Double-layer substrate of shale ceramsite and active alumina tidal flow constructed wetland enhanced nitrogen removal from decentralized domestic sewage.

This study explored the application of shale ceramsite (SC) overlaid onto active alumina (AA) to function as a double-layer substrate in tidal flow constructed wetland (TFCW, SC-AA-TFCW) for decentralized domestic sewage treatment. This was compared to AA or SC substrate alone (AA-TFCW or SC-TFCW) for nitrogen removal, variation of dissolved oxygen and porosity in TFCWs, as well as structure of bacterial communities at varied hydraulic load (HL) of 0.204-2.448 m3/m2 d with time ratio of the wet and dry phase of 3:1. The results demonstrate that SC-AA-TFCW removed 86% NH4+-N and 79% total nitrogen at HL of 0.612 m3/m2 d, which was better than AA-TFCW(76%) or SC-TFCW(49%). The higher nitrogen removal performance in SC-AA-TFCW was mainly attributed to enhanced oxygen transportation due to non-uniform flow field and irregular gap distribution in layered structure, as well as less pore blockage during long-term operation. Denitrifying bacteria including Dechloromonas, Acidovorax, Chryseobacterium and Thermomonas species took up 32% of the microbiome in SC-AA-TFCW, which was higher than in AA-TFCW (17%) and SC-TFCW (7.7%). This study highlighted the importance of layered structures and determined an optimal HL of TFCW to achieve an efficient and stable nitrogen removal for domestic sewage treatment.

Enhanced simultaneous organics and nutrients removal in tidal flow constructed wetland using activated alumina as substrate treating domestic wastewater.

A tidal flow constructed wetland (TFCW), a commonly applied system to clean wastewater, contains a substrate to assist pollutants removal, while the choice of substrate affects the formation of bacterial biofilms. Herein, activated alumina-TFCW (A-TFCW) with hydraulic load of 1.35 m3/(m2·d) parallel with shale ceramisite (S-TFCW) was investigated for treating domestic wastewater, aiming to enhance simultaneous long-term removal of organics, nitrogen and phosphorus. A-TFCW achieved significantly higher COD, NH4+-N, TN and TP removal efficiency than S-TFCW, with the removal efficiency of 85.9% COD, 85.4% NH4+-N, 72.8% TN and 96.4% TP respectively. Denitrifying bacteria dominated in both formed biofilms, with higher relative abundance of nitrifying bacteria and denitrifying bacteria in A-TFCW. These results demonstrated that AA substrate was more suitable to be applied in enhancing the removal performance in TFCW for the treatment of domestic wastewater.

Effect of different enrichment strategies on microbial community structure in petroleum-contaminated marine sediment in Dalian, China.

An oil spill occurred at Xingang Port, Dalian, China in 2010. Four years after this spill, oil contamination was still detected in samples collected nearby. In this study, the strains that evolved in the sediment were screened by high-throughput sequencing technology. Most of these strains were genera reported to have functions associated with crude oil biodegradation. The diversities and numbers of microbes were monitored through enrichment culturing; the dominant strains propagated at first, but the enrichment could not be continued, which indicated that the prolonged culture was not effective in the enrichment of the micro-consortium. Oxygen was also observed to affect the propagation of the dominant microbes. The results showed the role of culture strategies and oxygen in the enrichment of the petroleum-degrading microbes. Therefore, dominant strains could be screened by optimizing both the enrichment time and oxygen concentration used for culturing to facilitate oil biodegradation in the marine ecosystem.

[Qualitative Determination of Organic Vapour Using Violet and Visible Spectrum].

Vapours of organic matters were determined qualitatively employed with ultraviolet-visible absorption spectroscopy. Vapours of organic matters were detected using ultraviolet-visible spectrophotometer employing polyethylene film as medium, the ultraviolet and visible absorption spectra of vegetable oil vapours of soybean oil, sunflower seed oil, peanut oil, rapeseed oil, sesame oil, cotton seed oil, tung tree seed oil, and organic compound vapours of acetone, ethyl acetate, 95% ethanol, glacial acetic acid were obtained. Experimental results showed that spectra of the vegetable oil vapour and the organic compound vapour could be obtained commendably, since ultra violet and visible spectrum of polyethylene film could be deducted by spectrograph zero setting. Different kinds of vegetable oils could been distinguished commendably in the spectra since the λ(max), λ(min), number of absorption peak, position, inflection point in the ultra violet and visible spectra obtained from the vapours of the vegetable oils were all inconsistent, and the vapours of organic compounds were also determined perfectly. The method had a good reproducibility, the ultraviolet and visible absorption spectra of the vapours of sunflower seed oil in 10 times determination were absolutely the same. The experimental result indicated that polyethylene film as a kind of medium could be used for qualitative analysis of ultraviolet and visible absorption spectroscopy. The method for determination of the vapours of the vegetable oils and organic compounds had the peculiarities of fast speed analysis, well reproducibility, accuracy and reliability and low cost, and so on. Ultraviolet and visible absorption spectrum of organic vapour could provide feature information of material vapour and structural information of organic compound, and provide a novel test method for identifying vapour of compound and organic matter.

Antioxidant Vitamin C attenuates experimental abdominal aortic aneurysm development in an elastase-induced rat model.

BACKGROUND: We investigated the hypothesis that an antioxidant, Vitamin C, could attenuate abdominal aortic aneurysm (AAA) development in a rat model. METHODS: An AAA model induced by intraluminal infusion was created in 36 male Sprague Dawley rats, which were randomly distributed into three groups: Sham (saline infused, placebo treated), Control (elastase infused, placebo treated), and Vitamin C (elastase infused, vitamin C treated). Vitamin C and placebo were intraperitoneally injected, initiating 1 wk before the infusion and continuing throughout the study. The aortic dilatation ratio was measured, and aortic tissues were further examined using biochemical and histologic techniques. RESULTS: Vitamin C attenuated the development of AAA, decreasing maximal aortic diameter by 25.8% (P < 0.05) and preserving elastin lamellae (P < 0.05). Vitamin C also decreased 8-hydroxyguanine (a marker of oxidative damage to DNA) and 8-isoprostane content (a marker of oxidative stress) in aortic tissues (P < 0.05, respectively). The proteins of matrix metalloproteinase (MMP)-2, MMP-9, and interleukin 6 were markedly downregulated (P < 0.05, respectively), accompanied with notably reduced messenger RNA expression of tumor necrosis factor-α, MMP-2/9, and interleukin 1ß (P < 0.05, respectively). However, messenger RNA of tissue inhibitors of metalloproteinase-1 and tissue inhibitors of metalloproteinase-2 were both significantly upregulated in Vitamin C group. Vitamin C treatment had no significant effect on systolic blood pressure (P > 0.05). CONCLUSIONS: Vitamin C attenuated AAA development in an elastase-induced rat model via crucial protective effect, which was mediated by an increased level of antioxidant in cooperation with preserving elastin lamellae, inhibiting matrix-degrading proteinases and suppressing inflammatory responses.

Inhibition of experimental abdominal aortic aneurysm in a rat model by way of tanshinone IIA.

BACKGROUND: The purpose of the present study was to investigate whether tanshinone IIA (Tan IIA), one of the major lipophilic components of Salvia miltiorrhiza Bunge, could inhibit the development of elastase-induced experimental abdominal aortic aneurysms (AAAs). METHODS: Male Sprague-Dawley rats (n = 12/group) were randomly distributed into three groups: Tan IIA, control, and sham. The rats from the Tan IIA and control groups underwent intra-aortic elastase perfusion to induce AAAs, and the rats in the sham group were perfused with saline. Only the Tan IIA group received Tan IIA (2 mg/rat/d). The maximum luminal diameter of the abdominal aorta was measured before and 5, 12, 18, and 24 d after perfusion. The systolic blood pressure was measured twice using the tail cuff technique before administration and death. Aortic tissue samples were harvested at 24 d and evaluated using reverse transcriptase-polymerase chain reaction, Western blot, immunohistochemistry, and Miller's elastin-Van Gieson staining. RESULTS: The rats in the control group had significantly increased aortic sizes compared with the sham group after 24 days (P < 0.05), and the Tan IIA group had a significant reduction in aortic size (Tan IIA versus control, P < 0.05) without affecting blood pressure (P > 0.05). The overexpression of matrix metalloproteinase-2, metalloproteinase-9, monocyte chemotactic protein-1, and inducible nitric oxide synthase and the depletion of elastic fibers and vascular smooth muscle cells induced by elastase perfusion were significantly decreased by Tan IIA treatment (P < 0.05). CONCLUSIONS: Tan IIA inhibited the development of elastase-induced experimental AAAs by suppressing proteolysis, inflammation, and oxidative stress and preserving vascular smooth muscle cells. It could be a new pharmacologic therapy for AAAs.