Simplification and simulation of evaluation process for low efficiency constructed wetlands based on principal...

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Ecological Engineering

Background:

• Current performance evaluation of constructed wetlands (CWs) is complex and lacks simplified simulation models, particularly for low-efficiency CWs (LECWs).
• LECWs are defined as those with an average close-degree < 0.6, calculated using the entropy weight method.

Purpose of the Study:

• To develop a simplified and reliable performance evaluation method for LECWs.
• To establish accurate simulation models for predicting CW operational efficiency.
• To identify key factors influencing the operational efficiency of LECWs.

Main Methods:

• Applied the entropy weight method (EWM) for initial CW operational efficiency evaluation.
• Utilized principal component analysis (PCA) to simplify evaluation indicators.
• Developed random forest (RF) models to validate simplified indicators and logistic regression (LR) for simulation models.

Main Results:

• Evaluation indicators for CWs were effectively simplified to chemical oxygen demand (COD) and total nitrogen (TN), showing no significant difference from original models (P < 0.05).
• Developed simulation models for subsurface flow CWs (SSF CWs) and surface flow CWs (SF CWs) demonstrated high reliability with R² values > 0.8.
• Operational efficiency of LECWs is more sensitive to COD removal rates than TN removal rates.
• Optimal operational efficiency for both SSF CWs and SF CWs occurs when the influent COD/TN ratio is between 3 and 5.

Conclusions:

• Simplified evaluation indicators (COD and TN) provide a reliable and efficient method for assessing CW performance.
• The developed simulation models accurately predict CW efficiency and support informed management decisions.
• Findings offer valuable insights for streamlining the evaluation and daily management of LECWs.