Anaerobic biodegradability of category 2 animal by-products : methane potential and inoculum source

Category 2 animal by-products that need to be sterilized with steam pressure according Regulation (EC) 1774/2002 are studied. In this work, 2 sets of experiments were performed in mesophilic conditions: (i) biomethane potential determination testing 0.5%, 2.0% and 5.0% total solids (TS), using sludge from the anaerobic digester of a wastewater treatment plant as inoculum; (ii) biodegradability tests at a constant TS concentration of 2.0% and different inoculum sources (digested sludge from a wastewater treatment plant; granular sludge from an upflow anaerobic sludge blanket reactor; leachate from a municipal solid waste landfill; and sludge from the slaughterhouse wastewater treatment anaerobic lagoon) to select the more adapted inoculum to the substrate in study. The higher specific methane production was of 317 mL CH4 g−1 VSsubstrate for 2.0% TS. The digested sludge from the wastewater treatment plant led to the lowest lag-phase period and higher methane potential rate.This work was partially supported by project PEst-C/EQB/LA0020/2011, financed by FEDER through COMPETE - Programa Operacional Factores de Competitividade and by FCT - Fundacao para a Ciencia e a Tecnologia. FCT is acknowledged for the financial support given to Tatiana Pozdniakova through the PhD scholarship (SFRH/BD/45144/2008) and Jose Carlos Costa through the grant (SFRH/BDP/48962/2008)

Process enhancement at near neutral pH of a homogeneous photo-Fenton reaction using ferricarboxylate complexes: Application to oxytetracycline degradation

This work demonstrates the application at near neutral pH of a photo-Fenton reaction mediated by ferricarboxylates on the treatment of aqueous solutions containing the antibiotic Oxytetracycline (OTC) under solar irradiation. The formation of a Fe:OTC complex after Fe2+ oxidation to Fe3+, in the presence of H2O2, showed the inconvenience of using the conventional Fe2+/H2O2/UV-Vis process at near neutral pH levels, as the complex is retained in the filter. To overcome this, a Fe3+/Oxalate/UV-Vis or Fe3+/Citrate/H2O2/UV-Vis process was proposed. The higher tendency of Fe3+ to form complexes with carboxylates avoids the formation of Fe:OTC complexes and allows for proper OTC detection along reaction times. The photo-Fenton process itself is improved by the extension of the iron solubility to higher and more practical pH values, by the increase of the quantum yield of Fe2+ production and by presenting stronger radiation absorption at wavelengths up to 580 nm. In this way, process efficiency was evaluated for different variables such as Fe3+ concentration, pH, temperature and irradiance, using a compound parabolic collector (CPC) photoreactor at lab-scale under simulated solar radiation. Reaction rates were compared in the presence of different inorganic anions and humic acids, and in two different real wastewater matrixes. Results obtained in a CPC pilot-scale plant under natural solar light, using an iron/oxalate molar rati

Turning Carbon Dioxide and Ethane into Ethanol by Solar-Driven Heterogeneous Photocatalysis over RuO2- and NiO-co-Doped SrTiO3

[EN] The current work focused on the sunlight-driven thermo-photocatalytic reduction of carbon dioxide (CO2), the primary greenhouse gas, by ethane (C2H6), the second most abundant element in shale gas, aiming at the generation of ethanol (EtOH), a renewable fuel. To promote this process, a hybrid catalyst was prepared and properly characterized, comprising of strontium titanate (SrTiO3) co-doped with ruthenium oxide (RuO2) and nickel oxide (NiO). The photocatalytic activity towards EtOH production was assessed in batch-mode and at gas-phase, under the influence of different conditions: (i) dopant loading; (ii) temperature; (iii) optical radiation wavelength; (vi) consecutive uses; and (v) electron scavenger addition. From the results here obtained, it was found that: (i) the functionalization of the SrTiO3 with RuO2 and NiO allows the visible light harvest and narrows the band gap energy (ca. 14-20%); (ii) the selectivity towards EtOH depends on the presence of Ni and irradiation; (iii) the catalyst photoresponse is mainly due to the visible photons; (iv) the photocatalyst loses > 50% efficiency right after the 2nd use; (v) the reaction mechanism is based on the photogenerated electron-hole pair charge separation; and (vi) a maximum yield of 64 mu mol EtOH g(cat)(-1) was obtained after 45-min (85 mu mol EtOH g(cat)(-1) h(-1)) of simulated solar irradiation (1000 W m(-2)) at 200 degrees C, using 0.4 g L-1 of SrTiO3:RuO2:NiO (0.8 wt.% Ru) with [CO2]:[C2H6] and [Ru]:[Ni] molar ratios of 1:3 and 1:1, respectively. Notwithstanding, despite its exploratory nature, this study offers an alternative route to solar fuels' synthesis from the underutilized C2H6 and CO2.This work was financially supported by the Base Funding-UIDB/50020/2020 of the Associate Laboratory LSRE-LCM-funded by national funds through FCT/MCTES (PIDDAC). Larissa O. Paulista also wants to acknowledge for her doctoral fellowship (reference SFRH/BD/137639/2018), supported by FCT. Tania F. C. V. Silva and Vitor J. P. Vilar acknowledge the FCT Individual Call to Scientific Employment Stimulus 2017 (CEECIND/01386/2017 and CEECIND/01317/2017, respectively). Josep Albero and Hermenegildo Garcia are also grateful to the Spanish Ministry of Science and Innovation (RTI2018-098237-CO2-R1 and Severo Ochoa), Generalitat Valencia (Prometeo 2017/083) and European Union's Horizon 2020 research and innovation programme under grant agreement No 862453, project FlowPhotochem, by financial contribution.Paulista, LO.; Albero-Sancho, J.; Martins, RJE.; Boaventura, RAR.; Vilar, VJP.; Silva, TFCV.; García Gómez, H. (2021). Turning Carbon Dioxide and Ethane into Ethanol by Solar-Driven Heterogeneous Photocatalysis over RuO2- and NiO-co-Doped SrTiO3. Catalysts. 11(4):1-18. https://doi.org/10.3390/catal1104046111811

Mechanisms underlying skeletal muscle insulin resistance induced by fatty acids: importance of the mitochondrial function

Insulin resistance condition is associated to the development of several syndromes, such as obesity, type 2 diabetes mellitus and metabolic syndrome. Although the factors linking insulin resistance to these syndromes are not precisely defined yet, evidence suggests that the elevated plasma free fatty acid (FFA) level plays an important role in the development of skeletal muscle insulin resistance. Accordantly, in vivo and in vitro exposure of skeletal muscle and myocytes to physiological concentrations of saturated fatty acids is associated with insulin resistance condition. Several mechanisms have been postulated to account for fatty acids-induced muscle insulin resistance, including Randle cycle, oxidative stress, inflammation and mitochondrial dysfunction. Here we reviewed experimental evidence supporting the involvement of each of these propositions in the development of skeletal muscle insulin resistance induced by saturated fatty acids and propose an integrative model placing mitochondrial dysfunction as an important and common factor to the other mechanisms

Immobilization of L-asparaginase towards surface-modified carbon nanotubes

L-asparaginase (LA) is an enzyme that catalyzes L-asparagine hydrolysis into L-aspartic acid and ammonia and is mainly applied in pharmaceutical and food industries. The LA currently commercialized for pharmaceutical purposes is produced from two main bacterial sources: recombinant Escherichia coli and Erwinia chrysanthemi. However, some disadvantages are associated with its free form, such as the shorter half-life. Immobilization of LA has been proposed as an efficient approach to overcome this limitation. In this work, a straightforward method, including the functionalization of multi-walled carbon nanotubes (MWCNTs) through a hydrothermal oxidation treatment and the immobilization of LA by adsorption over pristine and modified MWCNTs was investigated. Different operation conditions, including pH, contact time, ASNase/MWCNT mass ratio, and the operational stability of the immobilized LA, were evaluated. The characterization of the LA-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA), and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial LA above 95%, under the optimized adsorption conditions (pH 8, 60 min of contact, and 1.510–3 g.mL-1 of LA). The LA-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), proving its suitability for application in industrial processes.publishe

Immobilization of L-asparaginase towards surface-modified carbon nanotubes

L-asparaginase (ASNase, EC 3.5.1.1) is an enzyme that catalyzes L-asparagine hydrolysis into L-aspartic acid and ammonia and is mainly applied in pharmaceutical and food industries [1]. The ASNase currently commercialized for pharmaceutical purposes is produced from two main bacterial sources: recombinant Escherichia coli and Erwinia chrysanthemi. However, some disadvantages are associated with its free form, such as the shorter half-life [2]. Immobilization of ASNase has been proposed as an efficient approach to overcome this limitation [3]. In this work, a straightforward method, including the functionalization of multi-walled carbon nanotubes (MWCNTs) through a hydrothermal oxidation treatment with nitric acid, and the immobilization of ASNase by adsorption over pristine and modified MWCNTs was investigated. Different operation conditions, including pH, contact time, ASNase/MWCNT mass ratio, and the operational stability of the immobilized ASNase were evaluated. The characterization of the ASNase-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA), and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial ASNase above 95%, under the optimized adsorption conditions (pH 8, 60 min of contact and 1.5´10–3 g.mL-1of ASNase). The ASNase-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), proving its suitability for application in industrial processes.publishe

An Innovative Photoreactor, FluHelik, To Promote UVC/H2O2 Photochemical Reactions: Tertiary Treatment of an Urban Wastewater

This is the accepted manuscript of the following article: Espíndola et al. Science of the Total Environment, 2019, 667, 197-207. https://doi.org/10.1016/j.scitotenv.2019.02.335An innovative photoreactor, FluHelik, was used to promote the degradation of contaminants of emerging concern (CECs) by a photochemical UVC/H2O2 process. First, the system was optimized for the oxidation of a model antibiotic, oxytetracycline (OTC), using both ultrapure water (UPW) and a real urban wastewater (UWW) (collected after secondary treatment) as solution matrices. Following, the process was evaluated for the treatment of a UWW spiked with a mixture of OTC and 10 different pharmaceuticals established by the Swiss legislation at residual concentrations (∑CECs <660 μg L−1). The performance of the FluHelik reactor was analyzed both at lab and pre-pilot scale in multiple and single pass flow modes. The efficiency of the FluHelik photoreactor, at lab-scale, was evaluated at different operational conditions (H2O2 concentration, UVC lamp power (4, 6 and 11 W) and flow rate) and further compared with a conventional Jets photoreactor. Both photoreactors exhibited similar OTC removal efficiencies at the best conditions; however, the FluHelik reactor showed to be more efficient (1.3 times) in terms of mineralization when compared with the Jets reactor. Additionally, the efficiency of the UVC/H2O2 photochemical system using the FluHelik photoreactor in reducing the toxicity of the real effluent containing 11 pharmaceuticals was evaluated through zebrafish (Danio rerio) embryo toxicity bioassays. FluHelik scale-up from laboratory to pre-pilot to promote UVC/H2O2 photochemical process proved to be feasibleThis work was financially supported by: Associate Laboratory LSRE-LCM - UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC). V.J.P. Vilar acknowledges the FCT Investigator 2013 Programme (IF/00273/2013). J.C.A. Espíndola acknowledges CNPq (Brazil) for his scholarship (205781/2014-4). R. Montes, R. Rodil and J.B. Quintana acknowledge the financial support of Spanish "Agencia Estatal de Investigación" (ref. CTM2017-84763-C3-R-2) and Xunta de Galicia (ref. ED431C2017/36), both confounded by FEDER/ERDFS

Superior operational stability of immobilized L-asparaginase over surface-modified carbon nanotubes

L-asparaginase (ASNase, EC 3.5.1.1) is an enzyme that catalyzes the L-asparagine hydrolysis into L-aspartic acid and ammonia, being mainly applied in pharmaceutical and food industries. However, some disadvantages are associated with its free form, such as the ASNase short half-life, which may be overcome by enzyme immobilization. In this work, the immobilization of ASNase by adsorption over pristine and modified multi-walled carbon nanotubes (MWCNTs) was investigated, the latter corresponding to functionalized MWCNTs through a hydrothermal oxidation treatment. Different operating conditions, including pH, contact time and ASNase/MWCNT mass ratio, as well as the operational stability of the immobilized ASNase, were evaluated. For comparison purposes, data regarding the ASNase immobilization with pristine MWCNT was detailed. The characterization of the ASNase-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA) and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial ASNase above 95% under the optimized adsorption conditions (pH 8, 60 min of contact and 1.5 × 10-3 g mL-1 of ASNase). The ASNase-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), paving the way for its use in industrial processes.publishe