title: Phosphorus removal in laboratory-scale unvegetated vertical subsurface flow constructed wetland systems using alum sludge as main substrate.
abstract: This research has two eventual goals: (1) To optimize performance of subsurface constructed wetlands for removal of phosphorus (P) (2) To demonstrate that dewatered alum sludge (a by-product), can be reused as a constructed wetland substrate. To achieve these, alum sludge from a water treatment plant was characterized and used as main substrate in four experimental vertical sub-surface flow constructed wetland systems treating dairy farm wastewater. Results show that the alum sludge has suitable hydraulic characteristics (uniformity coefficient = 3.6) for use as a substrate, and in the batch studies, up to 48.6 mg-P was removed by 1 g of the alum sludge at a P concentration of 360 mg-P/l and a dosage of 5 g/l. Results from the experimental systems highlight the significant P removal ability of the alum sludge. However, the inclusion of pea gravel at the infiltrative surface of some of the systems had a negative effect on the P removal performance. Sequential P-fractionation results show that there was no significant increase in the easily extractable P, but for total P, there was significant increase, although this was found to decrease with depth. This study shows that the novel use of dewatered alum sludge can bring about high P removal in vertical subsurface flow constructed wetland systems.
authors.affiliation: School of Architecture, Centre for Water Resources Research, Landscape and Civil Engineering, University College Dublin, Newstead, Belfield, Dublin 4, Ireland. akintunde.babatunde@ucd.ie
authors.forename: A O
authors.initials: AO
authors.lastname: Babatunde
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Zhao
mesh_terms: D000327:Adsorption; D000534:Alum Compounds / Q000032:analysis / Q000737:chemistry; D003247:Conservation of Natural Resources / Q000379:methods; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D004867:Equipment Design; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D011189:Potassium Chloride / Q000737:chemistry; D012722:Sewage; D013997:Time Factors; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods*; D053833:Wetlands
chemical_list: D000534:Alum Compounds; D012722:Sewage; D014874:Water Pollutants, Chemical; D010758:Phosphorus; C041524:aluminum sulfate; D011189:Potassium Chloride