Robust planning of sanitation services in urban informal settlements: An analytical framework

Abstract

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.

Early testing of new sanitation technology for urban slums: The case of the Blue Diversion Toilet

“…Fears that a collection service will be unreliable could also pose a serious barrier to purchase. Our own research (Schmitt et al, 2016) has shown that it is possible to plan and optimize a collection service. But more research in this neglected area is urgently needed.…”

“…As discussed in Section 1, a resource-recovering UDDT was chosen as a model for the BDT. Since a number of processes exist for medium-scale resource recovery from source-separated toilet waste (McConville et al, 2014), we propose a system for the safe manual collection and transport of source-separated feces and urine to a local resource-recovery plant serving about 1000 people (Schmitt et al, 2016). …”

Toilet revolution in China

“…A sanitation system – compared to a sanitation technology – considers all components required for the adequate management of human wastes, such as storage, collection, transport, treatment, discharge or reuse at the following levels ( Zurbrügg and Tilley, 2009 ). Starting at the household level with waste generation, a system can include storage and potentially also treatment and reuse of all products such as urine, excreta, greywater, rainwater/stormwater or even solid waste ( Schmitt et al., 2017 ). However, problems can rarely be solved at the household level alone.…”

Sanitation 4.0

“…And yet this also impacts urban life and society even as the core sanitation requirements for the sustainability of urban cities are not treated (Anastasiadis & Metaxas, 2013, Czischke et al, 2015Jewitt, 2011;Lehmann, 2010a;Parkinson et al, 2009). Most of the time people will avoid the subject of faeces and urine and tuck them away under less unsavoury concepts such as wastewater and solid waste management while the real concerns overrun our metropolitan areas, which then hinders the SDGs targets for inclusive, safe and resilient cities hinged on a resource-based paradigm (RBP) (Bai et al, 2016;Schmitt et al, 2017;UNDP, 2016).…”