Principal Component Analysis (PCA) is a method based on statistics and linear algebra techniques, used in hyperspectral satellite imagery for data dimensionality reduction required in order to speed ...up and increase the performance of subsequent hyperspectral image processing algorithms. This paper introduces the PCA approximation method based on a geometric construction approach (gaPCA) method, an alternative algorithm for computing the principal components based on a geometrical constructed approximation of the standard PCA and presents its application to remote sensing hyperspectral images. gaPCA has the potential of yielding better land classification results by preserving a higher degree of information related to the smaller objects of the scene (or to the rare spectral objects) than the standard PCA, being focused not on maximizing the variance of the data, but the range. The paper validates gaPCA on four distinct datasets and performs comparative evaluations and metrics with the standard PCA method. A comparative land classification benchmark of gaPCA and the standard PCA using statistical-based tools is also described. The results show gaPCA is an effective dimensionality-reduction tool, with performance similar to, and in several cases, even higher than standard PCA on specific image classification tasks. gaPCA was shown to be more suitable for hyperspectral images with small structures or objects that need to be detected or where preponderantly spectral classes or spectrally similar classes are present.
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•BAC was significantly removed by ozonation.•BAC degradation pathway and ozone dose were influenced by NiO-NPs.•BAC abatement was influence by water matrix.•BAC toxicity was ...completely removed by ozonation.
The continuous ozonation of benzalkonium chloride (BAC) and nickel oxide nanoparticles (NiO-NPs) has been performed in a synthetic water matrix and in a sewage treatment plant influent. This study aims to assess ozonation as pre-treatment of an activated sludge process, with emphasis on the toxicity of treated water. BAC was completely removed in synthetic matrix independently of the presence of NiO-NPs, although the ozone dose was influenced by NPs co-occurrence. The extent of mineralization was limited and a number of intermediate transformation products (TPs) appeared, twelve of which could be identified. The degradation pathway was shown to initiate both on the hydrophobic (alkyl chain) and hydrophilic (benzyl and ammonium moiety) region of the surfactant. The reactions on the hydrophilic region were affected by the presence of NiO-NPs as a consequence of the adsorption of BAC onto NP surface via the aromatic group. Water matrix strongly influenced BAC depletion. The aquatic toxicity of treated mixtures was assessed using a biotest battery composed of single species (the bacteria Vibrio fischeri and Pseudomonas putida and the protozoan Tetrahymena thermophila), as well as a whole biological community assay using activated sludge. Although, BAC showed considerable aquatic toxicity in all bioassays, ozonation decreased the toxic effects of treated water samples at ozone dosages below those required for total BAC depletion. Further treatment would not be justified, neither for a significant increase in BAC abatement nor concerning the toxicity of treated wastewater, which increased as a result of nickel leaching from the NPs.
Pharmaceuticals in the aquatic environment do not appear singly and usually occur as complex mixtures, whose combined effect may exhibit toxicity to the aquatic biota. We report an environmental ...application of the combination index (CI)-isobologram equation, a method widely used in pharmacology to study drug interactions, to determine the nature of toxicological interactions of three fibrates toward two aquatic bioluminescent organisms,
Vibrio fischeri and the self-luminescent cyanobacterial recombinant strain
Anabaena CPB4337. The combination index-isobologram equation method allows computerized quantitation of synergism, additive effect and antagonism. In the
Vibrio test, the fibrate combinations showed antagonism at low effect levels that turned into an additive effect or synergism at higher effect levels; by contrast, in the
Anabaena test, the fibrate combinations showed a strong synergism at the lowest effect levels and a very strong antagonism at high effect levels. We also evaluated the nature of the interactions of the three fibrates with a real wastewater sample in the cyanobacterial test. We propose that the combination index-isobologram equation method can serve as a useful tool in ecotoxicological assessment.
A coupled coagulation–Fenton process was applied for the treatment of cosmetic industry effluents. In a first step, FeSO
4 was used as coagulant and the non-precipitated Fe
2+ remaining in ...dissolution was used as catalyst in the further Fenton process. In the coagulation process a huge decrease in total organic carbon (TOC) was achieved, but the high concentration of phenol derivatives was not diminished. The decrease in TOC in the coagulation step significantly reduces the amount of H
2O
2 required in the Fenton process for phenol depletion. The coupled process, using a H
2O
2 dose of only 2
g
l
−1, reduced TOC and total phenol to values lower than 40 and 0.10
mg
l
−1, respectively. The short reaction period (less than 15
min) in TOC and phenol degradation bodes well for improving treatment in a continuous regime. The combination of both processes significantly reduced the ecotoxicity of raw effluent and markedly increased its biodegradability, thus allowing easier treatment by the conventional biological units in conventional sewage treatment plants (STPs).
Remote sensing data has known an explosive growth in the past decade. This has led to the need for efficient dimensionality reduction techniques, mathematical procedures that transform the ...high-dimensional data into a meaningful, reduced representation. Projection Pursuit (PP) based algorithms were shown to be efficient solutions for performing dimensionality reduction on large datasets by searching low-dimensional projections of the data where meaningful structures are exposed. However, PP faces computational difficulties in dealing with very large datasets—which are common in hyperspectral imaging, thus raising the challenge for implementing such algorithms using the latest High Performance Computing approaches. In this paper, a PP-based geometrical approximated Principal Component Analysis algorithm (gaPCA) for hyperspectral image analysis is implemented and assessed on multi-core Central Processing Units (CPUs), Graphics Processing Units (GPUs) and multi-core CPUs using Single Instruction, Multiple Data (SIMD) AVX2 (Advanced Vector eXtensions) intrinsics, which provide significant improvements in performance and energy usage over the single-core implementation. Thus, this paper presents a cross-platform and cross-language perspective, having several implementations of the gaPCA algorithm in Matlab, Python, C++ and GPU implementations based on NVIDIA Compute Unified Device Architecture (CUDA). The evaluation of the proposed solutions is performed with respect to the execution time and energy consumption. The experimental evaluation has shown not only the advantage of using CUDA programming in implementing the gaPCA algorithm on a GPU in terms of performance and energy consumption, but also significant benefits in implementing it on the multi-core CPU using AVX2 intrinsics.
The treatment of a non-biodegradable agrochemical wastewater has been studied by coupling of preliminary coagulation—flocculation step and further Fenton oxidation. High percentages of chemical ...oxygen demand (COD) removal (up to 58 %) were achieved in a first step using polyferric chloride as coagulant. This reduced significantly the amount of H₂O₂ required in the further Fenton oxidation. Using the stoichiometric amount relative to COD around 80 % of the remaining organic load was mineralized. The combined treatment allowed achieving the regional discharge limits of ecotoxicity at a cost substantially lower than the solution used so far where these wastewaters are managed as hazardous wastes.
This review aims to assess different technologies for the on-site treatment of hospital wastewater (HWW) to remove pharmaceutical compounds (PhCs) as sustances of emerging concern at a bench, pilot, ...and full scales from 2014 to 2020. Moreover, a rough characterisation of hospital effluents is presented. The main detected PhCs are antibiotics and psychiatric drugs, with concentrations up to 1.1 mg/L. On the one hand, regarding the presented technologies, membrane bioreactors (MBRs) are a good alternative for treating HWW with PhCs removal values higher than 80% in removing analgesics, anti-inflammatories, cardiovascular drugs, and some antibiotics. Moreover, this system has been scaled up to the pilot plant scale. However, some target compounds are still present in the treated effluent, such as psychiatric and contrast media drugs and recalcitrant antibiotics (erythromycin and sulfamethoxazole). On the other hand, ozonation effectively removes antibiotics found in the HWW (>93%), and some studies are carried out at the pilot plant scale. Even though, some families, such as the X-ray contrast media, are recalcitrant to ozone. Other advanced oxidation processes (AOPs), such as Fenton-like or UV treatments, seem very effective for removing pharmaceuticals, Antibiotic Resistance Bacteria (ARBs) and Antibiotic Resistance Genes (ARGs). However, they are not implanted at pilot plant or full scale as they usually consider extra reactants such as ozone, iron, or UV-light, making the scale-up of the processes a challenging task to treat high-loading wastewater. Thus, several examples of biological wastewater treatment methods combined with AOPs have been proposed as the better strategy to treat HWW with high removal of PhCs (generally over 98%) and ARGs/ARBs (below the detection limit) and lower spending on reactants. However, it still requires further development and optimisation of the integrated processes.
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•This review focuses on 2014 to 2020 papers related to hospital effluents treatments.•Membrane bioreactors remove pharmaceuticals (>80%) at pilot plant scale.•Advanced Oxidation processes require further development at high scales.•Combined technologies also remove antibiotic resistance bacteria and genes.•Advanced oxidation processes are promising alternatives to treat hospital effluents.
Constructing a large biological model is a difficult, error-prone process. Small errors in writing a part of the model cascade to the system level and their sources are difficult to trace back. In ...this paper we extend a recent approach based on Event-B, a state-based formal method with refinement as its central ingredient, allowing us to validate for model consistency step-by-step in an automated way. We demonstrate this approach on a model of the heat shock response in eukaryotes and its scalability on a model of the Formula: see text signaling pathway. All consistency properties of the model were proved automatically with computer support.
The aquatic toxicity of eight preservatives frequently used in personal care products (PCPs) (iodopropynyl butylcarbamate, bronopol, diazolidinyl urea, benzalkonium chloride, zinc pyrithione, ...propylparaben, triclosan and a mixture of methylchloroisothiazolinone and methylisothiazolinone) was assessed by means of two different approaches: a battery of bioassays composed of single species tests of bacteria (Vibrio fischeri and Pseudomonas putida) and protozoa (Tetrahymena thermophila), and a whole biological community resazurin-based assay using activated sludge. The tested preservatives showed considerable toxicity in the studied bioassays, but with a marked difference in potency. In fact, all biocides except propylparaben and diazolidinyl urea had EC50 values lower than 1 mg L−1 in at least one assay. Risk quotients for zinc pyrithione, benzalkonium chloride, iodopropynyl butylcarbamate and triclosan as well as the mixture of the studied preservatives exceeded 1, indicating a potential risk for the process performance and efficiency of municipal sewage treatment plants (STPs). These four single biocides explained more than 95% of the preservative mixture risk in all bioassays. Each individual preservative was also tested in combination with an industrial wastewater (IWW) from a cosmetics manufacturing facility. The toxicity assessment was performed on binary mixtures (preservative + IWW) and carried out using the median-effect principle, which is a special case of the concept of Concentration Addition (CA). Almost 70% of all experiments resulted in EC50 values within a factor of 2 of the values predicted by the median-effect principle (CI values between 0.5 and 2). The rest of the mixtures whose toxicity was mispredicted by CA were assessed with the alternative concept of Independent Action (IA), which showed higher predictive power for the biological community assay. Therefore, the concept used to accurately predict the toxicity of mixtures of a preservative with a complex industrial wastewater depends on degree of biological complexity.
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•Preservatives showed considerable toxicity in the studied bioassays, but with a marked difference in potency.•Individual preservatives and their mixture displayed a potential risk for activated sludge process.•The prediction of mixture toxicity of a preservative with an industrial wastewater depends on degree of biological complexity.
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