How to Select Appropriate Technologies along the Sanitation Value Chain for Specific Conditions?

Selecting locally appropriate sanitation technologies and combining them into viable sanitation systems can be complex: there are many aspects to consider and trade-offs to make. It helps to proceed in several steps. In the initial phase, the focus is on providing safe community latrines (toilet user interfaces and on-site storage). Soon, as latrines fill up, appropriate technologies must be identified for on-site treatment, transport of excreta or sludge and off-site treatment, safe disposal or reuse. Using a systematic assessment framework that includes the technology options and assessment criteria for each functional group along the sanitation chain and in different response phases, helps to eliminate inappropriate choices, consider the entire sanitation value chain and plan for incremental improvements and upgrades. 

Relevance/Importance

Inappropriate technology choices lead to misuse, a lack of ownership and resources for operation and maintenance and the failure of sanitation intervention; this has direct consequences for people and the environment.  

Typical examples of inappropriate technologies include flush toilets where there is no water, dry toilets where people use water for anal cleansing and flushing, on-site cesspits where there is a high groundwater table or no access for emptying, no space for the safe disposal of faecal sludge or activated sludge treatment or when there is an insufficient energy supply or budget for operation and maintenance. In addition to these technical and geophysical factors, the identification and selection of appropriate sanitation technologies require consideration of socio-cultural, financial and institutional aspects as well as skills and capacities. Systematically matching technology options with these different factors helps practitioners to identify more appropriate options. It is also important to consider options that are new to the area but better fit the context than conventional solutions. The Compendium of Sanitation Technologies in Emergencies and SaniChoice are online tools that provide a simple, advanced technology appropriateness filter and decision-making tool. 

Overview

A sanitation technology is defined as infrastructure that is designed to contain, transform or transport sanitation products; there are dry technologies and water-based technologies. A sanitation system is defined as a combination of sanitation technologies which, in the selected configuration, manage sanitation products along the sanitation value chain. They are organised into five functional groups: the user interface, on-site collection and storage/treatment, conveyance or transport, decentralised or centralised treatment and disposal or use. The output of a technology from one functional group becomes the input of the technology in the next group and determines whether they are compatible.  

An appropriate sanitation system is a combination of appropriate and compatible technologies that provide a socially and environmentally acceptable service at an affordable cost. The technologies are further assessed against geophysical, technical, socio-cultural, legal and financial factors as well as capacity and management criteria.  

As outlined in Technology Identification and Selection, the focus during the acute phase is on the user interface and safe on-site storage. In the stabilisation and recovery phase, the aim is to establish a full and sustainable sanitation system. 

Acute response: the priority is the installation of latrines (user interface and on-site storage) that are safe for the users and prevent public health risks from faecal waste (see also How to Design and Implement Appropriate and Sustainable Toilets?). During this phase consider socio-cultural preferences, geophysical factors such as the risk of flooding, the availability of funds and materials and how fast a solution is required. 

Both SaniTweaks (Oxfam 2022) and Excreta Disposal in Emergencies (Harvey 2007) provide simple checklists to answer these questions. The Initial Assessment must ensure that the information is collected along with the specific needs of the targeted communities. For instance, for vulnerable groups, simple add-ons like lighting or handrails at the stairs can make a big difference. How to Design and Implement Appropriate and Sustainable Toilets/Latrines also provides additional guidance. 

Stabilisation phase: the focus is to move away from community latrines to shared or household toilets and to provide a solution for the management of excreta and faecal sludge. Aspects to consider in this phase include whether the infrastructure could be upgrades and the availability of service providers, trucks and equipment and whether the environment has access and space for on-site treatment or removal. See also the following pages for more details: How to Select Appropriate Emptying and Transport Technologies? and How to Select Appropriate Treatment Technologies?

Recovery phase: the aim is to establish a longer-term sanitation service with appropriate technologies along the entire service chain (including treatment and safe disposal or reuse) that can be operated and maintained either directly by the community or by public institutions or private service providers (see also Exit Strategy). This means on-site facilities may need to be upgraded, safe treatment and disposal facilities put in place and Management Plans and Financial Plans developed according to the locally available budget, skills and capacities. Standards need to be in place. 

The technology for treatment will depend on the latrines and collection services already in place. Assess the overall treatment objectives, including local demand for reuse, the capital and operational costs of different options and the availability of fuel and electricity. Establish standards and look for synergies with the existing infrastructure and avoid creating inequalities with the host population. 

It is important to note that often there is no perfect solution; trade-offs must be made, for example combining more or less appropriate technologies to deliver an entire system.  

Practitioners often select technology options that the target or host communities are most used to. However, there is a case for thinking out of the box and considering alternative options which are potentially more appropriate. The Compendium of Sanitation Technologies in Emergencies and SaniChoice provide information on various established and emerging technology options. 

Process & Good Practice

• Conduct a rapid assessment of the main socio-cultural preferences and physical and economic constraints 
• Install, in the acute phase a solution that provides safe toilets for people and avoids the spreading of faecal waste. The main criteria to consider are: 
  • Socio-cultural acceptance 
  • Physical aspects: soil conditions, flooding, groundwater table (if flooding and high groundwater tables are a problem, stormwater management and drainage should be set up at the same time). 
  • Inclusive design 
  • Number of facilities (ratio of toilets to users) 
  • Need and frequency for emptying 
  • Speed of implementation (How fast is a solution required?) 
  • Economic factors: materials and workforces readily available for construction and regular repairs and the availability of finance 

• Identify specific solutions for difficult contexts as described in Specific Challenging Contexts.  
• Plan, during the stabilisation phase, for appropriate Emptying and Transport Technologies, Treatment Technologies and Safe Treatment and Disposal Technologies. The criteria to consider include, among others: 
  • Rehabilitation/upgrading of existing infrastructure: Is there any existing infrastructure that could be repaired or upgraded? Are there existing service providers (such as for Desludging or Mobile Toilets)?  
  • Physical aspects: soil conditions, flooding, groundwater table, distance to drinking water sources 
  • Water availability (most water-based systems require a minimal amount of water) 
  • Does the environment allow water-based on-site or decentralised treatment, e.g. in Twin Pits, or Septic Tanks or is there a need for emptying and transport? 
  • What workforces and equipment are available for emptying and transporting faecal sludge? Are trucks and fuel available or is there an alternative solution (e.g. gulpers or vacuum trucks). Is a dry solution (e.g. Container-Based Toilets or Urine Diversion Dry Toilets) preferred? 
  • Population density 
  • Vehicular access (quality and width of roads, distance) 
  • Land availability off-site 
  • Electricity/fuel availability  

• Aim for sustainability in the recovery phase. A full sanitation system should have the potential to be sustainable. The key criteria to consider are: 
  • Scalability (expansion, upgrading) 
  • Availability of construction materials and spare parts (local or through surge supply) 
  • Availability of human and financial capacities for operation and maintenance and long-term management 
  • Synergies with infrastructure and services in host communities 
  • Possibilities for resource recovery (urine as fertiliser, compost, effluent for irrigation etc.) 
  • What are the Quantities of Faecal Sludge generated and what is the required emptying service? 
  • What are the Capital and Operational Costs for different collection and treatment options and how would they be distributed? Which solutions would be affordable? 
  • Is fuel and/or electricity available? 
  • What are the treatment objectives? Can the effluents and sludge be safely disposed of or is advanced treatment required? Is there a demand for fertiliser or reclaimed water for agricultural production? See also How to Ensure Safe Disposal and Reuse of Treated Faecal Sludge and Other Sanitation Products.  
  • What are the Standards and Accountability mechanisms in place to ensure long-term operation and maintenance? 
  • How to best use the synergies with existing infrastructure and avoid inequalities between the host communities and resettled populations? 

• Plan systematically: the many different technology options and criteria can be overwhelming and make it difficult to plan for entire systems. Use the following procedure: 
  • Identify the products that are generated and/or available (e.g. anal cleansing water, flushwater or organics for composting) 
  • For each functional group, identify three to five potentially appropriate technologies. Parts of a sanitation system may already exist and can be integrated 
  • Score each technology regarding a few key criteria such as space, soil conditions and user acceptance on a scale of e.g. one to five. This matrix should be discussed with all relevant stakeholders (including the representatives of the affected population) to ensure ownership and involvement in decision-making 
  • Consider the input/output products of each technology and assemble the preferred technologies into entire systems ensuring that output and input products are compatible 
  • Compare the systems and iteratively change individual technologies based on, for example, scalability, operation and maintenance requirements and the demand for specific end-products (e.g. compost), economic constraints, and technical feasibility 

• Plan for an Exit Strategy. A sustainable sanitation system protects human health and the environment, is technically appropriate, financially viable, socio-culturally and institutionally accepted and allows for resource recovery and reuse (SuSanA 2008). This might be difficult to achieve during the intervention but the implementation of an entire sanitation system and its operation, maintenance and management in the long-term should be part of the Exit Strategy
• Establish a monitoring system. Appropriate technology selection is not a guarantee of success. Failure can still occur because incorrect assumptions were made, information was missing or the situation changed (e.g. number of people to be served or volume of water used). To support continuous adaptation, Response Monitoring is essential 
• Address any existing Standards along the Sanitation Value Chain when making decisions and designing response monitoring 
• While the criteria above mainly describe sanitation in terms of the management of human excreta, they can also be applied to the technologies required for greywater treatment