The causes for this increase are mainly population growth, the rapid urbanization to which is added the development of water supply and sanitation systems, and the improvement of lifestyles.
Four billion people (almost two-thirds of the world’s population) currently live in areas affected by water scarcity for at least one month each year. Lack of non-renewable resources, such as fossil groundwater, will force to transfer water from areas rich in water or to displace people in case of severe water scarcity. Climate change will aggravate the scarcity of water issues because the variations of the water cycle increase the gap between water demand and water supply, exacerbating the extreme events at the local level (floods and droughts).
The availability of water resources is strictly linked to water quality, because the increase of agricultural runoff and untreated wastewater from industry or domestic use lead to the degradation of the environment and the water sources, deteriorating the water quality in the world. If this trend remains unchanged over the next few decades, especially in countries in arid areas, water quality degradation will further contribute to water scarcity, endangering human health and ecosystems, and holding back sustainable development.
Therefore, wastewater is a crucial component of water resource management. Neglecting wastewater issues generates significant negative impacts on the environment, the occurrence of waterborne diseases ue to the use of contaminated water sources, and the well-being of communities [3]. Underestimating the impacts related to wastewater means seriously compromising the achievement of the Sustainable Development Goals (SDGs) of the 2030 Agenda.
The achievement of this target is critical for achieving the entire 2030 Agenda and, in particular, for SDGs concerning health, education, cities, and industry.
Freshwater withdrawn for human activity stands at nearly 4000 km3/year across the globe. 56% of it is discharged as wastewater from urban and industrial activities or drainage from irrigation water. High-income countries collect and treat the majority of wastewater worldwide. In these countries, around 70% of urban and industrial wastewater is treated.
Upper-middle-income countries treat only 38%, for lower-middle-income countries the ratio is 28%, while, in low-income countries, only 8% is treated. In developing countries, the release of untreated wastewater remains a common practice due to lacking infrastructure, technical and institutional capacity, and financing. Wastewater management services are generally inadequate, thus wastewater treatment and disposal is a matter of concern that needs to be addressed.
Considering the figures related to Africa, the situation is critical. Africa is the second driest continent after Oceania and less than 9% of the global renewable water resources (3930 km are located there. Moreover, there is also a huge disparity across African countries, ranging from 25 m3/inhabitant/year of renewable water in Egypt to 121,000 m inhabitant/year in Gabon.
Only a few of the 54 African countries—and almost all located in the northern region—met the Millenium Development Goal (MDG) target for sanitation. Nearly 750 million people (69% of the African population)—mostly in sub-Saharan countries—did not have access to improved sanitation services in 2017.
A Guest Editorial