title: The effect of high hydraulic loading rate on the removal efficiency of a quadruple media filter for tertiary wastewater treatment.
abstract: It is well known that filtration removal efficiency falls with an increase in flow rate; however, there is limited supporting experimental data on how removal efficiency changes for filters with multiple layers of media and for wastewater filtration, a practice that is becoming more common. Furthermore, information is not available on the characteristics of particles that are removed at different flow rates. Here, a quadruple media filter was operated at hydraulic loading rates (HLRs) between 5 and 60 mh-1with subsequent measurement of total suspended solids, turbidity and particle size distribution (PSD). Samples were collected from the filter influent, effluent and also from between media layers. Pressure changes across the filter layers were also measured. The solids removal efficiency of the filter varied inversely with the increase in filtration rate. However, the multiple media layers reduced the negative impact of increased HLR in comparison to a single media filter. High filtration rates were shown to transport solids, such that particle retention and headloss development was distributed across the entire depth of the multi-media filter. There was also a progressive decrease in the suspension particle size leaving each of the filter layers. The particle hydrodynamic force simulation was consistent with the changes in measured PSD through the filter layers.
authors.affiliation: Cranfield Water Science Institute, Cranfield University, College Road, Cranfield, Bedfordshire, MK43 0TE, UK.
authors.forename: Philani
authors.initials: P
authors.lastname: Ncube
authors.affiliation: Cranfield Water Science Institute, Cranfield University, College Road, Cranfield, Bedfordshire, MK43 0TE, UK.
authors.forename: Marc
authors.initials: M
authors.lastname: Pidou
authors.affiliation: Cranfield Water Science Institute, Cranfield University, College Road, Cranfield, Bedfordshire, MK43 0TE, UK.
authors.forename: Tom
authors.initials: T
authors.lastname: Stephenson
authors.affiliation: Cranfield Water Science Institute, Cranfield University, College Road, Cranfield, Bedfordshire, MK43 0TE, UK.
authors.forename: Bruce
authors.initials: B
authors.lastname: Jefferson
authors.affiliation: Cranfield Water Science Institute, Cranfield University, College Road, Cranfield, Bedfordshire, MK43 0TE, UK. Electronic address: p.jarvis@cranfield.ac.uk.
authors.forename: Peter
authors.initials: P
authors.lastname: Jarvis
mesh_terms: D005374:Filtration; D010316:Particle Size; D012722:Sewage; D014865:Waste Disposal, Fluid; D062065:Wastewater; D018508:Water Purification
chemical_list: D012722:Sewage; D062065:Wastewater
keywords: Filtration; Hydrodynamics; Media; Particles; Wastewater