Wastewater - Turning Problem to Solution

What are the resources that can be recovered from wastewater?

energy, and for sustaining environmental flows (box 5; figure 2.5). The cost and effort of recovery and benefits vary depending on the targeted resource(s) (figure 2.6). This section describes selected resource recovery with case study examples.

There are a range of resources that can be recovered from wastewater streams, including water, nutrients, energy and heavy metals, with a wide range of applications for domestic, agricultural and industrial uses of non-conventional water resources, fertilizers and

Box 5: Overview of the potential for resource recovery from wastewater

Water recycling

The full nutrient recovery potential from wastewater has been estimated to offset around 13.4 per cent (Qadir et al. 2020) of global fertilizer demand in agriculture and generate a revenue of approximately US$ 13.5 billion (as of 2015), (Qadir et al. 2020) noting that fertilizer prices in some cases doubled or trebled between 2020 and 2022 (FAO and World Trade Organization [WTO] 2022). In another study focusing on the use of human urine as a nutrient source, Simha (2021) projected that up to 25 per cent of the global demand for nitrogen and phosphorus from agriculture could be met by collecting and processing our urine. Benefits include: • increasing the self-sufficiency of energy-intensive water treatment plants • providing an alternative to fossil fuels Based on estimations of methane production, with an estimated global calorific value of 1908 × 109 million joules (MJ) (531 × 109 kilowatt hours [kWh]), and anticipating the average household electricity needs of 3 350 kWh (World Energy Council 2016), enough energy can be recovered to provide electricity for half a billion people (Qadir et al. 2020). Another alternative fuel source is the production of solid fuel briquettes from faecal sludge, which can provide a heating value of 25 MJ/kilogram, comparable to that of commercial charcoal briquettes (Ward, Yacob and Montoya 2014). Energy recovery

Benefits include: • reducing the demand on fresh water, especially for non-potable uses • providing a consistent supply of water in water stressed regions It is estimated that 160 per cent of the globally available water will be needed to meet the demands by 2030 (Vo et al. 2014). At the same time, wastewater volumes are increasing. To put wastewater as a potential alternative resource into perspective, Jones et al. (2021) estimated that the over 360 billion m 3 per year of wastewater produced is more than 10 times greater than the global desalination capacity (34.6 billion m 3 estimated in 2019 according to Jones et al. 2019). It is obvious that the potential of wastewater is drastically under realized, although it is predicted that the planned reuse of treated municipal water will increase 271 per cent from approximately 7 billion m 3 /year in 2011 to 26 billion m 3 /year in 2030 (Global Water Intelligence 2014). Benefits include: • reducing nutrient run-off into freshwater and coastal environments, reducing eutrophication and the development of dead zones in coastal waters and the ocean, leading to the recovery of freshwater and marine biodiversity, and supporting human activities such as fisheries • provide an alternative to chemical nitrogen (N), phosphorus (P) and potassium (K) fertilizers Nutrient recovery

Figure 2.5: Potential resources that can be recovered from wastewater.

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