Eggshell waste as catalyst: A review Laca, Amanda; Laca, Adriana; Díaz, Mario
Journal of environmental management,
07/2017, Letnik:
197
Journal Article
Recenzirano
Odprti dostop
Agricultural wastes are some of the most emerging problems in food industries because of their disposal cost. However, it is also an opportunity for the bioeconomy society if new uses for these ...residual materials can be found. Eggshells, considered a hazardous waste by UE regulations, are discarded, amounting hundreds of thousands of tonnes worldwide. This egg processing waste is a valuable source material, which can be used in different fields such as fodder or fertilizer production. Additionally, this residue offers interesting characteristics to be used in other applications, like its employment as an environment-friendly catalyst. In the present review we provide a global view of eggshell waste uses as catalyst in different processes. According to reviewed researching works, a huge variety of added value products can be obtained by using this catalyst which emphasised the interest of further investigations in order to widen the possible uses of this cheap green catalyst.
•Eggshell is produced at large amounts by egg processing industries.•This waste can be successfully employed as an environment-friendly catalyst.•A huge variety of added value products can be obtained by using this catalyst.•A global view of eggshell waste uses as catalyst in different processes is provided.
Microbial associations are frequent in traditional fermented foods and beverages, conferring upon them their characteristic organoleptic, physical and nutritional properties. Moreover, the search for ...novel products that satisfy the needs of consumers, especially foods with health-giving properties, means that new combinations of microorganisms are tested on a wide variety of substrates. In these microbial consortia, lactic acid bacteria (LAB) are frequently the major bacterial starters, usually combined with other species such as propionic and acetic acid bacteria and yeasts. The ability of LAB to produce a wide variety of metabolites is a determining factor in the establishment of associations with the interacting microbiota, which can be positive, negative or neutral. In liquid-phase fermentations, the control of these interactions represents a great challenge, due to the rapid rate of bioconversion and the direct liberation of the metabolites into the medium. Therefore, the understanding of the co-culture dynamics is of vital importance. The present review compiles data referring to the microbial consortia involving LAB, traditionally used to obtain artisanal products, as well as the new associations proposed and tested for the development of novel fermented liquid foods and beverages. The different types of interactions that have been found in these microbial consortia are discussed, including some mathematical models that have been proposed to simulate and control the development of fermentations. Some of the strategies, techniques and devices that are being developed and implemented to improve the efficiency of co-cultures are finally presented.
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•Mixed starter cultures are present in most traditional and novel food fermentations.•Lactic acid bacteria antimicrobials can control the development of mixed cultures.•Amensalism, competition, mutualism and commensalism can occur in microbial consortia.•Encapsulation and continuous inoculation increase stress tolerance in antagonism.•Sequential fermentation allows sensitive strains to develop their metabolism freely.
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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.
The Covid-19 lockdown reduced drastically human presence outdoors, providing an uncontrolled experiment for disentangling direct and indirect effects of human presence on animal fearfulness. We ...measured 18,494 flight initiation distances (FIDs, the distance at which individual animals fly away when approached by a human) from 1333 populations of 202 bird species taken in four European cities both before, during and after the lockdown. FIDs decreased during lockdown in rural habitats but increased in urban habitats, especially for singing birds. Height above ground increases during lockdown in non-singing birds only, and birds adjusted horizontal tolerance to approach according to height outside lockdown, in rural habitats and while not singing. Responses showed lagged effects after lockdown in urban but not in rural habitats. Differential responses to lockdown among habitats and between signing and non-singing birds were consistent with relaxation of direct disturbance effects on birds in rural habitats during lockdown, as well as with increased indirect fear effects mediated by predator release in cities. FIDs seemed to measure the balance of direct and indirect effects of humans on predations risk and food needs rather than direct effects of humans on fear.
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•Bird fear decreased during lockdown in rural habitats but increased in cities.•Height above ground increases during lockdown in non-singing birds.•Birds adjusted horizontal tolerance to height outside lockdown in rural habitats.•Lockdown responses lagged afterwards in urban but not in rural habitats.•Results indicated both direct and indirect effect of humans on bird fear.
Lactobionic acid has appeared on the commercial scene as a versatile polyhydroxy acid with numerous promising applications in the food, medicine, pharmaceutical, cosmetics and chemical industries. ...This high value-added bio-product has recently received growing attention as a bioactive compound, providing an excellent chemical platform for the synthesis of novel potentially biocompatible and biodegradable drug delivery vehicles. Recent advances in tissue engineering and nanomedicine have also underlined the increased importance of this organic acid as a key biofunctionalization agent. The growing commercial relevance of lactobionic acid has therefore prompted the development of novel systems for its biotechnological production that are both sustainable and efficient. The present review explores recent advances and studies related to lactobionic acid bio-production, whether through microbial or enzymatic approaches, highlighting the key bioprocessing conditions for enhanced bio-production. Detailed overviews of the current microbial cell factories as well as downstream processing methodologies for lactobionic acid production are also presented. Furthermore, the potential prospects and current applications of this polyhydroxy acid are also discussed, with an emphasis on the role of lactobionic acid as a key platform in the development of novel drugs, biomaterials, nanoparticles and biopolymer systems.
Feral cat colonies in cities improve the wellbeing of people who feed and care for them, but they can have negative effects on biodiversity due to the predatory behaviour of cats. We analyse the ...effect of the presence of the 1171 colonies of feral cats reported for the city of Madrid (Spain) on the flight escape distances (FIDs) of birds to approaching human observers under standardized conditions. Location of cat colonies was obtained from maps maintained by the city authorities. The FID is a behavioural trait that integrates effects on bird's fearfulness of exposure to predation, disturbance, and physiological and reproductive needs. Shorter flight distances are associated with less exposure to predators and disturbance and better access to food and mates. Shorter FIDs are also associated to higher abundances and more positive population trends, at least in Spain. Mean FIDs of 694 birds of 34 species measured in nine city areas in the spring of 2021 were 10% longer in zones with colonies of feral cats than in neighbouring paired zones without colonies but similar regarding other factors potentially affecting FIDs (i.e. urban landscape structure). Birds were 33% higher above ground in zones with colonies, with no significant effects of perching higher on bird fleeing behaviour. Cat colonies were therefore increasing the fearfulness of individual birds and, presumably, downgraded their population trends. Compromising bird conservation with wellness effects of cat colonies on citizens at the city scale will thus imply the maintenance of colony-free areas, especially for ground-foraging birds. In addition, provision of perches for its use as temporal refuges around colonies might reconcile positive and negative effects at local scales.
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•Feral cat colonies in cities have positive and negative effects on citizen’s wellbeing. Cats are major predators of birds.•Flight initiation distances (FIDs) to approaching human observers estimate bird fearfulness. FIDs are associated with bird population trends.•FIDs were 10% longer in city areas with colonies of feral cats than in neighbouring areas without colonies•Birds were 33% higher above ground in areas with colonies. Perch height did not influence fleeing behaviour.•Colony-free areas would reconcile bird conservation and cat caretaking. Provision of perches might also help.
Alzheimer's disease (AD) is a neurodegenerative disease caused by abnormal functioning of critical physiological processes in nerve cells and aberrant accumulation of protein aggregates in the brain. ...The initial cause remains elusive-the only unquestionable risk factor for the most frequent variant of the disease is age. Lipid rafts are microdomains present in nerve cell membranes and they are known to play a significant role in the generation of hallmark proteinopathies associated to AD, namely senile plaques, formed by aggregates of amyloid β peptides. Recent studies have demonstrated that human brain cortex lipid rafts are altered during early neuropathological phases of AD as defined by Braak and Braak staging. The lipid composition and physical properties of these domains appear altered even before clinical symptoms are detected. Here, we use a coarse grain molecular dynamics mathematical model to predict the dimensional evolution of these domains using the experimental data reported by our group in human frontal cortex. The model predicts significant size and frequency changes which are detectable at the earliest neuropathological stage (ADI/II) of Alzheimer's disease. Simulations reveal a lower number and a larger size in lipid rafts from ADV/VI, the most advanced stage of AD. Paralleling these changes, the predictions also indicate that non-rafts domains undergo simultaneous alterations in membrane peroxidability, which support a link between oxidative stress and AD progression. These synergistic changes in lipid rafts dimensions and non-rafts peroxidability are likely to become part of a positive feedback loop linked to an irreversible amyloid burden and neuronal death during the evolution of AD neuropathology.
Microbial production of organic acids has become a fast-moving field due to the increasing role of these compounds as platform chemicals. In recent years, the portfolio of specialty ...fermentation-derived carboxylic acids has increased considerably, including the production of glyceric, glucaric, succinic, butyric, xylonic, fumaric, malic, itaconic, lactobionic, propionic and adipic acid through innovative fermentation strategies. This review summarizes recent trends in the use of novel microbial platforms as well as renewable and waste materials for efficient and cost-effective bio-based production of emerging high-value organic acids. Advances in the development of robust and efficient microbial bioprocesses for producing carboxylic acids from low-cost feedstocks are also discussed. The industrial market scenario is also reviewed, including the latest information on the stage of development for producing these emerging bio-products via large-scale fermentation.
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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