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We developed a novel three-dimensional graphene oxide/allylamine/allyl glycidyl ether, and evaluated its adsorption performance for humic acid removal in an aqueous solution. The effective parameters were optimized by the Taguchi design method. Effective parameters on the removal of humic acid, including adsorbent dosage, solution pH, contact time, and temperature were evaluated using an L9 orthogonal array. The optimum parameters were adsorbent dosage of 0.02 g, pH of 6, contact time of 120 min, temperature of 25°C, and the removal efficiency of humic acid was 58%. Also, analysis of variance showed the most significant factors were adsorbent dosage and contact time with 33.58% and 51.62% contribution, respectively. The prepared nanoadsorbent was characterized by Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy with energy-dispersive X-ray analysis, and thermogravimetric analysis. The equilibrium data were evaluated by different isotherm models, where the data followed a Langmuir model with a maximum sorption capacity of 25.97 mg/g. Also, the kinetic adsorption data were well evaluated by the pseudo-secondorder model. The thermodynamic data shown that the sorption of humic acid onto the nanoadsorbent was an exothermic, favorable, and spontaneous process. The regeneration test indicated that the nanoadsorbent could be reused in the water treatment application. This study concluded that nanoadsorbent is a very hopeful nanoadsorbent for the remediation of water polluted by humic acid. [ABSTRACT FROM AUTHOR]

The use of Orbal reactors for wastewater treatment by activated sludge is deemed efficient by various literature sources. Furthermore, it is interesting to determine the potential methodologies to improve removal efficiencies. This study aims to investigate the performance of removal efficiency when a magnetic field is incorporated within the reactor. In this experiment, two magnetic fields of different intensities (1.3 and 2 mT) were used. To generate these magnetic fields, several neodymium magnets were applied to the reactor. The experiment and sampling lasted approximately over a 156-d period to observe the performance of the reactor, with and without the application of a magnetic field. Upon the reactor achieving a steady-state, results were taken. It should be highlighted that, before application, four different inflows were discharged into the reactor to attain the optimum retention time. To confirm the validity, results from relatable studies were compared with this study's findings. Upon application of the magnetic fields, removal efficiencies of total nitrogen, chemical oxygen demand, and biochemical oxygen demand for five days increased by 11%, 6%, and 7%, respectively. Nitrate concentration in effluent had decreased by 21%. Furthermore, the food to microorganism ratio had decreased within a 13%-15% range. Results indicated, also, that the application of different strength magnetic fields had minor effects on removal efficiency. [ABSTRACT FROM AUTHOR]