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Micellar enhanced ultrafiltration is a promising technology for removing trace amounts of organic pollutants in wastewater, but membrane fouling caused by Gemini micelles is a significant problem restricting its industrial application. In this study, a flat sheet ultrafiltration membrane with four types of Gemini surfactant systems and various feed concentrations was used to treat phenol wastewater, while the flux behavior and fouling mechanism were investigated. The optimal permeate flux of phenol decreased in the sequence as follows: CG 12 > CG 16 > CG 12 − Brij35 > CG 16 − Brij35. In order to study the rate of membrane fouling, a developed liner regression method was utilized to help determine the threshold flux, as well the degree of concentration polarization and membrane fouling. Furthermore, limiting flux was investigated to avoid extensive cake layer formation. Threshold flux and limiting flux strongly depended on the feed concentration and the type of micelles. The threshold flux reduced gradually with feed concentration, due to the increased fouling rate and presence of irreversible fouling. Owing to the effect of charge density and hydrophobicity of micelles, CG 12 exhibited the highest threshold flux and limiting flux. Flux-TMP relation was divided into three regions for analyzing the corresponding changes of permeate flux, filtration resistance and conceptual particle deposition model. Besides, fouling mechanism of MEUF was discussed. This study provides a guideline for analyzing membrane fouling and seeking an optimum operation strategy for controlling fouling in membrane water treatment. [ABSTRACT FROM AUTHOR]

Adsorption can effectively remove recalcitrant micro-pollutants in wastewater. However, its industrial application is constrained by the adsorption saturation. This work introduces a novel technique to directly immobilize the laccases onto the CNTs (Laccase-Carbon nanotubes) to improve its adsorption performance. Comprehensive investigations were carried out to compare and understand the adsorption performance at various operational conditions for Carbon nanotube and Laccase-Carbon nanotubes. By calculating the adsorption thermodynamics, adsorption kinetics and particle diffusion kinetics, the removal improvement mechanisms were revealed. The results showed that Laccase-Carbon nanotubes performed much better regarding the dye removal rate (96% within 3 h) and better stability than Carbon nanotubes (84% within 3 h), under various operating conditions (carbon nanotube concentration (0.02–0.08 g/L), laccase ratio (0.25–1.25), dye concentration (10–60 mg/L), temperature (15–35 °C), and rotating speed (0–250 rpm)). Besides, the isothermal adsorption model and adsorption kinetic indicated that Laccase-carbon nanotubes possessed greater adsorption capacity than carbon nanotubes, which may maybe due to the fact that adsorbed dyes onto carbon nanotubes were timely eliminated by laccases, achieving regeneration of adsorption capacity. Moreover, based on the particle diffusion kinetic, the diffusion rate of dyes onto the surface or into the internal of Laccase-Carbon nanotubes was clearly higher than that of carbon nanotubes. Additionally, Scanning Electron Microscope, BET-specific surface area and Fourier Transform Infrared Spectroscopy were utilized to observe the microstructure of enzyme immobilization. This biomimetic nanocomposite sheds light upon conventional wastewater treatment processes for recalcitrant micro-pollutants. Image 1 • Laccase-CNTs nanocomposites were prepared by laccase immobilization onto CNTs. • The Laccase-CNTs exhibited a very high enzyme loading and laccase activity. • Laccase-CNTs had a much better pollutant removal and more stable performance than CNTs. • The adsorption mechanism models of Laccase-CNTs (thermodynamics, kinetics and particle diffusion) were calculated. • Adsorption capacity can be regenerated timely by enzymatic degradation. [ABSTRACT FROM AUTHOR]

Coalbed methane (CBM) is an unconventional natural gas, and vigorous development of CBM has great significance for improving the current status of global coal mine safety production, alleviating market gas supply pressure, and protecting the ecological environment. CBM mainly consists of CH 4 , CO 2 and a small amount of H 2 S. In order to improve the comprehensive energy utilization efficiency of CBM, it is necessary to capture both CO 2 and H 2 S from CBM. In this paper, a comprehensive 2D model was established by COMSOL Multiphysics for simultaneously removing CO 2 and H 2 S in CBM. The K 2 CO 3 /potassium lysinate (PL) mixed solution was employed as the absorbent in a membrane contactor. The impacts of gas and liquid velocities, liquid concentration and temperature on the absorbent performance were studied. The results obtained by using the simulated membrane contactor were consistent with the experimental data in the literature. The results indicate that the gas velocity was the most significant influential factor to the gases removal efficiency. Furthermore, it was concluded that the K 2 CO 3 /PL mixed solution had a better decarburization performance than the single K 2 CO 3 solution. The optimal operating conditions for simultaneous removal process by using K 2 CO 3 /PL mixed solution were obtained by response surface method. More importantly, the blends of amino acid salts and carbonate solution have great prospects in the membrane absorption of acid gases from CBM. Image 1 • Simultaneous removal of CO 2 and H 2 S from coalbed methane using membrane contactor are investigated. • K 2 CO 3 /potassium lysinate mixed solution exhibits high removal efficiencies of CO 2 and H 2 S. • Response surface methodology was used for parametric optimization analysis. [ABSTRACT FROM AUTHOR]

An integrated peroxymonosulfate (PMS)-assisted electrolytic oxidation/coagulation (EO/EC) and ceramic ultrafiltration (UF) process was applied for antibiotic removal in surface water. Stable permeation was achieved in the case of surface water containing sulfamethazine (SMZ) (0–800 μg/L), and the optimum conditions appeared to be an electrical current (I) of 0.2 A, electrolysis time of 60 s, pH 7.5 (nearly 0.56 mg/L Fe2+, considering the pH value of the initial solution) and PMS dosage of 100 μM. During the PMS activation process, SMZ and organic matter were degraded by sulfate radicals (SO 4 ·-) or hydroxyl radicals (·OH), which was confirmed by electron paramagnetic resonance spectroscopy (EPR), and scanning electron microscopy (SEM) and X-ray energy-dispersive spectroscopy (EDS) indicated that the ceramic UF membrane could effectively retain coagulants containing C, S and Fe. Moreover, PMS-assisted electro-oxidation/coagulation pretreatment could generate larger coagulated aggregates (206–275 μm) regardless of the humic acid (HA) (0–20 mg/L) and kaoline particle (0–100 mg/L) content of surface water, thus significantly decreasing the fouling rate. In particular, this process could achieve stable permeation and retain better filtration performance in the case of high antibiotic and organic matter contents in real surface water treatment. This electrically powered process could be used to treat micro-polluted water in remote regions. Image 1 • PMS-assisted electro-oxidation/coagulation combined with a ceramic UF was applied for micro-polluted surface water treatment. • EO/EC could offer a good effluent for sulfamethazine degradation. • Humic-like substance with larger MWs could cause membrane fouling. • PMS-assisted EO/EC pretreatment could enhance ceramic UF membrane fouling control. [ABSTRACT FROM AUTHOR]

Gravity-driven biomimetic membrane (GDBM) has been developed as a promising membrane separation technology regarding ecological water treatment. Given its catalytic function on micro-pollutant removal and fouling control, detailed mechanism for fabrication material influence, organic micro-pollutants (OMPs) degradation, and operation strategy optimization have not been clear so far. In this work, the GDBM performance with various activated carbon (AC) materials (wood, coal, column and powder AC), and hydrostatic heights were investigated and verified. The activated carbon-gravity driven biomimetic membrane (AC-GDBM) fabrication tests demonstrated that AC-GDBM with powdered wooden AC had better filtration performance (up to 55 LMH flux and 97.5% removal rate) than AC-GDBM with other ACs. Furthermore, the effects of operation strategies (AC dosage, lacasse dosage, carbamazepine (CBZ) concentration, hydraulic height and rotating speed) on the filtration performance of AC-GDBM were conducted. At 25 g m−2 AC dosage, 30 g m−2 lacasse dosage, 10 mg L−1 CBZ concentration, and 5 cm hydraulic height, the optimized flux and removal rate were obtained. Further investigation revealed the surface morphology and property of AC-GDBM, displaying that powdered wooden AC and laccase formed the even biomimetic layer on base membrane. Additionally, for treating various OMPs (CBZ, tetracycline hydrochloride (TET), quinolones (norfloxacin (NFX)), and sulfonamides (sulfamethoxazole (SMZ))), with the optimized conditions, the removal rate and flux of AC-GBDM could maintain at high levels. This study demonstrates an example of a niche application, where GDBM is expected to offer a highly efficient and cost-effective ecological water treatment technology. [Display omitted] • Gravity-driven biomimetic membrane (GDBM) was used for organic micro-pollutant removal. • Powdered wooden AC was the best fabrication material (55 LMH flux and 97.5% removal rate). • Increasing hydraulic height strengthened the flux within the critical flux range. • Powdered wooden AC and laccase formed the even biomimetic layer on base membrane. • AC-GDBM can effectively remove various organic micro-pollutants. [ABSTRACT FROM AUTHOR]