Eggshell waste as catalyst: A review Laca, Amanda; Laca, Adriana; Díaz, Mario
Journal of environmental management,
07/2017, Letnik:
197
Journal Article
Recenzirano
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.
Brain lipid homeostasis is an absolute requirement for proper functionality of nerve cells and neurological performance. Current evidence demonstrates that lipid alterations are linked to ...neurodegenerative diseases, especially Alzheimer’s disease (AD). The complexity of the brain lipidome and its metabolic regulation has hampered the identification of critical processes associated with the onset and progression of AD. While most experimental studies have focused on the effects of known factors on the development of pathological hallmarks in AD, e.g., amyloid deposition, tau protein and neurofibrillary tangles, neuroinflammation, etc., studies addressing the causative effects of lipid alterations remain largely unexplored. In the present study, we have used a multifactor approach combining diets containing different amounts of polyunsaturated fatty acids (PUFAs), estrogen availabilities, and genetic backgrounds, i.e., wild type (WT) and APP/PS1 (FAD), to analyze the lipid phenotype of the frontal cortex in middle-aged female mice. First, we observed that severe n-3 PUFA deficiency impacts the brain n-3 long-chain PUFA (LCPUFA) composition, yet it was notably mitigated by hepatic de novo synthesis. n-6 LCPUFAs, ether-linked fatty acids, and saturates were also changed by the dietary condition, but the extent of changes was dependent on the genetic background and hormonal condition. Likewise, brain cortex phospholipids were mostly modified by the genotype (FAD>WT) with nuanced effects from dietary treatment. Cholesterol (but not sterol esters) was modified by the genotype (WT>FAD) and dietary condition (higher in DHA-free conditions, especially in WT mice). However, the effects of estrogen treatment were mostly observed in relation to phospholipid remodeling in a genotype-dependent manner. Analyses of lipid-derived variables indicate that nerve cell membrane biophysics were significantly affected by the three factors, with lower membrane microviscosity (higher fluidity) values obtained for FAD animals. In conclusion, our multifactor analyses revealed that the genotype, diet, and estrogen status modulate the lipid phenotype of the frontal cortex, both as independent factors and through their interactions. Altogether, the outcomes point to potential strategies based on dietary and hormonal interventions aimed at stabilizing the brain cortex lipid composition in Alzheimer’s disease neuropathology.
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.
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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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