Abstract

DIAZ C, Alex; ATENCIO G, Víctor  and  PARDO C, Sandra. Assessment of an artificial free-flow wetland system with water hyacinth (Eichhornia crassipes) for treating fish farming effluents. Rev Colom Cienc Pecua [online]. 2014, vol.27, n.3, pp.202-210. ISSN 0120-0690.

Background: fish farming effluents are mainly composed of organic matter and are considered a source of environmental pollution. Objective: to evaluate the efficiency of an artificial free-flow wetland system using water hyacinth (Eichhornia crassipes) to treat fish farming effluents under various hydraulic loadings. Methods: effluents generated from fingerling ponds of Oreochromis sp. and Piaractus brachypomus were passed through a constructed wetland system (40 m long and 7.7 m wide) to measure NO₂^-, NO₃^-, NH₄⁺, total phosphorus (TP), and Biochemical Oxygen Demand (BOD₅) removal efficiency. The hydraulic retention time was measured for six months in five assessment phases under real production conditions by using five hydraulic loadings (44.9, 45.3, 43.1, 41.6, 42.0 cm/day). Results: the hydraulic retention time of the constructed wetland system was 1.6 days, and its removal efficiency rates were: 67.9% for NH₄⁺, 32.1% for BOD₅, 27.1% for NO₂^-, 23.0% for TP, and 16.7% for NO₃^-. Removal rate was positively correlated with the loading rate of total inorganic nitrogen during the five phases of this study (r=0.956). Also, highest removal values and efficiency increase were reached in phase 5. Conclusions: the free-flow wetland with E. crassipes is efficient for removing nitrogen compounds, TP and BOD₅.

Keywords : fish waste water; macrophytes; nitrogen compounds; nutrient removal.

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