Wastewater - Turning Problem to Solution

Box 3: Wastewater reuse and climate change

Water security is critical to achieve the SDGs and will require climate-resilient, circular solutions (IPCC 2022), including in the wastewater sector. Climate change is projected to increase variability in weather patterns and rainfall, with around half of the world’s population facing severe water scarcity for at least one month per year (IPCC 2022). This affects people’s access to safe water, in particular vulnerable groups, including women, children and older persons. For example, as water scarcity increases the amount of water available for farming decreases, particularly the informal sector on which women are particularly dependent. This results in greater vulnerability to income and food security (Food and Agriculture Organization of the United Nations [FAO] 2017). Extreme conditions also disrupt wastewater collection and treatment services. The wastewater sector produces emissions from the organic breakdown of matter, which are important sources of methane and nitrous oxide, both powerful greenhouse gases (GHGs), particularly over the short term (Bartram et al. 2019). Globally, wastewater and sludge management are responsible for 257 million tonnes of carbon dioxide equivalents, almost half being energy-related emissions. In addition, 267 million tonnes

of carbon dioxide equivalents from on-site sanitation. It also estimates that nitrous oxide is responsible for 32 per cent of emissions from sewered wastewater treatment (Lutkin et al. 2022). It is estimated that the degradation of organic matter during wastewater treatment contributes ~1.57 per cent of global GHG emissions and 5 per cent of global non-carbon dioxide GHG emissions (Dickin et al. 2020). In addition, the conventional treatment processes to deal with wastewater are energy intensive and are estimated to account for 3 per cent of global electricity consumption (Dickin et al. 2020). As countries implement measures to increase wastewater treatment, towards the ambitions of SDG 6.3, these figures are likely to increase. For example, increased urbanization and consequently an increase in wastewater treatment plants has meant emissions from domestic wastewater increased 400 per cent between 2000 and 2014 (Du et al. 2018) and still requires significant increase in treatment capacity by 2030 to meet the target (Jones et al. 2022). Water was identified as an imperative for climate action at the Conference of the Parties to the United Nations Framework Convention on Climate Change in November 2022 (COP 27), with calls for a more integrated, circular approach to water management, and the potential

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