title: Effect of filter media thickness on the performance of sand drying beds used for faecal sludge management.
abstract: The effect of sand filter media thickness on the performance of faecal sludge (FS) drying beds was determined in terms of: dewatering time, contaminant load removal efficiency, solids generation rate, nutrient content and helminth eggs viability in the dried sludge. A mixture of ventilated improved pit latrine sludge and septage in the ratio 1:2 was dewatered using three pilot-scale sludge drying beds with sand media thicknesses of 150, 250 and 350 mm. Five dewatering cycles were conducted and monitored for each drying bed. Although the 150 mm filter had the shortest average dewatering time of 3.65 days followed by 250 mm and 350 mm filters with 3.83 and 4.02 days, respectively, there was no significant difference (p > 0.05) attributable to filter media thickness configurations. However, there was a significant difference for the percolate contaminant loads in the removal and recovery efficiency of suspended solids, total solids, total volatile solids, nitrogen species, total phosphorus, chemical oxygen demand, dissolved chemical oxygen demand and biochemical oxygen demand, with the highest removal efficiency for each parameter achieved by the 350 mm filter. There were also significant differences in the nutrient content (NPK) and helminth eggs viability of the solids generated by the tested filters. Filtering media configurations similar to 350 mm have the greatest potential for optimising nutrient recovery from FS.
authors.affiliation: Institute for Public Health and Environmental Engineering (iPHEE), School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK E-mail: cn10m3m@leeds.ac.uk; musamanga@cedat.mak.ac.ug; Department of Construction Economics and Management, College of Engineering, Design, Art and Technology (CEDAT), Makerere University, P.O. Box 7062, Kampala, Uganda.
authors.forename: M
authors.initials: M
authors.lastname: Manga
authors.affiliation: Institute for Public Health and Environmental Engineering (iPHEE), School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK E-mail: cn10m3m@leeds.ac.uk; musamanga@cedat.mak.ac.ug.
authors.forename: B E
authors.initials: BE
authors.lastname: Evans
authors.affiliation: Institute for Public Health and Environmental Engineering (iPHEE), School of Civil Engineering, University of Leeds, Leeds LS2 9JT, UK E-mail: cn10m3m@leeds.ac.uk; musamanga@cedat.mak.ac.ug; Departamento de Ingeniería Química, Universidad Nacional de Colombia, Campus La Nubia, Manizales, Colombia.
authors.forename: M A
authors.initials: MA
authors.lastname: Camargo-Valero
authors.affiliation: AquaEnviro Ltd, Appleton Court, Calder Park, Wakefield WF2 7AR, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Horan
mesh_terms: D000818:Animals; D003890:Desiccation; D005243:Feces / Q000737:chemistry; D006376:Helminths; D009584:Nitrogen / Q000032:analysis; D010063:Ovum; D010758:Phosphorus / Q000032:analysis; D012722:Sewage / Q000737:chemistry / Q000469:parasitology; D012822:Silicon Dioxide; D018505:Waste Management / Q000379:methods*
chemical_list: D012722:Sewage; D010758:Phosphorus; D012822:Silicon Dioxide; D009584:Nitrogen