Abstract
The efficiency of a series of wetland colonized with Eichhornia crassipes and Salvinia molesta to treat the effluent of a giant river prawn (Macrobrachium rosenbergii) broodstock pond was evaluated in this study. The experimental design was completely randomized and was performed in 9 rectangular tanks (1.6 m3) with three treatments (constructed wetlands) and three replicates. The treatment types included: a wetland colonized with E. crassipes and S. molesta (EcSm) arranged sequentially, a wetland with E. crassipes only (Ec) and a wetland with S. molesta only (Sm). The means of suspended particulate material (SPM), total inorganic nitrogen (TIN), total Kjeldahl nitrogen (TKN), P-orthophosphate (PO4-P) and total phosphorus (TP) of the treated effluents were compared using ANOVA followed by Tukey's test (P<0.05). The effluent treated in Ec and EcSm wetlands exhibited lower SPM concentrations. The Ec wetland reduced TIN, TKN, PO4-P and TP by 46.0, 43.7, 44.4 and 43.6%, respectively. In the EcSm wetland, the reduction of TIN (23.0%), TKN (33.7%) and PO4-P (26.7%) was similar to the Sm wetland (19.8% TIN, 30.9% TKN and 23.8% PO4-P). The Ec wetland was more efficient in treating pond effluent due likely to the higher root surface of E. crassipes, which forms an extensive area favorable to retention and adsorption of debris and absorption of nutrients.
Highlights
Aquaculture is a very important activity of the worldwide economy
The effluent treated in the wetlands colonized with E. crassipes (Ec and E. crassipes and S. molesta (EcSm)) had lower levels of suspended particulate material (SPM)
SPM decreased an average of 47.0% and 27.0% in the E. crassipes only (Ec) and EcSm wetlands, respectively
Summary
This study aimed to test effluent treatment by a joint system consisting of two macrophytes arranged in series: E. crassipes in the first half of the wetland and S. molesta in the second half. The objective of this study was to verify if wetlands arranged in series by plants with different nutritional requirements would be more efficient in treating aquaculture effluent than wetlands colonized by a single species alone
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