This paper discusses the potential of wastewater as a resource and the associated challenges and opportunities. The paper starts with a brief explanation of the current global situation regarding wastewater and a simple overview of wastewater treatment, before going into more detail about the resources that can be recovered from it and how. To conclude, a summary of the challenges and opportunities involved in using wastewater as a resource is provided along with an overview of recent developments in the European Union.
Volumes of wastewater have been steadily increasing over time with the growing population, improvements in water supply, enhanced living standards and economic growth. Each year, 380 billion m3 of municipal wastewater are generated globally. Wastewater production is expected to increase by 24% by 2030 and 51% by 20502 . However, as the common perception remains that wastewater is a source of pollution that needs to be treated and disposed of, wastewater is perceived as a growing problem rather than a valuable and sustainable source of water, energy and nutrients.
A paradigm shift is currently underway, with developed countries taking a proactive interest in improved wastewater management. The goal is to go beyond pollution abatement and to seek to obtain value from wastewater. As a result, the wastewater sector in developed countries has started moving away from simply treating wastewater in wastewater treatment plants and has instead started seeing the potential of these plants as water resource recovery facilities. These recovery facilities can produce clean water, recover nutrients and reduce fossil fuel consumption through the production and use of renewable energy.
Despite the opportunities that wastewater presents, the global reality is that only a very small portion of the total wastewater produced is collected and treated, let alone exploited for the recovery of resources. It is estimated that, globally, over 80% of all wastewater produced is discharged into the environment without adequate treatment although the level varies across different regions.
According to UN Water, high-income countries treat on average about 70% of the wastewater they generate. Thisratio drops to 38% in upper middle-income countries and to 28% in lower middle-income countries. In low-income countries, only 8% of wastewater generated undergoes treatment of any kind.