[Urban non-point source pollution control by runoff retention and filtration pilot system]

Area of Science:

• Environmental Engineering
• Water Quality Management
• Stormwater Runoff Treatment

Background:

• Urban runoff is a significant source of water pollution.
• Stormwater runoff carries various pollutants, including suspended solids (SS), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP).
• Effective treatment systems are crucial for mitigating non-point source pollution.

Purpose of the Study:

• To design and evaluate a pilot system for runoff retention and filtration.
• To analyze the long-term purification effects of the system on urban runoff.
• To assess the system's performance in treating pollutants during typical runoff events.

Main Methods:

• A pilot system combining retention and filtration was designed and implemented.
• Runoff pollution characteristics were analyzed during two typical events.
• The treatment efficiency of the pilot system was monitored over time.

Main Results:

• Runoff was severely polluted, with high event mean concentrations (EMCs) of SS (361 mg/L), COD (135 mg/L), TN (7.88 mg/L), and TP (0.62 mg/L).
• A first flush effect was observed, with the initial 25% of flow contributing over 50% of total SS, TP, DTP, and PO4(3-) loading.
• The system achieved high removal rates: SS (97.4-98.6%), COD (61.8-65.4%), TN (22.6-55.1%), TP (85.1-92.6%), DTP (72.1%), and PO4(3-) (85.2%).

Conclusions:

• The pilot system effectively removes non-point source pollution from urban runoff.
• The system demonstrates stability and high pollutant removal efficiency, particularly for SS and TP.
• Retention and filtration are viable strategies for managing stormwater runoff quality.