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Dunzhu Li

PhD Researcher
Dept. of Civil, Structural & Environmental Engineering



Analysis of CSOs formation and removal mechanism

Keywords: combined sewer overflows (CSOs); stormwater; contamination characteristics; formation; CSOs simulation; filter material; treatment.


Many of the largest cities in the world, such as Dublin, are served by combined sewer system. Combined sewer overflows (CSOs) are caused during intense rainfall events, when stormwater generated on impervious surfaces exceeded the conveyance capacity of combined sewer system. Discharging of CSOs, which contains a mixture of raw wastewaters and stormwater, can dramatically degrade the quality of receiving water body by increasing the concentrations of mineral, organ and microbiological pollutants. In order to ensure the water ecological security, it is greatly important to gain an in-depth understanding of the variability of CSOs pollutants by different impact factors such as rainfall intensity and deduce effectively method to control the pollution of CSOs.


At present, there are many studies focused on the pollution and treatment of CSOs. However, there are still lack of in-depth understanding in the CSOs research and treatment in some aspects. Firstly, there are few studies focused on the particles of CSOs, and the understanding of the corresponding between particles and rainfall intensities is limited. Secondly, the CSOs treatment facilities such as wetland cannot maintain a good balance between feeding and dry periods. And the removal efficiency fecal bacteria and virus are limited. Finally, the CSOs studies carried out in Ireland are few while it must meet the water environmental goals of European Union.

This research aims to gain an in-depth understanding of CSOs pollution characteristics variability with different factors in Dublin, analyse the corresponding between particles and rainfall intensities, and try to create some effective filter materials to prompt the treatment of CSOs in Dublin.





Project Supervisor: Assistant Prof. Liwen Xiao