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Updated: Aug 5, 2026

Mesocosm-Scale Constructed Wetland Design for Wastewater Treatment
Published on: May 2, 2025
Substrate-Sequence Effects on Pollutant Removal and Microbial Succession in Modular Constructed Wetlands Under
Yansong Wang1, Renxu Wang2, Yongchen Zong2
1Research Center of Civil, Hydraulic and Power Engineering of Xizang, Department of Education of Xizang Autonomous Region, Xizang Agricultural and Animal Husbandry University, Linzhi 860000, China.
None:
Constructed wetlands operated in plateau habitats may experience constrained biological treatment because low temperature, low atmospheric pressure, and low-carbon wastewater can jointly limit microbial metabolism. This 80-day pilot screening study evaluated three nonreplicated modular constructed wetland configurations (MCW1-MCW3) containing different sequences of zeolite, ceramsite, and quartz sand and planted with Veronica anagallis-aquatica. Each configuration consisted of one independent treatment train; therefore, the comparisons were interpreted as configuration-specific and exploratory rather than as statistically generalizable treatment effects. Pollutant-removal performance and microbial community succession were evaluated through repeated water-quality monitoring and 16S rRNA gene sequencing. MCW1 showed the highest observed mean NH4+-N removal efficiency (88.6%), whereas MCW3 showed the highest observed mean TP and COD removal efficiencies (79.56% and 47.40%, respectively) and an NH4+-N removal efficiency of 85.51%. TN removal by MCW3 remained limited at 20.49%, consistent with carbon limitation of denitrification. Under the naturally low-temperature plateau laboratory conditions, the observed COD reduction indicated partial mineralization or retention of organic pollution loads, potentially supported by substrate biofilms and cold-adapted microbial assemblages. Apparent module-contribution analysis suggested that zeolite contributed substantially to NH4+-N reduction, whereas ceramsite contributed to TP and COD removal under the tested sequences. Because plant biomass and tissue nutrient contents were not measured, nitrogen and phosphorus removal could not be attributed quantitatively to hydrophyte uptake. Overall, substrate sequence influenced pollutant-removal patterns and microbial community assembly, providing preliminary evidence for habitat-adapted optimization of modular constructed wetlands for plateau domestic wastewater.
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