Transport of Colloids in Filter Columns: Laboratory and Field Experiments

Urbanization, the development and improvement of infrastructure leads to a steady increase of the fraction of sealed surfaces. The direct consequence is an increasing volume of surface runoff producing relevant loads of contaminants. The problem arising must be addressed in terms of runoff volume, rate characteristics (low retention) as well as water quality. Currently, most of the runoff is infiltrated, collected in dual urban sewer systems and discharged without further treatment or is partly passed through water treatment plants where it is cleaned up with comparably expensive treatment methods. Direct seepage into soils or infiltration ditches is commonly favoured as an alternative, since it supports the desired groundwater recharge. However, persistent contaminants that are ubiquitous in these runoff waters will not be permanently stored in filters or soils, but may migrate slowly towards groundwater, causing a long-term potential threat for the degradation of groundwater quality (

Pitt et al. 1996

). The present study deals with the transport potential of solids in runoff with respect to the transfer of micropollutants into the groundwater zone as well as with the efficiency of advanced filtration facilities to remove small-sized pollutant-loaded particles.