Metson Geneviève S, Powers Steve M, Hale Rebecca L, Sayles Jesse S, Öberg Gunilla, MacDonald Graham K, Kuwayama Yusuke, Springer Nathaniel P, Weatherley Anthony J, Hondula Kelly L, Jones Kristal, Chowdhury Rubel B, Beusen Arthur H W, Bouwman Alexander F
1Department of Physics, Chemistry, and Biology (IFM), Linköping University, 581 83 Linköping, Sweden.
2National Research Council, National Academies of Science, USA and School of the Environment, Washington State University, Pullman, WA USA.
Reg Environ Change. 2018;18(5):1387-1401. doi: 10.1007/s10113-017-1257-7. Epub 2017 Dec 19.
Understanding how cities can transform organic waste into a valuable resource is critical to urban sustainability. The capture and recycling of phosphorus (P), and other essential nutrients, from human excreta is particularly important as an alternative organic fertilizer source for agriculture. However, the complex set of socio-environmental factors influencing urban human excreta management is not yet sufficiently integrated into sustainable P research. Here, we synthesize information about the pathways P can take through urban sanitation systems along with barriers and facilitators to P recycling across cities. We examine five case study cities by using a sanitation chains approach: Accra, Ghana; Buenos Aires, Argentina; Beijing, China; Baltimore, USA; and London, England. Our cross-city comparison shows that London and Baltimore recycle a larger percentage of P from human excreta back to agricultural lands than other cities, and that there is a large diversity in socio-environmental factors that affect the patterns of recycling observed across cities. Our research highlights conditions that may be "necessary but not sufficient" for P recycling, including access to capital resources. Path dependencies of large sanitation infrastructure investments in the Global North contrast with rapidly urbanizing cities in the Global South, which present opportunities for alternative sanitation development pathways. Understanding such city-specific social and environmental barriers to P recycling options could help address multiple interacting societal objectives related to sanitation and provide options for satisfying global agricultural nutrient demand.
了解城市如何将有机废物转化为宝贵资源对于城市可持续发展至关重要。从人类排泄物中捕获和回收磷（P）及其他必需营养素，作为农业的替代有机肥料来源尤为重要。然而，影响城市人类排泄物管理的一系列复杂社会环境因素尚未充分纳入可持续磷研究。在此，我们综合了磷在城市卫生系统中的路径信息，以及城市间磷回收的障碍和促进因素。我们采用卫生链方法研究了五个案例城市：加纳的阿克拉、阿根廷的布宜诺斯艾利斯、中国的北京、美国的巴尔的摩和英国的伦敦。我们的跨城市比较表明，伦敦和巴尔的摩从人类排泄物中回收至农田的磷比例高于其他城市，且影响各城市回收模式的社会环境因素存在很大差异。我们的研究突出了磷回收可能“必要但不充分”的条件，包括获得资本资源。全球北方大型卫生基础设施投资的路径依赖与全球南方快速城市化的城市形成对比，后者为替代卫生发展路径提供了机遇。了解此类特定城市的磷回收选项的社会和环境障碍，有助于实现与卫生相关的多个相互作用的社会目标，并为满足全球农业养分需求提供选择。
