Preparation and Adsorption Properties of Soybean Dreg/Hydrocalumite Composites.

The application of biomass-based composites in the field of adsorption has attracted extensive attention. Herein, soybean dreg/hydrocalumite composites were prepared by in situ self-assembly from soybean dregs and applied to the adsorption of Congo Red (CR). The composites were characterized by scanning electron microscopy, X-ray diffraction, Fourier infrared spectroscopy, and N2 physical adsorption-desorption. The results showed that the adsorption property of soybean dregs/hydrocalumite for CR was better than that of soybean dregs or hydrocalumite. Effects of preparation and adsorption conditions on the adsorption of CR by soybean dregs/hydrocalumite were also investigated. The removal rate of soybean dregs/hydrocalumite (30%BD-LDH) prepared under the optimized conditions reached 97.4% with a 486.8 mg·g-1 adsorption capacity. Also, the adsorption capacity of 30%BD-LDH was about 2.4 times and 3.0 times that of hydrocalumite and soybean dregs, respectively. In addition, the adsorption process of CR by 30%BD-LDH was more in line with the pseudo-second-order kinetic and Langmuir isothermal models.

Effect of Preparation Methods on the Adsorption of Glyphosate by Calcined Ca-Al Hydrotalcite.

Calcined Ca-Al hydrotalcites were prepared by the clean method (Ca-LDO-1) and traditional co-precipitation method (Ca-LDO-2), respectively. The effect of the preparation method on the adsorption of glyphosate by calcined Ca-Al hydrotalcites was investigated. The adsorbents were also characterized by X-ray diffraction (XRD), thermogravimetric (TG) analysis, inductively coupled plasma optical emission spectroscopy (ICP-OES), and low-temperature N2 adsorption-desorption, respectively. Compared with Ca-LDO-2, Ca-LDO-1 had higher specific surface area and pore volume, which caused it to show better adsorption performance and reusability for the adsorbing of glyphosate. In addition, the kinetics and thermodynamics of the adsorption of glyphosate by Ca-LDO-1 were studied. The results showed that it was more consistent with the pseudo-second-order kinetic equation and Langmuir isotherm equation.

Enhanced adsorption of hexavalent chromium and the microbial effect on quartz sand modified with Al-layered double hydroxides.

To enhance the hexavalent chromium (Cr(VI)) removal performance of simulated constructed rapid infiltration systems (CRIS) with quartz sand (QS) substrate, QS coated with Al-layered double hydroxides (Al-LDHs@QS) was prepared by the co-precipitation method under alkaline conditions. A scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD) were used to characterize QS before and after modification. The result showed that the Al-LDHs were successfully coated on the surface of the QS. The isotherm adsorption experiment indicated that compared with the original QS, the adsorption property of the modified QS changed from monolayered chemical adsorption to multilayered physical adsorption, perhaps because of different types of adsorption forces. Moreover, the adsorption capacity of modified QS was significantly enhanced and ZnAl-LDHs@QS had a maximum adsorption capacity (1428.57 mg·kg-1) nearly 6 times greater than that of the original QS (232.56 mg·kg-1). Adsorption experiments at different pH showed that the adsorption capacity of ZnAl-LDHs@QS gradually increased as acidity decreased. High-throughput sequencing revealed that the relative abundance of chrome-tolerant microorganisms at the phylum and family levels were increased in modified QS compared with original QS. Hemocytometer counting revealed enhanced microbial quantity on the surface of QS after modification. The content of extracellular polymeric substances (EPS) and the enzymatic activity of the microorganisms adhered to the surface of modified and original QS were detected, results showed that Al-LDHs had an obvious influence on the promotion of EPS secretion and enhanced the enzymatic activity of microorganisms. These changes indicated that the modified QS created better conditions for microorganism growth, and the improved microbial effect caused strong biosorption, resulting in greatly enhanced Cr(VI) removal. Thus, ZnAl-LDHs@QS is a better choice for CRIS to remove Cr(VI).

A Global Overview of SARS-CoV-2 in Wastewater: Detection, Treatment, and Prevention.

A novel coronavirus (SARS-CoV-2) causing corona virus disease 2019 (COVID-19) has attracted global attention due to its highly infectious and pathogenic properties. Most of current studies focus on aerosols released from infected individuals, but the presence of SARS-CoV-2 in wastewater also should be examined. In this review, we used bibliometrics to statistically evaluate the importance of water-related issues in the context of COVID-19. The results show that the levels and transmission possibilities of SARS-CoV-2 in wastewater are the main concerns, followed by potential secondary pollution by the intensive use of disinfectants, sludge disposal, and the personal safety of workers. The presence of SARS-CoV-2 in wastewater requires more attention during the COVID-19 pandemic. Thus, the most effective techniques, i.e., wastewater-based epidemiology and quantitative microbial risk assessment, for virus surveillance in wastewater are systematically analyzed. We further explicitly review and analyze the successful operation of a sewage treatment plant in Huoshenshan Hospital in China as an example and reference for other sewage treatment systems to properly ensure discharge safety and tackle the COVID-19 pandemic. This review offers deeper insight into the prevention and control of SARS-CoV-2 and similar viruses in the post-COVID-19 era from a wastewater perspective.