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Investigations have shown the traces of antibiotics in surface water, groundwater, wastewater treatment plants, and drinking water. However, conventional wastewater treatment is not entirely effective for vancomycin degradation. Advanced oxidation is one of the most widespread methods of antibiotic degradation in aqueous media. Vancomycin was quantified by high-performance liquid chromatography. The Response Surface Methodology (RSM) based on Central Composite Design (CCD) was used to explore and optimise the effect of the independent variables on vancomycin degradation. Independent variables were as follows: pH (3–11), vancomycin concentration (15–75 mg/L), TiO2–clinoptilolite (25–125 mg in 250 mL reactor volume), the temperature (25–45°C), and the reaction time (15–75 min). The validity and adequacy of the model were confirmed by the corresponding statistics (F–value = 111.5, correlation coefficient R2 = 0.98, adjusted R2 = 0.97, and prediction R2 = 0.95). The vancomycin degradation efficiency was 97% under optimal conditions (pH = 5, vancomycin concentration = 30 mg/L, TiO2-clinoptilolite content = 50.2 mg in a 250 mL reactor volume, temperature = 32.24°C, and reaction time = 50.9 min). This process followed the zero-order reaction kinetics model (R2 = 0.98), and the removal rate of Total Organic Carbon (TOC) under optimal conditions was 56%. The results indicated that supporting TiO2 on clinoptilolite particles could increase the photocatalytic properties. [ABSTRACT FROM AUTHOR]

Optimized methods for simultaneous removal of nitrate, nitrite and ammonium are important features of nutrient removal. Nitrogen removal efficiency in an intermittently aerated sequencing batch reactor (IA-SBR) with multiple filling events was studied. No external carbon source was added and three filling events were considered. Oxidationreduction potential (ORP) and pH curve at solids retention time (SRT) of 20 d were analyzed. Effects of three organic loading rates (OLR), 0.67, 1.0 and 1.5 kgCOD/m3d, and three nitrogen loading rates (NLR), 0.054, 0.1 and 0.15 kgN/m3d, on nitrogen removal were studied. Nitrate Apex in pH curve and Nitrate Knee in ORP profile indicated that the end of denitrification would be achieved sooner. The kinetic coefficients of endogenous decay (kd) and yield (Y) were identified to evaluate heterotrophic specific denitrification rate (SDNRb). In period 2 at NLR of 0.054 kgN/m3d and considering 2 anoxic and 3 aerobic phases, nitrogen removal efficiency was 91.43%.

The elevated levels of nitrate in ground waters are severe menace for human health and environment. The present study examined a new approach for removal of nitrate from high-contaminated ground waters (100 mg.L−1). Citric acid as carbon sources was employed to evaluate the nitrate removal from bioreactors filled with four media: polypropylene, polyethylene, porous Pumice stone and sand collected from local river within 20 month operation. Furthermore, ozonation process was employed to eliminate the residual carbon sources in effluent before transfer to local water network. The denitrification bioreactors seeded with denitrifying bacteria collected from local wells showed high removal efficiency (62–81%). Furthermore, the ozonation process with concentration level of 5 gr.h−1 significantly reduced the chemical oxygen demand. The result indicated that denitrifying bioreactor with citric acid as carbon source is a promising method for nitrate removal from ground water. [ABSTRACT FROM AUTHOR]

In the present study, the ACF-TiO2 catalyst was synthesised and used as a catalyst for the destruction of toxic cyanide in both synthetic and real industrial wastewaters. The ACF-TiO2 catalyst was found to be micro-porous with the BET surface area of 163 m2/g. The effect of different operational parameters such as catalyst concentration, cyanide concentration, operation time, and ozone concentration were target parameters in the present study. The findings show that 500 mg/L of catalyst is the optimum value for the photocatalytical process to completely oxidise 25 mg/L of cyanide within 10 min. While it was found that 300 mg/L of catalyst in the presence of 200 mg/h ozone is enough to remove 25 mg/L cyanide within operation time of 24 min. Degradation of the cyanide in both investigated processes follow the pseudo-first-order kinetic and the reaction rate constant is almost 2 times higher in the photocatalytical process compared with catalytic ozonation process. Furthermore, the quenching tests using salicylic acid demonstrated the hydroxyl radical generation in the investigated process. Generation of highly oxidising hydroxyl radical makes the photocatalytical process a promising process for the transformation of noxious cyanide to much less toxic compounds (ammonia and nitrate). Accordingly, it can be concluded that ACF-TiO2 could be a catalyst for degradation and detoxification of cyanide. [ABSTRACT FROM AUTHOR]

Paper-recycling mills are serious environmental threats due to their high water consumption and highly polluted wastewater. Particles are the most common issue of paper-recycling wastewater, and their removal is of particular interest for recycling. Rotating dissolved air flotation (RDAF) is a system for separating particles, and the mixing zone of this system, where particles collide with air bubbles, is the most important part. As a widely used system in various industries, RDAF has rarely been investigated in the literature in terms of its optimization and efficiency improvement. In general, RDAF processes are basically the same as those of conventional dissolved air flotation (DAF) systems; thus the results of RDAF can be applied to other DAF systems. In this work, the mixing zone of a full-scale RDAF for the paper-recycling mill wastewater treatment was investigated to predict particle-bubble collision efficiency, consisting of both particle-bubble transport and attachment, and the diameter of the formed particles in different turbulence conditions. ANSYS CFX R18.0, mathematical modeling, and experimental analysis were simultaneously conducted in this research. Based on experimental operation, four scenarios including flow rates and the discharge condition of effluent into the mixing zone were studied. Bubbles with sizes of 60, 80, and 100 µm, the turbulences were calculated. The obtained particle-bubble collision efficiencies indicated the diameter of output particles ranged from 50 to 300 µm. Also, the static light scattering test was performed to determine the particle sizes. The modeling and experimental results both showed that the collision efficiency was higher with the production of larger particles when valves #3 and #4 were opened in the mixing zone. [ABSTRACT FROM AUTHOR]

Rotating dissolved air flotation (RDAF) has been utilized for several decades in paper‐recycling wastewater treatment; however, it has rarely been addressed in the literature, which makes research into this system challenging and complicated. However, in this work, a full‐scale industrial wastewater treatment system for a paper‐recycling mill in Mazandaran province, Iran, was evaluated. Experiments indicated that under the same wastewater and chemical conditions, there are differences in the removal efficiencies. This finding was investigated by conducting simulation in ANSYS CFX R18.0 and experimentation simultaneously. Thus, the main purpose of this research was to optimize the operation to achieve the highest removal efficiencies in a cost‐effective manner. For simulation, the flow was considered as a two‐phase homogeneous flow with a continuous solid–fluid phase, which discharges into the separation zone at different scenarios. Particles with diameters of 250, 500 and 1000 μm were introduced at four frame rotating speeds of 0.125, 0.25, 0.5 and 0.75 rpm. Measured qualitative parameters of the effluent included COD, BOD, TSS, TDS, conductivity and turbidity, whose removal efficiency ranges were (32.2%–54.8%), (32.7%–54.47%), (94.5%–97.1%), (0.47%–0.55%), (0.48%–0.59%) and (more than 55%), respectively. Moreover, the optimum rotating speeds of the frame for particles with diameters of 250, 500 and 1000 μm were obtained as 0.25, 0.5 and 0.125 rpm, respectively; these values were compared and found to agree with the experimental results. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the photocatalytic degradation of anthracene using Fe-doped TiO2 nanoparticles in the presence of UV. The structure and morphology of Fe-doped TiO2 nanoparticles were studied by X-ray diffraction, scanning electron microscopy, and energydispersive X-ray spectroscopy. The applied nanoparticles were synthesized by the sol--gel method. The effect of influential parameters on the degradation of anthracene, including pH, time, nanoparticles dosage, and the concentration of anthracene was studied. Using the UV/Fe-doped TiO2 system, the optimum experimental values were obtained to be as follows: pH = 7, contact time = 60 min, anthracene concentration = 5 mg/L, and nanoparticle dosage = 100 mg/L. Based on the results, it could be concluded that the photocatalytic degradation of anthracene using the UV/Fe-doped TiO2 provides suitable efficiency. In addition, it was found that the doped TiO2 could be considered as a proper catalyst in photocatalytic degradation processe [ABSTRACT FROM AUTHOR]

In this study, silica-coated magnetic nanoparticles (SCMNPs) were modified with ten generations of organic dendrimer containing methyl acrylate and melamine. At the final stage, benzophenone ligand bonded as an active surface actuator functional group on the sorbent product. This novel nanosorbent was used for naphthalene (NAP) removal. The synthesized nanosorbent was characterized by X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, Brunauer-Emmett-Teller, and scanning electron microscopy- energy-dispersive X-ray spectroscopy. The diameter range of the final sorbent was found 20-70 nm. The operational sorption parameters were optimized in a batch system. The best removal efficiency was obtained at pH = 7 during a 20 min process with the 0.4 g L-1 sorbent dosage in the presence of 20 mg L1 NAP at 25°C. Finally, NAP removal from the real samples (complex industrial waste and aqueous samples) was studied via gas chromatography-mass spectrometry with the 90%-100% NAP removal from the samples. The data were evaluated with various isotherm models and kinetic studies where the Langmuir isotherm exhibited a high compatibility (R2 = 0.9969) in the pseudo-second- order kinetic (R² = 0.9998) process. The present study revealed that the synthesized magnetic polymer has a high protentional for NAP removal from aqueous samples (>99%), because of the high sorption capacity (qm = 94.33 mg g-1), pH independence, rapid sorption process, and high recovery. [ABSTRACT FROM AUTHOR]

TiO2/Zeolite composite was synthesized through a sol-gel approach continuously. TiO2/Zeolite composite was exposed to laser irradiation until conversion to TiO2/Zeolite nanocomposite (T/Z) and T/Z was modified with m-phenylenediamine (N-T/Z). The resulting N-T/Z was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray, dynamic light scattering, and thermogravimetric analysis. The average range of particle size of the N-T/Z was about ~140 nm. The N-T/Z product was evaluated as a sorbent for removing 2,4-D from aqueous solutions. The adsorption operational parameters were investigated in a batch system. The complete removal of 2,4-D was investigated under optimum conditions in real samples by high-performance liquid chromatography. A 2,4-D removal efficiency of 72%-99% was obtained from the river, well, and agricultural drainage water samples. The pseudo-second-order kinetic model fitted the 2,4-D removal, and equilibrium data well followed the Langmuir model. The maximum adsorption capacity of the obtained sorbent was qmax = 4.914 mg g-1. The product had excellent stability for reprocessing in several runs without losing adsorptivity significantly. [ABSTRACT FROM AUTHOR]