Advanced solutions for the abatement of VOCs and odours

2017 - 2018In the last decades, atmospheric pollution has become an increasingly alarming problem, due to its adverse effects at the global, regional and local scales. In this context, the emissions of Greenhouse Gases (GHGs), Volatile Organic Compounds (VOCs) and odours from chemical manufacturing plants, petrochemical sector and other hazardous sources pose a major challenge. Global warming, due to increased GHGs level in the atmosphere, has been identified as one of the key challenges in this century. Indeed, the impacts of global warming have caused severe damages towards human and environment ecosystem. VOCs are included among the priority gaseous organic contaminants, with BTEX identified among the most dangerous for human health. They are also considered responsible for the photochemical pollution as a result of their reaction in the atmosphere with nitrogen oxides in presence of solar radiation. In addition, their tendency to volatilize readily to the atmosphere leads to problems connected to odour annoyance. These aspects triggered the enforcement of stricter regulations and, consequently, boosted the necessity of properly manage atmospheric emissions. The conventional chemical-physical processes mainly used for the treatment of these kinds of emissions envisage the contaminants transfer to other phases and, thus, the necessity of further treatments. Biological processes and Advanced Oxidation Processes (AOPs), instead, are able to support the degradation and mineralization of organic compounds, resulting in more effective solutions. Furthermore, AOPs applied as pretreatments at biological processes may improve VOCs biotreatability and control the accumulation of biomass. Moreover, since the biological treatment of high concentrations of VOCs might cause a limitation of the oxygen available for the aerobic degradation due to the reduced water-solubility of this compound, the synergic activity of microalgae and bacteria represents an efficient alternative to support the simultaneous abatement of CO2 and VOCs. In algal-bacterial photo-bioreactors, microalgae produce oxygen during the photosynthetic process in the presence of light and CO2, while heterotrophic bacteria utilize the additional O2 supply to accelerate the oxidation of organic compounds. In turn, the CO2 resulting from the mineralization process is fixed by the microalgae. Mechanisms underlying microalgae activity might not only prevent oxygen limitation but also enhance the biodegradability of the target VOC. In this context is framed the research activity discussed in the present work, aimed to: the comparative evaluation of UV-assisted ozonation and its combination with conventional processes in different operating conditions; the comparative evaluation of two different biological reactors and the assessment of their continuous toluene degradation performances under different operating conditions; the scale-up of the proposed systems and the assessment of the technical feasibility. To this end, experimental activity was structured in two main steps: the first one was focused on the assessment of ozone and photolysis effectiveness in promoting toluene degradation; the second part was focused on the assessment of enhanced biological processes for the continuous removal of gaseous toluene. The first part of the research, focused on the comparative assessment of different configuration of AOPs systems, was performed at the Sanitary Environmental Engineering division (SEED) of Salerno University. Toluene was identified as target compound for the experimental activities. A lab-scale UV/O3 reactor was investigated for the degradation of VOCs emissions under different operating conditions, in order to highlight the influence of the inlet concentrations and the ozone dosages. A novel configuration with an additional scrubbing phase is proposed and assessed to improve the removal efficiency and to prevent the release of polluting intermediates of the single-step process. The combined system boosted higher performance and stability compared to the stand-alone (UV/O3) process along with a more economical and environmental sustainability. In the second phase, the experimental activity was performed at the Department of Chemical Engineering and Environmental Technology of Valladolid University. The experimental activity aimed at evaluating and systematically comparing the continuous toluene degradation performance of the proposed biological reactors, a conventional bacterial Biotrickilng Filter (BTF) and an innovative Tubular Photo-BioReactor (TPBR). Different operating conditions have been investigated, varying the Empty Bed Residence Time (EBRT) and the toluene inlet concentration to gradually increase the Inlet Load (IL) entering the systems. Toluene mass transfer tests have been carried out in order to determine the limiting stage, and a final robustness test performed to assess the capacity of the systems to face inlet load fluctuations. The results obtained demonstrated the potential of the synergic effects between bacteria and microalgae. The higher DO concentrations ensured oxygen availability for the microbial community and improved the process performances. The carbon dioxide released from mineralization process was utilized for the valuable biomass production. Conventional processes with AOPs pretreatment and microalgae-bacteria consortium inoculation thus represent innovative and promising methods for the increase of treatment efficiencies, biomass valorization and GHGs reduction. The combination of conventional and advanced processes represents a sustainable platform to reduce the emission of undesirable byproducts, besides treating high concentrations of VOC. [edited by Author]XXXI cicl

Optimization of Classification Prediction Performances of an Instrumental Odour Monitoring System by Using Temperature Correction Approach

Odour emissions generated by industrial and environmental protection plants are often a cause of nuisances and consequent conflicts in exposed populations. Their control is a key action to avoid complaints. Among the odour measurement techniques, the sensory-instrumental method with the application of Instrumental Odour Monitoring Systems (IOMSs) currently represents an effective solution to allow a continuous classification and quantification of odours in real time, combining the advantages of conventional analytical and sensorial techniques. However, some aspects still need to be improved. The study presents and discusses the investigation and optimization of the operational phases of an advanced IOMS, applied for monitoring of environmental odours, with the aim of increasing their performances and reliability of the measures. Accuracy rates of over 98% were reached in terms of classification performances. The implementation of automatic correction systems for the resistance values of the measurement sensors, by considering the influence of the temperature, has been proven to be a solution to further improve the reliability of IOMS. The proposed approach was based on the application of corrective coefficients experimentally determined by analyzing the correlation between resistance values and operating conditions. The paper provides useful information for the implementation of real-time management activities by using a tailor-made software, able to increase and enlarge the IOMS fields of application

Imaging spectroscopic performances for a Si based detection system

We present the imaging and spectroscopic capabilities of a system based on a single photon counting chip (PCC) bump-bonded on a Si pixel detector. The system measures the energy spectrum and the flux, produced by a standard mammographic tube. We have also made some images of low contrast details, achieving good results

Corrigendum: Cancer survivorship at heart: a multidisciplinary cardio-oncology roadmap for healthcare professionals

Content: This corrects the article DOI: 10.3389/fcvm.2023.122366

Experimental study of Compton scattering reduction in digital mammographic imaging

In mammography, the first cause of image contrast reduction arises from the photons scattered inside the examined organ. The amount of Compton scattering strongly depends on the irradiation area and on the distance between the organ and the X-ray detector. We have experimentally evaluated how these geometrical conditions affect the scattering fraction. Our experimental setup includes a single photon counting device based on a silicon pixel detector as X-ray sensor; a lucite cylinder to simulate the breast tissue, and a lead collimator to define the irradiation area. We have evaluated the contrast and the signal-to-noise ratio for images acquired in different conditions

Experimental study of Compton scattering reduction in digital mammographic imaging

In mammography, the first cause of image contrast reduction arises from the photons scattered inside the examined organ. The amount of Compton scattering strongly depends on the irradiation area and on the distance between the organ and the X-ray detector. We have experimentally evaluated how these geometrical conditions affect the scattering fraction. Our experimental setup includes a single photon counting device based on a silicon pixel detector as X-ray sensor; a lucite cylinder to simulate the breast tissue, and a lead collimator to define the irradiation area. We have evaluated the contrast and the signal-to-noise ratio for images acquired in different conditions

The visible and near infrared module of EChO

The Visible and Near Infrared (VNIR) is one of the modules of EChO, the Exoplanets Characterization Observatory proposed to ESA for an M-class mission. EChO is aimed to observe planets while transiting by their suns. Then the instrument had to be designed to assure a high efficiency over the whole spectral range. In fact, it has to be able to observe stars with an apparent magnitude Mv = 9-12 and to see contrasts of the order of 10-4-10-5 necessary to reveal the characteristics of the atmospheres of the exoplanets under investigation. VNIR is a spectrometer in a cross-dispersed configuration, covering the 0.4-2.5 μm spectral range with a resolving power of about 330 and a field of view of 2 arcsec. It is functionally split into two channels respectively working in the 0.4-1.0 μm and 1.0-2.5 μm spectral ranges. Such a solution is imposed by the fact the light at short wavelengths has to be shared with the EChO Fine Guiding System (FGS) devoted to the pointing of the stars under observation. The spectrometer makes use of a HgCdTe detector of 512 by 512 pixels, 18 μm pitch and working at a temperature of 45 K as the entire VNIR optical bench. The instrument has been interfaced to the telescope optics by two optical fibers, one per channel, to assure an easier coupling and an easier colocation of the instrument inside the EChO optical bench. <P /

Study of GaAs detectors characteristics for medical imaging

In this work we present the results of a systematic study about SI GaAs detectors as a function of substrate and contact type, geometry and thickness. This study has been stimulated from the interest in using GaAs as a detector for medical imaging applications. GaAs detectors have been produced using crystals grown with different techniques and changing both the thickness (in the range 200 μm-1 mm) and the contacts type and geometry. We have measured the current-voltage characteristics and, using radioactive sources (109Cd, 20 keV photons, 241Am, 60 keV photons, 99mTc, 140 keV photons), we have studied the performance of our detectors in terms of charge collection efficiency and energy resolution as a function of the bias voltage. Besides we have also studied the electrical and spectroscopic properties of GaAs detectors with different types and concentrations of the dopants in the substrate. So we have found the optimal doping type and concentration to have the best spectroscopic performances and the higher breakdown voltage. Simulation programs made with Monte Carlo methods have been developed to describe the electric field distribution and the transport of charge carriers toward the electrodes in GaAs detectors. In these simulations we have considered the presence of deep energy levels in the bandgap, the thickness, the bias voltage and the charge deposition in the crystal after photon interaction

Inflammatory bowel disease nurse specialists for patients on biological therapies: a nationwide Italian survey

Background Management of inflammatory bowel disease (IBD) patients requires a multidisciplinary approach. Among the working team, the role of IBD nurse is expected to be particularly relevant when managing patients receiving biological therapies. We performed a survey to assess the presence of IBD nurse in centers where patients were receiving biologics. Methods For this Italian nationwide survey a specific questionnaire was prepared. IBD nurse was defined as a nurse directly involved in all phases of biological therapy, from pre-therapy screening, administration and monitoring during therapy, to follow up performed by a dedicated helpline, completed a specific training on biological therapy therapy, and observed international guidelines. Results A total of 53 Italian IBD centers participated in the survey, and 91 valid questionnaires were collected. Overall, 34 (37.4%) nurses could be classified as IBD specialists. IBD nurses had a significantly higher educational level than other nurses, they were more frequently operating in Central or Southern than in Northern Italy, they were working in an Academic center rather than in a General hospital, and in IBD centers with &gt;25 patients on biological therapy. On the contrary, mean age, gender distribution, years of nursing, and years working in the IBD unit did not significantly differ between IBD and other nurses. Conclusions Our nationwide survey showed that the presence of an IBD nurse is still lacking in the majority of Italian IBD centers where patients receive biological therapies, suggesting a prompt implementation