Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133, Milano, Italy; Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland; ETH Zürich, Institute of Environmental Engineering, 8093, Zürich, Switzerland.
Water Res. 2017 Mar 1;110:297-312. doi: 10.1016/j.watres.2016.12.007. Epub 2016 Dec 11.
New types of sanitation services are emerging to tackle the sanitation crisis in informal settlements. These services link toilet facilities to semi-decentralized treatment plants via frequent, road-based transport of excreta. However, information for the planning of such sanitation services is scarce, and their future operating conditions are highly uncertain. The key questions of this paper are therefore: a) what are the drivers behind success or failure of a service-based sanitation system in informal settlements and b) on what scales and under which conditions can such a system operate successfully? To answer these questions, already at an early stage of the planning process, we introduce a stochastic model to analyze a wide range of system designs under varying technical designs, socio-economic factors, and spatial condition. Based on these initial results, we design a sanitation service and use the numeric model to study its reliability and costs over a wide range of scales, i.e., system capacities, from very few to many hundred users per semi-decentralized treatment unit. Key findings are that such a system can only operate within a narrow, but realistic range of conditions. Key requirements are toilet facilities, which can be serviced rapidly, and a flexible workforce. A high density of facilities will also lower the costs. Under these premises, we develop a road-based sanitation service and model its functionality in different settings and under many scenarios. Results show that the developed sanitation system using a single vehicle is scalable (100-700 users), can provide reliable service, and can be cheap (<1.5 c/p/day). Hence, this paper demonstrates opportunities for road-based sanitation in informal settlements and presents a quantitative framework for designing such systems.
新型卫生服务正涌现出来，以解决非正规住区的卫生危机。这些服务通过频繁的道路运输，将厕所设施与半分散式处理厂连接起来。然而，规划这类卫生服务的信息很少，其未来的运营条件高度不确定。因此，本文的关键问题是：a）服务型卫生系统在非正规住区取得成功或失败的驱动因素是什么；b）在何种规模和条件下，这种系统可以成功运作？为了回答这些问题，我们在规划过程的早期阶段引入了一个随机模型，以分析在不同技术设计、社会经济因素和空间条件下的广泛系统设计。基于这些初步结果，我们设计了一种卫生服务，并使用数值模型研究其在广泛的规模范围内（即系统容量，从非常少数到每个半分散处理单元数百个用户）的可靠性和成本。主要发现是，这种系统只能在一个狭窄但现实的范围内运行。关键要求是能够快速服务的厕所设施和灵活的劳动力。设施的高密度也会降低成本。在这些前提下，我们开发了一种基于道路的卫生服务，并在不同的环境和许多场景下对其功能进行建模。结果表明，使用单辆车的开发卫生系统具有可扩展性（100-700 个用户），可以提供可靠的服务，并且成本低廉（<1.5 c/p/day）。因此，本文展示了非正规住区基于道路的卫生服务的机会，并提出了设计此类系统的定量框架。
