KnE Materials Science

Efficient Recovery of Lignin and Hemicelluloses from Kraft Black Liquor

Manorma Sharma, André Simões, Patrícia Alves, Licínio M. Gando- Ferreira — Wed, 10 Aug 2022 00:00:00 +0000

Black liquor (BL) from kraft pulping industries contains a large fraction of lignin and hemicelluloses and their efficient separation can open up new possibilities for integrated biorefineries. In this work, lignin and hemicelluloses were separated from BL and concentrated BL (obtained by ultrafiltration), by precipitation using acidification and antisolvent precipitation method, respectively. For lignin precipitation, different organic acids, namely acetic, lactic and citric acid, were used and the yield and purity of the extracted lignin were compared with the lignin precipitated using inorganic acids, namely sulphuric and phosphoric acid. Among the organic acids, the highest yield of lignin (57.2%) was obtained by lactic acid, but the extract also contained the highest levels of inorganic impurities (9.2%). The extract obtained from acetic acid contained lower inorganic impurities and the lignin yield was 48.1%. The hemicellulose was extracted from BL liquor that was concentrated using the ZnObased PES mixed matrix ultrafiltration membrane, which was started by first separating lignin (at pH 3.5, 4 and 4.5) from it. The supernatants from the lignin precipitation process were used as a source of hemicellulose and this was precipitated by using acetone as an antisolvent. The highest hemicellulose yield (54.4%) was obtained from the supernatant with the lowest lignin content and highest acetone to supernatant ratio.

Keywords: acidification, antisolvent precipitation, hemicelluloses, kraft black liquor, lignin

Effect of Pre-Hydrolysis Reaction Conditions on Xylooligosaccharides Extraction in Eucalyptus Globulus

André Cunha, Rogério Simões — Wed, 10 Aug 2022 00:00:00 +0000

Pre-hydrolysis-kraft of Eucalyptus globulus by autohydrolysis (batch) and with dilute acid hydrolysis (flow-through reactor) were explored in this study, to examine the recovery of xylooligosaccharides (XOs) from the pre-hydrolysis treatment. The results of this work support the potential reuse of the hydrolysate to increase the recovery yield of added value compounds. The pH of the dilute acid hydrolysis was maintained at 3.5 with acetic acid, to mimic the conditions of the batch reactor medium (autohydrolysis). An increase of XOs recovered was evident when the pre-treatment was in the flow-through reactor instead of the batch reactor. In the latter, a high concentration of furfural was recovered, showing the influence of time in XO conversion through hydrolysis. The total yield of pulp was higher in the flow-through reactor (36.4%) in comparison with the batch system (34.5%) after kraft pulping, which was expected, given the increasing time that the hydrolysate was present in the reactor; however, the difference was small and could have been the result of precipitated compounds in the latter, so this needs further analysis.

Keywords: cellulose, Eucalyptus globulus, pre-hydrolysis kraft, xylooligosaccharides

Assessment of Autofocus Techniques for Isolated Cellulose Microfiber 3D Imaging by Digital Holography

Francisca Silva, Paulo Fiadeiro, Elsa Fonseca — Wed, 10 Aug 2022 00:00:00 +0000

Studying the three-dimensional structure of paper fibrous networks is an important step towards understanding the relationship between manufacturing conditions and the resulting microstructural and mechanical properties. Digital holography is a promising three-dimensional imaging technique enabling quantitative phase evaluation of micro and nano-fibres. One of the advantages of this high-resolution method is the ability to perform numerical refocusing at several depths from a single shot acquisition. In this work, the suitability of 22 focusing functions to accurately identify the positions of cellulose microfibers, using digital holography, was inspected. The best performing metrics were identified and the trade-off between metric accuracy and robustness to variable conditions and their computational complexity were discussed.

Keywords: digital holography, autofocus, cellulose microfibre, morphology, tomography

E. Globulus Vessel and Fibre Chemical Analysis

Wed, 10 Aug 2022 00:00:00 +0000

Hardwood species have a complex cellular structure consisting of fibres, vessel elements and parenchyma cells with different chemical compositions. However, the presence of vessels with significant dimensions in their structure is a recurrent problem in the operation of industrial UWF paper printing. Since the 1980s, vessel picking and ink refusal are problems that paper professionals have tried to solve, but solutions for these have not yet been fully found. If vessels are concentrated in a stream, they can be pre-treated (e.g., by mechanical refining) and reincorporated into the pulp. Other strategies aim at vessel enzymatic and/or chemical passivation and sheet surface chemical treatment, altering the vessel adhesion to the fibre network. This requires vessel concentration at laboratorial level for proper chemical studies, such as FE-SEM, μ-XPS, TOF-SIMS and μFTIR. The main objective of our experimental study was to examine bleached kraft pulp E. globulus vessel and fibre composition. For this we performed EDX and μ-FTIR analysis on both fibre and vessel elements, and obtained the carbohydrate composition, the total acids content, the hexenuronic acids content and the zeta potential.

Keywords: E. globulus, vessel, EDX, μ-FTIR, sugar content, zeta potential

Development of Sustainable Cellulose-Based Tissue Materials Using an Innovative Experimental and Computational Methodology

Flávia Morais, Ana Carta, Maria Amaral, Joana Curto — Wed, 10 Aug 2022 00:00:00 +0000

In recent years, the tissue industry has been exposed to several challenges related to the growing demand for high-quality materials and sustainability. An approach that combined experimental and computational planning was implemented and presented in this work. For this purpose, a simulator that established relationships between the key fibre properties, the process steps that modify them, and the functional properties, named the SimTissue, was developed and validated. Different scenarios and a summary of the SimTissue research strategy are presented. The experimental planning design consisted of examining the influence of refining, enzymatic treatment, and incorporation of additives such as micro / nanofibrillated cellulose and biopolymers. The correlations between these tissue process inputs, and the softness, strength and absorption properties were established using the SimTissue. Overall, the SimTissue predicted and optimized several case studies for the management and optimization of sustainability formulations.

Keywords: 3D computational simulation, cellulose-based materials, furnish optimization, tissue materials

Agrimonia Eupatoria L.-Incorporated Electrospun Nanofibers and Cotton Composite for Antibacterial Wound Dressing Applications

Cláudia Mouro, Raul Fangueiro, Isabel Gouveia — Wed, 10 Aug 2022 00:00:00 +0000

Composite wound dressings which combine the suitable properties of distinct materials into one dressing are currently being explored, in combination with different types of bioactive compounds, to enhance the healing process and avoid skin infections. In the present work, poly(vinyl alcohol) and chitosan nanofibers containing Agrimonia eupatoria L. were fabricated using a needleless electrospinning method (through Nanospider technology) and deposited on top of a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cotton textile dressing. The negatively charged carboxyl groups on the cotton fibers interacted with the positively charged amino groups of chitosan, which was previously blended with poly(vinyl alcohol) and Agrimonia eupatoria L. to produce the nanofiber layer. The properties of the produced composite materials were analyzed to determine the dressing’s potential for antimicrobial wound dressing applications.

Keywords: cotton, textile dressing, electrospun nanofibers, Agrimonia eupatoria L., antibacterial composite wound dressings

Functionalization of Bacterial Cellulose With Bacterial Pigments: Optimization Using a Full Factorial Design Approach

Lúcia Amorim, Raul Fangueiro, Isabel Gouveia — Wed, 10 Aug 2022 00:00:00 +0000

Pigments from natural sources, such as bacterial pigments, have gained increased attention in recent years due to their biodegradability, non-toxicity, and noncarcinogenicity. The intention to replace synthetic and oil-derived compounds is not restricted to synthetic dyes; other applications include the replacement of oilderived polymers for more environmentally friendly options, such as biopolymers. In this work, the functionalization of a bacterial cellulose (BC) biopolymer with bacterial pigments was explored using a full factorial design methodology to evaluate the best functionalization conditions to produce colored BC. From the factors and interactions evaluated, it was possible to conclude that the variable duration of the functionalization procedure could be reduced to a low level without significantly affecting the functionalization of the BC samples with bacterial pigments. Moreover, BC is a product with high industrial applicability, versatility, and sustainability. Hence, the multifunctional colored BC can be applied in the packaging, paper, and textile industries, among others.

Keywords: bacterial pigments, bacterial cellulose, full-factorial design, optimization

Development of Biodegradable, Cellulose-Based, Essential Oil and Chitosan Drug Delivery Systems for Cosmetic Mask Applications

Joana Moreira, Catarina Lopes, Manuel-José Lis Arias, Lúcia Silva, Joana Curto — Wed, 10 Aug 2022 00:00:00 +0000

The goal of this research was the development of cellulose-based biodegradable drug delivery systems solutions for cosmetic mask applications. Cellulose-based materials derived from natural renewable sources provide a sustainable alternative to nonwoven cosmetic masks derived from nondegradable fossil-based raw materials. An experimental design was executed to assemble the 3D cellulose fibres matrix and the water in oil emulsion comprising the active molecules from Mentha piperita L. Two types of biopolymeric additives were used, one derived from a nano/micro fibrillated cellulose pulp and another one including chitosan. A 3D computational simulation study was performed to enhance porosity and strength properties. The results indicated that the cosmetic face mask optimized prototypes, made from a biodegradable 3D matrix of cellulose fibres and active molecules, are suitable for dermic use.

Keywords: biopolymers, dermic application, drug delivery systems (DDS), essential oil, Mentha piperita

Chemical Composition of the Essential Oils in Portuguese Daucus Carota Subspecies

Wed, 10 Aug 2022 00:00:00 +0000

This study focused on five different subspecies of Portuguese Daucus carota L., to identify the main compounds in the essential oils of umbels from each subspecies. The isolation of the essential oils was performed by hydrodistillation methods followed by further composition analysis by gas chromatography-mass spectrometry, ultimately demonstrating that each subspecies had different major compounds. This study concluded that the main compounds found in Daucus carota subsp. maritimus were geranyl acetate, followed by trans-methyl-isoeugenol, α-pinene, cis-asarone and elemicin. Daucus carota subsp. hispidus presented with the major compounds as geranyl acetate, caryophyllene oxide, trans-methyl-isoeugenol and sabinene. For Daucus carota subsp. maximus, the major compounds were cis-asarone, geranyl acetate and elemicin, which was similar to Daucus carota subsp. carota which presented with the major compounds as geranyl acetate, cis-asarone, trans-methylisoeugenol and α-pinene. Finally, the major components of Daucus carota subsp. sativus were carotol and daucol.

Keywords: essential oils, chemical composition, Daucus carota, hydrodistillation, GC-MS

Chemical Characterization of Essential Oils With a Biocide Base for Conservation and Restoration

Cecília Baptista, Luís Santos, Maria Emília Amaral, Lúcia Silva — Wed, 10 Aug 2022 00:00:00 +0000

Essential oils (EOs) are acclaimed for their antimicrobial properties, leading to their multiple applications in various fields. In this work, four aromatic plants were used, namely thyme (Thymus mastichina L.), everlasting (Helychrysum stoechas Moench), European pennyroyal (Mentha pulegium L.) and fennel (Foeniculum vulgare Mill.). Hydrodistillation was the extraction method used, and the obtained extracts were composed of a variety of volatile molecules, mainly terpenoids and phenylpropenoids. The EO yields were determined, and the chemical composition of these natural products was obtained by gas chromatography-mass spectrometry (GC-MS) analysis. The yields varied greatly in the range of 0.99 to 4.27% (v/w). The two major chemical constituents of the EOs analysed by GC-MS were as follows: thyme – 1,8-cineole and champhor; everlasting – α-pinene and limonene; European pennyroyal – pulegone and isomenthone; fennel – trans-anethole and limonene. This preliminary study is an important contribution to the understanding of EO bioactive compounds that are under investigation to establish their ability to control the biocolonization of cultural heritage.

Keywords: aromatic plants, chemical characterization, essential oils, green biocides

Degradation of C. I. Direct Red 80 by the Electro-Fenton Process

Wed, 10 Aug 2022 00:00:00 +0000

Electro-Fenton process was applied in the degradation of the textile dye C. I. Direct Red 80 (DR80), using a boron-doped diamond anode and a carbon-felt cathode. The influence of the applied current density and of the type of iron source was evaluated. The iron sources studied were iron sulfate, ferric chloride, iron oxide and chalcopyrite, a natural iron-containing mineral. The obtained results showed that the electro-Fenton process is effective in the DR80 degradation and in the pollutant load elimination. Higher treatment efficiencies were attained when using iron sulfate as iron source. Still, the results obtained with the natural mineral chalcopyrite were quite promising. Although DR80 removal was more efficient at lower applied current densities, the same was not observed for the chemical oxygen demand removal, indicating that, at lower applied current densities, the dye is not completely mineralized, but rather transformed into other by-products.

Keywords: C. I. Direct Red 80; Advanced oxidation processes; Electro-Fenton, Borondoped diamond anode, Carbon-felt cathode.

Diclofenac Photodegradation Under Visible Light With (La,Ba)(Fe,Ti)O3 Perovskites

Ana Sofia Rodrigues, Lurdes Ciríaco, Maria José Pacheco, Ana Lopes — Wed, 10 Aug 2022 00:00:00 +0000

Perovskites BaTiO₃ and BaFeO₃ were prepared by the ceramic and complex polymerization methods and the substituted perovskites La_0.2Ba_0.8TiO₃, BaFe_0.8Ti_0.2O₃, and BaFe_0.6Ti_0.4O₃ were prepared by the ceramic method. All of them were used as photocatalytic material for the degradation of the pharmaceutical diclofenac under visible light. The best diclofenac degradation results were obtained with the substituted perovskite La_0.2Ba_0.8TiO₃ (46%), prepared by the ceramic method, and with the nonsubstituted perovskite BaFeO₃ (43%), prepared by the complex polymerization method.

Keywords: visible light, perovskites, photocatalysis, (La,Ba)(Fe,Ti)O₃, diclofenac

Photocatalytic Activity of LaTi1−xFexO3 Perovskite-Type Oxides Under UV and Visible Light

Wed, 10 Aug 2022 00:00:00 +0000

LaTi_1−xFe_xO₃ (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) perovskite-type oxide samples were synthesized by the solid state reaction method and characterized, and their photocatalytic activity was tested in the degradation of Acid Orange 7 under ultraviolet and visible light. The oxides were successfully synthesized and the XRD results showed a phase change from monoclinic to orthorhombic, with an increase in Fe content (x), with LaTi_0.8Fe_0.2O₃ and LaTi_0.6Fe_0.4O₃ samples presenting both phases. All samples presented low photocatalytic activity under visible light radiation, with a maximum Abs_484nm removal of 2.9% for LaFeO₃ after one hour. The best results were obtained under ultraviolet radiation, for all samples, with the best photocatalytic activity exhibited by the La₂Ti₂O₇ perovskite, with 44.6% Abs_484nm removal after one hour.

Keywords: perovskites, LaTi_1−xFe_xO₃, photocatalysis, Acid Orange 7

Use of Vetiver Zizinioides Floating Beds to Improve the Quality of Surface Water in a Mediterranean Climate

José Correia, Adelaide Almeida, Anabela Durão, Ana Pardal, Teresa Borralho — Wed, 10 Aug 2022 00:00:00 +0000

Due to the negative effects of its main inflows, the water quality of Roxo stream, located in southern Portugal, an area characterized by Mediterranean climate, is degraded, causing consequences in irrigated agricultural activity. The eco technology of floating beds was used to improve the quality of this water. Three Vetiver zizinioides floating beds (3.3 m²/unit; density 40.5 plants/m²) were placed on the Roxo stream in May 2020 and the water quality was monitored until December 2020 in two places: at the floating beds location and 100 m higher up in the stream. The load mass was calculated for both sampling points and the removal rate for each parameter was monitored. The average removal rates obtained were: (i) TN = 33%; (ii) TP = 43%; (iii) COD = 44%; and (iv) Cl- = 15%. The DO level increased slightly, and the pH remained neutral. Although the water quality improved, the quality was still not high enough to be able to use the water for irrigation and to achieve good ecological status.

Keywords: Roxo stream, surface water quality, real scale, floating beds, Vetiver zizinioides

Treatment of Industrial Effluents by the Microalgae Selenastrum Sp.

Bruno Escobar, André Cunha, Rogério Simões — Wed, 10 Aug 2022 00:00:00 +0000

High consumption of clean water results in the generation of effluents that need to be treated and then safely discarded. Conventional methods for such treatment often do not offer an economical and sustainable result; therefore, new methods are needed, such as microalgae usage. Microalgae are unicellular beings capable of rapid adaptation, growth, and production of compounds of interest (pharmaceuticals, biofuels and others). This work aimed to study the effectiveness of the microalgae Selenastrum sp. in the treatment of effluents from the textile and pulp & paper industries, as well as the respective effects on its biomass development and accumulation of compounds. Four types of culture were carried out (for each type of effluent, a control, and a control with addition of glucose) lasting eight days, in duplicate, all with the addition of a standard culture medium and controlled abiotic factors. Analyses for compound removal (chemical oxygen demand and colour readings on the 200–800nm range) and biomass development (cell number, its dimensions, and weight) were performed four times during the process. At the end of the experiments, the average removal in effluents for COD and colour were 56.6% and 32.7% respectively, in addition to a biomass accumulation of 0.45 g/L. These results were comparable to those obtained for the control cultivation using glucose as a carbon source (70.0% COD removal and 0.51 g/L biomass accumulation). These results demonstrate the effectiveness of Selenastrum sp. in the treatment of industrial effluents, its resilience in stressful environments and the potential use of its accumulated compounds for biotechnological purposes.

Keywords: microalgae, Selenastrum sp., industrial effluent, textile effluent, pulp effluent, effluent treatment

Influence of Hydraulic Conditions on Reclaimed Water Polishing Using Soil and Sand Columns

Wed, 10 Aug 2022 00:00:00 +0000

The removal of residual pollutants from a synthetic effluent with a composition similar to that of urban effluent from secondary treatment was evaluated in vertical downflow columns. These were filled with soil, the fine fraction of the soil, and sand, and operated in discontinuous and continuous mode. The results showed high removal rates of organic matter, ammonium, nitrate and phosphate in the discontinuous and continuous experiments, especially for the fine fraction. Therefore, the soil is suitable for removing organic matter and nutrients (N-NH₄, N-NO₃, and P-PO₄), and can be used for polishing wastewater before its infiltration.

Keywords: wastewater reuse, organics removal, nutrient removal, residual soil, river sand

Investigation of Agricultural Waste as Economical and Effective Bio-Inhibitors for Inhibiting Scaling in Natural Hard Water

Wed, 10 Aug 2022 00:00:00 +0000

In this study, agricultural waste was utilized as new bio-inhibitors to prevent scale formation in hard waters. Aqueous extracts of strawberry and tomato leaves were utilized for reducing the scale deposits formed on metallic surfaces by Bounouara ground hard water, which supplies Constantine city in Algeria. Anti-scaling properties were evaluated by chronoamperometry and impedancemetry techniques. The effect of temperature and concentration on the efficiency of the bio-inhibitors was assessed. The results showed that the anti-scaling effect of strawberry leaf extracts started at the very low concentration of 1 ppm, with 31% efficiency, reaching complete scaling inhibition at 15 ppm (20ºC), whereas the inhibitory effect of tomato leaf extracts was noticed at 2.5 ppm, with 36% efficiency, and total inhibition at 20 ppm (20ºC). The efficiency of strawberry and tomato leaf extracts at 40∘C was also confirmed, although total inhibition was attained at a higher concentration.

Keywords: hard water, agricultural waste, strawberry leaves, tomato leaves, bioinhibitors, scaling inhibition

Opportunities for Microalgae-Bacteria Consortium Application to the Treatment of Effluents Generated in Fiber-Waste-Based Recycling Processes

Wed, 10 Aug 2022 00:00:00 +0000

Technologies based on microalgae-bacteria seem to be sustainable options for wastewater treatment and reuse, with lower costs than conventional biological treatment technologies. Furthermore, they can generate added-value products produced from algae biomass. Among other advantages, the consortium bacteriaalgae produce photosynthetic oxygen through the microalgae, which can be used by aerobic bacteria for oxidizing organic matter and nitrogen, thus reducing the need for introducing artificial oxygen. In this review paper, the main systems that use microalgaebacteria consortium are discussed. Microalgae-bacteria present advantages in the removal of organics, nitrogen and phosphorus, when compared with conventional biological treatment systems (e.g., activated sludge, percolating filters and ponds), and are able to produce final effluents for reuse (e.g., in agricultural irrigation, industry or aquifer recharge) and excess of microalgae that can be converted to added-value products such as biogas and biofuels. Attention is given to the innovative aspects of applying photobioreators to the treatment and reuse of pulp and paper effluents and fiber-waste-based recycling wastewaters, which seems to open a new opportunity for the pulp, paper and recycling paper industries.

Keywords: fiber-waste-based industry, microalgae-bacteria consortium, removal of nutrients, wastewater treatment

Phytoremediation of Boron From Wastewater in Vertical Flow Constructed Wetlands

Wed, 10 Aug 2022 00:00:00 +0000

The aim of this work was to evaluate the possibility of boron removal from synthetic wastewater using a vertical constructed flow (VFCW) planted with Vetiveria zizanioides. Two boron concentrations were used (15 ± 1 and 30 ± 1 mg L⁻¹) and a hydraulic load (H_L) of 191 ± 10 L m⁻²d⁻¹. The wastewater samples were taken and the flow rate in the inlet and outlet of the VFCW were measured. The levels of dissolved oxygen, electrical conductivity, pH and boron were determined in the wastewater. The concentrations of the essential elements and nutrients, namely total Kjeldhal nitrogen, phosphorus, calcium, magnesium, sodium and potassium in above growth biomass composition were measured. The results showed that: boron removal efficiencies depended on the boron concentration, so 60 ± 3% was obtained for the 15 mg L⁻¹ concentration and 26 ± 2% for 30 mg L⁻¹; calcium, magnesium, potassium and sodium concentrations in the vegetal biomass decreased to the boron concentration of 30 mg L⁻¹, and boron may have interfered with Vetiveria zizanioides growth.

Keywords: biomass composition, boron removal, light expanded clay aggregates, Vetiveria zizanioides, vertical flow constructed wetland

Phytoremediation as a Sustainable Alternative for Organic Matter Removal From Slaughterhouse Wastewater Pretreated by Immediate One-Step Lime Precipitation

Luís Madeira, Fátima Carvalho, Margarida Ribau Teixeira, Adelaide Almeida — Wed, 10 Aug 2022 00:00:00 +0000

In this study, slaughterhouse wastewater previously treated by immediate one-step lime precipitation was treated using a vertical flow constructed wetland (VFCW). A VFCW pilot scale planted with Vetiveria zizanioides in light expanded clay aggregates was used to study the influence of the organic load applied (3 to 212 g m⁻² d⁻¹) and the bed depth of the VFCW (0.35 and 0.70 m) on the organic matter removal (COD). Two VFCWs operated in parallel under continuous flow, and a hydraulic load of around 80 L m⁻² d⁻¹ was used. The results indicated that an increase in the organic load decreased COD removal efficiency. The bed depth of the VFCW had a significant influence on the removal of organic matter, with greater removal at high bed depths. For organic loads applied up to 9.5 g m⁻² d⁻¹, COD removal efficiencies of 71.4 ± 4.0% and 85.2 ± 3.4% were observed for lower and higher VFCW bed depth, respectively, which met the requirements for water reuse for irrigation. Throughout the tests, Vetiveria zizanioides did not show signs of toxicity, and its growth was substantial.

Keywords: slaughterhouse wastewater, vertical flow constructed wetlands, Vetiveria zizanioides, organic matter removal, immediate one-step lime precipitation

Removal of Emergent Pollutants by a Vertical Flow Constructed Wetland with Vetiveria Zizanioides: A Case Study for Caffeine

Wed, 10 Aug 2022 00:00:00 +0000

This work evaluated caffeine removal in a vertical flow constructed wetland (VFCW), planted with Vetiveria zizanioides. The feeding was continuous (synthetic influent: mineral medium and caffeine) to reduce the concentration variations in the bed. Two influent concentrations (0.75 ± 1.0 mg·L⁻¹ and 1.5 ± 1.0 mg·L⁻¹) were used with a constant hydraulic load (100 ± 10 L·m⁻²·d⁻¹). Plant growth was monitored weekly, and characterization was carried out to determine the levels of chlorophyll a and b, pigments and carotenoids, and nutrients (nitrogen, phosphorus, magnesium, calcium, sodium and potassium). HPLC-MS was used to determine the caffeine concentration. The caffeine removal efficiency reached averages of 93 ± 1% and 87 ± 1% (retention time: 6.23 ± 0.23 hours). The caffeine contents in the influent did not affect chlorophyll a, total chlorophyll or carotenoids, and an increasing trend throughout the tests was observed. Sodium and potassium contents also showed an increase with higher caffeine concentration. This preliminary study showed that removing caffeine from wastewater using a VFCW is promising.

Keywords: wastewater, emergent pollutants, caffeine, vertical flow constructed wetlands, Vetiveria zizanioides

Water Reuse: A Risk Assessment Model for Water Resources

Anabela Rebelo, Albertina Bento Amaro, Felisbina Quadrado — Wed, 10 Aug 2022 00:00:00 +0000

The increasing demands for water for multiple purposes combined with climate change challenges are leading to water scarcity and quality deterioration. Portugal is vulnerable to the impacts of climate change and therefore, the use of reclaimed waters has been identified as a suitable alternative water source for non-potable uses, such as irrigation, to overcome water shortages. In the last two years, new policies for water reuse have been approved at the Portuguese and European levels. The legal frameworks are supported in the international guidelines developed by the International Organization for Standardization, namely for irrigation, urban uses and health risk assessment. In this way, all reuse projects must follow a fit-for-purpose approach, i.e., the water quality needs to meet the requirements of its specific end-uses without compromising public health or the surrounding environment, and all reuse projects must conduct a risk assessment for health and the environment. Quantitative, qualitative or semiquantitative models can be used. Although a quantitative assessment may be desirable, these models tend to be complex and present high uncertainty. Furthermore, these usually require extensive data which are often not available. Accordingly, this study intended to develop a conceptual model to deal with the risk assessment for water resources, namely surface and ground waters. A semi-quantitative approach was employed for the risk characterization, using empirical qualitative judgment to assess the relative importance of hazards, exposure routes, scenarios and barriers in place. The use of a strategic assessment allows the quality standards that meet the needs of each project to be validated. The developed model was applied to a case study to illustrate its applicability.

Keywords: water reuse, water resources, risk assessment, semi-quantitative model, compounds of emerging concern

Water Reuse in a Municipal Sports Center

Flora Silva, Ana Maria Antão-Geraldes, António Albuquerque — Wed, 10 Aug 2022 00:00:00 +0000

Two potential measures for increasing water use efficiency in a municipal sports center were evaluated: (1) the reuse of water originating from showers in the flushing toilets in the indoor football court building; and (2) the reuse of water from swimming pool filter backwashing for irrigation. In the indoor football court building the total annual water consumption is around 3,500.5 m³ and from the showers is approximately 1,785.26 m³. Therefore, the greywater generated in showers can be reused in toilet flushing, which consumes about 840.12 m³ per year. The estimated annual water consumption for filter backwashing is 4,197.6 m³. The annual amount of water necessary for irrigating the lawn of the local football stadium is around 7,200 m³. Thus, the filter backwashed water, after being subjected to a sedimentation process, could be fully reused for this purpose.

Keywords: water efficiency, water reuse, swimming pools filter backwashing reuse, sports center, sustainability

Chemical and Mineralogical Characterization of Biomass Ashes for Soil Reinforcement and Liner Material

Wed, 10 Aug 2022 00:00:00 +0000

Mineralogical and chemical evaluations are necessary to investigate the background and origins of materials. In terms of residues commonly produced around the world, ashes biomass stands out for its high calorific capacity and use for energy production at thermoelectrical facilities. Given current sustainability issues and new demands from society, ashes and soil from pine biomass in the Castelo Branco region were investigated to research possible anthropogenic contaminations, heavy metals among their composition, and their physic-chemical characteristics. These properties can be used to define possible valorisation methods through residue introduction into the soil for its reinforcement and liner application. The results indicated that ashes biomass could help achieve these objectives and could be introduced into the soil, due to its enrichment with pozzolanic minerals and fine granulometry, while having a low-density, which could reduce final weight; however it was considerably different from the original biomass, and contained anthropogenic contaminations and high concentrations of heavy metals.

Keywords: biomass ashes, chemical and mineralogical properties, residue valorisation, soil reinforcement, liner material

Geotechnical Characterization of Biomass Ashes for Soil Reinforcement and Liner Material

Wed, 10 Aug 2022 00:00:00 +0000

Biomass ashes (BA) have been intensively studied as amendments for soil in earthworks. This paper aimed to geotechnically characterize BA from pines and olive trees compared to the soil from Castelo Branco, Portugal. Namely, granulometry, specific gravity, Atterberg limits and optimal compaction values were obtained and analyzed in order to valorize the residue incorporated into soils. This work is part of broader efforts to develop an alternative material that can be used in hydraulic barriers as liners and for soil reinforcement. Thus, BA can contribute to reductions in weight and plasticity, and filling properties. Further studies are needed, particularly mechanical and hydraulic performance tests.

Keywords: biomass ashes, geotechnical and mechanical properties, residue valorization, soil reinforcement, liner material

Biopolymer Geogrids for Geotechnics

Gabriel Oliveira, Isabel Falorca — Wed, 10 Aug 2022 00:00:00 +0000

This study focused on the mechanical characterisation of 3D printed biopolymer geogrids for civil and geotechnical engineering applications. The polylactic acid specimens were designed based on first-order similitude conditions and were produced by fused deposition modelling techniques. An experimental programme was carried out to investigate the mechanical behaviour of 1:2 scale model geogrids undergoing tensile loading conditions, in order to explore their use in soil reinforcement and stabilisation of geomaterials. The secant stiffness at 2.0% of strain and the ultimate tensile strength were used for this purpose. The results showed an average tensile strength of 4.5 ± 0.5 kN/m, which is in good agreement with that of fossil oil-derived polymer prototypes, while presenting a significantly lower elongation at failure. The printing process appeared stable and replicable. The influence of degradation on the tensile properties of 3D printed polylactic acid geogrids over time still needs to be studied.

Keywords: geogrid, additive manufacturing, biopolymer, tensile strength, geotechnics

Evaluation of Entre-os-Rios Thermal Aquifer Vulnerability Using DRASTIC Index

Vanessa Gonçalves, António Albuquerque, Victor Cavaleiro — Wed, 10 Aug 2022 00:00:00 +0000

The “Entre-os-Rios” thermal aquifer has a protection perimeter buffer zone for avoiding water contamination. A vulnerability map was generated, using geographic information systems (GIS) tools and the DRASTIC index, to evaluate the risk of contamination of the perimeter area. The results showed that the protection perimeter buffer zone has an insignificant to moderate risk of pollution, with the DRASTIC index’s values ranging from 47 to 127 points, and an average pollution vulnerability of 79 points. The alluvium-covered land is vulnerable to moderate contamination but is located far from the catchment point. Areas of minimal risk correspond to locations where the granitic massif has not been altered significantly.

Keywords: geographic information systems, vulnerability map, protection perimeter buffer zone, DRASTIC index

Dynamic Penetration Profile of Starch Betainate, Pluronics and PCC Coated Papers

Mohit Sharma, Roberto Aguado, Artur Valente, Dina Murtinho, Paulo Ferreira — Wed, 10 Aug 2022 00:00:00 +0000

Despite changes in optical and printing properties, the applied coating components on the paper surface have a significant impact on the surface chemistry of office paper. Depending on the use, such as ink penetration for printing and writing papers, an optimal hydrophobic and hydrophilic balance may be beneficial. In this study, several coating components including starch betainate, Pluronics, and precipitated calcium carbonate were employed to coat base paper (paper without any surface treatment). The influence of these components on water penetration was investigated using dynamic penetration. When compared to native starch coated papers, paper coated with starch betainate (a cationic starch ester) showed reduction in hydrophobicity and increased water penetration. Moreover, this effect was further enhanced with the use of Pluronics. Likewise, hydrophobicity decreased as the concentration of starch betainate, precipitated calcium carbonate and Pluronics increased. Furthermore, water penetrated even more quickly when the combination of these components compared with the individual component coatings.

Keywords: hydrophobicity, PCC, Pluronics, starch betainate, water penetration