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•Graphene nanomaterials (pGr, GO, RGO, FLG and MLG) have a different fate in WWTPs.•pGr, FLG and MLG settle down more easily than RGO in the primary clarifier.•GO hinders the ...anaerobic denitrification, but improves the anaerobic NH4+ oxidation.•Various minerals can adsorb GFNs and improve the pretreatment/primary sedimentation.•GO and RGO favoured the formation of disinfection by-products (trihalomethanes).
The release of graphene and its derivatives in soil, air and water seems an inevitable consequence of the massive future use of these carbonaceous allotropes. From an environmental engineering point of view, it should be noted that part of the aqueous streams containing these nanomaterials will end up in wastewater treatment plants, and there will be interactions between the nanomaterials, the other pollutants in the sewage and the microorganisms of the secondary treatment, which could affect the effectiveness of the depuration process. The present work reviews the available literature on the behaviour of these nanoallotropes in wastewater treatment plants (a literature which is almost exclusively focused on graphene oxide and reduced graphene oxide), and also includes research dealing with simpler systems: i) graphene in purified water, ii) graphene in purified water with salt, and iii) graphene in purified water with organic matter and salt. It is probable that the fate of most of the graphene-family nanomaterials will be the primary/secondary sludge, and that a small portion (mainly in the form of graphene oxide) will pass to the tertiary treatment. Besides, graphene oxide has a negative effect on the biological treatment.
Thermal pre-treatments of activated sludge involve the release of a high amount of polymeric substances into the bulk medium. The molecular size of these polymers will largely define the subsequent ...biological treatment of the liquid effluent generated. In this work, the effects of wet oxidation treatment (WO) on the fingerprints of the polymeric substances which compose the activated sludge, were analysed. For a better understanding of these transformations, the sludge was separated into its main fractions: soluble microbial products (SMP), loosely bound extracellular polymeric substances (LB-EPS), tightly bound extracellular polymeric substances (TB-EPS) and naked cells, and then each one was subjected to WO separately (190 °C and 65 bar), determining the fingerprints evolution by size exclusion technique. Results revealed a fast degradation of larger molecules (over 500 kDa) during the first minutes of treatment (40 min). WO also increases the absorptive properties of proteins (especially for 30 kDa), which is possibly due to the hydroxylation of phenylalanine amino acids in their structure. WO of naked cells involved the formation of molecules between 23 and 190 kDa, which are related to the release of cytoplasmic polymers, and more hydrophobic polymers, probably from the cell membrane. The results allowed to establish a relationship between the location of polymeric material and its facility to become oxidised; thus, the more internal the polymeric material in the cell, the easier its oxidation.
When working directly with the raw sludge, hydrolysis mechanisms played a key role during the starting period. Once a high degree of solubilisation was reached, the molecules were rapidly oxidised into other compounds with refractory characteristics. The final effluent after WO showed almost 90% of low molecular weight solubilised substances (0–35 kDa).
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•High and fast degree of solubilisation initially, with polymers ranging 23–190 kDa.•Oxidation reactions have a screening effect on molecular size of polymers.•Final effluent: 90% of low molecular weight solubilized substances (<35 kDa).•Possible proteins modification by phenylalanine hydroxylation during wet oxidation.•Refractoriness to oxidation: SMP > LB-EPS > TB-EPS > naked cells.
Sewage sludge can be treated by anaerobic processes that frequently are followed by physical separation processes. In this work, a high-throughput sequencing technology, based on variation in the ...bacterial 16S rRNA gene, has been used to characterise the bacterial populations present in samples taken from different points of an industrial anaerobic digestion process fed with sewage sludge. Relative abundances of phyla and classes throughout the biological process and the subsequent separation steps were determined. Results revealed that the Bacteroidetes, Firmicutes and Proteobacteria phyla were the most representative. However, significant changes in relative abundance were detected along treatments, showing the influence of operational parameters on the distribution of microorganisms throughout the process. After anaerobic digestion, phylum Firmicutes doubled its relative abundance, which seems to indicate that the anaerobic conditions and the nutrients favoured its growth, in contrast to other phyla that almost disappeared. After centrifugation, Proteobacteria went preferentially to the solid phase, in contrast to Firmicutes which was the dominant phylum in the liquid phase. After decanting the liquid phase during 45 h, an important growth of Proteobacteria, Spirochaetes and Tenericutes was detected. At class level, only significantly changes were observed for Proteobacteria classes being α-proteobacteria dominant in the digestate, while γ-proteobacteria was the majority since this point to the final steps. To know the changes on the kind and abundance of microbial populations throughout the anaerobic and separation processes is very important to understand how the facilities design and operation conditions can influence over the efficiencies of next biological treatments.
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•Microbiota of the digested sewage sludge and subsequent processes was investigated.•Sequencing of the hypervariable regions of the 16S rRNA gene was performed by PGM.•Firmicutes, Proteobacteria and Bacteroidetes were the most representative phyla.•Firmicutes was the predominant phylum in the digestate after anaerobic digestion.•Decantation process had a significant influence on the distribution of the phyla.
The objective of the InMEDIATE study was to evaluate the change in intensity of traumatic pain over the first 20 min in adult patients treated with methoxyflurane versus standard analgesic treatment ...in Spain. This the first randomized, active-controlled, multicenter trial of methoxyflurane in the emergency setting in Europe.
This was a randomized, controlled study that enrolled adult patients with acute moderate to severe (score ≥4 on the 11-point Numeric Rating Scale) trauma-associated pain in 14 Spanish emergency departments. Patients were randomized 1:1 to methoxyflurane (up to 2×3 mL) or standard analgesic treatment. Coprimary endpoints were the change from baseline in Numeric Rating Scale pain intensity score during the first 20 minutes of treatment and time to first pain relief.
Three hundred five patients were randomized (methoxyflurane 156; standard analgesic treatment 149). Most patients in the standard analgesic treatment group (70%) received intravenous first-step analgesics and 9.4% of patients were treated with opioids. Mean decrease from baseline in Numeric Rating Scale pain intensity score was greater for methoxyflurane than standard analgesic treatment at all points, with a significant treatment difference overall up to 20 minutes (repeated-measures model 2.47 versus 1.39; treatment difference 1.00; 95% confidence interval 0.84 to 1.32). Median time to first pain relief was significantly shorter for methoxyflurane than standard analgesic treatment (3 versus 10 minutes). Methoxyflurane achieved better patient and clinician ratings for pain control and comfort of treatment than standard analgesic treatment and exceeded patient and clinician expectations of treatment in, respectively, 77% and 72% of cases compared with 38% and 19% for standard analgesic treatment.
These results support consideration of methoxyflurane as a nonnarcotic, easy-to-administer, rapid-acting, first-line alternative to currently available analgesic treatments for trauma pain.
Adequate treatment of trauma pain is an integral part of the management of trauma patients, not just for ethical reasons but also because undertreated pain can lead to increased morbidities and worse ...long-term outcomes. Trauma pain management presents challenges in the pre-hospital setting, particularly in adverse or hostile environments as well as in busy emergency departments (EDs). Inhaled methoxyflurane, administered at analgesic doses via a disposable inhaler, has recently become available in Europe for the emergency treatment of moderate to severe pain in conscious adult trauma patients. A growing body of evidence demonstrates that inhaled methoxyflurane is well tolerated and effective in providing a rapid onset of analgesia. In this paper, we discuss the rationale for methoxyflurane use in trauma pain management, data from clinical trials recently conducted in Europe, its efficacy and safety profile compared to current standard treatments, its place in therapy and organizational impact. We conclude that inhaled methoxyflurane represents an effective treatment option in the different settings where trauma patients require rapid and flexible pain resolution, with potential organizational advantages.
Los procesos de base física son fundamentales para las aplicaciones de la Biotecnología, en etapas como, por ejemplo, la preparación de los sustratos, la separación y purificación de los bioproductos ...o la transferencia de energía hacia o desde los biorreactores. Se discuten aquí los factores más importantes en el diseño de operaciones de base física en un proceso de tipo biotecnológico, se tratan las especificidades al trabajar con moléculas de base biológica, y se analiza cómo se enseña el diseño de operaciones básicas en los grados en Biotecnología de distintas universidades españolas.
Hydrothermal liquefaction of Kraft black liquor is a promising method for the production of valuable organic chemicals. However, the separation of the biochar and biocrude leaves a residual aqueous ...phase in large volumes, which needs to be properly managed to make the process profitable. In this work, the persulphate-based advanced oxidation was assessed, for the first time ever, as a pretreatment of this aqueous phase to reduce its content of phenolic compounds and alcohols, which hinder further valorisation strategies. Results revealed that the phenolic compounds and the alcohols were oxidised in presence of low persulphate anion concentrations (<50 mM), mainly to quinone-like compounds and organic acids. At higher oxidant concentrations, these intermediates were subsequently oxidised to valuable acetic acid. When Fe (II) was added as the catalyst, low concentrations (<9 mM) enhanced the degradation of both phenolic compounds and alcohols due to the increase of the sulphate radicals, consequently reducing persulphate requirements for their removal. Nevertheless, higher Fe (II) doses produced the sequestration of sulphate radicals, thus decreasing the oxidation performance and generating undesired parallel reactions.
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•Persulphate-based advanced oxidation reduced the toxicity of the stream.•≤ 50 mM S2O82−: oxidation of phenolics and alcohols to intermediates.•> 50 mM S2O82−: oxidation of intermediates to acetic acid.•≤ 9 mM Fe2+: enhancement of the degradation of phenolics and alcohols.•> 9 mM Fe2+: reduction of oxidation yield due to sulphate radicals sequestration.
Waste activated sludge (WAS) is the main residue of wastewater treatment plants, which can be considered an environmental problem of prime concern due to its increasing generation. In this study, a ...non-energetic approach was evaluated in order to use WAS as a renewable resource of high value-added products. For this reason, WAS was treated by thermal hydrolysis, H2O2 oxidation and advanced thermal hydrolysis (ATH) promoted by H2O2. The influence of temperature, H2O2 concentration and dosing strategy on biomolecule production (proteins and carbohydrates), size distribution (fingerprints) and various physico-chemical parameters (VSS, total and soluble COD, soluble TOC, pH and colour) was studied. The results revealed a synergistic effect between TH and H2O2 oxidation, which led to a significant increase in the production of both proteins and carbohydrates. In this sense, the concentration of proteins and carbohydrates obtained during TH at 85 °C for120 min was found to be 1376 ± 9 mg/L (121 mg/gVSSo) and 208 ± 4 mg/L (18 mg/gVSSo), respectively. However, in the presence of 4.5 mM H2O2/gVSSo under the same process conditions, the concentrations of proteins and carbohydrates exhibited a significant increase of 1.9-fold and 3.1-fold, respectively. Besides, the addition of H2O2 promoted the transformation of hydrophobic compounds, such as proteins and or lipids, into hydrophilic compounds, which presented low and medium sizes. An increase in temperature improved the solubilization rate and the yield of biomolecules significantly. Besides, the analysis of the kinetics related to the dosing strategy of H2O2 suggested the existence of two fractions during WAS solubilization, one of them being easily oxidizable, whereas the other one was more refractory to oxidation. Thus, the value of kH2O2 for the first addition of 1 mM H2O2/g VSSo was 0.020 L0.4 mgH2O2−0.4 min−1, while it was 4.3 and 8 times lower for the second and third additions, respectively.
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•Synergistic effect between thermal hydrolysis and H2O2 oxidation in WAS treatment.•Advanced thermal hydrolysis enhanced protein and carbohydrate solubilization.•H2O2 reduced hydrophobic compounds, increasing low and medium hydrophilic molecules.•Positive effect of temperature on VSS kinetic constant and biomolecule yield.•H2O2 dosing strategy suggested two WAS fractions: easily oxidizable and refractory.
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•Research on valorisation of Kraft black liquor for non-energy purposes is analysed.•Promising approaches, but shortly studied and not validated at industrial scale.•Due to the ...heterogeneity of the feedstock, integrated processes are being proposed.•Greener proposals include the use of wasted acid, green solvents or co-treatments.•Integration of chemical production into the conventional Kraft process is key.
Around 1.3 billion tonnes of weak Kraft black liquor is produced every year, and is usually concentrated by evaporation and burned to produce energy. Nevertheless, this strategy implies that many valuable compounds of great industrial interest are destroyed. This article compiles the available information about valorising Kraft black liquor by obtaining chemical products. Although this topic is arousing interest, more research is needed, as only processes which have not yet been validated at industrial scale are described, except for lignin recovery. Due to the heterogeneity of the raw material, complex and integrated processes are being proposed to extract different existing and/or generated compounds. The most common approach is a first stage of lignin recovery by precipitation, followed by the use of the delignified black liquor to obtain principally organic acids, and/or as a fermentation medium, recirculating the by-product streams into the Kraft process to recover the inorganic salts.
Advanced oxidation processes (AOPs) are gaining importance as an alternative to the biological or physicochemical treatments for the management of leachates. In this work, it has been studied the ...effect of the characteristics of the leachate (content in humic acids, landfill age and degree of stabilization) on the wet oxidation process and final quality of the treated effluent. A high concentration of humic acids in the leachate had a positive effect on the COD removal because this fraction is more easily oxidizable. Additionally, it has been demonstrated that the simultaneous presence of humic acid and the intermediates generated during the oxidation process improved the degradation of this acid, since such intermediates are stronger initiators of free radicals than the humic acid itself. Similar values of COD removals (49% and 51%) and biodegradability indices (0.30 and 0.35) were observed, after 8 h of wet oxidation, for the stabilised leachate (biologically pretreated) and the raw one, respectively. Nevertheless, final colour removal was much higher for the stabilised leachate, achieving values up to 91%, whereas for the raw one only 56% removal was attained for the same reaction time. Besides, wet oxidation treatment was more efficient for the young leachate than for the old one, with final COD conversions of 60% and 37%, respectively. Eventually, a triangular “three-lump” kinetic model, which considered direct oxidation to CO2 and partial oxidation through intermediate compounds, was here proposed.
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•High effect of leachate composition on the efficiency of wet oxidation treatment.•The humic fraction is more easily oxidizable than the rest of the leachate matrix.•The degree of backmixing is an important design variable in leachate wet oxidation.•Lower mineralization rates and removals were obtained in older leachates.•A lumped kinetic model considering total and partial COD oxidation was proposed.
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