The Circular Economy of Wastewater

Camilo Sánchez (ESR8)



Global warming is creating many life-threatening changes on our planet. To reduce the human impact on the earth, reduce inequalities and bring peace, the sustainable development goals (SDGs) have been set as a guideline. Many innovative ideas and concepts regarding the circular economy, sustainability, and environment-friendly processes are at the heart of the SDGs.

Working in the water field, I realized that apart from contributing to goal 6 (clean water and sanitation), water treatment technologies can contribute to achieving several SDGs simultaneously, such as sustainable agriculture (goal 2), clean energy (goal 7), and climate action (goal 13).

It is well known that water scarcity is a serious issue that affects around 25% of the global population, and this percentage keeps increasing. Water reuse has been considered the most feasible solution to mitigate water scarcity, especially in agriculture, the highest water-demanding sector. Nowadays, several regulations worldwide support water reuse in agriculture to reduce the water stress in the regions.

Before reusing, wastewater must be treated using different technologies to fulfill environmental and safety regulations. Usually, these technologies generate some secondary “waste” that must be managed correctly to avoid another negative ecological impact: sludge generation. Nevertheless, this sludge could be seen as a valuable product. From one side, it could be digested to produce biogas, a renewable energy source. On the other hand, it can be composted to create a natural fertilizer for agriculture.

In the level of decentralized communities, for example, in rural areas, especially in developing countries, there is an accessible wastewater treatment technology that could reuse water while producing energy for cooking: biodigester. In this system, biogas is produced while water is treated. Besides, this treatment technology has an additional advantage; the treated water keeps the essential nutrients for agriculture (nitrogen and phosphorous). Thus, the crops are fertilized while they are irrigated. From this perspective, biodigester is an affordable treatment that promotes sustainable agriculture and sustainable energy and contributes to the protection of the environment.

In that sense, wastewater treatment plants can be seen as recovery centers, considering their value. Other valuable by-products can be obtained, such as energy, fertilizer, and others. These recovery centers fulfill all the requirements to be considered a sustainable, eco-friendly, and circular system that contributes to a better world.

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