By Michelle A. Urrea Vivas
Water is such a valuable resource for human beings that we no longer have the luxury of wasting since it is not an infinite resource.
Our present day water situation is the result of human negligence and behaviors that have destroyed this natural resource. The scarcity of water, its over-exploitation, contamination by industrial, commercial, agricultural, and residential activities evidences how inefficiently and unsustainably this resource has been handled, to date. What is the scarcity of water and how does this affect more than 40 percent of the global population? Water scarcity is the lack of water resources to satisfy the intake of water by a population and the development of community activities, in other words, it is the imbalances between availability and demand. Water scarcity is measured through the water/ population ratio. An area will experience water stress when its annual water supply falls below 1,700 m3 per person. When that same annual supply falls below 1,000 m3 per person, then we speak of water scarcity. And absolute scarcity of water occurs when the rate is less than 500 m3. For example, Middle East and North Africa are home to the largest number of countries that experience scarcity of water. One reason is that approximately 70 percent of all water abstracted from rivers, lakes and aquifers is used for agriculture irrigation and industrial processes, and the remainder is caused by the absence of infrastructures that ensure good management of water resources.
If we do not change our behaviors the end result will be devastating for humanity.
How can we avoid water stress through a circular economy model?
Throughout evolution, our economic systems have never moved beyond one fundamental characteristic established in the early days of industrialization: a linear model of resource consumption that follows a ‘take-make-dispose’ pattern. Global reasoning cannot continue to be based on the fact that resources are infinite, available, and cheap to eliminate. The circular economy model boosts all the processes as a system that is designed to be restorative and regenerative.
Water is one of the sectors that has opted for a metamorphosis in its management model. The main focus of this change is to maximize the efficiency of water resources, moving from a linear economy that is essentially based on extraction, usage, and pouring towards a circular economy where wastewater is purified and regenerated and then re-integrated back into the supply cycle as a new resource.
Most developing countries use an outdated linear economy model that is ineffective in managing water supply problems and needs. The water crisis arises from the discharge of wastewater into natural water sources, combined with water run-off from the agricultural and livestock sector, and wastewater that is inadequately treated by industries. All of these faulty processes lead to exceeding the regeneration limits of natural systems.
Water management worldwide must start from the challenge of meeting the demand for water while being sustainable, which implies not affecting or generating a negative impact on the contributing system, regardless of factors such as population growth or accelerated urbanization.
The rhetorical and controversial questions that countries ask themselves are: How to manage the water demand increase of 55 percent by 2050; if currently, 3 out of 10 people lack access to safely managed drinking water services and 6 out of 10 people lack access to safely managed sanitation facilities? How will the countries reduce 80 percent of wastewater from human activities discharged into rivers and aquifers without a pollution removal process? Will it be possible to reuse the reclaimed water for irrigation in agricultural sectors and reduce 70 percentof the water exploitation of rivers and aquifers. Moreover, how to avoid a panorama of uncertainty that threatens millions of people who will potentially lose access to drinking water? The solution to the problem is simple; it is transforming from a linear model into a circular economy model.
Water management based on the circular economy: Water is a vital but scarce resource.
The concept of circular economy simulates or replicates the behavior of natural systems. Therefore, the life of the water continues to be used over and over again in repeating cycles; this allows us to convert the wastewater into a new constant source of resource, avoiding an imbalance in the environment due to exploitation or contamination. Some estimates show that each inhabitant needs a minimum of 1,500 m3/year of water to meet their needs, but currently, the volume of renewable water available per inhabitant is less than 2,000 m3/year, for an approximate population of 7,700 million inhabitants (2020). These data show that not only the serious current situation of drought in aquifers and rivers, but also the destruction of natural ecosystems and the human struggle for access to drinking water.
Fig.1. Reuse of wastewater in the Circular Economy.
For example, regenerated wastewater can be used in agricultural irrigation, aquifer recharges, firefighting, industrial processes, and for irrigation of green areas. Reuse will avoid the net consumption of freshwater, reducing the environmental impact and generating cost savings associated with combating the problem of restoring water sources and contaminated soils. The circular economy model not only manages to regenerate and reuse wastewater, but also, in turn, it manages to generate by-products such as sludge, which after being subjected to different processes, can be used for agriculture, the cement industry, the production of compost, and for the restoration of degraded soils. A by-product of sludge processing is biogas which can be used as fuel for self-consumption in the treatment plant or another uses. This efficient use of biogas allows saving in the energy expenditure required by the wastewater treatment plant, implementing and innovating a sustainable method in the use of all the subproducts generated in the process (the implementation costs depend on the type of treatment that is selected and its characteristics).
That said, we can compare the circular economy with the first law of thermodynamics "Matter is neither created nor destroyed, it only transforms." The interpretation revolves around the exploitation and use of natural resources, which will become part of the environment in the form of waste in the short or long term. For example, Israel focuses on encouraging, promoting, and educating its citizens to be aware of the importance of the proper use of water resources in arid and desert areas. Israel reuses 85 percent of its wastewater, and almost 50 percent of recycled water is used in agriculture. It is exactly this circular economy model that makes Israel stand out as one of the largest water desalinators in the world, supplying almost 80 percent of its population with water from the sea. Currently, the desalination plant is trying to reduce the consumption of fossil fuels with the implementation of new technology and devices that allow maximizing energy recovery. This energy recovery is necessary because it is counterproductive to the process to use fossil fuels that release a large amount of Sulphur dioxide and Nitrogen, which when in contact with the gases in the atmosphere, precipitates in the form of acids, generating acidification in the water, causing damage to vegetation and polluting the soil and water.
CIRCULAR ECONOMY AND WATER MANAGEMENT MODELS.
The circular economy allows for the interaction of different water management models, managing to monitor and control the fluctuations of water used in the production processes of a good or service. For the implementation of a circular economy model, it is necessary to analyze:
1. Consumption of freshwater: Frankly, there is nothing we use, eat or buy that does not have water in its contents, so it is necessary to determine the amount of water used to produce a product and calculate how much impact it has exerted on the water resource. The analysis of the water footprint includes an essential question: What is the water footprint from the perspective of the production or consumption of a good or service? The answer for the first factor is mainly based on how much water was used for the production of that good or service at the local level, and consumption level is calculated as the sum of all goods and services that were consumed by the inhabitants of a country.
2. Virtual flows of water in product imports and exports: Countries boost their economies through imports and exports of goods and services, but it is unknown which products are made up of virtual water. The countries that suffer from water stress tend to import products whose production requires large quantities of water, helping them to alleviate the pressure exerted on their water resources; however, many times, the environmental impact that is generated at the time of marketing these products is not considered, this means that negative externalities are not quantified and not transferred to the producer of the good or service. For example, the production of beef requires 15,400 liters per kilogram, but when the final product is exported to other countries, the associated costs incurred by pollution caused by wastewater and deforested areas are not transferred. Therefore, the government and citizens have to pay for these impacts generated.
3. Synergy of a circular economy, water footprint, and virtual water flow: Boosting the innovation in the water sector is essential if we want to continue living on this planet. The dividing lines of each country make each one focus on being able to achieve a circular economy model that is efficient and sustainable, but, first of all, planning of the interactions between the productive sectors and the natural water cycle is required. The change in the circular economy business model should not only innovate in wastewater regeneration techniques but also the optimization and reduction of water consumption and pollution load, allowing a balance to be generated by alleviating the burden of overexploitation on natural resources and ecosystems.
Countries are increasingly aware of their responsibilities to mitigate the environmental impact of the over-exploitation and contamination of water resources. The circular economy model allows the full regeneration and reuse of wastewater, minimizing the net demand for water in high-consumption sectors such as agriculture or industry, as well as reducing the pressure generated in natural systems (rivers and aquifers) and minimizing the discharge load of contaminated water to drinking sources. The adoption of this model facilitates managing the water footprint when producing a good or service, focusing on strategies that reduce water consumption in sectors that suffer from water stress. Therefore, this water management model will contribute to the security of supply for future generations.
About the Author:
Michelle A. Urrea Vivas is a PhD candidate in Environmental Engineering from the Polytechnic University of Catalunya. She also has a Masters in Environmental Engineering from the Polytechnic University of Catalunya, Industrial Engineering degree from the Agraria University of Colombia, and Law degree from the Republicana University. Currently Michelle works as a consultant and researcher on environmental and sustainability issues, focused on climate change, circular economy, renewable energy, economic policy and project management for the regeneration and reuse of wastewater.