Constructed Wetlands in China: A Comprehensive Opinion of Technological Innovations, Large-scale Implementation, and Future Sustainability Challenges

Abstract

Constructed wetlands (CWs), as an eco-friendly wastewater treatment technology characterized by low investment and minimal energy consumption, are increasingly integral to global water environment management. This paper offers a systematic review of their international development and deployment, with particular emphasis on China’s innovative large-scale implementations and distinctive technological syntheses. Using the case of Shandong Mata Lake, this study demonstrates the effectiveness of a three-stage “treatment, utilization, and preservation” model in significantly improving water quality from below Grade V to Grade III standards, successfully raising regional groundwater levels by up to 5.2 meters, and enhancing local biodiversity. To counter efficiency loss in cold regions and limitations in treating low carbon-to-nitrogen wastewater, major technological advances are examined—including sulfur autotrophic denitrification that achieves over 95% total nitrogen removal without supplemental carbon—as well as novel functional fillers and intelligent operational tactics such as fouling prediction with 92.6% accuracy. The analysis further identifies persistent challenges such as reduced winter performance, heightened CH₄ emissions under saline conditions—reaching 4.2 times the global warming potential of conventional systems—and a lag in standardized design and ecological service valuation. Future development should prioritize resilient plant-microbe systems, flow optimization to cut CH₄ emissions by 30% via smart control platforms, and improved carbon accounting and biodiversity certification frameworks. These innovations will advance CWs toward intelligent, resource-recovering ecosystems capable of supporting closed-loop functions spanning wastewater treatment, energy recovery, and agricultural reuse, ultimately reinforcing their critical role in global carbon neutrality and sustainable aquatic ecosystem restoration.