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Adsorption process by activated carbon is widely used for removal of dyes. Because of economical limits, activated carbon derived from low cost materials seem to be economical. The aim of this work is preparation of activated carbon from poplar wood and investigation of its ability to removal of (AR18) dye. In this work, we prepared the activated carbon by chemical activation method in electric furnace. In addition we have investigated effect of various parameters such as pH, contact time, dye concentration and adsorbent dosage on dye removal. Langmuir and Freundlich isotherm models have been investigated. Pseudo-first order, pseudo-second order and modified pseudo-first order kinetic models have been used for experimental data. The results showed that removal efficiency was increased with increasing of adsorbent dosage, contact time and decreasing of pH, but with increasing of dye concentration, the removal efficiency was decreased. Adsorption isotherm models showed that Langmuir isotherm model was best fitted onto collected data (r2>0.978). In addition, kinetic models showed that sorption of AR18 onto activated carbon prepared from poplar wood follows the pseudo-first order model (r2>0.9758).

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Antibiotics are used globally and, after use, they enter water sources in different ways. The presence of these compounds in the environment has created concerns about the toxicity of aquatic organisms and the emergence of antibiotic-resistant bacteria. The purpose of this study was to remove cefalexin from aqueous solutions by enzymatic oxidation using response surface methodology (RSM). For this purpose, batch experiments were performed to evaluate the effect of independent variables, including temperature, pH, contact time, enzyme activity, HBT mediator concentration, and antibiotic concentration. The residual cefalexin concentration was determined by HPLC. The Box-Behnken design of experiments and RSM were used to evaluate the overlap between variables. The results showed that the oxidation efficiency increased with increasing contact time and enzyme activity and decreasing antibiotic concentration. The highest and lowest removal percentages were 90.5% and 5.54%, respectively. Considering the value of R 2 (0.946) and adjusted R 2 (0.95) in the RSM model, one can state that the selected model is suitable for data analysis. Finally, the second-order polynomial analysis and the quadratic model were used as the best model for finding the relationship between the main variables and cefalexin removal efficiency. The Box-Behnken Design model can be effective for optimizing enzymatic oxidation of cefalexin, and laccase can be used to remove cefalexin.

The presence of antibiotics in the environment, especially aquatic environments, is a major health and environmental concern.Wastewater treatment plants play an important role in the treatment of municipal and industrial wastewater and removal of contaminants.The aim of this study was to determine the concentration of prevalent antibiotics in municipal wastewater of Hamadan,Iran and to evaluate the removal efficiency of wastewater treatment plants. During 3 months (April, May, and June 2016), a total of 12 composite influent and effluent samples were collected from the wastewater treatment plants. Solid-phase extraction (SPE) was used for preparing the samples, which were then analyzed using high-performance liquid chromatography (HPLC) with UV detection.Based on the analysis of 6 antibiotics, three antibiotics, including amoxicillin, imipenem, and cefixime, were detected, and their concentrations were measured at 1.6, 10.7, and 5.8 ug/L, respectively. The removal efficiency of these antibiotics in wastewater treatment plants was 55.66%, 34.01%, and 24.33%, respectively. Due to the presence of examined antibiotics in the effluent and influent wastewater treatment plants, they might cause direct and indirect effects on human health and environment if proper measures are not taken by the authorities. Since the removal of these antibiotics from wastewater treatment plants is relatively poor, it is suggested to use advanced wastewater treatment plants to reduce antibiotics in effluent wastewater and decrease the adverse effects of these micropollutants.

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.

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