Effect of microalgae and bacteria inoculation on the startup of bioreactors for paper pulp wastewater and biofuel production.

The use of microalgae and bacteria as a strategy for the startup of bioreactors for the treatment of industrial wastewater can be a sustainable and economically viable alternative. This technology model provides satisfactory results in the nitrification and denitrification process for nitrogen removal, organic matter removal, biomass growth, sedimentation, and byproducts recovery for added-value product production. The objective of this work was to evaluate the performance of microalgae and bacteria in their symbiotic process when used in the treatment of paper pulp industry wastewater. The experiment, lasting fourteen days, utilized four bioreactors with varying concentrations in mgVSS/L of microalgae to bacteria ratio (R1-100:100, R2-100:300, R3-100:500, R4-300:100) in the startup process. Regarding the sludge volumetric index (SVI), the results show that the R1 and R2 reactors developed SVI30/SVI10 biomass in the range of 85.57 ± 7.33% and 84.72 ± 8.19%, respectively. The lipid content in the biomass of reactors R1, R2, R3 e R4 was 13%, 7%, 19%, and 22%, respectively. This high oil content at the end of the batch, may be related to the nutritional stress that the species underwent during this feeding regime. In terms of chlorophyll, the bioreactor with an initial inoculation of 100:100 showed better symbiotic growth of microalgae and bacteria, allowing exponential growth of microalgae. The total chlorophyll value for this bioreactor was 801.46 ± 196.96 µg/L. Biological removal of nitrogen from wastewater from the paper pulp industry is a challenge due to the characteristics of the effluent, but the four reactors operated in a single batch obtained good nitrogen removal. Ammonia nitrogen removal performances were 91.55 ± 9.99%, 72.13 ± 19.18%, 64.04 ± 21.34%, and 86.15 ± 30.10% in R1, R2, R3, and R4, respectively.

Impact of the Curing Temperature on the Manufacturing Process of Multi-Nanoparticle-Reinforced Epoxy Matrix Composites.

This study aims to analyze the effect of the curing temperature of nano-reinforcements during the manufacturing process on the mechanical properties of composites involving graphene (GNP), carbon nanofibers (CNFs), and a hybrid mixture of these two nanoparticles. In this context, the type of nanoparticles, their content, their type of resin, and their hybridization were considered. The results showed that both nanoparticles increased the viscosity of the resin suspension, with an increase of between 16.3% and 38.2% for GNP nanoparticles and 45.4% and 74% for CNFs depending on the type of resin. Shrinkage was also affected by the addition of nanoparticles, as the highest results were obtained with GNP nanoparticles, with a 91% increase compared with the neat resin, and the lowest results were obtained with CNFs, with a decrease of 77% compared with the neat resin. A curing temperature of 5 °C promoted the best bending and hardness performance for all composites regardless of the type of resin and reinforcement used, with improvements of up to 24.8% for GNP nanoparticles and 13.52% for CNFs compared with the neat resin at 20 °C. Hybridization led to further improvements in bending properties and hardness compared with single-reinforcement composites due to a synergistic effect. However, the effectiveness of hybridization depends on the type of resin.

Chemical Composition of Macroalgae Polysaccharides from Galician and Portugal Coasts: Seasonal Variations and Biological Properties.

Crude polysaccharides extracted from the Codium sp. and Osmundea sp. macroalgae collected in different seasons (winter, spring and summer) from the Galician and North Portugal coasts were characterised, aiming to support their biomedical application to wound healing. An increase in polysaccharides' sulphate content was registered from winter to summer, and higher values were obtained for Osmundea sp. In turn, the monosaccharide composition constantly changed with a decrease in glucose in Osmundea sp. from spring to winter. For Codium sp., a higher increase was noticed regarding glucose content in the Galician and Portugal coasts. Galactose was the major monosaccharide in all the samples, remaining stable in all seasons and collection sites. These results corroborate the sulphate content and antioxidant activity, since the Osmundea sp.-derived polysaccharides collected in summer exhibited higher scavenging radical ability. The biocompatibility and wound scratch assays revealed that the Osmundea sp. polysaccharide extracted from the Portugal coast in summer possessed more potential for promoting fibroblast migration. This study on seasonal variations of polysaccharides, sulphate content, monosaccharide composition and, consequently, biological properties provides practical guidance for determining the optimal season for algae harvest to standardise preparations of polysaccharides for the biomedical field.

Dissolving Kraft Pulp Production and Xylooligosaccharide Coproduction: Effect of Pre-Hydrolysis Conditions.

Due to cotton's declining sustainability, more lignocellulosic materials are being used to produce dissolving pulp for textile applications. Pre-hydrolysis kraft is one of the main processes used to produce this material. Pre-hydrolysis under conventional conditions removes most of the hemicelluloses, but the majority end up as xylose and furfural, traditionally burned in a recovery boiler. The xylooligosaccharides (XOS), derived from hemicelluloses are a specialty product and can be recovered but requires adapted operative conditions. Thus, the objective was to recover XOS and evaluate the effect of pre-hydrolysis conditions on the final pulp characteristics. A flow-through reactor (FTR) was used to study the pre-hydrolysis, which allowed for modification of the retention time of the xylan in the free liquor after extraction from wood. The results have shown that by changing the fluid retention time in the pre-hydrolysis, the proportion of XOS/xylose/furfural recovered can be strongly changed. The hemicellulose content of the dissolving pulp decreased from 6.8% to about 2.6% using the FTR pretreatment.

Alkali-Doped Nanopaper Membranes Applied as a Gate Dielectric in FETs and Logic Gates with an Enhanced Dynamic Response.

The market for flexible, hybrid, and printed electronic systems, which can appear in everything from sensors and wearables to displays and lighting, is still uncertain. What is clear is that these systems are appearing every day, enabling devices and systems that can, in the near future, be crumpled up and tucked in our pockets. Within this context, cellulose-based modified nanopapers were developed to serve both as a physical support and a gate dielectric layer in field-effect transistors (FETs) that are fully recyclable. It was found that the impregnation of those nanopapers with sodium (Na+) ions allows for low operating voltage FETs (<3 V), with mobility above 10 cm2 V-1 s-1, current modulation surpassing 105, and an improved dynamic response. Thus, it was possible to implement those transistors into simple circuits such as inverters, reaching a clear discrimination between logic states. Besides the overall improvement in electrical performance, these devices have shown to be an interesting alternative for reliable, sustainable, and flexible electronics, maintaining proper operation even under stress conditions.

Effect of enzymatic treatment on Eucalyptus globulus vessels passivation.

Hardwood vessel elements generate problems in industrial uncoated wood-free printing paper operation, causing vessel picking and ink refusal. These problems are mitigated using mechanical refining at the cost of paper quality. Vessel enzymatic passivation, altering its adhesion to the fiber network and reducing its hydrophobicity is a way of improving paper quality. The object of this paper is to study how the enzymatic treatment by xylanase and by an enzymatic cocktail containing cellulases and laccases affect elemental chlorine free bleached Eucalyptus globulus vessel and fiber porosities, bulk, and surface chemical compositions. Thermoporosimetry revealed the vessel structure to be more porous, surface analysis showed its lower O/C ratio and bulk chemistry analysis its higher hemicellulose content. Enzymes had different effects on porosity, bulk and surface composition of fibers and vessels, affecting vessel adhesion and hydrophobicity. Vessel picking count decreased 76% for papers containing vessels treated with xylanase and 94% for the papers with vessels treated with the enzymatic cocktail. Fiber sheet samples had lower water contact angle (54.1º) than vessels rich sheets (63.7º), that reduced with xylanase (62.1º) and cocktail (58.4º). It is proposed that differences in vessel and fiber porosity structures affect the enzymatic attacks, eventually causing vessel passivation.

Biopolymeric Delivery Systems for Cosmetic Applications Using Chlorella vulgaris Algae and Tea Tree Essential Oil.

Cosmetic products in which all the skincare compounds are biomolecules, biocompatible and biodegradable constitute a request of an educated consumer corresponding to a premium cosmetic segment. For this purpose, a cellulose-based delivery system was developed to retain biomolecules for dermic applications. The 3D matrix was built with microfibrillated cellulose, nanofibrillated cellulose and carboxymethylcellulose combined with a crosslinking agent, the alginate, to obtain a 3D matrix capable of retaining and releasing bioactive components of microalgae Chlorella vulgaris and tea tree essential oil. The porosity and pore dimensions and uniformity of this support matrix were optimized using 3D computational tools. The structures of the biopolymers were characterized using SEM, EDX, FTIR-ATR and DSC techniques. The essential oil and the microalgae components were successfully incorporated in a 3D stable matrix. The results indicate that the polymeric matrix retains and releases the essential oil biomolecules in a controlled way, when compared with tea tree essential oil, which is vaporized from 25 °C to 38 °C, without this 3D polymeric matrix. The microalgae and cellulose-based delivery system proved to be an interesting option for dermic and cosmetic applications because the exposure time of the therapeutic biomolecules was improved, and this factor consists of a competitive benefit for dermic systems.

Treatment of cork boiling wastewater using a horizontal subsurface flow constructed wetland combined with ozonation.

Cork boiling wastewaters (CBW) are strongly coloured complex aqueous solutions with high organic load of biorecalcitrant and toxic nature. The feasibility and efficiency of a CBW treatment process combining ozonation as pre- and post-treatment of a horizontal subsurface flow constructed wetland (HSFCW) was assessed. Over an extended monitoring period of 390 days, two lab-scale HSFCW units were tested; one planted with P. australis (CWP) and one unplanted-control (CWC) operated at average organic loads rates (OLR) of 5 and 10 g COD/m2/d. CWP always outperformed the control unit. The ozonation trials were run at pH values of 8.15-8.21 and 5.39-5.45 (without adjustment) at ozone to COD ratios of 0.25-0.29 and 0.24-0.59 when implemented as pre- and post-treatment, respectively. Average removals (calculated through mass balance basis) were 78-88%, 86-91%, 71-89% and 43-89% for COD, BOD5, Total Phenols (TPh) and colour when ozonation was implemented as post-treatment. For ozonation as pre-treatment, respective figures were 77-80%, 79-92%, 78-85% and 19-73%. Regardless of the treatment scheme and OLR, ozonation was very effective in biodegradability increase (i.e., BOD5/COD) from 0.18 to 0.42 when applied as pre-treatment, and decolourization after the HSFCW increased from 21% to 91% (post-treatment) with respective ozone consumed yields of 67-69% and 72-85%. The best results were obtained for the scheme CWP + Ozonation at OLR of 5.33 g COD/m2/d with COD reductions from 1950 mg/L to 81-88 mg/L in the effluent and TPh from 125 mg/L to 5-6 mg/L at limited ozone amounts of 0.21-0.45 g O3/m2/d.

Treatment of slaughterhouse wastewater by acid precipitation (H2SO4, HCl and HNO3) and oxidation (Ca(ClO)2, H2O2 and CaO2).

The treatment of slaughterhouse wastewater was investigated by both acid precipitations and by oxidation processes. Precipitation tests were developed using three acids (H2SO4, HCl and HNO3) at different operating pH (1-6). A decrease of the precipitation pH led to an increase of the conductivity values of the supernatant. Precipitation processes allowed the removal of chemical oxygen demand (COD) (41-97%), turbidity (56-99%) and total phosphorus (27-56%). Total phenols were removed (15-96%) from pH ≥ 2, depending on the precipitation process. Generally, precipitation processes decreased the hydroxide and bicarbonates species. Additionally, three different oxidation processes were tested at different concentrations (1-15 g L-1): Ca(ClO)2, H2O2 and CaO2. When Ca(ClO)2 and CaO2 were applied, an increase of the supernatant conductivity was achieved. COD removal ≥71% and turbidity elimination in the range of 85-100% were achieved by using oxidation processes. CaO2 was very effective to remove total phosphorus (81-96%). The increase of the oxidant concentration in H2O2 and Ca(ClO)2 oxidation processes led to a decrease in the removal of total phenols and bicarbonates species. Optical density of the microorganism cultures was efficiently eliminated (up to 100%) by oxidation processes. In addition, acid precipitation and oxidation allowed to remove total solids (TS), total volatile solids (TVS), total suspended solids (TSS), ammonia nitrogen, nitrates and biochemical oxygen demand (BOD5). Acid precipitation and oxidation produced sludge rich in organic matter and nutrients (Ca, Mg, P, Cl, Na and K). Despite the high removal efficiencies, a post-treatment following the precipitation and oxidation processes can be required.

Poly(lactic acid)/Cellulose Films Produced from Composite Spheres Prepared by Emulsion-Solvent Evaporation Method.

The compound of poly(lactic acid) (PLA) and cellulose was made by the emulsion-solvent evaporation technique in order to obtain spheres which are then compression molded to produce a biocomposite film. The effect of the dispersant (poly(vinyl alcohol)-PVA)/PLA ratio on the spheres yield was studied. Moreover, to evaluate the effect of cellulose particle size and surface chemistry on the process yield, unbleached eucalypt kraft pulp and microcrystalline cellulose (MCC), both unmodified and physically or chemically modified were used. PLA/cellulose spheres were characterized regarding its physical properties. It was found that the spheres yield is essentially determined by the PVA/PLA ratio and the percentage of cellulose incorporation is greatly affected by the surface chemistry of cellulose. Regarding the films, DSC runs showed a significant effect of the cellulose type incorporated into PLA matrix on the cold crystallization temperature and on the degree of crystallinity of the biocomposite films. The measurement of tensile properties of the biocomposite films revealed that the strength, elongation at break and toughness (tensile energy absorption at break) of the films incorporating unmodified and chemically modified MCC were substantially improved.

Investigation of lab-scale horizontal subsurface flow constructed wetlands treating industrial cork boiling wastewater.

The feasibility and treatment efficiency of horizontal subsurface flow constructed wetlands (HSFCW) was assessed for the first time for cork boiling wastewater (CBW) through laboratory experiments. CBW is known for its high content of phenolic compounds, complex composition of biorecalcitrant and toxic nature. Two lab-scale units, one planted with Phragmites australis (CWP) and one unplanted (CWC), were used to evaluate the removals of COD, BOD, total phenolic compounds (TPh) and decolourization over a 2.5-years monitoring period under Mediterranean climatic conditions. Seven organic and hydraulic loading rates ranging from 2.6 to 11.5 g COD/m2/d and 5.7-9.1 L/m2/d were tested under average hydraulic retention time (HRT) of 5 ±â€¯1 days required due to the CWB limited biodegradability (i.e., BOD5/COD of 0.19). Average removals of the CWP exceeded those of the CWC and reached 74.6%, 91.7% and 69.1% for COD, BOD5 and TPh, respectively, with respective mass removals rates up to 7.0, 1.7 and 0.5 (in g/m2/d). Decolourization was limited to 35%, since it mainly depends on physical processes rather than biodegradation. CBW concentration of nine phenolic compounds ranged from 1.2 to 38.4 mg/L (for the syringic and ellagic acids, respectively) in the raw CBW, with respective removals in the CWP unit ranging from 41.8 to 76.3%, higher than those in the control unit. Despite CBW high concentration of TPhs (average of 116.3 mg/L), the HSFCW reached organic load removals higher than those of conventional biological treatment methods.

Electrochemical treatment of cork boiling wastewater with a boron-doped diamond anode.

Anodic oxidation at a boron-doped diamond anode of cork boiling wastewater was successfully used for mineralization and biodegradability enhancement required for effluent discharge or subsequent biological treatment, respectively. The influence of the applied current density (30-70 mA/cm2) and the background electrolyte concentration (0-1.5 g/L Na2SO4) on the performance of the electrochemical oxidation was investigated. The supporting electrolyte was required to achieve conductivities that enabled anodic oxidation at the highest current intensities applied. The results indicated that pollutant removal increased with the applied current density, and after 8 h, reductions greater than 90% were achieved for COD, dissolved organic carbon, total phenols and colour. The biodegradability enhancement was from 0.13 to 0.59 and from 0.23 to 0.72 for the BOD/COD ratios with BOD of 5 and 20 days' incubation period, respectively. The tests without added electrolyte were performed at lower applied electrical charges (15 mA/cm2 or 30 V) with good organic load removal (up to 80%). For an applied current density of 30 mA/cm2, there was a minimum of electric conductivity of 1.9 mS/cm (corresponding to 0.75 g/L of Na2SO4), which minimized the specific energy consumption.

Biodegradability enhancement and detoxification of cork processing wastewater molecular size fractions by ozone.

Cork boiling wastewater pollutants were fractionated by sequential use of four ultrafiltration membranes and five fractions were obtained: four retentates (>100, 50-100, 20-50 and 10-20 kDa) and one permeate (<10 kDa); which were used to study the correlation of molecular size with biodegradability and toxicity before and after ozonation. The results show that molecular size is correlated with organic load and restrains biodegradability. The fraction with >100 kDa corresponds to 56% of the organic load and the one with <10 kDa only 8%. The biodegradability of fractions increased 182% with fractions molecular size reduction from >100 to <10 kDa and the chemical oxygen demand (COD) was from 3436 to 386 mg L(-1). For biodegradability enhancement the best outcome of ozonation was obtained with compounds having molecular size >20 kDa and range from 5% up to 175% for applied ozone doses to COD ratios between 0.15 and 0.38.

Determination of fast ozone oxidation rate for textile dyes by using a continuous quench-flow system.

To study the fast kinetic decolourisation of textile dyes by ozone a continuous quench-flow system was used. This system has not been used before for these purposes. Reaction times in the range of 7-3000 ms were explored. The reaction was quenched with potassium iodide, which proved to be very effective, and the indigo method was used to follow the ozone concentration. Dyes from the most representative chemical classes currently used in the textile industry, i.e. azo and anthraquinone, were selected. Using the initial slope method, the effect of dye and ozone concentrations was researched and the kinetic equations thus established. Using tert-butyl alcohol, as radical scavenger, and pH close to 2.5, the second-order rate constant of the reactant dyes at 280 K varies in the range of 1.20x10(4)-7.09x10(5)M(-1)s(-1); the Acid Orange 7 exhibiting thus its lowest value, the Acid Blue 45 its highest value and the Acid Green 25 and 27 and Direct Yellow 4 intermediate values (approximately 1.6x10(5)M(-1)s(-1)). Without radical scavenger and the pH close to 4, the reaction rate increases one order of magnitude, but, on the reverse, the efficiency of ozone to decolourisation decreases.

The influence of operating parameters on the biodelignification of Eucalyptus globulus kraft pulps in a laccase--violuric acid system.

The potential of a laccase mediator system on the delignification of Eucalyptus globulus kraft pulp was investigated under diverse operating conditions. A series of enzymatic treatments were performed to determine how biodelignification is influenced by pulp consistency, oxygen pressure, reaction time, dose of laccase, and dose of mediator. The mediator used was violuric acid. The results revealed that the extent of biodelignification remains practically constant between 1% and 2.5% of pulp consistency then decreases. However, its effect is less pronounced than the mediator or laccase charge. In fact, an increase in the mediator charge from 1% to 4% leads to an increase in the extent of delignification (fixed laccase charge = 20 IU/g and reaction time 120 min) from 28.4% to 52.2%. On the other hand, at a mediator charge of 4%, the increase of laccase charge from 10 to 40 IU/g has a similar impact on delignification. As for oxygen pressure, the extent of delignification increases with oxygen pressure, from 38.9% to 48.6%, when air and pure oxygen at 4 bar gauge are used. From the standpoint of reaction time, delignification is characterized by a very fast phase followed by a much slower one, leading to a plateau.