Development of ecological sanitation approaches for integrated recovery of biogas, nutrients and clean water from domestic wastewater

Water, sanitation, and hygiene (WASH) in developing countries are a serious concern and are responsible for millions of deaths every year worldwide (Uddin et al., 2015). About 36% of the global population lacks access to improved sanitation services, while nearly 1 billion people still lack access to clean drinking water to satisfy their daily requirements (WHO, 2006, Simha and Ganesapillai, 2017). Domestic wastewater is composed of black water (sources of pathogens), yellow water (from urine and rich in nutrients), and gray water (from shower drains and washing facilities) represents the largest portion of an overall wastewater flow. In developing countries, over 90% of the domestic wastewater is stored or discharged without any treatment to the nearby rivers, lakes and coastal areas causing serious ecological problems such as deterioration of water quality and the loss of biodiversity (Caspersen and Ganrot, 2018). It carries also various pathogenic agents that can cause several waterborne diseases such as cholera, dysentery, and typhoid (Taseli and Kilkis, 2016), which cause an increase in the global health burden (Moe and Rheingans, 2006).

In developing countries, conventional sanitation system still employs the “drop and store” and “flush and discharge” concepts to manage wastewater and to solve sanitation problems (Ganesapillai et al., 2015). In the highly populated areas of developing countries, digging a new pit or disposal into farmland when the old pit is full is mostly practiced as an alternative sanitation system (drop and store concept) that produces further problems and concerns to the agricultural and water sectors. These conventional sanitation systems had some short comings such as bad odor, vector attraction, and pathogenic contamination of soil and groundwater. In the other hand the conventional centralized wastewater treatment system which is known as water born sanitation system collects and transport wastewater via a sewer system, using potable water as transport medium and treat huge amounts of wastewater. But this system require the entire infrastructure, such as large pipelines and major excavations; consuming enormous amounts of energy and resources while still leaving a lot of emissions to eco-environments (Batstone et al., 2015). As a result, conventional sanitation systems, which focus on flush toilets and mixed-wastewater collection where huge amount of potable water used as transportation medium are neither ecologically nor economically sound sanitation system (Langergraber and Muellegger, 2005).

Therefore, there is a need to find an alternative sustainable sanitation approaches which considers human excreta and wastewater from households as a resource which can be reused. Ecological sanitation is an alternative and holistic sanitation approach to realize sustainable sanitation which is economically and ecologically sound. It is based on the closing of the nutrients’ loop between sanitation and agriculture for the full recovery of valuable resources from wastewater. For such a reason, introducing sustainable sanitation systems for the recovery of value-added products from human excreta and wastewater can become a useful tool for intervention as well as to contribute to the circular economy by recovering resources (biogas, fertilizer and clean water) to promote energy–food–water–health nexus (Batstone et al., 2015). With the growing interest of ecological sanitation approach to recover valuable resources from source separated wastes, yet there is gaps in knowledge and awareness about the application of this resource-oriented sanitation system for reclamation of mixed domestic wastewater. The aim of this paper was to review the application of ecological sanitation approaches for an integrated recovery of biogas, struvite and clean water from mixed domestic wastewater. Hence, the energy–food–water–health nexus assimilates thus valuable resources in the ecological sanitation platforms using different sustainable technologies.

source :

https://www.sciencedirect.com/science/article/pii/S2666916122000391