Wastewater - Turning Problem to Solution

Table 1.1: The connection between sustainable wastewater management, resource recovery and reuse, with key societal concerns.

Potential contribution to be gained from improved wastewater treatment, resource recovery and reuse

Societal concerns

Water security

Withdrawal of water resources continues to increase, with escalating costs and increasing pollution. A gap between water supply and demand of approximately 40 per cent is expected by 2030 if current practices continue (2030 Water Resources Group 2009). Closing this gap needs diversification of water supply sources, for both potable and non-potable applications, by integrating the use of unconventional water resources, including recovery from wastewater (Tzanakakis, Paranychianakis and Angelakis 2020) (see figure 1.3). The good news is that there is about five times more energy in wastewater than is required for its treatment (Hao et al. 2019). As the volumes of wastewater are expected to increase over time, by 2030, the energy embedded in wastewater could be enough to fulfil the energy needs of 196 million households, increasing to 239 million households by 2050 (Qadir et al. 2020). Another promising feature of wastewater is the nutrients it contains. Recovering these nutrients reduces dependence on high cost- and energy-intensive conventional fertilizers. Qadir et al. (2020) reported that the annual global volume of wastewater contains an estimated 16.6 million tonnes of nitrogen, 3 million tonnes of phosphorus and 6.3 million tonnes of potassium. Recovering these nutrients could offset 13.4 per cent of the global agricultural nutrient demand. Water is vital to peace and security (High-Level Panel on Water and Peace 2017). Sustainable management of wastewater can help contribute to achieving environmental security through not only optimizing how we use this resource, but also avoiding the environmental damage from pollution. Pollution, including from unmanaged or inadequately managed wastewater is recognized as one of the five direct drivers of biodiversity loss (IPBES 2019). In December 2022, a new global target was adopted under the Kunming-Montreal Global Biodiversity Framework, agreed at the 15th meeting of the Conference of Parties to the United Nations Convention on Biological Diversity, to “reduce pollution risks and the negative impact of pollution from all sources, by 2030, to levels that are not harmful to biodiversity and ecosystem functions and services, considering cumulative effects, including: reducing excess nutrients lost to the environment by at least half including through more efficient nutrient cycling and use…” (target 7) (Convention on Biological Diversity [CBD] 2022). The negative impact of excess nutrients in wastewater on aquatic biodiversity and ecosystem services is well documented (CBD 2022). Improving wastewater management will reduce pollutants entering receiving waters (including nutrients, harmful substances and plastics). Technologies exist to recover 75 per cent of nitrogen and 20–50 per cent of phosphorus for reuse in agriculture, while wastewater treatment technologies can reduce the concentration of nitrogen and phosphorus in wastewater by up to 80 per cent and 96 per cent, respectively (Kanter and Brownlie 2019). This would increase access to valued resources, reduce a key pressure on ecosystem integrity and contribute to alleviating one of the key drivers of biodiversity loss (CBD 2022).

Energy security

Food security

Environmental security

Biodiversity loss

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