Wastewater and the circular economy

Monday, 20 March 2017 11:50 GMT

Rice sprouts planted in the nursery are seen on a farm in Dabua, Bauchi, Nigeria March 2, 2017. REUTERS/Afolabi Sotunde

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A circular economy promotes sustainable social development by embracing principles of equity, justice and accountability

A circular economy balances economic development with environmental sustainability through the most efficient use resources. It seeks to minimize pollution, waste production and energy consumption, while maximizing the reuse and recycling of materials and improving the life-cycle of products. It involves applying cleaner production processes and integrated resource-based planning across industries, agriculture and urban areas. A circular economy also promotes sustainable social development by embracing principles of equity, justice and accountability.

Materials such as plastics and metals are recyclable but have a cradle-to-grave aspect – from their initial extraction/synthesis, through their (re)use and recycling, to their ultimate disposal. Water, on the other hand, is a naturally renewable resource. Although water too is extracted before use, and can be reused several times, it will inevitably find its way back to the natural water cycle (cradle-to-cradle) which is itself circular by definition.

Just as materials like tin, paper or plastic can be recycled through various chemical and physical processes (e.g. plastic can be melted and moulded into a new object), wastewater can be treated through chemical, physical and biological processes to be safely used over and over again (e.g. in the International Space Station).

Sustainable water management embraces all the features of a circular economy mentioned above – low consumption, minimizing waste and pollution, and high use efficiency. However, because of its very nature as the universal solvent, water is contaminated with additional substances every time it is used. For example, water used for agriculture may contain sediments, fertilizers and pesticides; water used for domestic purposes may contain human waste (rich in nutrients like phosphorus and nitrogen), microbial pathogens and a myriad household product from soaps to pharmaceuticals; water used by industry may contain a wide range of material from metals to persistent organic pollutants; and water used for power generation may contain excess heat.

In the context of a circular economy, it is the various contaminants of wastewater – or, more appropriately, its useful and recoverable by-products like nutrients, energy, metals, etc. – that make it unique compared to other substances.

Economically, the recovery of resources can provide additional revenue, thus helping to cover the overall costs of wastewater management and sanitation. Socially, lower costs improve the potential for expanding sanitation services, with significant implications for human health and wellbeing. And environmentally, improved levels of wastewater treatment enhance ambient water quality and water resource availability, which is of particular importance in areas facing recurring or chronic water scarcity.

In summary, the circular economy offers an additional and an affordable impetus for improved wastewater management through resource recovery.

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