Nutrient removal from polluted river water by using constructed wetlands.

Area of Science:

• Environmental Engineering
• Water Quality Management
• Ecological Engineering

Background:

• The Erh-Ren River in Taiwan faces severe pollution, exceeding the capacity of conventional water treatment methods.
• A pilot-scale constructed wetland (CW) was implemented to address the challenge of purifying highly polluted river water.

Purpose of the Study:

• To evaluate the efficacy of a pilot-scale constructed wetland in treating highly polluted river water.
• To gather data for the design and operation of a future full-scale constructed wetland system.

Main Methods:

• A pilot-scale constructed wetland was utilized for water purification.
• Monthly monitoring of nutrient removal rates, including chemical oxygen demand (COD), ammonia-nitrogen (AN), and orthophosphate (OP).
• Analysis of seasonal variations and river water quality impacts on treatment performance.

Main Results:

• Optimal nutrient removal was observed between April and October, with high removal rates for ammonia-N (78-100%) and orthophosphate (52-85%).
• After November, increased input COD levels correlated with significantly reduced removal rates for ammonia-N (16%) and orthophosphate (13%).
• Seasonal shifts and declining river water quality negatively affected macrophyte growth and overall treatment efficiency.

Conclusions:

• Constructed wetlands show potential for treating highly polluted river water, particularly during warmer seasons.
• Macrophyte health is crucial for effective constructed wetland performance, indicating a direct influence on water treatment.
• Seasonal changes and variations in influent water quality are critical factors that can inhibit macrophyte growth and reduce treatment efficiency.