The removal of brilliant green (BG) dye from an aqueous solution using activated carbon (AC) derived from guava tree wood is conducted in batch conditions. The influence of different factors such as contact time, pH, adsorbent dosage, initial dye concentration, and temperature on the adsorption of BG onto AC was investigated. FTIR, BET, and SEM analyses were performed to determine the characteristics of the material. The isotherm results were analyzed using the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms. Linear regression was used to fit the experimental data. It was found that the equilibrium data are best represented by the Freundlich isotherm, and the adsorption capacity (qe) was 90 mg dye/g AC. The values of the free energy (∆G), enthalpy (∆H), and entropy (∆S) were −86.188 kJ/mol, 43.025 kJ/mol, and 128 J/mol.K, respectively, at pH 7 for the BG dye. The kinetics of BG dye adsorption were analyzed using pseudo-first-order and pseudo-second-order models, and it was found that the pseudo-second-order model was suitable for the behavior of the BG dye at R2 = 0.999.

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Keywords: Oreochromis niloticusPhytoremediation Ceratophyllum demersum Lemna minorAquaculture Wastewater Pollution Two aquatic macrophytes, Ceratophyllum demersum and Lemna minor, were used in aquaculture wastewater treatment. Tilapia fish (Oreochromis niloticus) with total body weight of 50-60 g were placed in 60 L aquaria. Four treatment groups were included: control (no plant treatment, depended on artificial filtering for purification), Lemna minor (Lm), Ceratophyllum demersum (Cd), and mixed plants group (Lm+Cd). Each group had three replicates (5 fish/replicate). The experiment was conducted for 4 weeks. Physicochemical parameters of aquaculture wastewater including pH, total dissolved solids (TDS), conductivity, turbidity, dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD), total phosphorous (TPO 4 ), nitrate (NO 3 ), nitrite (NO 2 ), and ammonia were determined. The results reflected more effective removal of pollutants from fish aquaria by both plants than that by the artificial aeration/filtering. The effectiveness of pollution removal was higher in Cd group > Lm > Lm+Cd, compared to the control. This order of phytoremediation was confirmed by improvements in tilapia fish health status including liver function (AST, ALT, albumin), kidney function (creatinine, urea, uric acid), in addition to other nutritional and hematological parameters. It could be concluded that the phytoremediation using C. demersum is ecofriendly and effective in removing contaminants from Tilapia aquaculture wastewater and therefore, it is recommended to be applied in tilapia farms.

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