Reducing pathogens in combined sewer overflows using ozonation or UV irradiation

Area of Science:

• Environmental science
• Public health
• Water treatment technologies

Background:

• Fecal contamination of water resources poses a significant public health risk, especially in densely populated areas.
• Combined sewer overflows (CSOs) are a primary source of this contamination, necessitating urgent treatment solutions.
• Water bodies are critical for drinking water production and recreation, highlighting the need for effective CSO management.

Purpose of the Study:

• To evaluate the efficacy of ozonation and UV irradiation in reducing pathogenic microorganisms in CSOs.
• To compare the performance of ozonation versus UV irradiation for CSO treatment.
• To assess the impact of these technologies on bacteria, viruses, and protozoan parasites.

Main Methods:

• Experiments were conducted in parallel settings at a stormwater settling tank outflow in Germany.
• CSO discharges were treated using ozonation and UV irradiation.
• The reduction of pathogenic bacteria, viruses, and protozoan parasites was quantified for both treatment methods.

Main Results:

• Both ozonation and UV irradiation demonstrated effectiveness in reducing most hygienically relevant bacteria, parasites, and viruses in CSOs.
• Ozonation consistently yielded lower outflow concentrations for the majority of the tested parameters compared to UV irradiation.
• The study confirmed the potential of both technologies for mitigating microbial contamination from CSOs.

Conclusions:

• Ozonation and UV irradiation are viable methods for treating combined sewer overflows.
• Ozonation appears to be more effective than UV irradiation under the tested conditions for reducing a broad spectrum of pathogens.
• Effective treatment of CSOs is crucial for safeguarding public health and water resource quality.