Removal of antibiotics in sand, GAC, GAC sandwich and anthracite/sand biofiltration systems

Drinking water biofiltration offers the possibility of the removal of trace level micropollutants from source water. Sand, granular activated carbon (GAC), GAC sandwich (a layer of GAC loaded in the middle of sand bed), and anthracite-sand dual biofilters were set-up in duplicate at bench-scale to mimic the filtration process in real drinking water treatment works. During the 3-month system operation, removal of five antibiotics (amoxicillin, clarithromycin, oxytetracycline, sulfamethoxazole, and trimethoprim) and overall biofilter performance were evaluated. Natural surface water spiked with a mixture of the target antibiotics was used as feedwater to the biofilters. Results showed that the target antibiotics were substantially removed (>90%) by GAC-associated biofilters and partially removed (≤20%) by sand alone and anthracite-sand biofilters. In particular, the GAC sandwich biofilter exhibited superior performance compared to sand/anthracite biofilter, and the comparisons among all biofilters indicated that both adsorption and biodegradation contributed to the removal of the target antibiotics in the GAC-associated biofilters. Adsorption kinetics showed that sulfamethoxazole fitted with pseudo-first-order adsorption model, while trimethoprim, amoxicillin, oxytetracycline and clarithromycin fitted the pseudo-second-order model. All antibiotics fitted the Langmuir model according to the isotherm experiment. To date, this is the first study evaluating the removal of antibiotics by GAC sandwich biofilters. Overall, this research will provide useful information which can be used for optimising or updating existing biofiltration processes in industry to reduce antibiotic residues from source water

The effective fraction isolated from Radix Astragali alleviates glucose intolerance, insulin resistance and hypertriglyceridemia in db/db diabetic mice through its anti-inflammatory activity

<p>Abstract</p> <p>Background</p> <p>Macrophage infiltration in adipose tissue together with the aberrant production of pro-inflammatory cytokines has been identified as the key link between obesity and its related metabolic disorders. This study aims to isolate bioactive ingredients from the traditional Chinese herb Radix Astragali (Huangqi) that alleviate obesity-induced metabolic damage through inhibiting inflammation.</p> <p>Methods</p> <p>Active fraction (Rx) that inhibits pro-inflammatory cytokine production was identified from Radix Astragali by repeated bioactivity-guided high-throughput screening. Major constituents in Rx were identified by column chromatography followed by high-performance liquid chromatography (HPLC) and mass-spectrometry. Anti-diabetic activity of Rx was evaluated in db/db mice.</p> <p>Results</p> <p>Treatment with Rx, which included calycosin-7-β-D-glucoside (0.9%), ononin (1.2%), calycosin (4.53%) and formononetin (1.1%), significantly reduced the secretion of pro-inflammatory cytokines (TNF-α, IL-6 and MCP-1) in human THP-1 macrophages and lipopolysaccharide (LPS)-induced activation of NF-κB in mouse RAW-Blue macrophages in a dose-dependent manner. Chronic administration of Rx in db/db obese mice markedly decreased the levels of both fed and fasting glucose, reduced serum triglyceride, and also alleviated insulin resistance and glucose intolerance when compared to vehicle-treated controls. The mRNA expression levels of inflammatory cell markers CD68 and F4/80, and cytokines MCP-1, TNF-α and IL-6 were significantly reduced in epididymal adipose tissue while the alternatively activated macrophage marker arginase I was markedly increased in the Rx-treated mice.</p> <p>Conclusion</p> <p>These findings suggest that suppression of the inflammation pathways in macrophages represents a valid strategy for high-throughput screening of lead compounds with anti-diabetic and insulin sensitizing properties, and further support the etiological role of inflammation in the pathogenesis of obesity-related metabolic disorders.</p

The effect of Ga-doped nanocrystalline ZnO electrode on deep-ultraviolet enhanced GaN photodetector

published_or_final_versio

Efficient degradation of triclosan by aluminium acetylacetonate doped polymeric carbon nitride photocatalyst under visible light

Triclosan (TCS), as a typical toxic and harmful micro-pollutant, has been frequently detected in various water bodies, and its threat to the aquatic environment has raised significant concerns. In this study, aluminium acetylacetonate doped polymeric carbon nitride photocatalysts (PCN-AA) were synthesized to investigate the degradation properties of TCS under simulated visible light. The results showed that the best ratio material PCN-AA30 (k = 0.0529 min-1) can degrade 99.29 % of TCS in 90 min, which is 2.45 times the degradation of the original polymeric carbon nitride material PCN-AA0 (k = 0.0216 min-1). The degradation process of TCS presented different rules under the changing conditions of catalyst dosage, initial concentration of TCS, pH, common inorganic anions and natural organic matter in water. The results of radicals quencher experiment showed that ·O2- played the most important role in the photocatalytic degradation in the reaction system. This study also identified 10 degradation products of TCS using UPLC-Q-TOF technology and proposed the possible degradation pathways. In addition, the acute biotoxicity of PCN-AA materials were tested by luminescent bacteria method, indicating that the safety of PCN-AA was relatively high. These results demonstrated that the polymeric carbon nitride material doped with aluminium acetylacetonate is a promising catalyst for the degradation of micro-pollutants in water under visible light

Atomic Force Microscopy Study of Microbiologically Influenced Corrosion of Mild Steel

The anaerobic corrosion of mild steel in seawater was studied by atomic force microscopy (AFM). In the presence of sulfate reducing bacteria (SRB), corrosion was intensified and accelerated. A biofilm consists of heterogeneous microbial cells and extracellular polymeric substance with interstitial voids was observed on the surface of mild steel coupons. The greatest damage of steel occurred beneath the biofilm, in the form of pitting corrosion. The corrosion of steel can be quantified through section and bearing analyses. The depth of pits increased linearly with time whereas the volume of pits increased as f2.83, the 2.83 power of time. Compared with a control experiment without SRB, the depth of pitting corrosion is about one order of magnitude higher. Weight loss estimates from AFM images are about one order of magnitude smaller than actual weight loss experimental results. The problems of AFM quantification of corrosion rate al extended stage of corrosion are discussed. © 1999 The Electrochemical Society. S0013-4651(99)01-006-X. All rights reserved.published_or_final_versio

Effects of annealing temperature on the characteristics of Ga-doped ZnO film metal-semiconductor-metal ultraviolet photodetectors

published_or_final_versio

Enhancement of superoxide evolution by nickel-doped for the removal of organic pollutants and cyanobacteria

Organic pollutants and cyanobacteria exist in water widely, which make significant impacts on human health so that appropriate methods are needed for their removal. In this work, Ni doped Bismuth oxychloride (BiOCl) photocatalysts were successfully synthesized by a simple hydrothermal method. The light absorption and charge carriers separation involved in superoxide (·O2^{-}) generation can be optimized with the introduction of Ni element. And photocatalytic degradation experiments showed that the 9% Ni-BiOCl enhanced photodegradation activity of organic matter (Rh B and BPA) as well as M. aeruginosa. The degradation efficiency of Ni-BiOCl on the removal of Rh B and BPA were approximately 34.99% and 57% higher than that of pristine BiOCl. Furthermore, the algae inactivation was systematically studied by three-dimensional fluorescence spectrum. Results showed that ·O2− acted an irreplaceable role among the experiment of photocatalytic algae removal, and the details were described as ·O2^{−} and h^{+} first destroyed the cell wall of M. aeruginosa, secondly inactivated the active fluorescent substances in the cell, and then catalyzed the oxidation of intracellular exudates such as chlorophyll and phycocyanin as inorganic substances. This study provides a multifunctional catalyst for controlling water pollution and environmental restoration