**3. Circular economy and brines**

### **3.1 Why apply circular economy?**

The world is changing; the economic, environmental, and social challenges facing today's society are becoming increasingly demanding. In this sense, the principle of the "circular economy" is a good way to make this approach more sustainable [39]. Whereas, over the past 10 years, private/public sector actors, governments, policymakers, citizens, the media, and the scientific community have been working to make the world more sustainable [41], changing the economic model from extract-usedispose to an extract-use-reuse model. Thus, the circular economy seeks that system resources, energy, and materials are reused several times, considering a minimum processing for each subsequent use, through a closed loop. In other words, turning waste into a resource is an essential part of increasing our efficiency and moving toward a more circular economy [8].

In relation to the circular economy in water, in addition to complying with the reuse of this good, its quality and quantity must be prioritized [42]. Therefore, evaluating brine disposal management measures is an alternative to consider, depending on factors such as: (a) the volume or quantity of the concentrate, (b) quality of the concentrate, (c) physical and geographic location of the discharge point, (d) capital and operational costs, among others [43].

## **3.2 Circular economy principles**

In addition, it is worth mentioning that the Office of Agricultural Studies and Policies, 2019 [44], proposed 3 principles and 11 strategies of circular economy, based on theWorld Economic Forum, 2018. Each principle is related to the strategies defined as follows:

### **Principle 1 Plan for the optimal use of resources**

Design (R1): Integrate environmental impact in the development of products and services.

Reduce/Prevent (R2): Avoid use of unnecessary resources and prevent waste generation.

Optimize (R3): Maximize the usefulness of products, materials, resources, and assets. **Principle 2 Maximize the usefulness of materials at all times**

Reuse/Distribute (R4): Take advantage of discarded or old products in good condition so that they fulfill their original function.

Repair (R5): Repair defective or old products to fulfill their original function. Remanufacture (R6): Capture the value of components of discarded products to fulfill an original function, a new product.

Revaluate (R7): Transform discarded products, parts, or waste to condition a new function by capturing the value of materials.

Recycle (R8): Process materials to obtain products of equal or lower quality. Recover (R9): Energy recovery by incineration of materials.

**Principle 3 Preserve and improve the natural capital**

Regenerate (R10): Regenerate natural ecosystems to promote positive impact on the environment.

Supply (R11): Procure sustainable supply of inputs with the least environmental impact.
