title: Mechanisms of manganese removal from wastewaters in constructed wetlands comprising water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nutrient conditions.
abstract: This article discusses key mechanisms involved in removing 1 mg/L Mn from synthetic wastewaters in constructed wetlands comprising water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nutrient levels of 1-fold (28 mg/L and 7.7 mg/L of total nitrogen and total phosphorus, respectively), 2-fold, 1/4-fold, and 1/8-fold. A mass balance was carried out to evaluate the key removal mechanisms. Phytoremediation mainly due to phytoextraction substantially contributed to manganese removal. However, chemical precipitation was absent, suggesting that manganese has a higher solubility in the given average pH (6.2 to 7.1) conditions in constructed wetlands. Bacterial mediated immobilization mechanisms also did not contribute to manganese removal. Sediments constituted a minor sink to manganese, implying that manganese has a poor adsorption potential. Constructed wetlands comprising water hyacinth are effective at removing manganese from wastewaters despite the fact that the plants are grown under higher or lower nutrient conditions.
authors.affiliation: Environmental Foundation Limited, 146/34, Havelock Road, Colombo 5, Sri Lanka. RanilKularatne@yahoo.com.au
authors.forename: Ranil K A
authors.initials: RK
authors.lastname: Kularatne
authors.forename: Jagath C
authors.initials: JC
authors.lastname: Kasturiarachchi
authors.forename: Jagath M A
authors.initials: JM
authors.lastname: Manatunge
authors.forename: Suren L J
authors.initials: SL
authors.lastname: Wijeyekoon