A Study on Filtration Characteristics of Turbid Water in Construction Sites Using Bottom Ash as Filter Media II. Pilot-test filtration experiment

The bottom ash pilot-test filtration experiment was conducted to reduce the discharge of suspended solids from construction sites runoff using relatively large diameter (d≥10 mm) of bottom ash filter media.The filtration efficiency of the bottom ash increased with an increase in the input loadings of suspended solids.Whereas the filtration efficiencies of suspended solids were more than 20% up to the second filtration layer (L≤46.6 cm), while the filtration efficiencies of suspended solids were less than 20% after the third filtration layer (L > 46.6 cm).Additionally, more than 70% from total filtered amounts of suspended solids were removed by clogging the pores in the second filtration layer (L≤46.6 cm).On the other hand, the turbidity removal efficiencies were less than 20%, irrespective of the influent turbidity, and the order and length of the bottom ash filtration layer.As a result of the of mass balance analysis, the clogging time of bottom ash filter layer was about 510 minutes, the average filtration efficiency of suspended solids was 67.7%, and the average filtration efficiency of turbidity was calculated at 31.8%, indicating that bottom ash filter layer with relatively enhanced filtration efficiency is effective in reducing suspended solids in the construction sites runoffs.