Hashemi's Sanitation Sustainability Index: A Community-Based Indicator for Evaluating Sustainability
According to UNICEF and WHO, the population that utilizes safely managed sanitation services increased from 28% to 45% from 2000 up to 2017. Accordingly, 2.1 billion people gained access to at least basic sanitation services. Despite that, 2 billion people still have no access to a safe and sustainable sanitation system, 673 million people are practicing open defecation, and 3 billion people still lack basic sanitation; consequently, the sanitation crisis remains a global concern.
The sixth sustainable development goal (SDG6) is designed to solve these global issues before the year 2030. The objective of SDG6-2 is to provide full coverage of adequate and sustainable sanitation for the entire population. Following this objective, innovative approaches have been applied to new disciplinary understandings of sanitation, to provide sustainable sanitation for low-income regions.
Under this circumstance, evaluating the sustainability of sanitation systems is essential in achieving the sixth sustainable development goal. However, there is only a limited number of available evaluation indexes, which are utilized to determine a community’s sanitation coverage macroscopically. Consequently, an index is required, which can evaluate different sanitation options for a specific community.
Dr. Urine has recently suggested the sanitation sustainability index (SSI) as an indicator for evaluating the sustainability of sanitation systems. The SSI has sub-indexes that consider the technical, social, and economic aspects of the sanitation system. All the variables are dimensionless and heavily dependent on the current state of the community, where the sanitation system is going to be implemented.
The applicability of the SSI was demonstrated by evaluating the implementation of two onsite sanitation systems, including one septic tank system and one resource-oriented sanitation (ROS) system in South Korea.
The results showed that for South Korea, which has a profound history of utilizing human waste as fertilizer, utilizing the resource-oriented sanitation system is more sustainable. However, it has a lower social sub-index score compared to the septic tank system.
Overall, the SSI can be a useful tool for sanitation system designers, managers, and developers. Meanwhile, decision-makers can also use it for comparing different systems and choose the most sustainable one for implementation.
The sub-indexes and their variables are based on the understanding of the sanitation status of the community, where the system is going to be implemented. Accordingly, the scope of the index is narrowed to one specific community. This means that the value of the index is specifically valid for a particular community and may differ between communities. This feature gives sufficient flexibility to the index, rendering it entirely replicable. Nevertheless, in case of the availability of sufficient data reflecting the nation-wide sanitation status, SSI can also be used to evaluate sanitation systems at a national level.
A notable feature of the SSI is its application in determining the fate of wastes as well as the economic and social aspects of a sanitation system. Considering the high potential of a ROS system for waste recycling, it can be concluded that it is entirely sustainable in both technical and economic aspects. For example, In the case of comparing the sustainability of onsite sanitation systems implemented Seoul, South Korea, the index clearly showed that the implementation of the ROS has a higher capital cost compared to septic tank system, with the potential for providing direct economic benefits, which can cover both capital and maintenance costs.
The reliability of the SSI was examined through Monte Carlo simulation to forecast the statistical distribution of the calculated SSI scores. It became clear that the results were within the 95% confidence interval. Accordingly, the index can be reliably applied to any other community with different settings when the only requirement for the SSI input is relevant local data.
More information about Hashemi’s Sanitation Sustainability Index is available in the published open accessed article here: https://doi.org/10.3390/su12176937