This study explores roughing filtration as a viable pretreatment technique in small-community water filtration processes. The implications of this study for the design of roughing filters include: i.
|Title||Evaluation of roughing filtration design variables|
|Year of Publication||1994|
|Authors||Collins, MR, Roccaro, JV, Cole, JO, Westersund, CM|
|Pagination||xxvii, 181 p.: 83 fig., 50 tab.|
|Publisher||American Water Works Association|
|Place Published||Denver, CO, USA|
|Keywords||cab95/2, design criteria, efficiency, evaluation, filtration media, filtration rate, models, pretreatment, roughing filtration, small communities, statistics|
This study explores roughing filtration as a viable pretreatment technique in small-community water filtration processes. The implications of this study for the design of roughing filters include: i. pilot testing using a planned orthogonal experimental programme to design a full-scale roughing filter is appropriate and efficient; ii. the most influential design variable is filter length or depth (thus designers should maximize the length or depth of a roughing filter as much as possible); iii. characterizing the settling velocities of the particulate matter in raw water can result in a qualitative estimate of potential removals by gravel media filtration using the regression models developed in this study; and iv. although filtration direction was not a significant contributor to treatment performance, appropriate roughing filter configurations may be solely based on cleaning requirements. Example design considerations include: a. roughing filter underdrain systems should be designed to allow flushing rates greater than 30 m/h (the addition of piping manifolds across the filter bed at various bed lengths or depths was recommended); b. in order to maximize filter drying, underdrain modifications may include larger perforations and the addition of ventilation riser pipes; and c. in order to maximize cleaning efficiency, coarse media should not be placed over fine media sizes in any vertical roughing filter, suggesting downflow roughing filters should be configurated in series rather than in layers.