A critical review on graphene oxide membrane for industrial wastewater treatment.

An important way to promote the environmental industry's goal of carbon reduction is to promote the recycling of resources. Membrane separation technology has unique advantages in resource recovery and advanced treatment of industrial wastewater. However, the great promise of traditional organic membrane is hampered by challenges associated with organic solvent tolerance, lack of oxidation resistance, and serious membrane fouling control. Moreover, the high concentrations of organic matter and inorganic salts in the membrane filtration concentrate also hinder the wider application of the membrane separation technology. The emerging cost-effective graphene oxide (GO)-based membrane with excellent resistance to organic solvents and oxidants, more hydrophilicity, lower membrane fouling, better separation performance has been expected to contribute more in industrial wastewater treatment. Herein, we provide comprehensive insights into the preparation and characteristic of GO membranes, as well as current research status and problems related to its future application in industrial wastewater treatment. Finally, concluding remarks and future perspectives have been deduced and recommended for the GO membrane separation technology application for industrial wastewater treatment, which leads to realizing sustainable wastewater recycling and a nearly "zero discharge" water treatment process.

Insight into the binding properties of carbamazepine onto dissolved organic matter using spectroscopic techniques during grassy swale treatment.

Carbamazepine (CBZ) is a worldwide anti-epileptic drug, whose fate and migration can be greatly influenced by contact with dissolved organic matter (DOM). The properties of DOM in road runoff can be greatly changed by grassy swale (GS) treatment, which influences the complexation of CBZ with DOM. Spectroscopic techniques were employed to explore the different binding properties between CBZ and DOM, and to understand the migration and biogeochemistry of CBZ. The two-dimensional correlation spectroscopy (2D-COS)demonstrated that effluent DOM displayed more binding sites for CBZ than influent DOM, and the binding sequencing of CBZ with DOM fluorophores can be greatly influenced by GS treatment. The results also suggest that protein-like materials exhibit higher log KM values than other fluorescent components, indicating that fluorescent protein-like materials play a crucial role in the biogeochemical behavior of CBZ. Meanwhile, the log KM values showed a remarkable increase after GS treatment. GS treatment can also remove most fluorescent DOM, reducing the risk of CBZ in the water environment.

Molecular insights into the dissolved organic matter of leather wastewater in leather industrial park wastewater treatment plant.

Leather wastewater (LW) effluent is characterized by complex organic matter, high salinity, and poor biodegradability. To meet the discharge standards, LW effluent is often mixed with municipal wastewater (MW) before being treated at a leather industrial park wastewater treatment plant (LIPWWTP). However, whether this method efficiently removes the dissolved organic matter (DOM) from LW effluent (LWDOM) remains debatable. In this study, the transformation of DOM during full-scale treatment was revealed using spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry. LWDOM exhibited higher aromaticity and lower molecular weight than DOM in MW (MWDOM). The DOM properties in mixed wastewater (MixW) were similar to those in LWDOM and MWDOM. The MixW was treated using a flocculation/primary sedimentation tank (FL1/PST), anoxic/oxic (A/O) process, secondary sedimentation tank (SST), flocculation/sedimentation tank, denitrification filter (FL2/ST-DNF), and an ozonation contact reactor (O3). The FL1/PST unit preferentially removed the peptide-like compounds. The A/O-SST units had the highest removal efficiencies for dissolved organic carbon (DOC) (61.34 %) and soluble chemical oxygen demand (SCOD) (52.2 %). The FL2/ST-DNF treatment removed the lignin-like compounds. The final treatment showed poor DOM mineralization efficiency. The correlation between water quality indices, spectral indices, and molecular-level parameters indicated that lignin-like compounds were strongly correlated with spectral indices and CHOS compounds considerably contributed to the SCOD and DOC. Although the effluent SCOD met the discharge standard, some refractory DOM from LW remained in the effluent. This study illustrates the composition and transformation of DOM and provides theoretical guidance for improving the current treatment processes.

Catalytic ozonation of emerging pollutant and reduction of toxic by-products in secondary effluent matrix and effluent organic matter reaction activity.

In this study, the performance of LaCoO3 (LCO) catalytic ozonation was evaluated comprehensively, including the degradation efficiency of benzotriazole (BZA) as a typical emerging pollutant, toxic bromate reduction and the disinfection by-products (DBPs) precursors removal ability in effluent organic matter (EfOM), as well as EfOM reactive activity in catalytic ozonation. Additionally, the reduction of toxic halogenated by-products in (catalytic) ozonation was reported, which was not focused on previous researches before. Results showed that LCO catalytic ozonation improved the removal efficiency of BZA, UV254 and SUVA via enhanced HO· formation. Interestingly, LCO catalytic ozonation showed the ability on the reduction of aldehydes and toxic halogenated organic by-products. Moreover, the formed [trichloromethane (TCM)], [bromochloroacetonitrile (BCAN)] and [dichloroacetamide (DCAcAm)] decreased significantly in catalytic ozonation. Catalytic ozonation was also able to remove DBPs precursors to decline the formation of DBPs, such as TCM, bromodichloromethane (BDCM), trichloroacetonitrile (TCAN) and trichloronitromethane (TCNM). This process was involved in the transformation of EfOM in catalytic ozonation, which was confirmed by multi-spectrum methods, two-dimensional correlation spectroscopy (2D-COS) and hetero-spectral 2D-COS. In summary, LCO was shown to be an effective catalyst to improve the performance of the sole ozonation on the removal of emerging contaminants and DBPs precursors, as well as toxic by-products reduction. Additionally, the strategy of toxic by-products reduction in catalytic ozonation was proposed. Results indicated this technology was an important contribution on removal of refractory organics and formation of toxic by-products in water supply and wastewater treatment industry.

Fluorescent characteristic and compositional change of dissolved organic matter and its effect on heavy metal distribution in composting leachates.

Composting leachates were collected to investigate the fluorescent characteristic and compositional change of dissolved organic matter (DOM) and the effects of the DOM and nutrients on heavy metal distribution during a leachate combination treatment process. Excitation-emission matrix (EEM) fluorescence spectra showed that, with the progress of the treatment units, the content of fulvic-like, humic-like, and protein-like substances gradually decreased. One fulvic-like component (C1), three humic-like components (C2, C3, and C4), and three protein-like components (C5, C6, and C7) were identified in the leachate DOM by parallel factor analysis. Anaerobic-aerobic processes removed a large fraction of the tyrosine-like component (C7) and tryptophan-like component (C6) and a small amount of humic-like component (C2), while the membrane bioreactor showed a good removal effect on protein-like component. The ultra-filtration membrane treatment had a removal effect on fulvic-like and humic-like component and other recalcitrant compounds, while the reverse osmosis treatment had a good removal effect on both humic-like and protein-like components. Correlation analysis indicated that Mn and Cr were primarily associated with protein-like components and nutrients in the composting leachates. Ni and Pb were bound to fulvic-like, humic-like, and protein-like components, Co and Zn interacted with inorganic nitrogen and total phosphorus, and Cd only interacted with inorganic nitrogen.