As we stare down the barrel of a global water crisis, it’s clear that our traditional linear approach to water management is hopelessly outdated. Three billion people will join the global consumer class over the next two decades, accelerating the degradation of natural resources and escalating competition for them. Nowhere is this growing imbalance playing out more acutely than in the water sector.
Already, scarcity is so pronounced that we cannot reach many of our desired economic, social, and environmental goals. If we continue with business as usual, global demand for water will exceed viable resources by 40% by 2030. The future is bleak unless we take drastic action.
But what if I told you that the solution lies in embracing the principles of the circular economy? By redefining how we view and manage our most precious resource, we can transform the future of water and create a more sustainable, abundant, and prosperous world.
Escaping the Linear Trap
At the heart of our water crisis lies a fundamental flaw in how we think about this vital resource. For too long, we’ve pushed water into a linear model, where it becomes successively more polluted as it travels through the system, rendering future use impossible. This practice transforms our most valuable and universal resource into a worthless trickle, creating high costs for subsequent users and society at large.
Even countries with advanced water-management systems violate these fundamental rules. They often fail to purify water before discharging it back into the environment because the cleanup costs are high or prohibitive, even when energy or valuable chemicals could be extracted. The substances contained in the water then become pollutants, compounding the problem.
Equally troubling, any volume of water removed from the system is seldom replaced with a return flow of the same quality. This zero-waste imperative, the principle that lies at the heart of any circular economy, is routinely violated.
Embracing a Circular Approach
To break free from this linear trap, we must instead view water as part of a circular economy, where it retains full value after each use and eventually returns to the system. And rather than focus solely on purification, we should attempt to prevent contamination or create a system in which water circulates in closed loops, allowing repeated use.
This shift in mindset requires radical solutions, but it must happen immediately given the urgency of the situation. The global water crisis is real and graphically manifest, as evidenced by rivers that no longer reach the sea, exhausted aquifers, and polluted water sources like Lake Tai, one of the largest freshwater reserves in China.
When considering a redesign that will create a new circular water system, we can take three different views:
Water as a Product: If we consider water to be a product that is processed, enriched, and delivered, we must follow the same strict design rules applied to any other product in a circular economy.
Water as a Durable: When water is treated as a durable, it should be kept in a closed loop under zero-liquid-discharge conditions and reused as much as possible. The major goal is not to keep water free of contaminants, but to manage the integrity of the closed-loop cycle.
Water as a Consumable: When water is treated as a consumable, it must be kept pure and only brought into solution or suspension with matter that is easy or profitable to extract. All water, including freshwater and gray water (household waste water still fit for agriculture or industrial use), should flow into subsequent cascades where it may be used for another purpose.
Innovative Solutions for a Circular Water Future
Thankfully, we’re witnessing significant improvements in the way we treat and manage water, paving the way for a more circular future. Let’s explore some of the exciting innovations that are redefining the water landscape:
Extracting Energy and Nutrients
It is now commercially viable to generate heat and power from sludge and other organic wastes through thermal hydrolysis, which involves boiling them at high pressure followed by rapid decompression. This process sterilizes the sludge and makes it more biodegradable, as seen in facilities like the Billund BioRefinery in Denmark.
We can also recover a wide variety of substances from water, reducing both waste and costs. For instance, the potassium hydroxide used to neutralize the hydrofluoric acid in alkylation units can be extracted, decreasing costs for this substance by up to 75%. Substances can also be removed from sludge, such as polyhydroxyalkanoates and other biodegradable polyesters.
The technology has advanced so much that value can be obtained from substances that were formerly only regarded as contaminants. Ammonia removed from water, for example, can be used in the production of ammonium sulfate fertilizer rather than simply discarded.
Reusing Water through Innovative Treatments
We are witnessing significant improvements in membrane-based treatments that separate water from contaminants, allowing for reuse and commercialization at a grand scale. Many types of water benefit from this treatment, from gray water to Singapore’s branded NEWater, which is high-grade reclaimed water.
In fact, NEWater is so pure that it is mainly used by water-fabrication plants that have more stringent quality standards than those used for drinking water. In addition to innovative membrane-based technologies, experts have developed new source-separation systems that reduce mixing between chemical-carrying industrial and household wastewater, making purification easier.
Preventing Impurity and Contamination
While we should celebrate these improvements in treating water and safely returning it to the system, the creation of a truly circular economy will eventually require even more radical solutions. Achieving this would require the prevention of impurity and contamination in the first place.
In the European Union, for instance, 95 kilograms of nitrate per hectare are washed away from fields into rivers, an amount higher than the 80 kilograms allowed. Discontinuing this process would reduce both waste and contamination.
Similarly, in Saudi Arabia, where water used for agriculture comes almost exclusively from fossil aquifers that will be depleted in a few decades, future efforts must involve new irrigation sources such as gray water and follow more stringent guidelines for reducing waste.
Unlocking the Circular Water Economy
The shift to a circular water economy holds much promise. It would replace scarcity with abundance and greatly reduce the resources needed to run our global water infrastructure. At some point, a circular water economy might even eliminate rapidly growing cleanup costs because no harmful substances would ever be added to the water supply.
As the single most important shared resource across all supply chains and the largest untapped waste category, water is the natural starting point for the circular revolution. The water sector’s advanced technologies and proven record of multistakeholder agreements also lend themselves to circular solutions.
But to capture this unique opportunity, we must act now. Innovative utilities, product designers, and basin managers are already spearheading the creation of new technological solutions, pilot cases, and initiatives to improve water management. Many of these technologies are already generating profits or will be soon, including the bespoke polymers created during the biological digestion of wastewater and vapor-transfer irrigation systems that use low-cost plastic tubes to allow water vapor to pass but not water or solutes, making saltwater irrigation possible.
As we move forward, there are five key ideas that stand out as attractive integrated plays to drive the much-needed system-level transition from today’s linear model to tomorrow’s circular design:
Product-Design Partnerships: Wastewater operators should offer their expertise to producers and initiate product-design partnerships to ensure that water stays pure after use.
Resource-Positive Utilities: Wastewater utilities should champion further advances, including those that aim to convert wastewater to energy, integrate grids, and recover nutrients.
Management for Yield: Improved site-level water management can increase yields and create significant value, turning water into a major value driver.
Basin Management: Connecting interested parties and minimizing the bureaucracy associated with basin-management agreements can help protect floodplains and prevent freshwater contamination.
Local Organic Nutrient Cycles: Aggregating local organic waste flows can help communities deal with their sludge and fragmented contaminated streams while also creating vibrant local markets for fertilizer components.
The time for action is now. By embracing the principles of the circular economy and harnessing the power of innovation, we can redefine the future of water resource management and ensure a more sustainable, abundant, and prosperous world for all. Let’s dive in and make it happen!