Letting nature do the work: A self-sustaining wetland for rural sewage treatment
Published 02 March, 2026
The management of rural sewage faces significant challenges due to the dispersed settlements and inadequate infrastructure characteristics of rural areas. While constructed wetlands (CWs) are recognized as a viable nature-based solution, their long-term sustainability is often compromised.
Traditional systems depend on specific, non-native functional plants that require costly periodic replanting and maintenance, undermining ecological and economic viability. In a new study published in Water & Ecology, a research team led by Tianlong Zheng from Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences and Pengfei Cao from the Ministry of Water Resources, developed a horizontal subsurface flow constructed wetland (HSCW) that integrates native plants (Aster subulatus and Pterodactylus sp.) with a functional plant (Arundo donax) to create a self-sustaining, low-maintenance solution for rural sewage treatment.
"Out experiment centered on HSCWs treating rural domestic sewage," shares Zheng. "The system started with Arundo donax as the primary functional species but was deliberately designed to allow native species—Aster subulatus and Pterodactylus sp.—to spontaneously colonize and establish over time."
The system operated for 365 days without any human intervention, such as replanting or harvesting, simulating a real-world, low-management scenario.
"The performance of this self-regulating HSCW was remarkably stable. It achieved mean removal efficiencies of 35.05% for chemical oxygen demand (CODCr), 48.92% for ammonium nitrogen (NH₄⁺-N), 40.57% for total nitrogen (TN), and 27.61% for total phosphorus (TP), with effluent meeting stringent Chinese discharge standards," syas Zheng.
This stable performance was underpinned by a more resilient microbial ecosystem. High-throughput sequencing revealed that the multispecies plant community fostered a more diverse and functionally versatile microbial consortium compared to monoculture systems, with Proteobacteria, Actinobacteriota, and Bacteroidota as the core phyla.
"Native plant polyculture enhanced microbial diversity and stability and reduced reliance on artificial maintenance," explains Zheng. "Our findings demonstrate that leveraging natural plant symbiosis in CWs enhances ecological and economic sustainability by promoting microbial resilience and self-regulating nutrient cycling."
Furthermore, metagenomic analysis pinpointed the core self-sustaining mechanism: highly adaptable microbial metabolic pathways for nitrogen and phosphorus cycling, driven by plant interactions. For nitrogen metabolism, the rhizospheres of the native plants Aster subulatus and Pterodactylus sp. exhibited a higher abundance of key functional genes (e.g., nirB, nirD, nrfH) compared to Arundo donax. This highlights a plant-driven niche differentiation.
"The synergy among Aster subulatus, Pterodactylus sp., and Arundo donax optimizes wetland nitrogen cycling by creating complementary aerobic and anaerobic zones. Simultaneously, the phosphorus metabolism pathway demonstrated remarkable seasonal adaptation," further explains Zheng. "Genes like ppk (for polyphosphate synthesis) were upregulated in winter as a microbial cold-adaptation strategy, while genes like pit and ugpB (for phosphorus uptake) more abundant in summer due to higher demand."
This regulation underscores a key finding: Aster subulatus, Pterodactylus sp, and Arundo donax synergistically regulate phosphorus metabolism through acid exudation, microbial hosting, and oxygen release.
Taken together, the findings offer a practical, scalable, and sustainable model for decentralized wastewater treatment, particularly suited to resource-constrained rural regions, aligning ecological principles with engineering solutions for long-term environmental management.
Contact author name, affiliation, email address:
Pengfei Cao, caopengfei84@163.com
-The Department of Policy Research, Water Conservation Promotion Center of the Ministry of Water Resources, Beijing 100038, China
Tianlong Zheng, tlzheng@rcees.ac.cn
-State Key Laboratory of Regional Environment and Sustainability, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
-University of Chinese Academy of Sciences, Beijing 100049, China
Funder:
This work was supported by Jing-Jin-Ji Regional Integrated Environmental Improvement-National Science and Technology Major Project [2025ZD1205400, 2025ZD1205403], the Central Guidance Local Science and Technology Development Fund Project (Grant No.2024ZY0130), Key R&D Program of Zhunger Banner (Grant No. 2024YF-07), National Natural Science Foundation of China (Grant No. 51838013), National Key R&D Program of China (Grant No. 2020YFD1100500), the Project of Inner Mongolia “Prairie Talents”Engineering Innovation Entrepreneurship Talent Team, and the Innovation Team of the Inner Mongolia Academy of Science and Technology (CXTD2023-01-016).
Conflict of interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.