As a self-proclaimed eco-warrior, I’ve always been fascinated by the intersection of wastewater treatment and urban greenspaces. It’s a topic that not only speaks to my love of the environment but also my desire to create cities that are truly livable and sustainable.
In today’s rapidly urbanizing world, the challenge of managing wastewater has become increasingly complex. Traditional “end-of-the-pipe” solutions, while effective, often fail to consider the broader ecosystem and the potential for nature-based solutions (NBS) to deliver multiple benefits. That’s where the integration of wastewater treatment and urban greenspaces comes into play – a marriage of innovation, efficiency, and environmental stewardship.
Unlocking the Power of Nature-Based Solutions
Nature-based solutions, as defined by the International Union for the Conservation of Nature, are “actions to protect, sustainably manage, and restore natural or modified ecosystems that address societal challenges effectively and adaptively, simultaneously providing human well-being and biodiversity benefits.” In the context of wastewater treatment, these solutions can utilize the power of plants, soil, and other natural elements to remove pollutants in a sustainable, low-cost, and low-impact manner.
What’s truly exciting about NBS is their ability to go beyond just treating the wastewater itself. These approaches can provide a host of co-benefits, such as:
- Improving water quality and protecting downstream ecosystems
- Enhancing urban biodiversity and creating green spaces for recreation
- Mitigating urban heat islands and regulating local microclimates
- Reducing stormwater runoff and flood risks
- Enabling water reuse and contributing to the circular economy
In essence, NBS can transform wastewater treatment from a necessary evil into a holistic, nature-based solution that benefits both people and the environment.
Tried-and-True NBS Approaches
The use of NBS in wastewater treatment is not a new concept. For centuries, communities around the world have relied on natural wetlands and other ecosystem-based approaches to manage their wastewater. As our cities have grown and the demand for more sophisticated treatment methods has increased, these nature-based solutions have continued to play a crucial role.
One well-established NBS approach is slow-rate soil infiltration, where wastewater is applied to a vegetated land surface, allowing it to infiltrate into the soil and percolate to the groundwater or be recovered for reuse. This method not only treats the wastewater but also provides irrigation for agricultural fields, pastures, or forest lands. A prime example is the Lubbock Land Application System in Texas, which has been in operation since the 1930s and has demonstrated the cost-effectiveness and water-saving benefits of this approach.
Another NBS technology gaining traction is vertical-flow treatment wetlands, as seen in the case of Shenzhen, China. These wetlands are designed as a polishing step to meet strict environmental standards, with the treated wastewater serving as an additional source of water for the local river and providing a green recreational area for residents. The wetlands also offer habitat for plants and animals, enhancing local biodiversity and providing valuable ecosystem services.
Innovative NBS in Urban Spaces
As our cities continue to evolve, we’re seeing the emergence of even more innovative NBS approaches that are tailored to the unique challenges of dense urban environments. These solutions are not only effective in treating wastewater but also seamlessly integrate with the built landscape, providing a multitude of benefits.
One such example is the use of green walls or living walls for greywater treatment, as demonstrated in Marina di Ragusa, Italy. These modular systems, which incorporate plants, allow for the filtration and biological treatment of greywater, which can then be reused for irrigation and toilet flushing. Beyond their wastewater treatment capabilities, green walls also contribute to reducing the urban heat island effect and enhancing local aesthetics, promoting a more sustainable and livable urban environment.
Another innovative NBS approach is the combination of green roofs and treatment wetlands, as seen in a demonstration project in Tilburg, the Netherlands. This integrated system not only treats domestic wastewater locally but also transforms the roof into a thriving ecosystem that supports biodiversity. The green roof also helps regulate building temperatures, reducing the need for energy-intensive air conditioning and mitigating the urban heat island effect.
Willow Systems: A Circular Approach
In peri-urban or rural settings, the use of willow systems has emerged as a promising NBS for wastewater treatment and reuse. These treatment wetlands, dominated by willows, are designed to treat all incoming water through evapotranspiration, resulting in a zero-discharge system. The biomass produced by the willows can then be harvested and used for energy purposes or as a soil amendment, creating a fully circular operation with minimal impact on the surrounding environment.
An example of a successful willow system application can be found on Zaeland Island, Denmark, where a community of 190-250 person equivalents has been utilizing this approach since 2017. The system not only treats the wastewater but also provides habitat for flora and fauna, while contributing to flood mitigation efforts.
Navigating the NBS Landscape
With so many NBS options available, it can be challenging for wastewater utility managers and local governments to determine the best approach for their specific needs and context. To help navigate this landscape, a web-based tool is currently under development that includes information on various NBS technologies, as well as case studies from around the world.
This tool can serve as a valuable resource for communities to learn about the viable options and requirements for using NBS in their wastewater management strategies. It covers key aspects such as the potential co-benefits, the level of expertise and manpower required, and the potential biohazards associated with each solution.
However, it’s important to note that the selection and design of NBS should be based on a thorough understanding of local conditions, constraints, and the desired outcomes. Wastewater operators and decision-makers should seek further technical guidance and expertise to ensure the NBS or combination of NBS they choose is tailored to their specific context.
The Policy and Action Landscape
As the benefits of integrating NBS into wastewater treatment and urban design become increasingly recognized, we’re seeing these solutions gaining traction in the policy and action realms.
Within the European Commission, NBS have been a key focus of the Horizon 2020 program, a financial instrument aimed at promoting innovation and growth. Similarly, the World Bank has integrated NBS into more than 100 projects across 60 countries, recognizing their potential to address a wide range of urban challenges.
Looking ahead, the COVID-19 recovery plans present a unique opportunity to build back better by incorporating NBS into the design of future infrastructure. According to a recent UN working paper, three-quarters of the infrastructure that will exist in 2050 has not yet been built, and this provides a chance to explore how to include nature in its design.
Moreover, NBS are fundamental to meeting the Sustainable Development Goals (SDGs), particularly SDG6 (Clean Water and Sanitation), SDG13 (Climate Action), SDG14 (Life Below Water), SDG2 (Zero Hunger), and SDG15 (Life on Land). As the policy landscape continues to evolve, we can expect to see even greater support and resources for the implementation of these nature-based solutions.
The Future of Wastewater Treatment and Urban Greenspaces
As I reflect on the journey of wastewater treatment and urban greenspaces, I’m filled with a sense of optimism and excitement. The integration of NBS is not only a practical solution for managing our water resources but also a way to create more livable, resilient, and sustainable cities.
By embracing the power of nature, we can transform wastewater treatment from a necessary evil into a strategic asset that delivers multiple benefits to our communities. From enhancing biodiversity and improving urban microclimates to enabling water reuse and contributing to the circular economy, these nature-based solutions hold the key to a more harmonious relationship between our built and natural environments.
As we continue to navigate the complexities of urban development and environmental stewardship, I’m confident that the integration of wastewater treatment and urban greenspaces will be a critical component of the solution. And who knows, maybe one day, the sight of a lush, thriving treatment wetland will become as common in our cities as the towering skyscrapers that currently dominate the skyline.
If you’re as passionate about this topic as I am, I encourage you to explore the resources mentioned throughout this article and to connect with the Alpha Wastewater team. Together, we can shape the future of our cities and create a more sustainable, livable world for all.