Fabrication and characterisation of fine-tuned Polyetherimide (PEI)/WO3 composite ultrafiltration membranes for antifouling studies

Performance and economic evaluation of a pilot scale embedded ends-free membrane bioreactor (EEF-MBR)

In this work, an embedded ends-free membrane bioreactor (EEF-MBR) has been developed to overcome the fouling problem. The EEF-MBR unit has a novel configuration where a bed of granular activated carbon is placed in the bioreactor tank and fluidized by the aeration system. The performance of pilot-scale EEF-MBR was assessed based on flux and selectivity over 140 h. The permeate flux fluctuated between 2 and 10 L.m^-2.h^-1 under operating pressure of 0.07-0.2 bar when EEF-MBR was used to treat wastewater containing high organic matter. The COD removal efficiency was more than 99% after 1 h of operating time. Results from the pilot-scale performance were then used to design a large-scale EEF-MBR with 1200 m³.day^-1 capacity. Economic analysis showed that this new MBR configuration was cost-effective when the permeate flux was set at 10 L.m^-2.h^-1. The estimated additional cost for the large-scale wastewater treatment was about 0.25 US$.m^-3 with a payback period of 3 years. KEY POINTS: • Performance of new MBR configuration, EEF-MBR, was assessed in long term operation. • EEF-MBR shows high COD removal and relatively stable flux. • Cost estimation of large scale shows the cost effective EEF-MBR application.

Enhanced Antifouling in Flat-Sheet Polyphenylsulfone Membranes Incorporating Graphene Oxide-Tungsten Oxide for Ultrafiltration Applications

In this study tungsten oxide and graphene oxide (GO-WO_2.89) were successfully combined using the ultra-sonication method and embedded with polyphenylsulfone (PPSU) to prepare novel low-fouling membranes for ultrafiltration applications. The properties of the modified membranes and performance were investigated using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), contact angle (CA), water permeation flux, and bovine serum albumin (BSA) rejection. It was found that the modified PPSU membrane fabricated from 0.1 wt.% of GO-WO_2.89 possessed the best characteristics, with a 40.82° contact angle and 92.94% porosity. The permeation flux of the best membrane was the highest. The pure water permeation flux of the best membrane showcased 636.01 L·m^-2·h^-1 with 82.86% BSA rejection. Moreover, the membranes (MR-2 and MR-P2) manifested a higher flux recovery ratio (FRR %) of 92.66 and 87.06%, respectively, and were less prone to BSA solution fouling. The antibacterial performance of the GO-WO_2.89 composite was very positive with three different concentrations, observed via the bacteria count method. These results significantly overtake those observed by neat PPSU membranes and offer a promising potential of GO-WO_2.89 on activity membrane performance.

Modification of reinforced hollow fiber membranes with WO3 nanosheets for treatment of textile wastewater by membrane bioreactor

In this study, performance of braid reinforced hollow fiber membrane containing polyvinylidene fluoride (PVDF) embedded with tungsten trioxide (WO₃) nanosheets in a membrane bioreactor (MBR) was examined for textile wastewater treatment. The WO₃ nanosheets was synthesized and blended at different concentrations (0.1-0.02 wt%) in casting solutions of the membranes. The WO₃ nanosheets characterized using various tests such as XRD, FTIR, SEM, EDS, dot-mapping, and TEM. Furthermore, the effects of the increased WO₃ nanosheets into the PVDF matrix on the membrane morphology, hydrophilicity, permeability, antifouling, and COD and color removal efficiency was investigated. The addition of 0.1 wt% of the nanosheets reduces the water contact angle from 69.3° to 62.5° while increasing overall porosity from 37.5 to 43.2%. COD and color removal for PVDF/0.10 wt% WO₃ membrane was between 86-89% and 72-76%, respectively. While the TMP of modified WO₃ membranes did not significantly increase due to antimicrobial properties of the WO₃ nanosheets, the TMP of the pure PVDF membrane increase, indicating considerable cake layer fouling. The results of this study showed that modification of PVDF braid reinforced hollow fiber membrane using WO₃ nanosheets is promising membrane for MBR systems.

Root-TRAPR: a modular plant growth device to visualize root development and monitor growth parameters, as applied to an elicitor response of Cannabis sativa

BACKGROUND

Plant growth devices, for example, rhizoponics, rhizoboxes, and ecosystem fabrication (EcoFAB), have been developed to facilitate studies of plant root morphology and plant-microbe interactions in controlled laboratory settings. However, several of these designs are suitable only for studying small model plants such as Arabidopsis thaliana and Brachypodium distachyon and therefore require modification to be extended to larger plant species like crop plants. In addition, specific tools and technical skills needed for fabricating these devices may not be available to researchers. Hence, this study aimed to establish an alternative protocol to generate a larger, modular and reusable plant growth device based on different available resources.

RESULTS

Root-TRAPR (Root-Transparent, Reusable, Affordable three-dimensional Printed Rhizo-hydroponic) system was successfully developed. It consists of two main parts, an internal root growth chamber and an external structural frame. The internal root growth chamber comprises a polydimethylsiloxane (PDMS) gasket, microscope slide and acrylic sheet, while the external frame is printed from a three-dimensional (3D) printer and secured with nylon screws. To test the efficiency and applicability of the system, industrial hemp (Cannabis sativa) was grown with or without exposure to chitosan, a well-known plant elicitor used for stimulating plant defense. Plant root morphology was detected in the system, and plant tissues were easily collected and processed to examine plant biological responses. Upon chitosan treatment, chitinase and peroxidase activities increased in root tissues (1.7- and 2.3-fold, respectively) and exudates (7.2- and 21.6-fold, respectively). In addition, root to shoot ratio of phytohormone contents were increased in response to chitosan. Within 2 weeks of observation, hemp plants exhibited dwarf growth in the Root-TRAPR system, easing plant handling and allowing increased replication under limited growing space.

CONCLUSION

The Root-TRAPR system facilitates the exploration of root morphology and root exudate of C. sativa under controlled conditions and at a smaller scale. The device is easy to fabricate and applicable for investigating plant responses toward elicitor challenge. In addition, this fabrication protocol is adaptable to study other plants and can be applied to investigate plant physiology in different biological contexts, such as plant responses against biotic and abiotic stresses.

Performance study of fouling resistant novel ultrafiltration membranes based on the blends of poly (ether ether sulfone)/poly (vinyl pyrrolidone)/nano-titania for the separation of humic acid, dyes and biological macromolecular proteins from aqueous solutions

This study explains the use of a ultrafiltration membrane made of polyvinyl pyrrolidone (PVP) and poly(ether ether sulfone) (PEES)/Nano-titania (n-TiO₂) for the separation of organic compounds. The results of the tests for porosity, water content, surface chemistry, membrane morphology, and contact angle demonstrated that the developed membranes have more hydrophilicity than PEES membranes due to the redundant hydrophilic nature of PVP and n-TiO₂. The membrane pure water flux, which contains 5 wt% PVP and 1.5 wt% n-TiO_2, was 312.76 Lm^-2h^-1, about three-fold higher than that of pristine membrane (95.71 Lm^-2h^-1). Employing bovine serum albumin as a model foulant, the fouling resistance of the PEES/PVP/n-TiO₂ membrane was examined. According to the analysis of flux recovery ratio and irreversible resistance, modified membranes were less likely to foul, and the PEES/n-TiO₂ membrane with 5% PVP addition was recommended as optimal. The fabricated membranes effectively removed more than 95% of various organic compounds such as humic acid, safranin O, egg albumin, pepsin, and trypsin from aqueous solution. Permeability of safranin O and humic acid of PEES/PVP/n-TiO₂ membranes was about 118 Lm^-2h^-1 and 138 Lm^-2h^-1, respectively.