3.4 Technology Identification and Selection

The type of sanitation technology and the system implemented will influence its long-term sustainability: user acceptance, availability of skills and resources for long-term Operation and Maintenance as well as long-term environmental and health protection and the potential for resource recovery.

There are various technologies that can be combined into dry or wet, on-site, decentralised or centralised systems. Using a clear framework to systematically match potential technology solutions with the relevant decision criteria makes technology selection easier. The Compendium of Sanitation Technologies in Emergencies or SaniChoice are tools that support technology identification and selection.

During the acute phase, the focus is on the user interface and on-site storage for community latrines to eliminate open defecation and contain the excreta safely. In the stabilisation phase, community latrines can be replaced by improved shared or household toilets and storage solutions. The next step is to plan and implement services for the emptying, collection, treatment and safe reuse and/or disposal of faecal sludge along the entire sanitation service chain to ensure public health and environmental protection. Greywater and Solid Waste Management should also be considered to avoid the mixing of greywater with excreta and to ensure that solid waste does not end up in pits or clog drains.

Types of sanitation technologies and systems

Sanitation systems and their associated technologies can be broadly divided into dry or water-based/wet (see also How to Select Appropriate Technologies?). Dry technologies do not use water for the transport and treatment of human excreta. Depending on the technology, they may rely on on-site storage, source separation, composting or dehydration, among others, to treat and stabilise human excreta or sludge products. They can produce valuable by-products such as compost or pit humus. Dry technologies can be particularly useful in areas where water is scarce or where water-based sanitation systems are not feasible due to geographical or environmental constraints. Wet systems instead use water for flushing and as a transport medium; they require treatment of faecal sludge or blackwater.

Sanitation systems can also be broadly divided into on-site and off-site systems (see also What Different Sanitation Systems Exist?). On-site systems allow for the storage and/or treatment and safe disposal of excreta, sludge and effluents on-site. Dry on-site storage technologies include, among others, Single Pit Latrines and Twin Pit Latrines, Ventilated Improved Pits (VIPs), Raised Latrines, Urine Diversion Dry Toilets or Container-Based Toilets. Common water-based on-site storage technologies include single or double pits, ventilated improved pits or Twin-Pits for Pour-Flush connected to e.g. a Septic Tank. For off-site systems, faecal sludge or human excreta are usually transported either using Manual or Motorised Emptying and Transport, while wastewater or blackwater are commonly transported through sewers (such as a Simplified Sewer or a Conventional Gravity Sewer). Sewers usually cost more and require large amounts of water; they are not usually relevant for a humanitarian response unless an existing system can be rehabilitated or expanded.

The sanitation service chain and sustainable sanitation

Combining technologies into entire systems builds a sanitation service chain from the user through to the final use or disposal. The sanitation service chain can be divided into five steps: the user interface (U), on-site storage and/or treatment (S), transportation or conveyance (C), treatment (T) and disposal or reuse (D) (see the table below).

In the acute response phase, the focus is always on the user interface and on-site storage and safe disposal, while the aim during the stabilisation and recovery phases is to have a full sanitation system in place. The long-term goal (beyond the humanitarian response) is to establish sustainable sanitation systems – systems that protect human health and the environment, that are technically appropriate, financially viable, socio-culturally and institutionally accepted and allow for resource recovery and reuse (SuSanA 2008).

Selecting appropriate technology and system options

The table below summarises the most common technological options as well as the key decision criteria to consider in each of the five functional groups in the three response phases. For more details on how to select locally appropriate technologies, refer to How to Select Appropriate Technologies?.

The focus of the stabilisation phase is to move from communal to shared latrines and then to household latrines. It is advisable to consider design options for the superstructure and the slab (user interface) and the pit (on-site storage) separately and to use locally available materials for each component where possible. Decisions about whether to integrate bathing units are taken in this phase and about how to deal with greywater in general. If desludging is needed, treatment focuses on safe containment and pathogen removal. In places where a system already exists but is damaged, the focus is on providing temporary emergency solutions while trying to rehabilitate the existing one. Often when the stabilisation phase is reached, there is hardly any budget remaining. Hence the best that can be achieved is simple pit latrines with household participation. However, using the table above to plan for sanitation infrastructure along the entire sanitation value chain from the beginning can support additional fund-raising or handover to other providers.

In the recovery phase, the objective is full coverage with household latrines, infrastructure and management practices along the entire sanitation chain. In this phase, the focus is on the selection of appropriate Emptying and Transport, Treatment and Safe Disposal or Use Technologies considering the Quantities of Faecal Sludge or compost/ pit humus. It is important to develop Management Plans and Financial Plans according to the locally available budget, skills, and capacities.

The development of an Exit Strategy is crucial to guarantee the services for the future. Here, it is important to consider potential synergies with host communities, space for on-site storage and off-site treatment and burial versus treatment according to commonly agreed Standards.

In some circumstances, reuse might be an option if demand exists. Simple reuse options include the application of Compost or Stabilised Sludge as soil conditioner, the Use of Stored Urine as fertiliser, pellets made from Dried Faeces for cooking stoves or controlled Irrigation with greywater of trees or other crops (see also How to Ensure Safe Disposal and Reuse?).