A Study on Filtration Characteristics of Turbid Water in Construction Sites using Bottom Ash as Filter Media I. Lab Scale Upflow Filtration Column Experiment

Abstract

The feasibility for usage of porous bottom ash with various diameters and high surface areas as filter media to reduce the discharge of suspended solids (SS) in construction sites was investigated. As a filter media in construction site runoffs, the filtration efficiency of bottom ash to reduce the discharge of SS was found to be dependent on the diameter and the distribution of bottom ash, the linear velocity of turbid water, and the inflow SS loadings. Although the filtration efficiency of bottom ash with diameters of 3~6 mm and 10~20 mm significantly decreased as the inflow SS loadings increased, the filtration efficiency of bottom ash with diameters of 6~10 mm was stable despite of the variations in the inflow SS loadings. Additionally, since the overall filtration efficiency of bottom ash filter media was significantly affected by the clogging of the inlet in filter media, the bottom ash with greater diameters was installed in the inlet in filter media, and longer life span of filter media was expected. Compared to other filter media, the filtration efficiency of bottom ash as a filter media was greater and more stable despite of the variations in the inflow SS loadings. Thus, the short-term clogging of bottom ash filter media was protected and greater filtration efficiency of SS can be maintained by efficiently arranging bottom ash of various diameters in construction sites. After the usage of bottom ash as an excellent filter media, the bottom ash can be used as landfill and mixing materials with existing soil at the construction site. Key words: Construction Site, Suspended Solids, Bottom Ash, Filtration, Filter Media, Inflow Loadings, Turbid Water, Clogging