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This study applied ultraviolet/peroxymonosulfate (UV/PMS) and UV/hydrogen peroxide (UV/H2O2) processes to the advanced treatment of membrane bioreactor (MBR) effluent. The degradation efficiency of refractory organic matter and the reaction mechanisms of the two processes were systematically investigated. The results showed that the degradation efficiency of the UV/PMS processes was significantly lower than that of the UV/H2O2 process when the PMS concentration was significantly lower than the H2O2 concentration, e.g. the UV254 removals under optimal conditions were 72.92% and 82.21%, respectively. Additionally, the UV/PMS process could operate over a broader pH range. The degradation efficiency of the UV/PMS process was slightly increased by HCO3– and Cl- due to the activation of PMS, while in the UV/H2O2 process, HCO3- and Cl- depressed the degradation efficiency by competing with organic matter to react with reactive oxygen species (ROS). After the two processes, the aromaticity, humification, condensation degree, and molecular weight of refractory organic matter in the MBR effluent were considerably decreased. Fulvic- (HA) and humic-like substances (FA) were greatly degraded by the two processes. The UV/PMS had a superior degradation efficiency for macromolecular HA in the early stage of the reaction, and the UV/H2O2 could degrade HA to protein-like substances in the latter stage of the reaction. These differences between the two processes could be attributed to the dominance of different ROS, with SO4•- and HO• dominating in the UV/PMS, and HO• dominating in the UV/H2O2. The results of this study provide theoretical support for the application of MBR effluent treatment. Highlights Comparison on the MBR effluent treatment of UV/PMS and UV/H2O2 is studied. UV/PMS process can better destroy humic-like substances in the early reaction stage. Humic-like substances are transformed into protein-like compounds in UV/H2O2 process. UV/PMS and UV/PMS performs differently due to their different dominant ROS. [ABSTRACT FROM AUTHOR]

In this study, nano zero-valent iron (nZVI) was used as the Fe2+ source in the Fenton reaction, and a UV-nZVI-H2O2 system was constructed to efficiently degrade and mineralize refractory organic matter in landfill leachate. The results showed that under the optimal conditions (initial pH = 3, UV = 14 W, nZVI = 0.5 g/L, and [H2O2] = 30 mM), the removal efficiencies of total organic carbon, absorbance at 254 nm, and color number were 61.38%, 83.89%, and 85.79%, respectively. Control experiments show that the UV-nZVI-H2O2 system has the highest removal rate and mineralization rate of refractory organic matter. The excellent performance of the UV-nZVI-H2O2 system is related to a higher H2O2 utilization rate. The H2O2 residue in the UV-nZVI-H2O2 system was the lowest, and the effective utilization rate of H2O2 was as high as 98.80%. Alcohol quenching experiments and hydroxyl radical quantitative experiments showed that the dominant reactive oxygen species in the UV-nZVI-H2O2 system was HO• and the yield of HO• was as high as 2007.80 μM, which was much higher than that in other systems. The results of spectra analysis showed that the low molecular weight, high fluorescence frequency organic matter, and relatively stable aromatic organic matter were significantly degraded after treatment with the UV-nZVI-H2O2 system and the aromatic degree, humification degree, molecular weight, and molecular polymerization degree of refractory organic matter were also significantly decreased. The mechanism of the UV-nZVI-H2O2 reaction includes homogeneous and heterogeneous Fenton reactions and adsorption and precipitation of organic matter by iron-based colloids. This study can provide theoretical and technical support for the advanced treatment of refractory organic matter in landfill leachate. [ABSTRACT FROM AUTHOR]

The aromatic organic compounds present in groundwater environments have low contents, high toxicity, long half-lives and stable chemical properties, which increase the difficulty of degradation under natural conditions. In this study, an zero-valent iron activated peroxymonosulfate system (Fe0/PMS) was constructed to remove common aromatic organic compounds in groundwater. The results showed that at an initial pH of 7.0, Fe0=0.3 g/L, PMS= 0.5 mM, and initial concentration of organic matter (C 0) =0.1 mM, the removal efficiency of the seven aromatic organic compounds by the Fe0/PMS system reached more than 70 %, which shows good removal ability. Alcohol quenching tests and liquid chromatography time-of-flight mass spectrometry tests showed that the main active oxygen species in the system were SO 4 •─ and OH•, which could efficiently degrade aromatic organic compounds through electrophilic substitution, hydroxylation, carbonylation and decarboxylation reactions and reduce the biological toxicity of organic compounds in wastewater to a certain extent. In the long-term dynamic reaction process, the removal rate of aromatic organic compounds in actual groundwater by the Fe0/PMS system can be maintained above 75 %, and the complex structure can be effectively destroyed. This research can provide a theoretical basis for the efficient treatment of aromatic organic compounds in groundwater. • The Fe0/PMS system is effective in degrading aromatic pollutants in contaminated groundwater. • The toxicity of typical aromatic pollutants was decreased by Fe0/PMS system. • Degradation pathways of typical aromatic pollutants in Fe0/PMS system are proposed. • The practical application of Fe0/PMS for degrading aromatic pollutants was proved. [ABSTRACT FROM AUTHOR]

Biochar addition can enhance soil quality and sequester carbon. However, changes in soil organic matter (SOM) molecular compositions in response to long‐term biochar addition have rarely been studied. Therefore, we quantified soil organic carbon fractions, carbon‐cycling enzyme activities, and a range of organic compounds and lignin‐derived phenols in the rhizosphere and bulk soils in different rice growth stages in the 8‐year field trial with biochar application rates of 0 (BC‐0), 4.5 (BC‐L), and 13.5 t ha−1 year−1 (BC‐H). We found that higher amounts of biochar addition (BC‐H) increased labile organic carbon (LOC), dissolved organic carbon (DOC) and particulate organic carbon (POC), and promoted activities of α‐1,4‐glucosidase, β‐D‐cellobiohydrolase and β‐1,4‐xylosidase; in contrast, BC‐L treatment reduced activities of these enzymes. The concentrations of dichloromethane/methanol‐extractable plant‐ and microbial‐derived organic compounds in the rhizosphere and bulk soils at tillering decreased significantly in the treatment with low amount of biochar addition. BC‐L also significantly altered the concentrations of extracted compounds in the rhizosphere soil at tillering and harvest. Concentration of lignin in the bulk soil was significantly reduced in BC‐L at tillering (by 19%) and harvest (by 28%). The concentrations of extracted compounds (e.g., n‐alkanols, n‐alkanoic acids, steroids, and carbohydrates) and lignin were generally significantly higher in the bulk than the rhizosphere soil at tillering and harvest. Long‐term biochar application (BC‐H) promoted lignin decomposition in the bulk soil (at tillering) and the rhizosphere soil (at harvest). Hence, biochar decreased stability of lignin in paddy soil. Our study provided evidence that long‐term biochar application changed the molecular composition and dynamics of degradation of SOM. These results deepen our understanding of the mechanisms governing SOM stability in agricultural ecosystems. [ABSTRACT FROM AUTHOR]

A combined coagulation and γ-Al2O3 catalytic ozonation process was used to treat semi-aerobic aged refuse biofilter (SAARB) effluent from treating mature landfill leachate. First, the coagulant providing the best pretreatment performance was selected. Then, the coagulated SAARB leachate was further treated in an optimized γ-Al2O3-catalyzed ozonation process. Characteristics of the γ-Al2O3-catalyzed ozonation process were determined, and a reaction mechanism was proposed. FeCl3 provided the best treatment efficiency (chemical oxygen demand (COD) removal of 65.8%, absorbance at 254 nm (UV254) removal of 68.55%, and color number (CN) removal of 79.4%). Under optimized O3 dosage (18.92 mg/min) and γ-Al2O3 dosage (10 g/L), efficiencies of removing COD, UV254, and CN were 54.3%, 82.9%, and 95.9%, respectively, at 30 min. In addition, spectral analysis indicated that fulvic-like substances in ultraviolet and visible regions were effectively degraded in the γ-Al2O3-O3 process and some smaller organic products were produced. Characterization of γ-Al2O3 showed that γ-Al2O3 was relative stable; its morphology and constituent elements did not change much after reaction. In addition, ozonation capacity was enhanced by heterogeneous catalytic effects of γ-Al2O3. The combined coagulation and γ-Al2O3 catalytic ozonation process was proven to be an efficient treatment method for removing bio-refractory organic matter contained in SAARB leachate. [ABSTRACT FROM AUTHOR]

Advanced oxidation technology based on peroxymonosulfate (PMS) has attracted much attention because of its good degradation and even mineralization of refractory organic matter, but it is less used in the removal of refractory organic matter from landfill-contaminated groundwater (CGW). In this study, an Fe0/PMS advanced oxidation system-based permeable reactive barrier (Fe0/PMS-PRB) has been employed to remove refractory organic matter from landfill leachate CGW. The results show that the Fe0/PMS system offers a significantly higher removal efficiency of organic matter, especially humus, from CGW than other control systems. The main active oxygen species are SO 4 •─ and HO•, which can facilitate electron-transfer, carbonylation, electrophilic addition, decarboxylation, and other pathways to effectively degrade various refractory organic substances (e.g., bisphenol A, diclofenac acid, and ciprofloxacin). The pseudo-first-order reaction rates reached 0.1083, 0.3030, and 0.0641 min−1, respectively, effectively reducing the bio-toxicity of the effluent. Based on observations by scanning electron microscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy, a reaction mechanism was proposed, which involves homogeneous oxidation, heterogeneous oxidation, adsorption, and precipitation of Fe0. In long-term seepage tests, under conditions of an Fe0 loading of 0.7 g, a PMS concentration of 0.8 m m , and a hydraulic retention time of 15 min, after running for 10 pore volumes, the removal extents of aromatic organic matter and total organic carbon from the CGW by the Fe0/PMS-PRB reached 79.01 % and 68.25 %, respectively. Therefore, Fe0/PMS-PRB can effectively remove refractory organic matter from CGW and has good application prospects. • The removal performance of Fe0/PMS, Fe0/PDS and Fe0/H 2 O 2 was compared. • Possible degradation pathway of organic matter in Fe0/PMS was proposed. • Removal mechanism of groundwater organic matter by Fe0/PMS system was unveiled. • The practicality the Fe0/PMS system for in-situ groundwater remediation was studied. [ABSTRACT FROM AUTHOR]

To date, IL-17A antibodies remain the only therapeutic approach to correct the abnormal activation of the IL-17A/IL-17R signaling complex. Why is it that despite the remarkable success of IL-17 antibodies, there is no small molecule antagonist of IL-17A in the clinic? Here we offer a unique approach to address this question. In order to understand the interaction of IL-17A with its receptor, we combined peptide discovery using phage display with HDX, crystallography, and functional assays to map and characterize hot regions that contribute to most of the energetics of the IL-17A/IL-17R interaction. These functional maps are proposed to serve as a guide to aid in the development of small molecules that bind to IL-17A and block its interaction with IL-17RA. [ABSTRACT FROM AUTHOR]

In this study, molybdenum disulfide (MoS 2) was used to enhance a zero-valent iron/hydrogen peroxide (Fe0/H 2 O 2) Fenton-like system, which was able to remove refractory organic matter from the effluent produced during the treatment of landfill leachate by a membrane bioreactor (MBR). The MoS 2 /Fe0/H 2 O 2 system could efficiently remove refractory organic matter (i.e., fulvic acid-like substances and humic-like substances) from the MBR effluent and also exhibited a strong synergistic effect. Under the conditions of initial pH = 3, H 2 O 2 = 40 mmol/L, Fe0 = 0.4 g/L, MoS 2 = 0.1 g/L, and t = 30 min, compared with a Fe0/H 2 O 2 system, the absorbance UV 254 , chroma (CN), and total organic carbon (TOC) removal rates in MBR effluent treated with MoS 2 /Fe0/H 2 O 2 increased to 48.68%, 63.85%, and 35.85%, respectively. Through the identification of reactive oxygen species (ROS), the hydroxyl radical (HO•) concentration and an analysis of the effective utilization rate of H 2 O 2 , as well as an analysis of the morphology of the material, the distribution of Fe compounds, valence changes, and the Fe ion concentration, it was proven that MoS 2 promoted the cycling of Fe3+/Fe2+ in the Fe0/H 2 O 2 process. The addition of MoS 2 promoted the Fe3+/Fe2+ cycling reaction through the exposed Mo4+ active center, significantly promoting the decomposition of H 2 O 2 and the formation of HO•. The MoS 2 /Fe0/H 2 O 2 system was able to remove a wide range of aromatic organics, indicating the wide applicability of the system. This study developed a new method for the efficient removal of refractory organic matter from landfill leachate. [Display omitted] • Synergistic effect of the MoS 2 /Fe0/H 2 O 2 system for the removal from MBR effluent. • The effect of important factors controlling the degradation from MBR effluent. • Propose a possible degradation pathway of organic matter in MoS 2 /Fe0/H 2 O 2 process. • Unveil the mechanism by which MoS 2 is enhanced in a heterogeneous Fenton reaction. [ABSTRACT FROM AUTHOR]

Fe0 and MoS 2 can synergistically activate H 2 O 2 to generate free radicals for the removal of refractory organic compounds. This study aims to evaluate the Fe0-H 2 O 2 -MoS 2 process for the removal of refractory organic compounds from bio-treated landfill leachate (BTL) under continuous operation mode. The results show that the dosage of H 2 O 2 , Fe0 and MoS 2 all affect the removal effect of the Fe0-H 2 O 2 -MoS 2 process on refractory organics during continuous operation. The removal rates of total organic carbon, absorbance at 254 nm and chroma at an initial pH of 3, [H 2 O 2 ] of 5 mM, Fe0 of 0.4 g/L, MoS 2 of 0.4 g/L and reaction time of 60 min were 65.83%, 85.11% and 93.14%, respectively. The Fe0-H 2 O 2 -MoS 2 process can not only effectively destroy the complex structure of refractory organic compounds in the BTL treatment but also reduce the biological toxicity of BTL to a certain extent. In addition, a high organic removal rate can still be maintained during the long-term dynamic reaction process. Therefore, the Fe0-H 2 O 2 -MoS 2 process has excellent performance in removing refractory organic compounds from BTL under continuous operation conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

This study applied two advanced oxidation processes dominated by different reactive oxygen species (ROS), microwave-iron-hydrogen peroxide (Microwave/ZVI/H 2 O 2) and microwave-iron-peroxydisulfate (MW Microwave/ZVI/PDS), to the degradation of refractory organic matter in the membrane bioreactor (MBR) effluent from landfill leachate treatment. The two processes were systematically compared according to their degradation efficiencies and transformation mechanisms toward refractory organic matter in MBR effluent. Controlled experiments and an influential factor analysis showed that the total organic carbon (TOC) removal efficiencies of the Microwave/ZVI/H 2 O 2 and Microwave/ZVI/PDS processes were 74.48% and 64.40%, respectively. After treatment by the two processes, fulvic-like substances with a low molecular weight and high fluorescence frequency, and humic-like substances with a large molecular weight, stable chemical structure, and high aromaticity were substantially degraded. In addition, the Microwave/ZVI/H 2 O 2 process had a better TOC removal efficiency than the Microwave/ZVI/PDS process over a wider pH range (3−11), which was mainly attributed to the different dominant ROS in the two processes. Both Fe 3 O 4 and FeOOH were found in the reacted ZVI of the two processes, and the reaction mechanisms included Fenton-like reactions and adsorption-precipitation by iron (hydro)oxides, which were promoted by microwave irradiation. This study provided a theoretical reference for the efficient treatment of MBR effluent. • Advanced oxidation of MBR effluent by MW/ZVIPDS and MW/ZVI/H 2 O 2 is studied. • MW/ZVI/H 2 O 2 has a better mineralization effect on organic matter in MBR effluent. • MW/ZVIPDS has a stable treatment performance over a wider pH range. • Humic- and fulvic-like substances are greatly degraded by MW/ZVI/PDS and MW/ZVIH 2 O 2. [ABSTRACT FROM AUTHOR]

Both warming and nitrogen (N) addition affect the chemistry and characteristics of soil organic matter (SOM). However, their interactive impacts on molecular compositions and origins (plant- or microbial-derived) in agroecosystems are indeterminate. A nine-year field trial study in Northern China was undertaken to quantify the effects of warming (+2 °C), N addition (315 kg N ha−1 yr−1), and their interaction on SOM content and its composition, using biomarkers (i.e., free lipids, lignin phenols and amino sugars) and 13C NMR. Despite insignificant changes in bulk SOM content, the characteristics (i.e., molecular constituents, lability and source origin) were significantly influenced by warming and/or N addition in surface soil (0–10 cm), but not in the subsurface soil (10–20 cm). The SOM was composed of approximately 18–27% microbial residues with the bulk derived from fungi (up to 4–fold higher than bacteria). Warming alone reduced total free lipids (mainly short-chain lipids,