As someone who cares deeply about the environment and the future of our cities, I’ve been fascinated by the growing trend of nature-based solutions (NbS) in wastewater treatment. It’s incredible to see how these innovative approaches can not only clean our water, but also deliver a host of additional benefits for people and the planet.
Unlocking the Power of Nature
NbS, as defined by the International Union for the Conservation of Nature, are actions that “protect, sustainably manage, and restore natural or modified ecosystems to address societal challenges effectively and adaptively, simultaneously providing human well-being and biodiversity benefits.” In the realm of wastewater treatment, these nature-based solutions harness the power of plants, soil, and other natural elements to remove pollutants in a sustainable, low-cost, and low-impact way.
The concept of using natural systems for wastewater treatment is not new. For centuries, communities have been discharging their wastewater directly into surface waters, leading to the development of natural wetlands that would effectively reduce pollutant loads. As populations grew and landscapes changed, however, the focus shifted towards more conventional wastewater treatment plants – often end-of-pipe solutions involving physical, chemical, and biological processes.
But now, there’s a growing realization that we can integrate the best of both worlds. By incorporating NbS into our wastewater management strategies, we can tap into the inherent treatment potential of natural systems while also unlocking a wealth of co-benefits that go beyond just water quality improvement.
Exploring Nature-Based Solutions in Action
Let’s take a closer look at some real-world examples of how NbS are being applied to wastewater treatment:
Slow-Rate Soil Infiltration
One well-established NbS approach is slow-rate soil infiltration, where primary or secondary wastewater is applied to a vegetated land surface. This not only provides treatment, but also serves as a form of irrigation for agricultural fields, pastures, or forest lands. The Lubbock Land Application System in Texas, USA, which has been in operation since the 1930s, is a great example of how this method can be a cost-effective and water-conserving solution, reducing the demand on freshwater resources.
Vertical-Flow Treatment Wetlands
Another innovative NbS is the use of vertical-flow treatment wetlands, as demonstrated in Shenzhen, China. These wetlands are designed to act as a polishing step to help meet environmental standards, with the treated wastewater being intermittently loaded onto the surface to percolate vertically through the system. The effluent from these wetlands not only improves water quality, but also serves as an additional source of water for the local river, while providing a green recreational area for residents and enhancing biodiversity.
Green Walls and Green Roofs
In dense urban areas, NbS like green walls and green roofs are being used to treat greywater, which can then be reused for purposes such as irrigation and toilet flushing. These systems not only provide effective water treatment, but also offer a host of co-benefits, including mitigating runoff, regulating microclimate, improving building insulation, and enhancing urban aesthetics. A great example is the demonstration project in Tilburg, Netherlands, where a green roof and treatment wetland were combined to reuse wastewater for toilet flushing, while also creating a green space that supports biodiversity.
Willow-Based Treatment Systems
Another emerging NbS approach suitable for peri-urban or rural settings is the use of willow systems – treatment wetlands dominated by willow plants. These systems are designed to treat all inflow water through evapotranspiration, resulting in a zero-discharge system with minimal environmental impact. The captured nutrients and carbon are bound in the willow biomass, which can then be harvested and used for energy or soil amendment purposes. An example of a successful application is the zero-discharge willow system on Zaeland Island, Denmark, which has been in operation since 2017.
Navigating the Complexities of NbS Implementation
While the potential of NbS for wastewater treatment is clear, it can still be challenging for wastewater utility managers and local governments to determine the best approach for their specific contexts. Factors like the type and combination of NbS, the quantity and quality of water to be treated, and local climate conditions all need to be carefully considered.
To help navigate these complexities, a web-based tool is currently under development that provides information on different NbS technologies, as well as case studies from around the world. This can serve as a valuable resource for communities looking to identify the most suitable NbS options for their wastewater treatment needs.
Integrating NbS into Policy and Practice
The growing recognition of the benefits of NbS is reflected in their increasing integration into policy and practice. The European Commission’s Horizon 2020 program, for example, has promoted the alignment of biodiversity and ecosystem services with goals of innovation, growth, and job creation. Similarly, the World Bank has integrated NbS into more than 100 projects across 60 countries, building a strong knowledge base to support their wider adoption.
Looking ahead, the COVID-19 recovery plans present a unique opportunity to “build back better” in a way that protects and restores the natural environment, addressing both climate change and promoting sustainable livelihoods. With three-quarters of the infrastructure we’ll need by 2050 yet to be built, it’s the perfect time to explore how we can incorporate nature into the very design of our cities and water systems.
Embracing the Future of Wastewater Treatment
As I continue to delve into this fascinating topic, I can’t help but feel excited about the future of wastewater treatment and the role that NbS will play. By harnessing the power of nature, we can not only clean our water more effectively and efficiently, but also generate a multitude of co-benefits that support the overall sustainability and resilience of our communities.
Alpha Wastewater, for example, is at the forefront of this movement, integrating nature-based solutions into their comprehensive wastewater treatment services. Their commitment to innovative, sustainable, and ecologically-minded approaches is truly inspiring and aligns perfectly with my own values and aspirations for a greener, more livable future.
As we continue to grapple with the challenges of urbanization, climate change, and resource scarcity, I’m convinced that NbS will play a crucial role in shaping the way we manage our water resources and build resilient, sustainable cities. It’s an exciting time to be part of this journey, and I can’t wait to see what the future holds.