Assessment of Separation Efficiency of Reconstructed Combined Sewer Overflow in Debr (Czech Republic)

This paper is aimed to assess the function of renovated combined sewer overflow (CSO) in Debr nad Jizerou. The former lateral CSO, which did not meet the requirements, was replaced with a modified type of tube CSO in 2012. The main goal of this study was to determine separation efficiency of the new CSO and to compare it to the previous situation. Monitoring itself included online observation of hydrological indicators in the sewer system, then continuous sampling during precipitation events and its assessment, moreover the chemical quality water judgment in recipient body in both immediate and long-term view. Comparing of current and older results, it is clear that the new CSO works better than the former CSO. The newly installed CSO decreases the pollution into the receiving body about 30–50% on average. Separation efficiency is improved and also values of the basic chemicals indicators in the recipient are better. Measuring on CSO showed the relevant correspondence of actual separation efficiency of suspended solids with the mathematical model.