title: Removal of aluminium by constructed wetlands with water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nutritional conditions.
abstract: This article reports the phytoremediation efficiencies of water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nutritional conditions for Al rich wastewaters in batch type constructed wetlands (floating aquatic macrophyte-based plant treatment systems). This study was conducted for 15 weeks after 1 week acclimatization by culturing young water hyacinth (average height of 20 +/- 2 cm) in 590 L capacity fiberglass tanks under different nutrient concentrations of 2-fold [56 and 15.4 mg/L of total nitrogen (TN) and total phosphorous (TP), respectively], 1-fold, 1/2-fold, 1/4-fold and 1/8-fold with synthetic wastewaters containing 5.62 Al mg/L. A control set-up of hyacinths comprising only Al with no nutrients was also studied. A mass balance was carried out to investigate the phytoremediation efficiencies and to identify the different Al removal mechanisms from the wastewaters. Chemical precipitation of Al(OH)3 was a dominant contribution to Al removal at the beginning of the study, whereas adsorption of Al3+ to sediments was observed to be a predominant Al removal mechanism as the study progressed. Phytoremediation mainly due to rhizofiltration was also an important mechanism of Al removal especially during the first 4 weeks of the study in almost all the set-ups. However, chemical precipitation and sediment adsorption of Al3+ was a dominant contribution to Al removal in comparison with phytoremediation. Plants cultured in the control set-up showed the highest phytoremediation efficiency of 63% during the period of the 4th week. A similar scenario was evident in the 1/8-fold set-up. Hence we conclude that water hyacinth grown under lower nutritional conditions are more ideal to commence a batch type constructed wetland treating Al rich wastewaters with a hydraulic retention time of approximately 4 weeks, after which a complete harvesting is recommended.
authors.affiliation: Department of Civil Engineering, University of Moratuwa, Sri Lanka. mahesh@civil.mrt.ac.lk
authors.forename: Mahesh W
authors.initials: MW
authors.lastname: Jayaweera
authors.forename: Jagath C
authors.initials: JC
authors.lastname: Kasturiarachchi
authors.forename: Ranil K A
authors.initials: RK
authors.lastname: Kularatne
authors.forename: Suren L J
authors.initials: SL
authors.lastname: Wijeyekoon
mesh_terms: D000535:Aluminum / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D031806:Eichhornia / Q000254:growth & development / Q000378:metabolism*; D052918:Environmental Restoration and Remediation / Q000379:methods; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods; D014877:Water Pollution, Chemical / Q000032:analysis / Q000517:prevention & control; D053833:Wetlands
chemical_list: D000535:Aluminum