Recovering human-derived nutrients can advance circular economies by linking increasingly urban global populations with local cropland, offsetting unsustainable fertilizer use and improving access in low-income countries. For 56 of the world’s largest cities, we analyse co-location of urban nutrients with surrounding agricultural needs (that is, the degree to which recoverable nutrients spatially align with crop demands), defining paths forward to close urban nutrient cycles. Estimated nutrient transport distances, which may constrain what recovery strategies are locally feasible, span two orders of magnitude and are often shorter among European, African and Asian cities due to high local cropland density. We further examine how growing nutrient-intensive crops and recovering highly concentrated nutrient products could impact distance and energy requirements. Broadly, locations with high cropland density, nutrient-intensive crops and compact urban area may find agricultural nutrient reuse particularly impactful and achievable, creating opportunities to boost productivity by coupling urban water and regional agriculture systems.
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Godfray, H. C. J. et al. Food security: The challenge of feeding 9 billion people. Science 327, 812–818 (2010).
Seto, K. C. et al. Urban land teleconnections and sustainability. Proc. Natl Acad. Sci. USA 109, 7687–7692 (2012).
Forkes, J. Nitrogen balance for the urban food metabolism of Toronto, Canada. Resour. Conserv. Recycl. 52, 74–94 (2007).
Villarroel Walker, R., Beck, M. B., Hall, J. W., Dawson, R. J. & Heidrich, O. The energy-water-food nexus: Strategic analysis of technologies for transforming the urban metabolism. J. Environ. Manage. 141, 104–115 (2014).
Särkilahti, M., Kinnunen, V., Kettunen, R., Jokinen, A. & Rintala, J. Replacing centralised waste and sanitation infrastructure with local treatment and nutrient recycling: Expert opinions in the context of urban planning. Technol. Forecast. Soc. Change 118, 195–204 (2017).
Ghisellini, P., Cialani, C. & Ulgiati, S. A review on circular economy: The expected transition to a balanced interplay of environmental and economic systems. J. Clean. Prod. 114, 11–32 (2016).
Transforming Our World: The 2030 Agenda for Sustainable Development (United Nations, 2015).
Cordell, D., Drangert, J.-O. & White, S. The story of phosphorus: Global food security and food for thought. Glob. Environ. Change 19, 292–305 (2009).
Fowler, D. et al. The global nitrogen cycle in the twenty-first century. Phil. Trans. R. Soc. B 368, 20130164 (2013).
Manning, D. A. C. Mineral sources of potassium for plant nutrition. A review. Agron. Sustain. Dev. 30, 281–294 (2012).
Smith, V. H., Tilman, G. D. & Nekola, J. C. Eutrophication: Impacts of excess nutrient inputs on freshwater, marine, and terrestrial ecosystems. Environ. Pollut. 100, 179–196 (1999).
Bouwman, A. F., Beusen, A. H. W. & Billen, G. Human alteration of the global nitrogen and phosphorus soil balances for the period 1970–2050. Glob. Biogeochem. Cycles 23, GB0A04 (2009).
Morée, A. L., Beusen, A. H. W., Bouwman, A. F. & Willems, W. J. Exploring global nitrogen and phosphorus flows in urban wastes during the twentieth century. Glob. Biogeochem. Cycles 27, 836–846 (2013).
Sheldrick, W. F., Syers, J. K. & Lingard, J. A conceptual model for conducting nutrient audits at national, regional, and global scales. Nutr. Cycl. Agroecosys. 62, 61–72 (2002).
Mihelcic, J. R., Fry, L. M. & Shaw, R. Global potential of phosphorus recovery from human urine and feces. Chemosphere 84, 832–839 (2011).
Trimmer, J. T., Cusick, R. D. & Guest, J. S. Amplifying progress toward multiple development goals through resource recovery from sanitation. Environ. Sci. Technol. 51, 10765–10776 (2017).
Green Growth and Climate Resilience: National Strategy for Climate Change and Low Carbon Development (Republic of Rwanda, 2011).
Steffen, W. et al. Planetary boundaries: Guiding human development on a changing planet. Science 347, 1259855 (2015).
Xu, M. et al. Gigaton problems need gigaton solutions. Environ. Sci. Technol. 44, 4037–4041 (2010).
Mihelcic, J. R. et al. The grandest challenge of all: The role of environmental engineering to achieve sustainability in the world’s developing regions. Environ. Eng. Sci. 34, 16–41 (2016).
Seto, K. C., Golden, J. S., Alberti, M. & Turner, B. L. Sustainability in an urbanizing planet. Proc. Natl Acad. Sci. USA 114, 8935–8938 (2017).
World Urbanization Prospects: The 2014 Revision, (ST/ESA/SER.A/366) (United Nations, Department of Economic and Social Affairs, Population Division, 2015).
Badami, M. G. & Ramankutty, N. Urban agriculture and food security: A critique based on an assessment of urban land constraints. Glob. Food Secur. 4, 8–15 (2015).
Verbyla, M. E., Oakley, S. M. & Mihelcic, J. R. Wastewater infrastructure for small cities in an urbanizing world: Integrating protection of human health and the environment with resource recovery and food security. Environ. Sci. Technol. 47, 3598–3605 (2013).
Wald, C. The new economy of excrement. Nature 549, 146–148 (2017).
Ostara Overview: Nutrient Management Solutions (Ostara, 2018).
Mehta, C. M., Khunjar, W. O., Nguyen, V., Tait, S. & Batstone, D. J. Technologies to recover nutrients from waste streams: A critical review. Crit. Rev. Environ. Sci. Technol. 45, 385–427 (2015).
van Loosdrecht, M. C. M. & Brdjanovic, D. Anticipating the next century of wastewater treatment. Science 344, 1452–1453 (2014).
Diener, S. et al. A value proposition: Resource recovery from faecal sludge—Can it be the driver for improved sanitation? Resour. Conserv. Recycl. 88, 32–38 (2014).
Larsen, T. A., Alder, A. C., Eggen, R. I. L., Maurer, M. & Lienert, J. Source separation: Will we see a paradigm shift in wastewater handling? Environ. Sci. Technol. 43, 6121–6125 (2009).
Metson, G. S., MacDonald, G. K., Haberman, D., Nesme, T. & Bennett, E. M. Feeding the corn belt: opportunities for phosphorus recycling in US agriculture. Sci. Total Environ. 542, 1117–1126 (2016).
Tran, Q. K., Schwabe, K. A. & Jassby, D. Wastewater reuse for agriculture: Development of a regional water reuse decision-support model (RWRM) for cost-effective irrigation sources. Environ. Sci. Technol. 50, 9390–9399 (2016).
Van Drecht, G., Bouwman, A. F., Harrison, J. & Knoop, J. M. Global nitrogen and phosphate in urban wastewater for the period 1970 to 2050. Glob. Biogeochem. Cycles 23, GB0A03 (2009).
Friedler, E., Butler, D. & Alfiya, Y. in Source Separation and Decentralization for Wastewater Management (eds. Larsen, T. A. et al.) 241–258 (IWA Publishing, London, 2013).
Ewing, R., Hamidi, S., Grace, J. B. & Wei, Y. D. Does urban sprawl hold down upward mobility? Landsc. Urban Plan. 148, 80–88 (2016).
Small, C. & Nicholls, R. J. A global analysis of human settlement in coastal zones. J. Coast. Res. 19, 584–599 (2003).
Food and Agricultural Organization Statistics Division (FAOSTAT, 2018, accessed 21 April 2018); http://faostat3.fao.org/home/E
Mueller, N. D. et al. Closing yield gaps through nutrient and water management. Nature 490, 254–257 (2012).
Alexandratos, N. & Bruinsma, J. World Agriculture Towards 2030/2050: The 2012 Revision (FAO, 2012).
d’Amour, C. B. et al. Future urban land expansion and implications for global croplands. Proc. Natl Acad. Sci. USA 114, 8939–8944 (2017).
Pakistan Food Security Bulletin: Issue 6, August 2017 (Vulnerability Analysis and Mapping Unit, World Food Programme, 2017).
Hogeboom, R. J. & Hoekstra, A. Y. Water and land footprints and economic productivity as factors in local crop choice: The case of silk in Malawi. Water 9, 802 (2017).
Tchobanoglous, G., Stensel, H. D., Tsuchihashi, R., & Burton, F. Wastewater Engineering: Treatment and Resource Recovery (McGraw-Hill, New York, 2014).
Etter, B., Tilley, E., Khadka, R. & Udert, K. M. Low-cost struvite production using source-separated urine in Nepal. Water Res. 45, 852–862 (2011).
Tarpeh, W. A., Barazesh, J. M., Cath, T. Y. & Nelson, K. L. Electrochemical stripping to recover nitrogen from source-separated urine. Environ. Sci. Technol. 52, 1453–1460 (2018).
Wilsenach, J. A., Schuurbiers, C. A. H. & van Loosdrecht, M. C. M. Phosphate and potassium recovery from source separated urine through struvite precipitation. Water Res. 41, 458–466 (2007).
Maurer, M., Schwegler, P. & Larsen, T. A. Nutrients in urine: Energetic aspects of removal and recovery. Water Sci. Technol. 48, 37–46 (2003).
Progress on Drinking Water, Sanitation and Hygiene: 2017 Update and SDG Baselines (WHO/UNICEF, 2017).
Malik, O. A., Hsu, A., Johnson, L. A. & de Sherbinin, A. A global indicator of wastewater treatment to inform the Sustainable Development Goals (SDGs). Environ. Sci. Policy 48, 172–185 (2015).
Samberg, L. H., Gerber, J. S., Ramankutty, N., Herrero, M. & West, P. C. Subnational distribution of average farm size and smallholder contributions to global food production. Environ. Res. Lett. 11, 124010 (2016).
Monfreda, C., Ramankutty, N. & Foley, J. A. Farming the planet: 2. Geographic distribution of crop areas, yields, physiological types, and net primary production in the year 2000. Glob. Biogeochem. Cycles 22, GB1022 (2008).
Wichmann, W. IFA World Fertilizer Use Manual (International Fertilizer Association, 1992).
World Database of Large Urban Areas, 1950–2050 (Nordpil, 2010, accessed 10 June 2017); https://nordpil.com/resources/world-database-of-large-cities/
Standard Country or Area Codes for Statistical Use (M49): Methodology (United Nations Statistics Division, 2017, accessed 10 June 2017); https://unstats.un.org/unsd/methodology/m49/
Gridded Population of the World, Version 4 (GPWv4): Population Count Adjusted to Match 2015 Revision of UN WPP Country Totals (Center for International Earth Science Information Network, 2016).
Gridded Population of the World, Version 4 (GPWv4): Population Density Adjusted to Match 2015 Revision of UN WPP Country Totals (Center for International Earth Science Information Network, 2016).
Global 30 Arc-Second Elevation (GTOPO30) (USGS, 1996).
Gridded Population of the World, Version 4 (GPWv4): Land and Water Area (Center for International Earth Science Information Network, 2016).
World Development Report: Reshaping Economic Geography (The International Bank for Reconstruction and Development/The World Bank, 2009).
Martellozzo, F. et al. Urban agriculture: A global analysis of the space constraint to meet urban vegetable demand. Environ. Res. Lett. 9, 064025 (2014).
Seto, K. C., Güneralp, B. & Hutyra, L. R. Global forecasts of urban expansion to 2030 and direct impacts on biodiversity and carbon pools. Proc. Natl Acad. Sci. USA 109, 16083–16088 (2012).
Mayer, B. K. et al. Total value of phosphorus recovery. Environ. Sci. Technol. 50, 6606–6620 (2016).
Pradhan, S. K., Mikola, A. & Vahala, R. Nitrogen and phosphorus harvesting from human urine using a stripping, absorption, and precipitation process. Environ. Sci. Technol. 51, 5165–5171 (2017).
Shoener, B. D., Bradley, I. M., Cusick, R. D. & Guest, J. S. Energy positive domestic wastewater treatment: The roles of anaerobic and phototrophic technologies. Environ. Sci. Process. Impacts 16, 1204–1222 (2014).
Gellings, C. W. & Parmenter, K. E. in Efficient Use and Conservation of Energy Vol. 11 (eds. Gellings, C. W. & Blok, K.) (UNESCO, EOLSS Publishers, Paris, 2004); http://www.eolss.net/ebooks/sample%20chapters/c08/e3-18-04-03.pdf
Hauke, J. & Kossowski, T. Comparison of values of Pearson’s and Spearman’s correlation coefficient on the same sets of data. Quaest. Geogr. 30, 87–93 (2011).
Ramankutty, N., Evan, A. T., Monfreda, C. & Foley, J. A. Farming the planet: 1. Geographic distribution of global agricultural lands in the year 2000. Glob. Biogeochem. Cycles 22, GB1003 (2008).
GDP per Capita (Current US$). World Bank Open Data (World Bank, 2017, accessed 9 October 2017); https://data.worldbank.org/indicator/NY.GDP.PCAP.CD
Vargha, A. & Delaney, H. D. The Kruskal–Wallis test and stochastic homogeneity. J. Educ. Behav. Stat. 23, 170–192 (1998).
The authors acknowledge the Illinois Distinguished Fellowship at the University of Illinois at Urbana-Champaign for funding support for J.T.T., and thank R. Cusick for discussions related to the recovery of crystal products.
The authors declare no competing interests.
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Trimmer, J.T., Guest, J.S. Recirculation of human-derived nutrients from cities to agriculture across six continents. Nat Sustain 1, 427–435 (2018). https://doi.org/10.1038/s41893-018-0118-9
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