Understanding sludge rheology and optimizing equipment performance is crucial for energy efficiency in wastewater treatment plants (WWTPs). This study examined sludge rheology after thermal hydrolysis pretreatment (THP) at 60, 80, and 120 ◦C for 2 h, followed by anaerobic digestion (AD) at 37 ◦C for 20 days, and assessed impacts on pump and agitator performance. Post-treatment, sludge showed reduced viscosity and improved flowability, indicated by changes in Herschel-Bulkley parameters, enhancing pump and agitator efficiency, particularly at 120 ◦C. These rheological improvements were correlated to the solubilization of sludge components after THP and solids reduction after AD, highlighting the interconnectedness of rheology and treatment outcomes. Despite high heat demands, an energy balance showed that THP scenarios, especially at 120 ◦C, had lower energy requirements for pumps and agitators, leading to energy savings without increased heat consumption. These findings underscore the influence of rheological changes in improving energy efficiency in WWTPs.
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This letter to the editor argues that the assumption of a single value for the acetate recovery factor in carbon-13 stable isotope research for different individuals, can lead to significant errors in the outcomes of substrate utilization measurements.
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Thermal disinfection is probably the oldest water treatment method ever used. Similarly to other disinfection processes, it targets the inactivation of pathogenic (micro)organisms present in water, wastewater and other media. In this work, a pilot-scale continuous-flow thermal disinfection system was investigated using highly contaminated hospital wastewater as influent without any pre-treatment step for turbidity removal. The results proved that the tested system can be used with influent turbidity as high as 100 NTU and still provide up to log 8 microbial inactivation. Further results have shown energy consumption comparable to other commercially available thermal disinfection systems and relatively low influence on the investigated physical–chemical parameters.
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Microbacterium aurum strain B8.A was isolated from the sludge of a potato starch-processing factory on the basis of its ability to use granular starch as carbon- and energy source. Extracellular enzymes hydrolyzing granular starch were detected in the growth medium of M. aurum B8.A, while the type strain M. aurum DSMZ 8600 produced very little amylase activity, and hence was unable to degrade granular starch. The strain B8.A extracellular enzyme fraction degraded wheat, tapioca and potato starch at 37 °C, well below the gelatinization temperature of these starches. Starch granules of potato were hydrolyzed more slowly than of wheat and tapioca, probably due to structural differences and/or surface area effects. Partial hydrolysis of starch granules by extracellular enzymes of strain B8.A resulted in large holes of irregular sizes in case of wheat and tapioca and many smaller pores of relatively homogeneous size in case of potato. The strain B8.A extracellular amylolytic system produced mainly maltotriose and maltose from both granular and soluble starch substrates; also, larger maltooligosaccharides were formed after growth of strain B8.A in rich medium. Zymogram analysis confirmed that a different set of amylolytic enzymes was present depending on the growth conditions of M. aurum B8.A. Some of these enzymes could be partly purified by binding to starch granules.
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This study evaluated the performance of anaerobic co-digestion of cow manure (CM) and sheep manure (SM) in both batch and continuous digesters at 37 °C. Synergistic effects of co-digesting CM and SM at varying volatile solids (VS) ratios (1:0, 0:1, 3:1, 1:1, 1:3) were observed in the batch experiment, with the most effective degradation of cellulose (56%) and hemicellulose (55%), and thus, the highest cumulative methane yield (210 mL/gVSadded) obtained at a CM:SM ratio of 1:3. Co-digesting CM and SM improved the hydrolysis, as evidenced by the cellulase brought by SM and the increases of cellulolytic bacteria Clostridium. Besides, co-digestion enhanced the acidogenesis and methanogenesis, reflected by the enrichment of syntrophic bacteria Candidatus Cloacimonas and hydrogenotrophic archaea Methanoculleus (Coenzyme-B sulfoethylthiotransferase). When testing continuous digestion, the methane yield increased from 146 mL/gVS/d (CM alone) to 179 mL/gVS/d (CM:SM at 1:1) at a constant organic loading rate (OLR) of 1g VS/L/d and a hydraulic retention time (HRT) of 25 days. Furthermore, the anaerobic digestion process was enhanced when the daily feed changed back to CM alone, reflected by the improved daily methane yield (159 mL/VS/d). These results provided insights into the improvement of methane production during the anaerobic digestion of animal manure.
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Penicillin acylase (PA) from Escherichia coli can catalyze the coupling of an acyl group to penicillin- and cephalosporin-derived beta-lactam nuclei, a conversion that can be used for the industrial synthesis of beta-lactam antibiotics. The modest synthetic properties of the wild-type enzyme make it desirable to engineer improved mutants. Analysis of the crystal structure of PA has shown that residues alphaR145 and alphaF146 undergo extensive repositioning upon binding of large ligands to the active site, suggesting that these residues may be good targets for mutagenesis aimed at improving the catalytic performance of PA. Therefore, site-saturation mutagenesis was performed on both positions and a complete set of all 38 variants was subjected to rapid HPLC screening for improved ampicillin synthesis. Not less than 33 mutants showed improved synthesis, indicating the importance of the mutated residues in PA-catalyzed acyl transfer kinetics. In several mutants at low substrate concentrations, the maximum level of ampicillin production was increased up to 1.5-fold, and the ratio of the synthetic rate over the hydrolytic rate was increased 5-15-fold. Moreover, due to increased tendency of the acyl-enzyme intermediate to react with beta-lactam nucleophile instead of water, mutants alphaR145G, alphaR145S and alphaR145L demonstrated an enhanced synthetic yield over wild-type PA at high substrate concentrations. This was accompanied by an increased conversion of 6-APA to ampicillin as well as a decreased undesirable hydrolysis of the acyl donor. Therefore, these mutants are interesting candidates for the enzymatic production of semi-synthetic beta-lactam antibiotics.
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A bioaugmentation approach was used to enhance the performance of anaerobic digestion (AD) using cow manure (CM) as the substrate in a continuous system. To obtain the desirable microbial culture for bioaugmentation, a biochemical methane potential test (BMP) was used to evaluate three commonly used inocula namely (1) municipal solid waste (MSW), (2) wastewater treatment plant (WWTP), and (3) cow manure digester (CMMD) for their hydrolytic capacity. The highest lignocellulose removal (56% for cellulose and 50% for hemicellulose) and the most profusion of cellulolytic bacteria were obtained when CM was inoculated with CMMD. CMMD was thus used as the seed inoculum in a continuously operated reactor (Ra) with the fiber fraction of CM as the substrate to further enrich cellulolytic microbes. After 100 days (HRT: 30 days), the Bacteria fraction mainly contained Ruminofilibacter, norank_o_SBR1031, Treponema, Acetivibrio. Surprisingly, the Archaea fraction contained 97% ‘cellulolytic archaea’ norank_c_Bathyarchaeia (Phylum Bathyarchaeota). This enriched consortium was used in the bioaugmentation experiment. A positive effect of bioaugmentation was verified, with a substantial daily methane yield (DMY) enhancement (24.3%) obtained in the bioaugmented reactor (Rb) (179 mL CH4/gVS/d) than that of the control reactor (Rc) (144 mL CH4/gVS/d) (P < 0.05). Meanwhile, the effluent of Rb enjoyed an improved cellulose reduction (14.7%) than that of Rc, whereas the amount of hemicellulose remained similar in both reactors' effluent. When bioaugmentation stopped, its influence on the hydrolysis and methanogenesis sustained, reflected by an improved DMY (160 mL CH4/gVS/d) and lower cellulose content (53 mg/g TS) in Rb than those in Rc (DMY 144 mL/CH4/gVS/d and cellulose content 63 mg/g TS, respectively). The increased DMY of the continuous reactor seeded with a specifically enriched consortium able to degrade the fiber fraction in CM shows the feasibility of applying bioaugmentation in AD of CM.
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Using either freshly pulped or preserved seaweed biomass for the extraction of protein can have a great effect on the amount of protein that can be extracted. In this study, the effect of four preservation techniques (frozen, freeze-dried, and air-dried at 40 and 70 °C) on the protein extractability, measured as Kjeldahl nitrogen, of four seaweed species, Chondrus crispus (Rhodophyceae), Ascophyllum nodosum, Saccharina latissima (both Phaeophyceae) and Ulva lactuca (Chlorophyceae), was tested and compared with extracting freshly pulped biomass. The effect of preservation is species dependent: in all four seaweed species, a differenttreatment resulted in the highest protein extractability. The pellet (i.e., the non-dissolved biomass after extraction) was also analyzed as in most cases the largest part of the initial protein ended up in the pellet and not in the supernatant. Of the four species tested, freeze-dried A. nodosum yielded the highest overall protein extractability of 59.6% with a significantly increased protein content compared with the sample before extraction. For C. crispus extracting biomass air-dried at 40 °C gave the best results with a protein extractability of 50.4%. Preservation had little effect on the protein extraction for S. latissima; only air-drying at 70 °C decreased the yield significantly. Over 70% of the initial protein ended up in the pellet for all U. lactuca extractions while increasing the protein content significantly. Extracting freshly pulped U. lactuca resulted in a 78% increase in protein content in the pellet while still containing 84.5% of the total initial total protein. These results show the importance of the right choice when selecting a preservation method and seaweed species for protein extraction. Besides the extracted protein fraction, the remainingpellet also has the potential as a source with an increased protein content.
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From the publisher: "Background: The introduction of whole new foods in a population may lead to sensitization and food allergy. This constitutes a potential public health problem and a challenge to risk assessors and managers as the existing understanding of the pathophysiological processes and the currently available biological tools for prediction of the risk for food allergy development and the severity of the reaction are not sufficient. There is a substantial body of in vivo and in vitro data describing molecular and cellular events potentially involved in food sensitization. However, these events have not been organized in a sequence of related events that is plausible to result in sensitization, and useful to challenge current hypotheses. The aim of this manuscript was to collect and structure the current mechanistic understanding of sensitization induction to food proteins by applying the concept of adverse outcome pathway (AOP). Main body: The proposed AOP for food sensitization is based on information on molecular and cellular mechanisms and pathways evidenced to be involved in sensitization by food and food proteins and uses the AOPs for chemical skin sensitization and respiratory sensitization induction as templates. Available mechanistic data on protein respiratory sensitization were included to fill out gaps in the understanding of how proteins may affect cells, cell-cell interactions and tissue homeostasis. Analysis revealed several key events (KE) and biomarkers that may have potential use in testing and assessment of proteins for their sensitizing potential. Conclusion: The application of the AOP concept to structure mechanistic in vivo and in vitro knowledge has made it possible to identify a number of methods, each addressing a specific KE, that provide information about the food allergenic potential of new proteins. When applied in the context of an integrated strategy these methods may reduce, if not replace, current animal testing approaches. The proposed AOP will be shared at the www.aopwiki.org platform to expand the mechanistic data, improve the confidence in each of the proposed KE and key event relations (KERs), and allow for the identification of new, or refinement of established KE and KERs." Authors: Jolanda H. M. van BilsenEmail author, Edyta Sienkiewicz-Szłapka, Daniel Lozano-Ojalvo, Linette E. M. Willemsen, Celia M. Antunes, Elena Molina, Joost J. Smit, Barbara Wróblewska, Harry J. Wichers, Edward F. Knol, Gregory S. Ladics, Raymond H. H. Pieters, Sandra Denery-Papini, Yvonne M. Vissers, Simona L. Bavaro, Colette Larré, Kitty C. M. Verhoeckx and Erwin L. Roggen
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Using the reversed phase high performance liquid chromatography with diode-array and massspectrometric (in ESI mode) detection, a composition of Catharanthus roseum petals was established. After the acid hydrolysis, all five anthocyanidins were found to be different comparing to the ordinary anthocyanidins from Vitis vinifera fruits. The anthocyanins were elucidated to be 7-O-methyl derivatives of delphinidin, cyanidin, petunidin, peonidin and malvidin by the analysis of retention in RP HPLC, mass- and UV-visible spectra.The anthocyanins were characterized with UV-visible spectra, having the same fixtures as the set of nonmethylated (in position 7) anthocyanin with hypsochromic (4 nm) of spectral maxima. The absorption bands for 7-methylcyanidin and 7-methylpeonidin aglycons and derivatives were indistinguishable while for the set of 7-methydelphinidin, 7-methypetunidin and 7-methylmalvidine (hirsutidin) a consecutive shift of absorption maximaby approximately 1 – 1.5 nm was found. The same was true for non-methylates at position 7 derivatives. The analysis of retention of anthocyanins of the flowers including the comparison with the retention of Mangifera indica skin anthocyanins, mass- and UV-visible spectra indicated that a minor set of anthocyanins included two sets of derivatives. The minor compounds were found to be 3-galactosides for samples under investigation, while the set of the major anthocyanins was represented by 3-rhamnosylgalactosides. Indeed, though through mass-spectra it was not possible to differentiate 3-rhamnosylgalatosides and 3-(p-coumaroylgalactosides) because of m/z coincidence, the retention difference between the two found anthocyanins sets as well as UV-visible spectra excluded the latter type of derivatives.
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