblock to widespread application of urine collection for fertilizer production is lack of infrastructure. The sewer system is not designed to separate urine from other waste. In addition, the team is working on processes to remove pathogens and contaminants (residual pharmaceuticals, toxins, etc…), so that it can be safely used on crops.
- Nancy Love is the principal investigator for UM's Urine Diversion research project. She and her team are also conducting social research to determine ways to overcome the “ick” factor, and engaging in social research and market research to understand how the public and relevant stakeholders such as farmers, regulators, wastewater treatment plant personnel, and legislators perceive urine-derived fertilizers.