title: Clogging of vertical-flow constructed wetlands treating urban wastewater contaminated with a diesel spill.
abstract: Clogging often leads to a decrease of the treatment performance of wetlands. The aims of this study were to compare the impact of different design and operational variables on the treatment efficiency and clogging processes and to model suspended solid (SS) accumulation within the saturated wetland zone using the Wang-Scholz model. Different vertical-flow constructed wetlands were operated from June 2011 until April 2014. Four treatment periods were assessed: set-up, first year after set-up period, second year after set-up period and diesel spill (for selected filters only). The filter with the highest chemical oxygen demand (COD) loading but no diesel contamination performed the best in terms of COD and biochemical oxygen demand (BOD) removal for the fourth and final treatment period. Filters contaminated by diesel performed worse in terms of COD and BOD but considerably better regarding nitrate-nitrogen removal. Serious clogging phenomena impacting negatively on the treatment performance and the hydraulic conductivity were not observed. Modelling results were generally poor for the set-up period, adequate for the first 2 years after the set-up period and variable after the diesel spill. The Wang-Scholz model performed well for less complex operations.
authors.affiliation: Civil Engineering Research Group, School of Computing, Science and Engineering, The University of Salford, Newton Building, Salford, M5 4WT, England, UK.
authors.forename: Rawaa
authors.initials: R
authors.lastname: Al-Isawi
authors.forename: Miklas
authors.initials: M
authors.lastname: Scholz
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Abdulkadir
authors.initials: A
authors.lastname: Sani
mesh_terms: D000465:Algorithms; D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D002947:Cities; D003198:Computer Simulation; D005374:Filtration; D005742:Gasoline / Q000032:analysis*; D009566:Nitrates / Q000302:isolation & purification; D009584:Nitrogen / Q000302:isolation & purification; D010710:Phosphates / Q000032:analysis; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification; D060753:Water Quality; D053833:Wetlands
chemical_list: D005742:Gasoline; D009566:Nitrates; D009584:Nitrogen; D010710:Phosphates; D062065:Wastewater; D014874:Water Pollutants, Chemical