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Updated: Jul 12, 2026
08:24
Mesocosm-Scale Constructed Wetland Design for Wastewater Treatment
Published on: May 2, 2025
Nitrogen dynamics in a constructed wetland system treating landfill leachate
C B Kinsley1, A M Crolla, N Kuyucak
1Campus d'Alfred--Université de Guelph, 31 St. Paul St., Alfred, Ontario, K0B 1A0, Canada. ckinsley@alfredc.uoguelph.ca
Summary
This pilot study demonstrates a multi-stage landfill leachate treatment system achieving high removal rates for biochemical oxygen demand (BOD5), total Kjeldahl nitrogen (TKN), and ammonium-nitrogen (NH4-N). The system effectively removes pollutants, even under increased loading conditions, showcasing its potential for effective wastewater management.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Waste Management
Background:
- Established a pilot-scale leachate treatment system at Laflèche Landfill, Canada in 2002.
- The system comprises a stabilization basin, peat trickling filter, subsurface flow wetland, surface flow wetland, and polishing pond.
- Operated from May to December, with leachate recirculation during winter months.
Purpose of the Study:
- To evaluate the performance of a multi-stage constructed wetland system for landfill leachate treatment.
- To assess pollutant removal efficiencies under progressively increasing hydraulic and organic loading rates.
- To determine the treatment capacity of the peat filter and evaluate kinetic models for nitrogen removal.
Main Methods:
- Implemented a series of treatment units: stabilization basin, peat trickling filter, subsurface flow (SSF) wetland, surface flow (FWS) wetland, and polishing pond.
- Increased hydraulic loading threefold and nitrogen/organic mass loading sixfold over four operating seasons.
- Applied first-order plug flow kinetic models to analyze total Kjeldahl nitrogen (TKN) and ammonium removal.
Main Results:
- Achieved excellent removal efficiencies: 93% BOD5, 90% TKN, and 97% NH4-N under highest loading conditions.
- Observed near-complete denitrification with nitrate-nitrogen (NO3-N) concentrations consistently below 5 mg L(-1).
- Peat filter reached capacity at 4 cm d(-1) hydraulic loading and 42 kg BOD ha(-1) d(-1) organic loading; kinetic models showed lower TKN removal rates than literature, suggesting refractory organics in leachate.
Conclusions:
- The multi-stage constructed wetland system is highly effective in treating landfill leachate, achieving significant reductions in key pollutants.
- The system demonstrates robustness and efficiency even with substantial increases in loading rates.
- Kinetic analysis suggests the presence of recalcitrant organic compounds within the leachate impacting TKN removal rates compared to domestic wastewater.
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