1,721,034 research outputs found
Secondary and tertiary treatment of high strength wastewater with vertical flow constructed wetland filters
No full textOptimization-based methodology for improving energy efficiency in wastewater treatment plants.
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TiO2 PHOTOCATALYTIC DEGRADATION OF CAFFEINE AND ECOTOXICOLOGICAL ASSESSMENT OF OXIDATION BY-PRODUCTS
No full textThe photocatalytic degradation of caffeine has been investigated in aqueous suspensions of titanium dioxide (TiO2) by monitoring process efficiency at varying TiO2 (29.3 – 170.7 mg l-1) and initial drug concentrations (0.76 - 9.24 mg l-1). The use of the response surface methodology (RSM) allowed to fit the optimal regions of the parameters leading to the degradation of the pollutant. Also, a single polynomial expression modelling the reaction was obtained. In parallel a set of bioassays (Daphnia magna, Pseudokirchneriella subcapitata and Lactuca sativa) was performed to evaluate the process in terms of detoxification of caffeine oxidation by-products under chronic and acute tests. Results clearly demonstrate that caffeine is quickly degraded, but not mineralized as quickly, and that persistent toxic organic intermediates resist further oxidation
Organotin compounds in marine sediment: Detection and concerns
Full text linkThe determination of organotin compounds (OTCs) in environmental matrices has been subject to great scientific attention during last years, as the accuracy and sensitivity of analytical methods need to be improved in order to be able to detect the compounds of interest in a complex matrix such as sediment. The European Union Water Framework Directive (2013/39/EU) sets very restrictive environmental quality standards for 45 priority substances and other pollutants, including OTCs. Therefore, it is necessary to develop analytical methods in compliance with the environmental quality standard (EQSs) proposed to protect the aquatic environment and human beings. So far various analytical procedures have been used, including gas chromatographic analyses. Most of these methods comprise different steps such as extraction, derivatisation, clean up and the use of several sophisticated instrumentations, as well. Among them the conversion of tributyltin into Sn to allow its determination by Atomic Absorption Spectrometry or Anodic Stripping Voltammetry (AVS) has also been attempted. A great number of studies have been performed on OTCs analysis in marine sediment. However, the only review available in literature discussing the upgrades of analytical methods is dated back to 1997. We reviewed the analytical procedures and discussed them comparatively in order to identify the current state-of-the-art in OTCs detection. Finally, environmental concerns about OTCs were discussed
Treatment of high strength wastewater with vertical flow constructed wetland filters
No full textThe aim of the present study was to evaluate the behaviour of vertical flow constructed wetlands to treat high strength wastewater. Influents were obtained mixing tap water with different percentages of MSW landfill leachate (5%, 10% and 20%). Phragmites Australis seedlings were used as macrophytes. The reeds were nurtured during three spring months, before the start of the experimental period. Three and four days of detention time were adopted. Influent concentrations of 510-2,050 mg L-1, 180-740 mg L-1 and 65-260 mg L-1 were obtained for COD, N-NH4+ and N-NO3-, respectively. The environmental temperature averaged around 31.0±1.4°C. During the experimental period, all parameters showed an increasing removal efficiency trend. Best results in terms of COD removal were obtained for mixtures at lowest rate of landfill leachate; while, denitrification process showed an opposite behaviour; finally, the removal of ammonia nitrogen appeared to be independent upon influent concentrations. Analysis carried out on the reed tissues showed a theoretic maximum storage of TKN in the leaves of about 55 mg/g dry weight. A leachate percentage of about 35% was derived to be able to full inhibit the growth of macrophytes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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