粪便流图：城市卫生系统的可视化管理工具

粪便流图（SFD）是一种用于展示城市卫生系统中人类排泄物管理情况的可视化工具。1该工具通过色码箭头区分处理方式的安全程度，其中绿色箭头表示安全管理的排泄物流，红色箭头表示不安全处理。1箭头的宽度比例反映该排泄物流所代表的人口百分比。1这一方法由可持续卫生联盟（SuSanA）、世界银行、瑞士水科技研究所（EAWAG）和比尔及梅琳达·盖茨基金会合作开发，12014年正式成立SFD推广倡议并获得盖茨基金会的资助。1

在全球低中收入国家的多个城市应用中，粪便流图揭示了卫生设施普及与排泄物安全管理之间的巨大差距。1坦桑尼亚巴巴蒂的情况表明，尽管82%的住房拥有卫生设施，但仅31%的排泄物被安全管理，69%遭到不安全排放。1乌干达坎帕拉的城市居民中99%使用化粪池或坑式厕所，然而53%的化粪池从未被清空，仅35%的粪便污泥被收集运往处理厂。1印度阿拉普扎的调查显示，尽管卫生设施广泛普及，但多数化粪池和坑式厕所设计不足，排放的污水造成地下水和运河严重污染，大多数水样本中都检出了大肠杆菌。1

The Sanitation Flow Diagram (SFD) is a visualization tool designed to track how human excreta moves through urban sanitation systems, distinguishing between safe and unsafe waste management practices 1. The diagram uses color-coded arrows—green for safely managed excreta flows and red for unsafe disposal—with arrow width proportional to the percentage of the population affected by each pathway 1.

The SFD was developed through collaboration between the Sustainable Sanitation Alliance (SuSanA), the World Bank, the Swiss Federal Institute of Aquatic Science and Technology (EAWAG), and the Bill & Melinda Gates Foundation 1. Following the Second Fecal Sludge Management Conference held in Durban, South Africa in 2012, the SFD promotion initiative was formally established in 2014 with funding from the Gates Foundation 1. The tool has since become widely adopted for urban sanitation planning across low and middle-income countries, employing data collection, stakeholder engagement, and systems analysis to inform policy decisions 1.

Real-world applications reveal persistent gaps between toilet access and safe waste treatment. In Babati, Tanzania, 82% of households have sanitation facilities, yet only 31% of excreta is safely managed, with 69% disposed unsafely 1. In Kampala, Uganda, 99% of the population uses septic tanks or pit latrines, but 53% of septic tanks have never been emptied, and only 35% of collected fecal sludge reaches treatment facilities 1. In Alappuzha, India, despite widespread toilet coverage, most septic tanks and pit latrines are inadequately designed, resulting in sewage that contaminates groundwater and canals, with E. coli detected in most water samples tested 1.