Building highway landscapes: urban wastewater treatment in the face of new challenges in China

Urban development in China has brought about numerous challenges in urban water management, among which urban wastewater treatment is a crucial issue. With the increasing urban population and expanding urban areas, the demand for efficient and sustainable wastewater treatment solutions has become more urgent than ever. This paper proposes a comprehensive strategy for urban water management that integrates multiple disciplines, including ecology, civil engineering, landscape design, and agricultural irrigation. The strategy is demonstrated through a case study of a constructed wetland system designed for the Huai’an city wastewater plant in Jiangsu province, which is located along the East-route Water Transfer Project of China.

In 2010, according to the report from the National Bureau of Statistics of China, the urban population had increased by about 13.5% compared to the year 2000. This rapid urbanization has led to a significant rise in the volume of wastewater generated, putting immense pressure on existing wastewater treatment facilities. The traditional centralized wastewater treatment systems often face challenges such as high energy consumption, high infrastructure costs, and significant environmental impacts. Moreover, these systems may not be able to cope with the increasing volume and complexity of urban wastewater, necessitating the development of innovative and sustainable solutions.

Sustainable wastewater treatment aims to minimize environmental footprints, conserve resources, and promote long-term ecological balance. This approach involves using natural processes, such as constructed wetlands, to treat wastewater while also considering the potential for resource recovery and reuse. Constructed wetlands have been widely used worldwide to improve water quality for domestic reuse, irrigation, and environmental protection. These systems combine physical, chemical, and biological processes to remove contaminants from wastewater, and they can be designed to achieve high levels of treatment efficiency while also providing aesthetic and ecological benefits.

The proposed strategy for urban water management in China integrates four major green directions: ecology, civil engineering, landscape design, and agricultural irrigation. This multidisciplinary approach aims to address the challenges of decreasing water resources, wastewater treatment, limited spaces, and ecological preservation in a holistic and sustainable manner. One of the key components of this strategy is the use of constructed wetlands, which can be designed to treat wastewater while also enhancing urban landscapes and promoting biodiversity.

The design of a complex constructed wetland system for the Huai’an city wastewater plant in Jiangsu province serves as an exemplary demonstration of the proposed strategy. This system is designed to treat wastewater from the city while also providing ecological and aesthetic benefits to the surrounding area. The constructed wetland system incorporates various treatment processes, including sedimentation, filtration, biological treatment, and disinfection, to ensure high-quality treated water. Additionally, the wetland system is integrated with the East-route Water Transfer Project, which enhances its overall efficiency and sustainability.

Constructed wetlands play a vital role in urban wastewater treatment by providing an effective and sustainable alternative to traditional treatment methods. These systems can be designed to remove a wide range of contaminants from wastewater, including organic matter, nutrients, pathogens, and suspended solids. The treatment processes in constructed wetlands involve the combined action of physical, chemical, and biological mechanisms, which work together to purify the wastewater. For example, aerobic and anaerobic microorganisms facilitate the decomposition of organic matter, while microbial nitrification and denitrification processes convert nitrogen compounds into harmless gases. Moreover, constructed wetlands can also provide additional benefits, such as habitat creation for wildlife, carbon sequestration, and recreational opportunities.

Despite the potential benefits of sustainable wastewater treatment solutions, there are still several challenges that need to be addressed. One of the main challenges is the limited availability of space in urban areas, which can make it difficult to implement large-scale treatment systems. Additionally, the high initial investment costs and the need for specialized expertise in the design and operation of these systems can also pose barriers to their widespread adoption. However, there are also many opportunities for innovation and collaboration in this field. For example, the integration of green infrastructure components, such as rain gardens, bioswales, and green roofs, can help to manage stormwater runoff and reduce the load on wastewater treatment facilities. Moreover, advancements in technologies such as membrane bioreactors (MBRs), anaerobic digestion, and ultraviolet (UV) disinfection can further enhance the efficiency and effectiveness of wastewater treatment processes.

Urban wastewater treatment is a critical component of sustainable urban water management in China. The proposed highway landscape strategy, which integrates multiple disciplines and incorporates constructed wetlands as a key treatment component, offers a promising solution to address the challenges of decreasing water resources, wastewater treatment, limited spaces, and ecological preservation. The case study of the constructed wetland system for the Huai’an city wastewater plant demonstrates the feasibility and potential benefits of this approach. By adopting sustainable and innovative wastewater treatment solutions, China can move towards a more sustainable future, ensuring the protection of human health, the environment, and the efficient use of water resources.