Assessing the TSS Removal Efficiency of Decentralized Stormwater Treatment Systems by Long-Term In-Situ Monitoring

Decentralized treatment of stormwater runoff from heavily polluted surface can be a good solution for effective source control. systems (DS) and test procedures to monitor their performance, have been developed in recent years. At present Germany, only lab-based tests are officially established determine the removal efficiency Total Suspended Solids (TSS), situ monitoring is still lacking. Furthermore, fine fraction TSS with particle sizes less than 63 µm (TSS63) as new design parameter because substitute characteristics adsorbing pollutant substances. For research evaluation purposes continuous data urban quantity quality at in- outflow two different DS sites were collected. Turbidity used surrogate TSS. Continuous turbidity time proportional sampling served obtain (i) regression coefficients (ii) DS. wide range events total DS1 was 29% 19% TSS63 DS2 16% TSS63. An event-based analysis revealed high variability efficiencies its uncertainties. Moreover, outwash suspended or remobilization already deposited material observed individual events. both dominates indicated by mean ratios 0.78 inflows 0.89 outflows A significant shift ratio inflow demonstrates that particles removed efficiently coarser DS1, too heterogeny. It clarifies common sedimentation methods contribute small extent reduction solid emissions if contains mainly fine-particle solids. The findings suggest pollution requires additional techniques such proper filtering retain more effective.