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The present work aimed to study the removal efficiency of Reactive Blue 222 (RB222) from aqueous solutions by applying a combined process with magnetic sodium alginate beads/H2O2. The effect of various operating parameters including sodium alginate dosage, H2O2 concentration, pH, and dye concentration on the efficiency of the process was investigated. The Freundlich and Langmuir isotherms were used to explain the adsorption process. Adsorption kinetics of RB222 with magnetic sodium alginate beads were also investigated using the pseudo‐first‐, second‐order, and intra‐particle diffusion kinetic models. Optimum conditions for dye removal were determined at [dye concentration] = 50 mg/L, [H2O2] = 250 mg/L, and [pH] = 3 with a reaction time of 180 min. Dye removal percentages obtained in this research were 54.51% and 90.39% using magnetic sodium alginate and magnetic sodium alginate/H2O2 processes, respectively. SEM and XRD were used for the characterization of the obtained magnetic sodium alginate beads. It was revealed that the adsorption of the dye in sodium alginate beads was more consistent with the Freundlich model (R2 = 0.9934) compared to that of the Langmuir model (R2 = 0.7457). Also, the results demonstrated that the adsorption of RB222 in magnetic alginate beads was consistent with the pseudo‐second‐order kinetic models (R2 = 0.9854). © 2018 American Institute of Chemical Engineers Environ Prog, 38: S205–S213, 2019

a b s t r a c tSince most industrial wastewaters contain phenol compounds, achieving eco-friendly and economic processes for filtration of such wastewaters is one of the concerns of environmental researchers. Thus, present study aims to determine the efficiency of bio-filter and activated sludge (BF/AS) combined process in phenol removal from aqueous solution. In this experimental study, BF/AS reactor in a pilot scale with continuous flow and useful volume of 24 L, made of Plexiglas was utilized. Effect of dissolved oxygen concentration, hydraulic residence time, mixed liquor suspended solids (MLSS) and glucose concentration on phenol removing efficiency were evaluated. In order to determine the phenol removal model and optimum removal conditions using central composite design in response surface methodology environment, the reactor was studied in separate runs according to software design. Accuracy of results was evaluated in MLSS concentrations of 2,250 mg/L, glucose of 250 mg/L and dissolved oxygen of 3 mg/L and quadratic model (R 2 = 0.99) well fitted to the results. With regard to high yield of BF/AS biological system in decreasing phenol content from wastewater, the system under study could be used widely in refining the toxic wastewaters of industries given the appropriate operation conditions.

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