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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]

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]

In this research, the efficiency of the integrated fixed‐film activated sludge‐oxic settling anoxic (IFAS‐OSA) system in biological nutrient removal was studied. The oxic‐settling anoxic (OSA) process is known as a cost effective way to reduce the nutrients (nitrogen and Phosphorus). According to the results, the percentages of total nitrogen removal efficiency in the IFAS, IFAS‐OSA2h and IFAS‐OSA4h systems were 78.56 ± 2.46, 83.60 ± 0.92 and 85.03 ± 1.69, respectively, while the percentages of phosphorus removal efficiency in these systems were 32.69 ± 8.25, 36.35 ± 6.73 and 39.87 ± 3.61, respectively. The PCR‐RFLP method showed that C. albicans had the greatest prevalence (n = 36, 90%). Moreover, Vorticella convallaria was identified as the most abundant species of protozoa. The current research demonstrated that the efficiency of the modified IFAS‐OSA process was higher than that of IFAS in the removal of nutrients (TN and PO43–P) and can be a suitable method for upgrading the wastewater treatment plants worldwide. [ABSTRACT FROM AUTHOR]

Integrated fixed film activated sludge-oxic settling anoxic system (IFAS-OSA) is a new, modified system for excess-sludge reduction. In this research, the efficiency of the IFAS-OSA system in biological excess-sludge reduction with the addition of an anoxic sludge-holding tank to the return line of the system was studied. The results showed that the average oxidation reduction potentials (ORPs) in the IFASAerobic , IFASRAS , IFAS-OSA2 h , and IFAS-OSA4 h processes were +80±15 , −62±22,–102±8 , and −140±13 mV , respectively. The average values of Yobs in the IFAS, IFAS-OSA2 h , and IFAS-OSA4 h processes were 0.43±0.01 , 0.31±0.02 , and 0.23±0.01 g MLSS/g COD, respectively. Accordingly, in the IFAS-OSA2 h and IFAS-OSA4 h processes, the sludge production was reduced by 27.9% and 46.5%, and the excess sludge was reduced by 13.65% and 22%, respectively, compared with the control system. Furthermore, as the average SVIs reached 95±12,63±6 , and 49±4 mL/g , the TSS values in the effluents of the IFAS, IFAS-OSA2 h , and IFAS-OSA4 h processes reached 16.5±3 , 7.2±1.5 , and 5.5±1.2 mg/L , respectively. The average percentages of total nitrogen (TN) removal efficiency in the IFAS, IFAS-OSA2 h , and IFAS-OSA4 h processes were 78.56±2.46 , 83.60±0.92 , and 85.03±1.69 , respectively, whereas the percentages of phosphorus removal efficiency in these processes were 32.69±8.25 , 36.35±6.73 , and 39.87±3.61 , respectively. This study revealed that the modified IFAS-OSA system had a more efficient performance than the IFAS system. [ABSTRACT FROM AUTHOR]

In the present research, a zinc oxide (ZnO)–silver (Ag)–neodymium (Nd) nanocomposite was synthesized via the combustion method for the degradation of dyes as organic pollutants. The synthesized nanophotocatalyst was characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques. The process of organic pollutant (Acid Red 18) removal was carried out in a semi-batch photoreactor equipped with an ultraviolet lamp. Also, the influence of key operational parameters such as pH, temperature, initial concentration of solution, and nanophotocatalyst dosage was investigated to evaluate kinetic and thermodynamic properties. Under optimum process conditions (pH = 6.21, dosage of nanophotocatalyst = 0.08 g/l, and low initial concentration of the solution), degradation of pollutant was monitored by measuring the total organic carbon of the solution. Finally, an economic study showed that the photocatalytic advanced oxidation process is an viable treatment method for low concentrations of organic pollutants. [ABSTRACT FROM AUTHOR]

In this paper, electrical wire explosion (EWE) was used as a simple, clean, in situ method to synthesise nano zero-valent iron (nZVI) particles in liquid mediums. The structural and physical properties of the synthesised nZVI particles were characterised by x-ray diffraction, Brunauer-Emmett-Teller analysis, field emission scanning electron microscopy and transmission electron microscopy. The synthesised spherical nanoparticles, at a specific size of 10-50 nm, possessed large surface areas of approximately 13.27 m2/g, reinforcing the significant advantages of EWE, that is, less aggregation and in situ production of nanoparticles with enhanced removal efficacy, for groundwater treatment. After 1 h the adsorption capacity for Cr(VI), Ni(II), and Cd(II) ( Q60 = Cions/ Ciron (mg/g)) at pH 4 was approximately 143.4 (89.0%), 137.5 (79.0%), and 132.6 mg/g (72.0%), respectively. The effect of temperature was also examined at initial metal ions concentration of 70 mg/L, nZVI dosage of 0.2 g/L and pH 4. The results showed 45°C was the optimum temperature for adsorption of Cr(VI), Ni(II), and Cd(II) ions, and over a 60-min period at this temperature adsorption capacity increased to 153.56 (95.3%), 158.91 (91.3%), and 163.90 mg/g (89.0%), respectively. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Optimization of ultrasonic density and exposure time using specific energy index. • The effect of sonicated sludge recycle ratio on MBBR setup performance. • Evaluation of COD removal and turbidity of MBBR setups. • Excess sludge reduction of MBBR system in different sonicated sludge recycle ratios. • Comparison of ultrasound energy consumption in various sludge recycle ratios. Abstract Sludge handling is a common issue in all biological wastewater treatment methods. In this study, sonication technique as a state-of-the-art technology has been applied to a continuous MBBR system with the aim of sludge reduction. A novel configuration of MBBR with an additional recycle stream of sonicated sludge was used as the experimental setup. Based on exposed energy and sludge disruption performance, optimized sonication density and exposure time were obtained 1.5 W/mL and 15 min, respectively. This condition provided 42.2% increase in soluble COD as a result of sludge disintegration. Our results revealed that the performance of MBBR and excess sludge reduction were affected by sonicated sludge recycle ratio (SRR). The energy consumption index (EC) was defined to evaluate the optimum recycle ratio. The maximum excess sludge reduction was observed at 80% SRR, however, the effluent COD and turbidity were deteriorated considerably in comparison to control reactor. The recommended SRR was 60%, where the COD removal efficiency, effluent turbidity and excess sludge reduction were 89.7%, 19 NTU and 61.7%, respectively. Under this condition, the lowest energy consumption of 72.9 kWh kg removed sludge was observed. [ABSTRACT FROM AUTHOR]