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Mesocosm-Scale Constructed Wetland Design for Wastewater Treatment
Published on: May 2, 2025
Solids accumulation in six full-scale subsurface flow constructed wetlands
Aracelly Caselles-Osorio1, Jaume Puigagut, Emma Segú
1Environmental Engineering Division, Hydraulics, Coastal and Environmental Engineering Department, Technical University of Catalonia, c/ Jordi Girona 1-3, Mòdul D-1, 08034 Barcelona, Spain.
Water Research
|February 6, 2007
Summary
Accumulated solids in horizontal subsurface flow constructed wetlands (SSF CWs) were higher near inlets. Improving primary treatment is crucial to prevent clogging from recalcitrant organic matter and maintain wetland function.
Area of Science:
- Environmental Engineering
- Wastewater Treatment Technologies
- Constructed Wetlands
Background:
- Horizontal subsurface flow constructed wetlands (SSF CWs) are utilized for wastewater treatment in small communities.
- Accumulation of solids within the granular media of SSF CWs can impact treatment efficiency and system longevity.
Purpose of the Study:
- To quantify solids accumulation in SSF CWs.
- To examine the relationship between solids accumulation, wastewater characteristics, and hydraulic conductivity.
- To assess the biodegradability of accumulated organic matter.
Main Methods:
- Evaluation of solids in six full-scale SSF CWs.
- Analysis of wastewater quality and load.
- Measurement of hydraulic conductivity.
- Aerobic and anaerobic biodegradability tests on accumulated solids.
Main Results:
- Solids accumulation was significantly higher at the inlet (3-57 kg DM/m2) compared to the outlet (2-12 kg DM/m2).
- Annual accumulation rates (0.7-14.3 kg DM/m2 year) correlated positively with loading rates.
- Accumulated organic matter was largely recalcitrant and difficult to biodegrade, with low organic content (<20%).
- Hydraulic conductivity decreased significantly towards the inlet (0-4 m/d) versus the outlet (12-200 m/d).
Conclusions:
- High solids accumulation, particularly near the inlet, can lead to reduced hydraulic conductivity and potential clogging.
- The recalcitrant nature of the organic matter contributes to the persistence of solids.
- Enhanced primary treatment is recommended to reduce solids loading and prevent premature clogging of SSF CWs.
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