Two alternative modes for diffuse pollution control in Wuhan City Zoo

Area of Science:

• Environmental Engineering
• Urban Ecology
• Water Resource Management

Background:

• Urban pollution from diffuse and small point sources, particularly in zoos, is a significant environmental challenge.
• Control strategies for such pollution have historically received limited research and implementation.
• Ecological engineering offers potential solutions for managing complex urban pollution scenarios.

Purpose of the Study:

• To design and evaluate online and offline ecological engineering technologies for controlling pollution from small point and diffuse sources in an urban zoo.
• To investigate the characteristics and performance of these systems during various runoff events.
• To compare the effectiveness of online versus offline modes in improving water quality and retaining pollutants.

Main Methods:

• Implementation of online and offline ecological engineering systems in Wuhan City Zoo.
• Monitoring and analysis of sixteen runoff events between 2003 and 2005.
• Measurement of event mean concentrations (EMCs) for total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP).
• Calculation of pollutant load retention rates and runoff storage capacities for both modes.

Main Results:

• Both online and offline modes significantly improved runoff water quality, reducing EMCs of TSS, COD, TN, and TP.
• The online mode achieved higher reductions (e.g., 88% TSS) and annual pollutant load retention (94.9%-98.5%) compared to the offline mode (e.g., 77% TSS, 70.5%-86.4% retention).
• The online mode could store runoff from 66.7 mm rainfall, while the offline mode stored 31.3 mm, demonstrating substantial water retention capabilities.

Conclusions:

• Online and offline ecological engineering are effective strategies for managing diffuse and small point source pollution in urban environments like zoos.
• The online mode offers superior pollutant removal, water retention, rainwater utilization, habitat creation, and aesthetic value.
• The offline mode presents a land-saving, economical, and effective alternative for diffuse pollution control in urban areas.