Intensification of ozonation processes in a novel, compact, multi-orifice oscillatory baffled column

A novel approach for the intensification of ozonation of water and wastewater is presented using a highly efficient and compact Multi-Orifice Oscillatory Baffled Column (MOBC) ozonation contactor. The MOBC uniquely yielded full (i.e. 100%) use of the ozone supplied with a very short (2.25 min) liquid contact time under continuous operation and reducing the need of further gas-liquid contacting equipment downstream from the MOBC. The increased performance of the MOBC ozonation reactor was benchmarked against a bubble column (BC) design and resulted in 20% increase on the rate of p-hydroxybenzoic acid (p-HBA) degradation, 75% increase in the rate of mineralization of p-HBA per mole of ozone consumed, and 3.2-fold increase in the rate of mineralization of p-HBA per mole of ozone supplied. This results from the very small size of bubbles (few hundreds of microns) and enhanced gas-liquid mass transfer and hold-up generated in the presence of small fluid pulsations and orifice baffles

Agro-industrial wastewater treatment with Acacia dealbata coagulation/flocculation and photo-fenton-based processes

The removal of dissolved organic carbon (DOC) and total polyphenols (TPh) from agro-industrial wastewater was evaluated via the application of coagulation–flocculation–decantation (CFD) and Fenton-based processes. For the CFD process, an organic coagulant based on Acacia dealbata Link. leaf powder (LP) was applied. The results showed that the application of the LP at pH 3.0, with an LP:DOC ratio of 0.5:1 (w/w), achieved a high removal of turbidity, total suspended solids (TSS), and volatile suspended solids (VSS) of 84.7, 79.1, and 76.6%, respectively. The CFD sludge was recycled as fertilizer in plant culture (germination index ≥ 80%). Afterwards, the direct application of Fenton-based processes to raw WW was assessed. The Fenton-based processes (UV/Fenton, UV/Fenton-like, and heterogeneous UV/Fenton) showed high energy efficiency and a cost of 1.29, 1.31 and 1.82 €/g/L DOC removal, respectively. The combination of both processes showed the near complete removal of TPh and DOC after 240 min of reaction time, with high energy efficiency. In accordance with the results obtained, the combination of CFD with Fenton-based processes achieves the legal limits for the disposal of water into the environment, thus allowing the water to be recycled for irrigation.Fundação para a Ciência e a Tecnologia | Ref. UIDB/00616/2020Fundação para a Ciência e a Tecnologia | Ref. UI/BD/150847/2020CCRN - Comissão de Coordenação da Região Norte | Ref. NORTE-01-0145-FEDER-00004

Combined organic coagulants and photocatalytic processes for winery wastewater treatment

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGDue to the consumers demand for quality wines, washing and disinfection operations are necessary in wine productions, leading to the generation of large volumes of winery wastewater (WW) with a high organic content which has the potential to cause irreversible environmental impacts. The aim and novelty of this work is the production of natural organic coagulants (NOCs) to be applied in coagulation-flocculation-decantation (CFD) process. To complement this treatment process, it is also aimed the performed a photo-Fenton process, combining hydrogen peroxide (H2O2) and potassium persulfate (KPS). The Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) showed that NOCs are carbon-based materials with adsorption capacity. Under the best operational conditions, NOCs achieved a turbidity removal between 86.2 and 98.9%, a total suspended solids (TSS) removal ranging between 85.0 and 94.9% and a dissolved organic carbon (DOC) removal ranging between 14.1 and 44.9%. To degrade the DOC present in the WW, different advanced oxidation processes (AOPs) were tested. Results showed that KPS-photo-Fenton, under the best operational conditions [Fe2+] = 2.5 mM, [KPS] = 1.0 mM, pH = 3.0, radiation UV-C mercury lamp (254 nm), agitation 350 rpm, temperature 298 K, reaction time 240 min achieved a DOC removal of 91.2 and 96.8%, with a H2O2 consumption of 156.9 and 199.0 mM, respectively for red and white WW. With application of combined CFD-KPS-photo-Fenton process, it was observed an increase of DOC removal with lower H2O2 consumptions. The energy consumption of the photosystem was evaluated by application of electric energy per mass (EEM). The application of KPS-photo-Fenton process achieved an EEM of 0.308 and 0.0309 kWh/g/L DOC, with a cost of 2.05 and 2.59 €/g/L DOC respectively for red and white WW. The combination of CFD-KPS-photo-Fenton decreased significantly the costs of treatment and the treated wastewater achieved the Portuguese legal values for wastewater discharge. This work shows that NOCs are a promising technology that can be an alternative to traditional metal salts, the combination of sulfate radicals with hydroxyl radicals can achieve high DOC removal and the combination of CFD with KPS-photo-Fenton process can decrease the operational costs.Fundação para a Ciência e a Tecnologia | Ref. UIDB/00616/2020Fundação para a Ciência e a Tecnologia | Ref. UI/BD/150847/202

Rethinking Ductility -- A Study Into the Size-Affected Fracture of Polymers

Ductility quantifies a material's capacity for plastic deformation, and it is a key property for preventing fracture driven failure in engineering parts. While some brittle materials exhibit improved ductility at small scales, the processes underlying this phenomenon are not well understood. This work establishes a mechanism for the origin of ductility via an investigation of size-affected fracture processes and polymer degree of conversion (DC) in two-photon lithography (TPL) fabricated materials. Microscale single edge notch bend ($\mu$SENB) specimens were written with widths from 8 to 26 $\mu$m and with different laser powers and post-write thermal annealing to control the DC between 17\% and 80\%. We find that shifting from low to high DC predictably causes a $\sim$3x and $\sim$4x increase in strength and bending stiffness, respectively, but that there is a corresponding $\sim$6x decrease in fracture energy from 180 $J/m^2$ to 30 $J/m^2$. Notably, this reduced fracture energy is accompanied by a ductile-to-brittle transition (DBT) in the failure behavior. Using finite element analysis, we demonstrate that the DBT occurs when the fracture yielding zone size ($r_p$) approaches the sample width, corresponding with a known fracture size-affected transition from flaw-based to strength-based failure. This finding provides a crucial insight that ductility is a size-induced property that occurs when features are reduced below a characteristic fracture length scale and that strength, stiffness, and toughness alone are insufficient predictors of ductility.Comment: 17 pages, 6 figure

Symbiotic behaviour in the Public Goods game with altruistic punishment

Finding ways to overcome the temptation to exploit one another is still a challenge in behavioural sciences. In the framework of evolutionary game theory, punishing strategies are frequently used to promote cooperation in competitive environments. Here, we introduce altruistic punishers in the spatial public goods game. This strategy acts as a cooperator in the absence of defectors, otherwise it will punish all defectors in their vicinity while bearing a cost to do so. We observe three distinct behaviours in our model: i) in the absence of punishers, cooperators (who don't punish defectors) are driven to extinction by defectors for most parameter values; ii) clusters of punishers thrive by sharing the punishment costs when these are low iii) for higher punishment costs, punishers, when alone, are subject to exploitation but in the presence of cooperators can form a symbiotic spatial structure that benefits both. This last observation is our main finding since neither cooperation nor punishment alone can survive the defector strategy in this parameter region and the specificity of the symbiotic spatial configuration shows that lattice topology plays a central role in sustaining cooperation. Results were obtained by means of Monte Carlo simulations on a square lattice and subsequently confirmed by a pairwise comparison of different strategies' payoffs in diverse group compositions, leading to a phase diagram of the possible states

Treatment of winery wastewater with a combination of adsorption and thermocatalytic processes

The release of winery wastewater (WW) into the environment, without proper treatment, can cause severe problems to freshwater quality and natural fauna and flora. Therefore, in this work a treatment process was studied, combining adsorption and thermocatalytic oxidation processes. In a more specific way, it optimized the combination of activated sodium bentonite (Na-Mt) and potassium persulfate (KPS)/sodium percarbonate (SPC) as oxidant agents. With the combination of best operational conditions of adsorption ([Na-Mt] = 5.0 g/L, pH = 3.0, V = 500 mL, agitation 350 rpm, T = 298 K, t = 24 h) and thermocatalytic oxidation processes (S2O82−/H2O2 ratio = 1:0.25, S2O82−/H2O2 dosage = 0.1:0.025 (g/g), pH = 7.0, T = 343 K, agitation 350 rpm, t = 2 h), a total organic carbon, chemical oxygen demand and total polyphenols removal of 76.7, 81.4 and >99% was achieved, respectively. Finally, it was evaluated the effect of the treatment processes in the germination index (GI) of different plant seeds. A GI > 80% was achieved, showing a low phytotoxicity effect of the processes applied in the winery wastewater treatment.CCRN - Comissão de Coordenação da Região Norte | Ref. NORTE-01-0145-FEDER-000041Fundação para a Ciência e a Tecnologia | Ref. UIDB /00616/2020Fundação para a Ciência e a Tecnologia | Ref. UI/BD/150847/202

State of the art: iterative CT reconstruction techniques

Owing to recent advances in computing power, iterative reconstruction (IR) algorithms have become a clinically viable option in computed tomographic (CT) imaging. Substantial evidence is accumulating about the advantages of IR algorithms over established analytical methods, such as filtered back projection. IR improves image quality through cyclic image processing. Although all available solutions share the common mechanism of artifact reduction and/or potential for radiation dose savings, chiefly due to image noise suppression, the magnitude of these effects depends on the specific IR algorithm. In the first section of this contribution, the technical bases of IR are briefly reviewed and the currently available algorithms released by the major CT manufacturers are described. In the second part, the current status of their clinical implementation is surveyed. Regardless of the applied IR algorithm, the available evidence attests to the substantial potential of IR algorithms for overcoming traditional limitations in CT imaging

Heterogeneous contributions can jeopardize cooperation in the Public Goods Game

When studying social dilemma games, a crucial question arises regarding the impact of general heterogeneity on cooperation, which has been shown to have positive effects in numerous studies. Here, we demonstrate that heterogeneity in the contribution value for the focal Public Goods Game can jeopardize cooperation. We show that there is an optimal contribution value in the homogeneous case that most benefits cooperation depending on the lattice. In a heterogeneous scenario, where strategy and contribution coevolve, cooperators making contributions higher than the optimal value end up harming those who contribute lower. This effect is notably detrimental to cooperation in the square lattice with von Neumann neighborhood, while it can have no impact in others lattices. Furthermore, in parameter regions where a higher-contributing cooperator cannot normally survive alone, the exploitation of lower value contribution cooperators allows their survival, resembling a parasitic behavior. To obtain these results, we employed various distributions for the contribution values in the initial condition and conducted Monte Carlo simulations

Textile dye removal by Acacia dealbata Link. Pollen adsorption combined with UV-A/NTA/Fenton Process

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGThe decolourization of an aqueous solution of the textile dye Acid Red 88 (AR88) and the control of the invasive plant species Acacia dealbata Link. (ADL) were addressed in this work. The aims of the study were (1) characterization of the ADL pollen, (2) application of the pollen powder in adsorption processes, (3) selection of the best operational conditions for nitriloacetic acid (NTA)-UV-A-Fenton process and (4) assess the efficiency of the combined treatment adsorption and NTA-UV-A-Fenton in AR88 decolourization. In a first step, ADL pollen was used as a AR88 bioadsorbent. Fourier-transform infrared spectroscopy (FTIR) analysis were performed and revealed the presence of proteins, fatty acids, carbohydrates and lignin in the pollen. Afterwards, trough scanning electron microscopy (SEM), it was possible to verify that ADL pollen has several empty spaces that can be used for dye adsorption. Biosorption results showed higher adsorption of AR88 with application of pH 3.0 and [pollen] = 3.0 g/L with 18.8 mg/g of dye adsorbed. The best fitting was observed with Langmuir, SIPS and Jovanovic isotherms (0.993, 0.996 and 0.994, respectively). To complement the biosorption, a UV-A-Fenton process was applied, and results showed a higher AR88 removal with (NTA) addition. Higher irradiance power favored the oxidation process with high Ф photodegradation value and low Electric Energy per Order (EEO) and Specific Applied Energy (ESAE). The combination of biosorption with NTA-UV-A-Fenton was the most efficient system with an AR88 decolourization of 98.5% and a total organic carbon (TOC) removal of 83.5%.Fundação para a Ciência e a Tecnologia | Ref. UI/BD/150847/202