Attachment factor determination in upflow gravel filter in layers

Abstract

This paper describes the process for determining the attachment factor in an upflow gravel filter in layers UGFL. The study was carried out in a pilot filter fed with natural water for influent turbidity between 15-70 NTU and operating with three filter velocities (vf) applying the trajectory theory model approach looking at total suspended solids and particle size removal. In a UGFL sedimentation represents the main particle removal mechanism but the findings clearly show that attachment and flow velocities also have a significant role. Progressive reduction of smaller particles with small media size along the filter height was observed. Single collector efficiencies increased with decreasing vf. Attachment factors for each gravel size calculated by the model were highest for gravel size of 6.4 mm for vf 0.75 and 1.0 m/h.