Browsing by Author "Kularatne, R. K. A"

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    Mechanisms of Manganese Removal from Wastewaters in Constructed Wetlands Comprising Water Hyacinth (Eichhornia crassipes (Mart.) Solms) Grown under …
    (Water Environment Federation, 2009-02) Kularatne, R. K. A; Kasturiarachchi, J. C; Manatunge, J. M. A; Wijeyekoon, S. L. J
    This article discusses key mechanisms involved in re- moving 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, suggest- ing 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. Water Environ. Res., 81, 165 (2009)
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    Relationships among anthropogenic disturbances representative riparian and non-riparian herbaceous indicators (biomass and diversity), land use, and lotic water quality …
    (Springer International Publishing, 2014-09) Gomes, P. I. A; Wai, O. W. H; Kularatne, R. K. A; Priyankara, T. D. P; Anojika, K. G. M. S; Kumari, G. M. N. R
    This study was carried out to evaluate the linkages among herbaceous plant biomass (i.e., aboveground and litter biomasses) and diversity (ShannonWiener index) in riparian and non-riparian areas, land use, and lotic water quality (which included first- and second-order natural streams, a canal, and a reach of a lowland river). Herb stands selected were free from anthropogenic disturbances such as farming and construction activities for a period of 3 years (this was the dominant and peak frequency of disturbances of the study area). The results suggested that herb indicators are good representatives of the land use. However, land use explanations for herb indicators were complex and not universal for all lotic waters. The correlations between herb indicators and water quality were strong for the low-order natural streams. In these streams, herb indicators explained >36 % of the total variation with several statistically significant herb indicators. However, the large river section showed weak correlations. Furthermore, the canal’s hydrology (connectivity to sea) seemed to be more influential in shaping its water quality. This study demonstrated that the rehabilitation works with a span of 3–4 years using herbs in riparian and/or non-riparian areas could significantly improve water quality of low-order streams with natural origin.
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    Removal of aluminium by constructed wetlands with water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nutritional conditions
    (Taylor & Francis Group, 2007-01-01) Jayaweera, M. W; Kasturiarachchi, J. C; Kularatne, R. K. A; Wijeyekoon, S. L. J
    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.