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Most visual odometry (VO) and visual simultaneous localization and mapping (VSLAM) systems rely heavily on robust keypoint detection and matching. With regards to images taken in the underwater environment, phenomena like shallow water caustics and/or dynamic objects like fishes can lead to the detection and matching of unreliable (unsuitable) keypoints within the visual motion estimation pipeline. We propose a plug-and-play keypoint rejection system that rejects keypoints unsuitable for tracking in order to obtain a robust visual ego-motion estimation. A convolutional neural network is trained in a supervised manner, with image patches having a detected keypoint in its center as input and the probability of such a keypoint suitable for tracking and mapping as output. We provide experimental evidence that the system prevents to track unsuitable keypoints in a state-of-the-art VSLAM system. In addition we evaluated several strategies aimed at increasing the inference speed of the network for real-time operations.

Modern societies produce ever-increasing amounts of waste, e.g. organic fraction of municipal solid waste (OFMSW). According to the best available techniques, OFMSW should be treated through anaerobic digestion to recover biogas and subsequently composted. An innovative scheme is under investigation, where anaerobic digestion is combined with hydrothermal carbonization (HTC) and composting. The final product, referred to as hydrochar co-compost (HCO), is under study to be used as an unconventional soil improver/fertilizer. Recent studies showed that HCO is not phytotoxic. However, nothing is known about the toxicity of HCO on cells as part and organisms as a whole. This study aims to investigate in vitro genotoxicity and cytotoxicity of the HCO and its precursors in the production process. In particular, we tested water and methanolic extracts of HCO (WEHCO and MEHCO) from one side and methanolic extracts of hydrochar (MEH) and OFMSW digestate (MED) as well as liquor produced downstream HTC (HTCL) from the other side. Genotoxicity was investigated using cytokinesis-block micronucleus assay in Chinese Hamster Ovarian K1 (CHO-K1) cells. Cytotoxicity was tested in vitro against a panel of human cells line. Zebrafish embryo toxicity upon MEH treatment was also investigated. Results show that incubation of CHO-K1 cells with all the tested samples at different concentrations did not cause any induction of micronucleus formation compared to the vehicle-treated control. Treatment of cells with MEH, MED, HTCL and MEHCO, but not WEHCO, induced some degree of cytotoxicity and MEH showed to be more cytotoxic against tested cells compared to the MEHCO. Toxicity effect at the highest tested concentrations of MEH on zebrafish embryos resulted in coagulation, induction of pericardial edema and death. In conclusion, the hydrochar co-compost cytotoxicity is similar to standard compost cytotoxicity. Hence composting the hydrochar from OFMSW digestate is a good step to eliminate the cytotoxicity of hydrochar.

The chemical-physical processes controlling hydrothermal carbonization (HTC) are still not completely understood. This paper focuses on two aspects: the influence on the hydrochar formation of the particle size of the feedstock and the presence of solved compounds in the feedwater. To address these, brewer’s spent grains were crushed to 250 μm proved by HPLC analysis of liquid byproducts, particularly when rPW, containing readily condensable/polymerizable intermediates, is added. This has a positive effect on the yield and carbon content of the hydrochars caused mainly by an increase in its secondary char fraction. The reaction pathways involved are discussed in detail.

This study evaluates the effects of thermal hydrolysis (TH) pretreatment on anaerobic digestion (AD), through results obtained by biochemical methane potential (BMP) tests under mesophilic conditions (35 °C). Thickened sludge from a wastewater treatment plant (WWTP) was thermally treated under two different temperatures (150 and 170 °C) and reaction times (30 and 60 min). Results show a significant increase in soluble COD, compared with the untreated sludge, when sludge was treated at 170 °C for 60 min. Moreover, the following BMP tests point out that TH pretreatment of sludge accelerated the AD rate and increased the biogas yield contributing to an increase in methane production, ranging between 17 and 24% compared with the raw sludge. Furthermore, the hydrolysis constant was estimated and methane production and degree of disintegration of the TH pretreated sludge were correlated, in order to deep the knowledge on the hydrolysis as the AD rate-limiting step. Further, the combined effects of TH pretreatment and AD on sludge show a reduction of total and volatile solids up to 19% and 24%, respectively.

Co-firing of biomass and coal may increase short-term renewable fuel usage. However, the lower heating value and higher reactivity (at lower temperatures) of raw biomass can result in fuel segregation in boilers, causing burnout at lower temperatures, lower steam generation efficiency and fouling. In addition, the relatively high water content of some biomasses requires extensive drying prior to combustion. These issues may be addressed by hydrothermally carbonizing moist biomasses to produce hydrochars that more closely resemble coal’s properties prior to co-firing. In the present work, we probe the co-oxidation behavior of a series of hydrothermally carbonized biomass samples over a range of hydrochar-coal blend ratios to determine the degree of carbonization necessary to reduce fuel segregation. However, due to the presence of an extractable amorphous secondary char, even highly carbonized hydrochars have considerably higher oxidative reactivity than a representative bituminous coal sample. When blended, the hydrochars and coal display distinct derivative thermogravimetric oxidation ranges, in which a low-temperature peak is dominated by the secondary char oxidation, followed by a high-temperature char oxidation peak of the primary solid hydrochar. After extraction of the secondary char, the primary char displays a lower reactivity than the coal. As a co-fired fuel, it appears that blending hydrochars up to 10 wt% with a bituminous coal is possible as a partial fuel substitution. To increase the percentage of hydrochars blended with coal, it may be necessary to extract this secondary char (which contains valuable biofuels and platform chemicals) before blending.

This work presents a scale‐up and feasibility study for the establishment of supercritical CO₂ extraction plants to produce grape seeds oil. The scale‐up factors are determined using experimental and modelling results based on seeds from six grape cultivars over 2 harvest years. The purchased cost of the production plant is estimated using ‘the six‐tenth rule’ from the cost of a pilot scale unit. The results indicate that, at the current minimum retail selling price of extra virgin grape seeds oil, the proposed project is technically viable and economically feasible with a breakeven point of US$ 7.46 per kg‐oil and rate of return on investment of 28%.

The best available technique (BAT) for managing the organic fraction of municipal solid waste (OFMSW) is represented by anaerobic digestion (AD) and subsequent composting. This research explored a new industrial model in the framework of the C2Land international project, with the insertion of hydrothermal carbonization (HTC) as a post-treatment for OFMSW digestate. The reaction was set for 3 h at three different temperatures (180 ÷ 220 °C); the wet solid hydrochar obtained after filtration was then co-composted with greenery waste as a bulking agent and untreated OFMSW digestate in four different proportions in bench-scale bioreactors. The hydrochars and the hydrochar co-composts were suitable for agro-industrial applications, while the HTC liquors were tested in biochemical methane potential (BMP) for internal recirculation to AD. The scenarios proposed can be beneficial for plant enhancement and increased biogas production. This study reports results connected to the production phase. Mass balances confirmed that, during HTC, phosphorus precipitated into the solid products, organic nitrogen partially mineralized into ammonium, and oxidizable organic matter solubilized. The selected hydrochar obtained at 200 °C had mean (dry) solid, liquid, and gaseous yields equal to 77, 20, and 3 %

The increased quantities of manure being generated by livestock and their extensive agronomic use have raised concerns around run-off impacting soil and groundwater quality. Manure contains valuable nutrients (especially phosphorus) that are critical to agriculture, but when directly land-applied the run-off of such nutrients contributes to eutrophication of waterways. This study investigates the hydrothermal carbonization of cow manure at two industrially feasible process extremes: 190 °C, 1 h and 230 °C, 3 h, to concentrate and then recover phosphorus from the solid hydrochar via acid leaching and precipitation. Up to 98 wt% of phosphorus initially present in the hydrochar (88% in the raw manure) can be recovered, with the dominant crystalline species being hydroxyapatite. Acid leached hydrochars were subsequently pyrolyzed at 600 °C for 30 min, and then evaluated as adsorbent materials for water remediation by using methylene blue as a model adsorbate. Although pyrolyzed hydrochars have surface areas an order of magnitude higher (160-236 m

Hydrothermal Carbonization (HTC) refers to the conversion of biogenic wastes into char-like solids with promising perspectives for application, but a process water (PW) results which is difficult to dispose untreated. Thus, a biorefinery approach including one or two recirculation steps with the additional objective of improving the physico-chemical characteristics of the solid was performed. During HTC, constitutive biomass molecules decompose into hundreds of organic compounds, following complex reactions. To get deeper insights a combination of proximate, ultimate and structural analysis for solid products as well as liquid chromatography for liquid products were the choice. The main reactions could be identified by key compounds of low and high molecular weight resulting from hydrolysis, dehydration, decarboxylation, deamination as well as amide formation and condensation reactions. Their intensity was influenced by the feedwater pH and reaction temperature. Reactions of Maillard character result in N-containing heterocycles incorporated into the hydrochar (HC), which promises the fabrication of high added-value materials, i.e. N-doped carbonaceous materials.

Hydrothermal carbonization (HTC) is known for being exothermic, an aspect that can lower the external energy demand necessary to face thermal losses and therefore be conducive to the overall HTC process thermal efficiency. Also, heat profiles can help explore kinetics and generally provide an insight into the HTC process. Despite the potential of the HTC exothermicity, only a few studies examined it and with different methodologies. This work aims to deepen this aspect by exploring heat profiles, enthalpy of reaction, and comparing two experimental methods by performing an experimental campaign using a power-compensated high-pressure differential scanning calorimeter (DSC). Three substrates (glucose, cellulose, and grape seeds) were hydrothermally carbonized at 180, 200, 220, and 250 °C at a biomass to water mass ratio of 0.25. To determine net heat profiles and enthalpies, water thermal effects were removed using two approaches, consisting of running a thermal program on the water alone or the exhaust, i.e. the products after the reaction. An instrument baseline considering both a zero-line and a time-drift was considered. Results show that both methods allow inferring similar enthalpy values at low operating temperature, while at high temperature a difference in the heat capacity of the liquid phase (due to the production of compounds dissolved in the liquid phase and absorbed on the solid) can affect the results related to the exhaust approach. In both cases, higher temperatures favor the exothermic peak intensity, the curve sharpening, and the increase (in absolute value) of reaction enthalpies. These are in the ranges −0.20 ÷ −0.86 MJ/kg, −0.61 ÷ −1.33 MJ/kg, and −0.42 ÷ −1.53 MJ/kg for glucose, cellulose, and grape seeds, respectively.

We studied the effect of temperature gradients within a packed bed on the SuperCritical (SC) CO2 extraction of oil from pelletized cranberry seeds. Temperature gradients were imposed on the extractor by using different temperatures for the SC-CO2 flow and the extractor vessel wall in heating and cooling experiments (60 and 40 °C, and viceversa) for oilseed pellets and glass beads at 48 MPa. A two-phase heat transfer model and a linear-driving-force mass transfer model described temperature profiles and oil extraction curves. Overall, temperatures in the packed bed were more affected by the vessel wall than the SC-CO2 inlet condition. Extraction curves for heating and cooling experiments were between the isothermal extraction curves for 40 and 60 °C, being affected by the vessel wall temperature in the solubility-controlled period of the extraction and approaching each other after 1-h of dynamic extraction. Both heat and mass transfer models allowed a satisfactory prediction of such a behavior and represent a step forward in the prediction of SC-CO2 oil extraction course.

Hydrothermal carbonization (HTC) technology is addressed in the framework of sewage digestate management. HTC converts digestate into a stabilized and sterilized solid (the hydrochar) and a liquor (HTCL) rich in organic carbon. This study aims to optimize the HTC operating parameters, namely the treatment time, in terms of hydrochar production, HTC slurry dewaterability, HTCL bio-methane yields in anaerobic digestion (AD), and process energy consumption. Digestate slurry was processed through HTC at different treatment times (0.5, 1, 2 and 3 h) at 190 °C, and the dewaterability of the treated slurries was addressed through capillary suction time and centrifuge lab-testing. In addition, biochemical methane potential (BMP) tests were conducted for HTCL under mesophilic conditions. Results show that by increasing the HTC treatment time the dewaterability was further improved, ammonium concentration in HTCL increased, and methane potential of HTCL decreased. 0.5 h HTCL had the highest bio-methane potential of 142 ± 3 mL CH4/g COD yet the treatment time was not sufficient for improving the slurry's dewaterability. HTC treatment time of 1 h at 190 °C was identified as the optimum trade-off for improved dewaterability and utilisation of HTCL for biogas production. 1 h HTCL bio-methane potential can cover around 25% of the HTC and AD thermal and electrical energy needs without considering the eventual use of the hydrochar as a biofuel.

Globally, as societies urbanize and demand for energy increases, the need to manage mounting quantities of municipal solid waste (MSW), produce renewable energy, and insure clean water supplies becomes more pressing each year. These issues could be addressed by integrating pyrolysis of MSW to recover liquid and gaseous biofuels and a solid biochar, with CO2 activation of the latter to produce activated biochars for water treatment. This potential conversion pathway is experimentally demonstrated by pyrolyzing a model MSW stream at 408 °C, the peak mass loss rate pyrolysis temperature and compared to pyrolysis at 900 °C. As pyrolysis temperature increases, we see conversion of plastic intermediaries into paraffins and polycyclic aromatic compounds, though the desirable gas components (methane, hydrogen, carbon monoxide) of the pyrolysis gas increase substantially. The CO2 activated biochars (activated at 600 °C and 900 °C) show surface areas over 300 m2/g, with the lower pyrolysis temperature and higher activation temperature yielding the highest areas. Adsorption experiments were performed with methylene blue to determine the ability of the activated MSW-biochar to remove organic pollutants from water. Adsorption is well described by the Langmuir isotherm, with equilibrium adsorption capacities upwards of 250 mgdye/g for all activated biochars.

This study reports the implications of using spent coffee hydrochar as substrate for anaerobic digestion (AD) processes. Three different spent coffee hydrochars produced at 180, 220 and 250 °C, 1 h residence time, were investigated for their biomethane potential in AD process inoculated with cow manure. Spent coffee hydrochars were characterized in terms of ultimate, proximate and higher heating value (HHV), and their theoretical bio-methane yield evaluated using Boyle-Buswell equation and compared to the experimental values. The results were then analyzed using the modified Gompertz equation to determine the main AD evolution parameters. Different hydrochar properties were related to AD process performances. AD of spent coffee hydrochars produced at 180 °C showed the highest biomethane production rate (46 mL CH4/gVS.d), a biomethane potential of 491 mL/gVS (AD lasting 25 days), and a biomethane gas daily composition of about 70%.

Opuntia ficus-indica cladodes are a potential source of solid biofuel from marginal, dry land. Experiments assessed the effects of temperature (180-250°C), reaction time (0.5-3h) and biomass to water ratio (B/W; 0.07-0.30) on chars produced via hydrothermal carbonization. Multivariate linear regression demonstrated that the three process parameters are critically important to hydrochar solid yield, while B/W drives energy yield. Heating value increased together with temperature and reaction time and was maximized at intermediate B/W (0.14-0.20). Microscopy shows evidence of secondary char formed at higher temperatures and B/W ratios. X-ray diffraction, thermogravimetric data, microscopy and inductively coupled plasma mass spectrometry suggest that calcium oxalate in the raw biomass remains in the hydrochar; at higher temperatures, the mineral decomposes into CO2 and may catalyze char/tar decomposition.

This study investigates the suitability of a sequencing batch reactor (SBR) for treating the liquor (HTCL) derived from hydrothermal carbonization (HTC) of sewage sludge in addition to the influent municipal wastewater. The SBR was fed for 80 days with an increasing mixing ratio HTCL/municipal wastewater. HTCL was used as external carbon source to enhance the denitrification process in the water line of the wastewater treatment plant (WWTP). The feeding of the HTCL caused an overloading in the COD and TKN concentration of the biological treatment equal to, respectively, 25% and 8% (Period II), 50% and 16% (Period III) and 100% and 32% (Period IV). Results revealed that good efficiencies of COD removal were obtained during the entire experimental test, accounting up to 91% in Period IV. Moreover, the removal of TN was improved increasing from 28% in the reference period (Period I), where no HTCL was fed, to 33%, 47% and 64% respectively in Period II, III and IV. Thus, an improvement in the denitrification process was obtained when HTCL was fed to the biological reactor in addition to the influent wastewater. The implementation of the SBR system was supported by nitrate uptake rate (NUR) tests and respirometric assays to evaluate the nitrate removal after the addition of HTCL and the fraction of readily biodegradable COD (RBCOD) and soluble biodegradable COD (sCODbio) on the total COD of the HTCL.

Hydrothermal carbonization (HTC) and pyrolysis are two promising thermochemical conversion strategies to valorize agricultural wastes, yet neither process can be implemented alone to sustainably upgrade both wet and dry feedstocks. HTC is ideal for wet feedstocks, such as manure, but its solid hydrochars suffer from low surface area and stability. Pyrolysis is well suited to dry agricultural residues, but pyrolysis biochars have low nutrient contents and bio-oils are often highly oxygenated. We propose an integrated process that co-pyrolyzes a nutrient-rich cow manure hydrochar with raw agricultural residues, which effectively reduces the environmental impact of these wastes while producing value-added bioproducts. Biochars produced from the proposed process are more suitable for soil amendments due to their enhancement in bioavailable nutrients and surface area than the manure hydrochars and raw biomass. Co-pyrolysis of blends enriched with cow manure yield oils higher in alkanes and alkenes with fewer oxygenated compounds.

The present work reports a case study for the industrialization of a biorefinery aimed at valorizing fish processing residues in order to obtain ω-3 concentrates for the nutraceutical sector. The biorefinery includes a series of processes: oil extraction from fish waste, fish oil transesterification with ethanol, ω-3 concentration based on supercritical CO2 fractionation. The biorefinery is at first designed and then modeled by Aspen Plus™: this allows for a comprehensive picture (mass and energy flows, processing costs and costs for investment) of the overall process. In accordance with the zero-waste concept, all the biorefinery by-products are valorized: fish proteins as fishmeal, and glycerol, saturated fatty acids and short chain unsaturated fatty acids as liquid biofuel. In addition, fish oil transesterification with ethanol is also experimentally tested in different operational conditions in order to maximize fish oil conversion to fatty acid ethyl esters. A trout processing company located in Trentino Province, Italy, represents the case study. The company produces 870 t/year of fish waste. Mass balances allow estimating a production of 26.6 t/year of ω-3 rich oil (income: 1.3 M€), 160 t/year of fish proteins (income: 0.27 M€), and 160 t/year of liquid biofuel. The biofuel, fed to a 100 kWel CHP unit, allows to produce 720 MWhe/year and 870 MWhth/year, covering the total electricity consumption of the plant and providing more than 45% of the thermal energy needs. This translates into a reduction in utility costs of about 0.12 M€ and avoids the emission of 416 t/year of CO2. Finally, the total investment costs for the whole biorefinery amount to about 3.34 M€. In conclusion, this study demonstrates that the production of ω-3 rich fish oils in a bio-refinery concept could become a good opportunity for valorizing fish by-products and increasing the competitiveness of the fish processing industry.

Hydrothermal carbonisation was used to upgrade fuels from two types of agro-industrial wastes: olive tree trimmings and olive pulp. Hydrochar yield, elemental and proximate analyses, thermal stability, higher heating value (HHV), and energy yield at different reaction temperatures (120, 150, 180, 200, 220, 235 and 250 °C) and solid load (biomass to water ratios − B/W − equal to 7, 10, 15 and 25%) were assessed for a fixed reaction time of 30 min. HHV varied linearly with hydrochar mass yield and reaction temperature in the temperature range 180–250 °C. Solid load proved to be a crucial parameter in determining the energy properties of hydrochars. The higher B/W, the higher were the degree of carbonisation (in terms of fixed and total carbon), the hydrochar HHV, and the hydrochar yield. Elemental analysis showed that during HTC, olive pulp samples underwent a greater degree of carbonisation when compared to the corresponding olive tree trimmings residues. High solid load and high reaction temperature promoted secondary char formation. Secondary char showed a sphere-like structure formed by overlapping layers. EDS microanalysis showed that secondary char is characterised by a significantly higher carbon content than parent primary char, thus confirming its contribution towards enhancing the HHV of hydrochars.

Reliable Radar Cross Section (RCS) measurements require complex radar instrumentation systems, very expensive and dedicated test ranges and operations, especially in the case of full scale targets.The capability to perform RCS measurements exploiting near field (NF) test ranges and non-ideally anechoic environments is more and more attractive. Applications related to these topics are recently gaining great interest especially in the design-prototyping loop of low observable platforms and full scale components. To this purpose, Ingegneria dei Sistemi (IDS) has been developing validated RCS measurement solutions and innovative processing techniques for more than ten years.This paper describes a radar image based near-field to far-field (NF2FF) processing procedure to get RCS plots of full scale aerial targets measured in near field conditions, exploiting clutter controlled manufacturing areas, open sites and semi-anechoic laboratories, avoiding perfect anechoic chambers and complex supporting structures.

Reliable Radar Cross Section (RCS) measurements require complex instrumentation systems, expensive and dedicated test ranges and operations, especially when dealing with full-scale targets. Thus performing RCS measurements using near field test ranges and non-ideally anechoic environments is a very attractive option. Applications related to these topics have recently been of increasing interest especially in the design-prototyping loop of low observable platforms and full-scale components. To this purpose, IDS has been developing and using reliable RCS measurement solutions and innovative processing techniques for more than fifteen years. This paper focuses on the major contributions to uncertainty in radar image based near field to far-field RCS measurement, by reviewing each of the principal sources of uncertainty, both random and systematic, and underlining possible error mitigation strategies.

Hydrothermal carbonization (HTC) is a thermochemical process that can reduce the environmental burdens of wet, heterogeneous biomasses such as the organic fraction of municipal solid waste (OFMSW). Whilst the effect of processing parameters on hydrochar properties is well known, post-treatments to valorize hydrochars are infrequently investigated. Moreover, more severely carbonized hydrochars have a reactive species present on their surface that may limit hydrochars’ use as a solid fuel or soil amendment/environmental adsorbent. To address these potential limitations, a low-temperature (180 °C) thermal treatment and a chemical extraction (1:4 methanol: dichloromethane) were performed on OFMSW hydrochars. The thermal extraction removed up to 12% of this reactive volatile matter, comprised of alkanes, furans, ketones, and fatty acids. Chemical extraction removed up to 61% of the hydrochar, and the extract comprised mostly fatty acids, suggesting a potential pathway for recovery of fatty acids and condensation of fuel molecules in the solid hydrochar. The higher heating values of the extracts were much greater than the non-extractable solid hydrochar. The non-extractable primary char showed similar oxidative and pyrolytic behavior to a standard bituminous coal. The results indicate that HTC could valorize OFMSW by converting this wet waste into a dry solid fuel, soil amendment or environmental adsorbent while simultaneously extracting valuable biodiesel and biofuel precursors. Given increasing legislative pressure to divert OFMSW from landfills, this new pathway offers an alternative to traditional anaerobic digestion management strategies that produce only methane as a green energy product.

Hydrothermal carbonization (HTC) was evaluated as a promising treatment to enhance the biomethane potential during anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW). The OFMSW was carbonized at different conditions and HTC products were tested for biomethane potential into AD. Results proved that the use of HTC liquid and slurry into AD led to an increase in biomethane production up to 37% and 363%, respectively, compared to OFMSW. Methane production increased as the HTC process severity decreased, reaching its maximum at 180 °C, 1 h for both HTC products. Energy assessment demonstrated that the combustion of biogas produced by AD of HTC liquid and slurries covers up to 30% and 104% of the HTC thermal demand, respectively. When the energy from hydrochar and biogas combustion was recovered, the process efficiency reached 60%. Hence, HTC coupled with AD demonstrates to be an efficient way to valorize OFMSW.

The solubility of grape (Vitis vinifera L.) seed oil in supercritical CO2 was measured in the temperature range 313–343 K and pressure range 20–50 MPa using the dynamic technique. Several data and global trends were reported. The results show that, at constant temperature, the solubility increases with the increase in pressure, while the effect of the temperature is different for low and high pressure. The experimental data were modeled by eight density-based models and a thermodynamic model based on the Peng-Robinson equation of state. By best fitting procedures, the “free parameters” of the various models were calculated: in general, all the tested models have proved to be able to predict the solubility of grape seed oil in supercritical CO2. Differences in model capabilities have been discussed based on the main characteristics of the various models, evidencing their distinct and common features. The predictive capability of the thermodynamic model was comparable to that of the density-based models.

Food processing residues are often rich in bioactive compounds which, if properly extracted and recovered, can be re-utilized as food supplements or in nutraceutical formulations, with obvious advantages from the health and economical standpoints. High pressure extraction processes can be utilized for such purpose. They are usually performed or using supercritical fluids, namely supercritical CO 2 suitable for extracting non-polar solutes, or using pressurized liquids, for instance water capable to extract polar and semi-polar compounds. This short review highlights the application of high pressure technologies for the extraction of bioactives from food processing residues with special emphasis on the most recent works and patents.

This study focuses on the maximization of the phenolic compounds of spent coffee grounds, by coupling hydrothermal delignification with ultrasonic assisted extraction. Temperatures of 200°C, 230 °C and 260 °C were applied for hydrothermal treatment for 1h and 3h. Produced hydrochars contain high values of fuel ratio (0.35 - 0.69) compared to raw feedstock (0.20). The increment of the reaction severity decreases the energy yield from 95.23 % to 82.99 %. After the hydrothermal treatment, the total phenolic content (TPC of the process water), determined relatively to a gallic acid standard (GAE), was found to be in a similar range for all process conditions (9.52 – 8.07 mg GAE / mg of dry sample). Using methanol as a solvent into produced dry hydrochars during ultrasonic assisted extraction reveals the highest values of TPC (20.33 – 11.66 mg GAE/ mg of dry sample).This study focuses on the maximization of the phenolic compounds of spent coffee grounds, by coupling hydrothermal delignification with ultrasonic assisted extraction. Temperatures of 200°C, 230 °C and 260 °C were applied for hydrothermal treatment for 1h and 3h. Produced hydrochars contain high values of fuel ratio (0.35 - 0.69) compared to raw feedstock (0.20). The increment of the reaction severity decreases the energy yield from 95.23 % to 82.99 %. After the hydrothermal treatment, the total phenolic content (TPC of the process water), determined relatively to a gallic acid standard (GAE), was found to be in a similar range for all process conditions (9.52 – 8.07 mg GAE / mg of dry sample). Using methanol as a solvent into produced dry hydrochars during ultrasonic assisted extraction reveals the highest values of TPC (20.33 – 11.66 mg GAE/ mg of dry sample).

Conventional activated sludge systems, still widely used to treat wastewater, produce large amounts of solid waste that is commonly landfilled or incinerated. This study addresses the potential use of Hydrothermal Carbonization (HTC) to valorize sewage sludge residues examining the properties of hydrochars depending on HTC process conditions and sewage sludge withdrawal point. With increasing HTC severity (process residence time and temperature), solid yield, total Chemical Oxygen Demand (COD) and solid pH decrease while ash content increases. Hydrochars produced from primary (thickened) and secondary (digested and dewatered) sludge show peculiar distinct properties. Hydrochars produced from thickened sludge show good fuel properties in terms of Higher Heating Value (HHV) and reduced ash content. However, relatively high volatile matter and O:C and H:C ratios result in thermal reactivity significantly higher than typical coals. Both series of carbonized secondary sludges show neutral pH, low COD, enhanced phosphorous content and low heavy metals concentration: as a whole, they show properties compatible with their use as soil amendments.

Research around hydrothermal carbonization (HTC) has seen a huge development in recent years, materializing in the first pilot and industrial plants. Even though HTC reactions are slightly exothermic, the overall process entails energy consumption to both reach operating conditions and tackle heat losses. To face this issue and to develop a zero-energy process, this work proposes an innovative solution: the coupling of an HTC reactor with a solar concentrator, designed to fully cover the HTC energy needs. A 300 ml stainless steel HTC reactor was constructed and positioned on the focus of a parabolic dish concentrator (PDC), consisting of one parabolic mirror of 0.8 m2. To maximize the light absorption, the illuminated side of the HTC reactor was coated with a thin layer of nanostructured copper oxide, realized via electron beam deposition. Then, the effectiveness of the hybrid solar-HTC solution was demonstrated by carrying out an experimental campaign on a residual agro-biomass (grape seeds), which was treated at 180, 220, and 250 °C for 2 h. The coating confers excellent absorbing performances to the system, exhibiting an absorptance of up to 95.6% (at 300 nm wavelength). Heating times, yields, composition, and energy properties of “solar hydrochars” resemble those of studies performed in traditional HTC systems. This research work proves the feasibility of the solar-HTC prototype apparatus and opens the way to the development of a zero-energy solar-HTC technology.

This paper presents a flying target for monostatic radar verification. It consists of a corner reflector mounted on an Unmanned Aerial Vehicle (UAV). The main advantages of this configuration are the lower weight and wind resistance with respect to spheres having the same Radar Cross Section (RCS), leading to an enhanced overall operability. The UAV-mounted target has been tested with indoor and outdoor RCS measurements (X band). Predicted and experimental data are in good agreement.

The measurement of the intensity of electromagnetic emissions is a relevant topic and is of great interest in both the civil and military fields, especially when the levels of the emissions are high. Another similarly current sector is that of UAVs (Unmanned Aerial Vehicles), which are increasingly used as supporting tools by the armed forces and for public security activities. This paper describes the activities carried out and the results obtained within the “PLASTIc” (PLatform Agnostic Sensors for opTImised design of midlife ship refitting) research project, that combines the above application areas. The demonstrator built for the research project is able to carry out a dual task: the measurement of high intensity electrical fields and the taking of pictures to enable the creation of an accurate 3D CAD model reconstruction of the naval systems. In order to fulfill these two tasks, a payload was developed consisting of the necessary electronics and sensors, which was integrated on-board an electrically propelled UAV. The specific research will address, as operational case, the testing after a midlife ship refitting.

An olive waste stream mixture, coming from a three phase-continuous centrifugation olive oil mill industry, with a typical wet basis mass composition of olive pulp 39 wt%, kernels 5 wt% and olive mill waste water 56 wt%, was subjected to hydrothermal carbonisation (HTC) at 180, 220 and 250 °C for a 3-hour residence time in a 2-litre stainless steel electrically heated batch reactor. The raw feedstock and corresponding hydrochars were characterised in terms of proximate and ultimate analyses, higher heating values and energy properties. Results showed an increase in carbonisation of samples with increasing HTC severity and an energy densification ratio up to 142% (at 250 °C). Hydrochar obtained at 250 °C was successfully pelletised using a lab scale pelletiser without binders or expensive drying procedures. Energy characterisation (HHV, TGA), ATR-FTIR analysis, fouling index evaluation and pelletisation results suggested that olive mill waste hydrochars could be used as energy dense and mechanical stable bio-fuels. Characterisation of HTC residues in terms of mineral content via induced coupled plasma optical emission spectroscopy (ICP-OES) as well as Total and Dissolved Organic Carbon enabled to evaluate their potential use as soil improvers. Nutrients and polyphenolic compounds in HTC liquid fractions were evaluated for the estimation of their potential use as liquid fertilisers. Results showed that HTC could represent a viable route for the valorisation of olive mill industry waste streams.

Supercritical water gasification (SCWG) of biomass was studied by means of a stoichiometric thermodynamic model. Such approach is based on reaction equilibria and it allows calculating the extent of the single reactions involved. A very simple model was proposed, involving only 6 components and 3 independent reactions. The model was validated against literature experimental data for different feedstock and it was used to understand the influence of biomass and operating conditions. The analyses allowed calculating the values of the reaction extent of water-gas shift (WGS) and CO methanation at equilibrium: a graphical approach was proposed in order to interpret the outcomes. Results showed that the influence of pressure is very limited. Moreover, it was observed that the maximum H 2 production is linked to a parameter ψ , function of the H/C and O/C ratios of the feedstock. Finally, considerations about the role of WGS and methanation in the production of H 2 were traced.

Polyphenols were extracted from grape skins and defatted grape seeds (cultivar: Pinot Nero) by using subcritical water in a semi-continuous mode. Extractions were performed at a pressure of 10 MPa, at three different temperatures (80, 100 and 120 °C) and with two water flows. For both skins and defatted seeds, total polyphenol (TP) yield significantly increased with temperature: for skins from 44.3 ± 0.4 to 77 ± 3 mg/g, while for defatted seeds from 44 ± 2 to 124 ± 1 mg/g when the temperature increased from 80 to 120 °C. Importantly, TP yield decreased with flow rate at constant temperature. The extraction kinetics was simulated by a simple model from literature. The model adjustable parameters were calculated by best fitting procedures with experimental data: the model fitted the experimental kinetics curves in a satisfactory way, providing reference values for the adjustable parameters. The present research outlines the potentialities of using subcritical water for extracting valuable polyphenols from food processing by-products, and the effect of the operating conditions. Moreover, it proves that a very simple model from literature allows the interpretation of the extraction curves on the base of mass transfer and partition coefficients.

The effect of the main process variables affecting the supercritical CO 2 extraction of oil from seeds (namely grape seeds) was investigated, both experimentally and through modeling. The dependency of the extraction kinetics on the variables more tested in the literature (pressure, temperature, particle size and solvent flow rate) was confirmed, and original trends were obtained for the less investigated variables, such as the bed porosity ɛ and the extractor diameter to length ratio ( D / L ). The extraction kinetics did not depend on ɛ for 0.23 ≤ ɛ ≤ 0.41, while a further decrease in ɛ lowered the extraction rate, likely due to the occurrence of channeling. The effect of a variable D / L ratio was studied letting constant the ratio of substrate mass to CO 2 mass flow rate: the lower was D / L , the lower the specific CO 2 consumption. Through modeling, the values of internal and external mass transfer parameters were calculated and critically discussed on the basis of well-known literature correlations.

Summary Grape seeds collected from vinification of various grape varieties were extracted by supercritical CO2 for oil recovery. The defatted residues thus obtained were considered as a re-utilisable co-product and assessed for phenolic content, reducing capacity and inhibitory activities against mammalian α-amylase and α-glucosidase enzymes. Supercritical CO2 treatment led to higher recovery of anthocyanins. Reducing capacity of phenolic extracts reached up to ~2200 mmolFe(II) kg−1, much higher than that of various natural phenolic sources. The anthocyanin-rich extracts showed the highest inhibitory effectiveness towards α-glucosidase (I50 value equal to ~40 μg gallic acid equivalents (GAE)/mL ~ half than acarbose). Inhibitory effectiveness towards α-amylase activity was similar among grape varieties, with I50 values comparable to that of acarbose and correlated with proanthocyanidin contents. These results could pave the way for an efficient processing of grapes, including cascade processes, namely: winemaking, oil extraction from recovered grape seeds and phenolic extraction from defatted grape seeds as potential cost-effective nutraceuticals.

Supercritical water gasification (SCWG) is an interesting technology for the production of energy from wet and residual biomass. To date, the complete understanding of the fundamental phenomena involved in SCWG is still an open issue. An interesting aspect to be investigated is represented by the interactions among the single constituents of biomass, such as cellulose and lignin. This can be accomplished by using glucose and phenol as model compounds. In the present study, four glucose/phenol mixtures were utilized. All mixtures presented a constant organics mass fraction of 5%, where the relative fraction of phenol ranged from 0% (pure glucose) to 30%. The mixtures were gasified at 400 °C and 25.0 MPa in a continuous tubular reactor, with a residence time between 10 and 240 s. Results showed that, at the considered reaction conditions, phenol mostly behaves as a sort of inert in terms of total gas production, although it plays an inhibitory action towards H 2 . The analysis of the liquid phase revealed that phenol likely inhibits Cannizzaro and de-carbonylation reactions and it advantages the pathways involving de-hydration reactions.

The objective of this study was to evaluate the feasibility of supercritical oil extraction from Jatropha curcas L (JCL). The influence of the operating conditions on oil yield, free fatty acid content of JCL oil, and oil quality was examined, which included pressure, temperature, particle size, and percentage of hull. The conditions for the fractionation of fatty acid were selected to obtain good-quality oil for biodiesel production. Finally, an experiment was conducted under different conditions in which the greatest amount of free fatty acids (FFA) (26.3 wt.%) was extracted during the first fractions and then the pressure was increased to achieve good oil removal (91 wt.% oil yield) performance with low content of free fatty acids (1 wt.%). This study has a promising role to fill as a more cost-effective processing technology, and it is not necessary to carry out a degumming, esterification and dehydration in the oil of the last fractions. Furthermore, all the phorbol ester was removed from the oil by conducting a supercritical extraction using CO 2 .

Hydrochar is the product of the hydrothermal carbonization process, which is able to convert biomass into a carbon-rich material at mild hydrothermal conditions. This article is aimed at exploring a novel possibility, that is converting hydrochar into a valuable fuel gas by means of another hydrothermal technology: supercritical water gasification (SCWG), which operates at higher temperatures and pressures. Tests were performed in 5 ml micro-autoclaves with a hydrochar concentration of 15 wt.%. Residence times between 1 h and 16 h were adopted. The results showed that hydrochar derived from maize silage can still be gasified, producing a gas rich in CO2 and CH4. The data here obtained were also compared with literature data concerning the SCWG of glucose and beech sawdust, highlighting the main differences in terms of solid, liquid and gaseous yields. The solid material obtained after SCWG was observed by means of scanning electron microscopy after different residence times, highlighting the formation of coke spheres. Finally, the effect of the addition of an alkali catalyst (K2CO3) was tested and discussed.

The current study focuses on the recovery of grape seed oil by supercritical CO2 extraction. Grape seeds from six grape cultivars were extracted in two subsequent harvesting years, and the resulting oils were characterized for the relative amount of: (a) lipid classes; (b) lipid acyl chains; and (c) tocopherols and tocotrienols. Comparative extractions were performed by utilizing n-hexane as solvent and by mechanical pressure. A well-established modeling approach was applied to evaluate the mass transfer parameters affecting the kinetics of supercritical CO2 extraction: with these parameters, process scale-up can be addressed. The results reported in this study testify the potentiality of grape seed oil as a source of unsaturated fatty acids and tocols. Moreover, they offer a clear picture of the similarities and differences among oils from different grape cultivars and obtained through different extraction techniques.

Biopharmaceutical, nutraceutical and food sectors are experiencing an increasing market interest in omega-3 concentrates. Fish and fish processing by-products represent the major source of lipids rich in omega-3. The present work focuses on the supercritical CO 2 fractionation of fish oil derivatives for obtaining omega-3 concentrates, which seems a promising process given that it allows utilizing low temperatures (well below 100 °C) and it can be performed also at industrial scale. The process was conceived, modeled, and evaluated in terms of the main parameters affecting its performances: solvent to feed ratio, reflux ratio, temperature, and pressure of both the fractionation column and the column head separator. The process was further optimized minimizing its operating costs. The optimum foresaw operating the column at high temperature (80 °C) and pressure (19.5 MPa), which allowed for a reduced reflux ratio (=0.92) and solvent to feed ratio (=63). At these conditions, the process cost per unit product (omega-3 concentrate) turned out to be of about 2.3 €/kg. Finally, the plant was designed for three different throughputs: 10, 100, and 300 kg/h. This allowed estimating the investment costs, in order to outline a preliminary process feasibility evaluation.

The possibility of measuring antennas in a non-anechoic environment presents several practical advantages in terms of reduced costs and complexity of the test range and test execution, making it feasible to effectively integrate the testing process in an industrial design, verification and production flow. The challenge is, however, to achieve reliable and accurate results, fit for the purpose of the application. This paper presents the approach and solution developed by IDS for the case of measuring large radar antennas in strong near-field conditions in a non-anechoic indoor test chamber. The paper describes the instrumentation and procedure employed for such an application, presenting some examples of results for the case of a narrow beam dish antenna in X band and a 19ft slotted waveguide antenna in X band.

Batch reactors made of stainless steel and Inconel® 625 were used for the hydrothermal gasification of glucose and beech sawdust under both subcritical (350 °C) and supercritical (400 °C) conditions at a pressure of 30 MPa. These tests were executed over residence times ranging from 60 to 300 min. The amounts of solid, liquid and gas produced and the composition of the resulting gas phase were measured. The results showed that a higher H 2 output was achieved in the stainless steel reactors, while the Inconel® 625 reactors were more effective for the synthesis of CH 4 and light hydrocarbons. A visual observation of the metal surfaces was performed using scanning electron microscopy to explain the persistence of catalytic activity even after an aging treatment and many hours of operation.

The supercritical water gasification (SCWG) of biomass for H2 production is analyzed in terms of process development and energetic self-sustainability. The conceptual design of a plant is proposed and the SCWG process involving several substrates (glycerol, microalgae, sewage sludge, grape marc, phenol) is simulated by means of AspenPlus™. The influence of various parameters – biomass concentration and typology, reaction pressure and temperature – is analyzed. The process accounts for the possibility of exploiting the mechanical energy of compressed syngas (later burned to sustain the SCWG reaction) through expansion in turbines, while purified H2 is fed to fuel cells. Results show that the SCWG reaction can be energetically self-sustained if minimum feed biomass concentrations of 15–25% are adopted. Interestingly, the H2 yields are found to be maximal at similar feed concentrations. Finally, an energy balance is performed showing that the whole process could provide a net power of about 150 kWe/(1000 kgfeed/h).

The aim of this work is to model the supercritical water gasification (SCWG) of methanol by means of a detailed kinetics model based on elementary reactions. The challenge consists in modeling SCWG by using existing models developed for combustion or supercritical water oxidation (SCWO) and adjusting their initial conditions to make them suitable for SCWG. To this purpose, three models (GRI-Mech 3.0, Brock and Savage and Webley and Tester) were selected, implemented in MatLab ® and run. Webley and Tester's model seems to describe quite well methanol conversion as a function of time. On the other hand, some mechanisms, like water–gas shift and methanation, are not correctly predicted. The main reaction pathways are identified and outlined.

Thermo-gravimetric analysis (TGA) was performed on grape seeds, skins, stalks, marc, vine-branches, grape seed oil and grape seeds depleted of their oil. The TGA data was modeled through Gaussian, logistic and Miura–Maki distributed activation energy models (DAEMs) and a simpler two-parameter model. All DAEMs allowed an accurate prediction of the TGA data; however, the Miura–Maki model could not account for the complete range of conversion for some substrates, while the Gaussian and logistic DAEMs suffered from the interrelation between the pre-exponential factor k0 and the mean activation energy E0 – an obstacle that can be overcome by fixing the value of k0 a priori. The results confirmed the capabilities of DAEMs but also highlighted some drawbacks in their application to certain thermodegradation experimental data.

Winemaking by-products present a high environmental impact due to their considerably high biochemical and chemical oxygen demands. This study is focused on the optimization of the traditional solvent extraction technology of phenols from Pinot Noir grape skins (Vitis vinifera). To such a purpose, the combined effects of the extraction time (9, 19 and 29 h) and the solid-liquid ratio (0.10, 0.20 and 0.30 gDW/mL), were investigated by a 32 full factorial design combined with response surface methodology; total polyphenols, flavonoids and trans-resveratrol extraction yields were used as response variables. Results demonstrated that Pinot Noir skins had high levels of both total polyphenols (3.22 mgGAE/gDW) and flavonoids (1.01 mgCE/gDW), being the optimum extraction time 19 h approximately. t-resveratrol was found in a considerable amount (2.24 mg/100 gDW), while the main phenolic compounds analyzed with Reverse Phase-High Performance Liquid Chromatography were gallic acid, catechin and quercetin. A significant linear correlation was found between polyphenols concentration and their antiradical power. PRACTICAL APPLICATIONS Winery by-products (grape marc) are a possible font of antioxidants and their extracts can represent a significant economic and social benefit. The research of the efficient methods for phenolics compound extraction is one of great interest. Collected experimental data could be used in further studies as a comparison with those of other innovative technologies, such as supercritical fluid, ultrasound and/or microwave-assisted extraction.

In the present work, the supercritical water gasification (SCWG) of biomass is analyzed with a view to outlining the possible thermodynamic constraints that must be taken into account to develop this new process. In particular, issues concerning the formation of solid carbon and the process heat duty are discussed. The analysis is conducted by means of a two-phase non-stoichiometric thermodynamic model, based on Gibbs free energy minimization. Results show that char formation at equilibrium only occurs at high biomass concentrations, with a strong dependence on biomass composition. As regards the process heat duty, SCWG is mostly endothermic when biomass concentration is low, although a very small amount of oxidizing agent is able to make the process exothermic, with only a small loss in the heating value of the syngas produced.