title: Performance of subsurface flow constructed wetland mesocosms in enhancing nutrient removal from municipal wastewater in warm tropical environments.
abstract: Nutrient-rich effluents from municipal wastewater treatment plants (WWTPs) have significantly contributed to eutrophication of surface waters in East Africa. We used vertical (VF, 0.2 m(2)) and horizontal (HF, 0.45 m(2)) subsurface flow (SSF) constructed wetland (CW) configurations to design single-stage mesocosms planted with Cyperus papyrus, and operating under batch hydraulic loading regime (at a mean organic loading rate of 20 g COD m(-2) d(-1) for HF and 77 g COD m(-2) d(-1) for VF beds). The aim of the investigation was to assess the performance of SSF CWs as hotspots of nutrient transformation and removal processes between the WWTP and the receiving natural urban wetland environment in Kampala, Uganda. C. papyrus coupled with batch loading enhanced aerobic conditions and high efficiency regarding the elimination of suspended solids, organic matter, and nutrients with significant performance (P < .05) in VF mesocosms. The mean N and P elimination rates (g m(-2) d(-1)) were 9.16 N and 5.41 P in planted VF, and 1.97 N and 1.02 P in planted HF mesocosms, respectively. The lowest mean nutrient elimination rate (g m(-2) d(-1)) was 1.10 N and 0.62 P found in unplanted HF controls. Nutrient accumulation in plants and sediment retention were found to be essential processes. It can be concluded that whereas the SSF CWs may not function as independent treatment systems, they could be easily adopted as flexible and technologically less intensive options at a local scale, to increase the resilience of receiving environments by buffering peak loads from WWTPs.
authors.affiliation: a Institute for Hydrobiology and Aquatic Ecosystem Management , University for Natural Resources and Life Sciences , Vienna , Austria.|b Wasser Cluster Lunz-Interuniversity Center for Aquatic Ecosystem Research , Lunz am See , Austria.|c Department of Environmental Management, College of Agricultural and Environmental Sciences , Makerere University , Kampala , Uganda.
authors.forename: Najib Lukooya
authors.initials: NL
authors.lastname: Bateganya
authors.affiliation: c Department of Environmental Management, College of Agricultural and Environmental Sciences , Makerere University , Kampala , Uganda.
authors.forename: Alex
authors.initials: A
authors.lastname: Kazibwe
authors.affiliation: d Institute of Sanitary Engineering and Water Pollution Control , University of Natural Resources and Life Sciences , Vienna , Austria.
authors.forename: Guenter
authors.initials: G
authors.lastname: Langergraber
authors.affiliation: c Department of Environmental Management, College of Agricultural and Environmental Sciences , Makerere University , Kampala , Uganda.
authors.forename: James
authors.initials: J
authors.lastname: Okot-Okumu
authors.affiliation: a Institute for Hydrobiology and Aquatic Ecosystem Management , University for Natural Resources and Life Sciences , Vienna , Austria.|b Wasser Cluster Lunz-Interuniversity Center for Aquatic Ecosystem Research , Lunz am See , Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hein
mesh_terms: D018533:Biomass; D029786:Cyperus / Q000254:growth & development; D019015:Geologic Sediments / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D013696:Temperature; D014329:Tropical Climate; D014454:Uganda; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000032:analysis; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis; D053833:Wetlands
chemical_list: D009584:Nitrogen; D010758:Phosphorus; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Cyperus papyrus; Municipal wastewater; batch hydraulic loading; constructed wetland mesocosms; nutrient elimination