1,721,023 research outputs found
Dark fermentation process as pretreatment for a sustainable denaturation of asbestos containing wastes
Full text linkA cement asbestos compound (CAC) sample was detoxified by a treatment train based on a dark fermentation (DF) process followed by a hydrothermal phase, which led to the complete degradation of the chrysotile fibers. During the biological pretreatment, the glucose was converted in biogas rich in H2 and volatile fatty acids (VFA). The latter caused the dissolution of all the Ca-based compounds and the solubilisation of 50% brucite-like layers of chrysotile fibers contained in the CAC suspended in the bioreactor (5 g/L). XRD analysis of the solids contained in the effluents of the DF process highlighted the disappearance of the chrysotile fiber peaks. However, a complete destruction of all the asbestos fibers is hard to prove and a hydrothermal treatment was carried out to dissolve the “brucite” layers still present in solution. Due to the presence of the VFA produced during the DF, a complete destruction of chrysotile fibers was achieved by a 24 h hydrothermal process performed with a [H2SO4]/[CAC] ratio 50% lower than that adopted in a previous finding. Consequently, the DF pre-treatment can contribute to lower the H2SO4 and the energy consumption of a CAC hydrothermal treatment, due to the production of VFA and H2
Novel Bioderived Composites from Wastes
Full text linkThe recycling and reuse of solid wastes can be considered important challenges for civil and environmental applications in the frame of a more sustainable model of development and the consumption of new resources and energy [...
Chemical Destabilization of Fresh and Spent Cutting Oil Emulsions: Differences between an Ecofriendly and Two Commercial Synthetic Lubricants
Full text linkThe aim of this study was to evaluate if eco-friendly lubricants had an additional advantage over conventional synthetic lubricants in terms of emulsion treatment of metalworking wastewater. To these purpose, two fresh commercial synthetic cutting oil emulsions were compared with an emulsion obtained from a new cutting oil produced from the reuse of slaughtering waste (CADT-605 from Kimya Srl, Bari, Italy). The breaking of the fresh emulsions was carried out with the addition of small amounts of sulfuric acid (2–20 mL/L) followed by pH neutralization by means of calcium hydroxide. During the two-step treatments, COD, BOD5 and non-ionic surfactant (NIS) concentrations were monitored in the aqueous phase. The results demonstrated that the best results were obtained with the emulsion produced with the bio-based lubricant. In addition, this cutting oil was tested in a metalworking plant within 30 days and the resulting spent emulsion was treated with the proposed process. In all the cases, the treatment led to a drastic decrease of the COD, BOD5 and NIS contents that allow the discharge of resulting aqueous phase in sewers or in surface water bodies, together with the other wastewater produced by the plant, in agreement with the Italian regulation
Selective oxidation processes of organic substances by means of photocatalytic systems
No full textSelective oxidation of benzyl alcohol to benzaldehyde in aqueous solution, at acidic conditions, through TiO2/Cu(II)/solar UV system was investigated. Different commercial TiO2 samples were tested. The best result found in terms of yield was of 35 % of benzaldehyde with respect to the initial benzyl alcohol. During each run a partial conversion of benzaldehyde to benzoic acid was also observed. The study suggested that different operative parameters, such as the composition of photocatalyst, amount of catalyst, pH, ionic components in water and the initial concentration of Cu(II) played an important role in the photocatalytic oxidation of benzyl alcohol, at the end of the process, Cu(II) could be regenerated and reused, through a re-oxidation of Cu(0), produced during the photolytic run, with air at dark. © 2011, AIDIC Servizi S.r.l
Evaluation of the hydraulic and hydrodynamic parameters influencing photo-catalytic degradation of biopersistent pollutants in a pilot plant
No full textA kinetic study on the photo-catalytic degradation of bio-persistent micro-pollutants, as
methyl red and methylene blue dyes, was carried out on an innovative unit by changing
the hydraulic and hydrodynamic parameters of the system. The catalyst (TiO2, anatase) was
embedded into a cement matrix and deposited at the bottom of a channel to activate the
UVB photo-degradation reactions. The influence of the catalyst dosage, substrate concentration
c0, and pH was evaluated on the degradation rates. The optimum catalytic dose was
obtained at 0.79 g/cm3 while the best results were observed at 0.7 mg/L influent dye concentration.
The pH of the solution influenced the sorption phenomena because the charge
of the substrates functional groups as well as the charge of the catalyst surface were
affected by this parameter. Different unit geometries, hydraulic loads (hw) and gradients (i)
affected speed and flow-rate (Q) of the liquid phase and, as a consequence, the irradiated
retention times (Irt) of the substrates to the UV/TiO2 system. Kinetics resulted faster at
increasing flow-rates of the liquid flowing through the channel, constant the hydraulic load,
whereas the increase in the hydraulic load did not improve the performances. Finally, degradation
rates slightly decreased after the increase in the hydraulic gradient of the channel
Technical and Economic Feasibility Investigation for the Treatment of Microplastic-Contaminated Marine Sediments Through an Environmentally Sustainable Separation Process
No full textThis work provides a comprehensive study of a density separation treatment through sucrose solution for the removal of microplastics (MPs) from marine sediments. The theoretical determination of flotation velocities for 1.0 mm diameter spherical MPs with a density of 1.3 g/cm 3 at various solution temperatures and sucrose contents was performed. An optimal velocity of 1.03 m/h was observed with a 70% sucrose solution at 50 °C. The validation of theoretical velocities was carried out through experimental tests at optimal operating conditions for polypropylene (PP), high-density polyethylene (HDPE), polylactic acid (PLA), and polyvinyl chloride (PVC) as target MPs. The results showed an experimental floating velocity slightly lower than the theoretical predictions for PP, HDPE, and PLA. PVC, instead, characterized by a higher density than the separation solution, showed a settling velocity 42% lower than the theoretical one. Further tests were performed to assess the solid-to-liquid (S/L) ratio effect on MPs' separation efficiency. The results showed an optimal S/L of 75 kg/m 3 with 80% PVC removal and total PP, HDPE, and PLA removal. Finally, the design and cost optimization of a longitudinal settling tank were proposed for the pilot/real-scale treatment. The observed outcomes provided in-depth details useful for the development of an environmentally sustainable treatment for the preservation of marine areas
A Preliminary Evaluation of the Public Risk Perception Related to the COVID-19 Health Emergency in Italy
Full text linkGovernments faced with the spread of COVID-19 pandemic are adopting strict and severe mitigation measures to influence people’s behaviors. Public perception of health risk plays a key role in the adoption of these actions, in people’s feelings, and in their daily habits. To support decision makers from international to local levels to face with future sanitary emergencies, this study aims at investigating Italian public perceptions of health risk. To this purpose, a questionnaire was designed and administered within the period of Italian COVID-19 lockdown and quarantine to almost 9000 citizens in Italy and abroad. The obtained results highlight a significative influence that mass media play on both the level of knowledge and the feelings of the respondents. The findings also point out future variations of some perceived behaviors consequent to the COVID-19 outbreak
Haloculture: A system to mitigate the negative impacts of pandemics on the environment, society and economy, emphasizing COVID-19
No full textCOVID-19 (coronavirus disease) is a global pandemic that started in China in 2019 and has negatively affected all economic sectors of the world, including agriculture. However, according to estimates in different countries, agriculture has suffered less than other sectors such as construction, industry and tourism, so agricultural development can be a good option to compensate for the economic damage caused to other sectors. The quality of available water and soil resources for agricultural development is not only limited, but is also decreasing incrementally, so the use of saline and unconventional soil and water resources is inevitable. Biosaline agriculture or haloculture is a system in which highly saline water and soil resources are used sustainably for the economic production of agricultural crops. It seems that in the current situation of the world (with COVID-19's impact on agriculture on the one hand and the quantitative and qualitative decline of freshwater and soil on the other), haloculture with a re-reading of territorial capabilities has good potential to provide a part of human food supply. In this review article, the potential of haloculture to offset the adverse impacts of the pandemic is analyzed from five perspectives: increasing the area under cultivation, using unconventional water, stabilizing dust centers, increasing the body's immune resistance, and reducing losses in agribusiness due to the coronavirus. Overall, haloculture is an essential system, which COVID-19 has accelerated in the agricultural sector
Fe(III)-photocatalytic partial oxidation of benzyl alcohol to benzaldehyde under UV-solar simulated radiation
No full textA great deal of interest is recorded among researchers in the identification of new catalytic systems that make possible the selective oxidation of organic species in the presence of non-toxic solvents, primarily water, through the use of inexpensive catalysts. The possibility to selectively oxidize benzyl alcohol to benzaldehyde is studied in the present work by using ferric ions as homogeneous catalysts and oxygen as an oxidant under UV-solar simulated radiation. Due to the possibility that Fe(iii) aquo-complex photolysis could generate undesired reactive OH radicals with the consequent occurrence of side reactions, most of the runs are carried out at pH = 0.5 at which these events have a reduced incidence. The results indicate that benzyl alcohol can be partially converted into benzaldehyde with yield and selectivity values higher than 40% and 80% respectively for the conditions adopted, with a minor occurrence of benzoic acid formation. Reaction schemes to account for the experimental observations are provided
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