537 research outputs found
Enhancing the environmental and economic sustainability of heterotrophic microalgae cultivation: Kinetic modelling and screening of alternative carbon sources
No full textHeterotrophic microalgae cultivation has been suggested to reduce conventional photo-autotrophic microalgal biomass production costs. In heterotrophic cultivation, the most relevant operational costs are constituted by the supply of pure substrates used as carbon source (e.g., glucose), and the high energy request for culture aeration. In addition, suboptimal conditions of temperature and pH reduce the algal productivity, further increasing production costs. In this work, an attempt was made to define more sustainable and cost-effective strategies for the heterotrophic cultivation of Chlorellaceae and Scenedesmaceae. Several by-products from a local confectionery industry were thus screened as alternative carbon sources. Manufacturing residues from peppermint and liquorice candies production allowed to achieve comparable maximum growth rates (1.44 d-1), biomass yields (0.33 g COD·g COD-1) and biomass productivities (370 mg COD·L-1·d-1) as those achieved using glucose. A preliminary economic evaluation showed that the operational costs could be lowered of up to 85.6% by substituting glucose with the selected industrial by-products. As for fermentation conditions, high growth rates could be maintained at relatively low dissolved oxygen (DO) concentrations, and in a large range of temperature and pH values. In addition, optimal temperatures (37.0 – 37.2°C), pH values (6.8 – 7.4), and DO concentrations (> 0.5 – 1 mg O2·L-1) were identified. On the overall, the study demonstrated the possibility of achieving the reduction of operational costs for heterotrophic microalgae cultivation, while implementing circular economy principles in the framework of resource recovery during the bioremediation of organic waste
Impact of Nannochloropsis gaditana diet on Sparus aurata metabolism by using an omics approach
No full textMicroalgae are recognised today as a promising functional feed and their inclusion in aquaculture feeding represents
a sustainable environment-friendly alternative. One of the more promising microalgae in terms of nutritional content
and easily integrable in biorefineries is Nannochloropsis gaditana. The main objective was to perform a metabolomic
untargeted profiling on Sparus aurata fillets to distinct following feeding trails performed: diet without microalgae
(Control) and four different diets with N. gaditana either with 5% raw microalgae or with 5% hydrolysed microalgae,
from inorganic nutrient or biorefinery. The fish fillets were analysed by liquid chromatography coupled with high-
resolution mass spectrometry (LC-HRMS, Q-Exactive – CD). Applying omics software, 320 molecules were identified.
The majority of recognized compounds belong to the class of amino acids and their metabolites, and products of
lipid metabolism. The presence of various lipids, products of glycolysis and pyruvate metabolism, principal mono/
oligosaccharides, nucleotides and nucleosides, and vitamins were confirmed as well. The content of some amino
acids and their metabolites revealed significant differences between experimental diets. Specifically, in the muscle of
fish fed with hydrolysed microalgae, there was an increase in essential amino acids: valine, methionine and arginine.
These compounds can be used as potential markers of higher nutritional quality of diets with hydrolysed microalgae.
The muscle of fish raised with the experimental diets also contains the highest amounts of glutathione and carnosine.
The incorporation of the microalgae in the fish diet had a significant and progressive impact on the fish metabolome
profile. The metabolites modulated by microalgae meal were involved in protein, lipids and energy metabolism. The
findings provide new insights into how the dietary food metabolome affects fish metabolism
Corrigendum to ‘Syncope in hypertrophic cardiomyopathy (part II): An expert consensus statement on the diagnosis and management’ [International Journal of Cardiology, 2023, 41:180–186] (International Journal of Cardiology (2023) 370 (330–337), (S0167527322016643), (10.1016/j.ijcard.2022.10.153))
No full textThe authors regret to inform the readers that affiliations for Gianfranco Parati were not properly identified. The current format of affiliations for all authors are as below: Michele Brignole a,*, Franco Cecchi a, Aris Anastasakis b, Lia Crotti a,c, Jean Claude Deharo d,e, Perry M. Elliott f, Artur Fedorowski g Juan Pablo Kaski h, Giuseppe Limongelli i, Martin S. Maron j, Iacopo Olivotto k, Steve R. Ommen l, Gianfranco Parati a,c, Win Shen m, Andrea Ungar n, Arthur Wilde o. a IRCCS Istituto Auxologico Italiano, Dept of Cardiology, Hospital S. Luca, Milan, Italy. b Unit of Inherited and Rare Cardiovascular Diseases, Onassis Cardiac Surgery Centre, Kallithea, Greece. c Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy. d Hopitaux de Marseille, Centre Hospitalier Universitaire La Timone, Service de Cardiologie, Marseille, France. e Aix Marseille Universitè, C2VN, Marseille, France. f Institute of Cardiological Sciences, University College London, UK. g Dept. of Cardiology, Karolinska University Hospital and Karolinska Institute, Stockholm, Sweden. h Institute of Cardiovascular Science, University College London and Great Ormond Street Hospital, London, UK. i Department of Translational Medical Sciences, University of Campania “Luigi VanvitellI”, AO Dei Colli-Monaldi Hospital, Naples, Italy. j HCM Center, Lahey Hospital and Medical Center, Burlington, MA, USA. k Meyer Children Hospital, Department of Experimental and Clinical Medicine, University of Florence, Italy. L Medicine, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA. m Mayo Clinic Arizona, Phoenix, AZ, USA. n Division of Geriatric and Intensive Care Medicine, Azienda Ospedaliero Universitaria Careggi, Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy. o Heart Centre, Department of Cardiology, Amsterdam Universitair Medische Centra, Amsterdam, location AMC, the Netherlands. The authors would like to apologise for any inconvenience caused. DOI of original article:
Biogas from mono- and co-digestion of microalgal biomass grown on piggery wastewater
No full textBiogas production has been suggested as a valid valorization solution for microalgal/bacteria biomass (MAB) grown on wastewater. The feasibility of utilizing MAB grown in an outdoor raceway fed on piggery wastewater for biogas production was assessed. Batch and continuous anaerobic tests were performed on the sole MAB and on a blend of MAB and carbonaceous substrates (deproteinated cheese whey and cellulose) to boost the carbon/nitrogen ratio. Results of batch biochemical CH4potential tests confirmed that the sole microalgal/bacteria biomass was poorly degradable (119 NmLmethane/gCOD) while blending it with deproteinated cheese whey or cellulose (80% of carbonaceous material and 20% of MAB, as chemical oxygen demand (COD)) had no synergistic effects on the CH4yield, although minimal improvements in the degradation kinetics were observed. Continuous anaerobic degradation tests at an organic loading rate of 1.5 gCOD/L-d, 35°C and 30 d of hydraulic retention time increased the overall CH4yield from 81 NmLmethane/gCOD(sole MAB) to 216 NmLmethane/gCOD(MAB and deproteinated cheese whey) and 122 NmLmethane/gCOD(MAB and cheese whey). However, data confirmed that no evident synergistic effects were observed
Microalgal Biostimulants and Biofertilisers in Crop Productions
No full textMicroalgae are attracting the interest of agrochemical industries and farmers, due to their biostimulant and biofertiliser properties. Microalgal biostimulants (MBS) and biofertilisers (MBF) might be used in crop production to increase agricultural sustainability. Biostimulants are products derived from organic material that, applied in small quantities, are able to stimulate the growth and development of several crops under both optimal and stressful conditions. Biofertilisers are products containing living microorganisms or natural substances that are able to improve chemical and biological soil properties, stimulating plant growth, and restoring soil fertility. This review is aimed at reporting developments in the processing of MBS and MBF, summarising the biologically-active compounds, and examining the researches supporting the use of MBS and MBF for managing productivity and abiotic stresses in crop productions. Microalgae are used in agriculture in different applications, such as amendment, foliar application, and seed priming. MBS and MBF might be applied as an alternative technique, or used in conjunction with synthetic fertilisers, crop protection products and plant growth regulators, generating multiple benefits, such as enhanced rooting, higher crop yields and quality and tolerance to drought and salt. Worldwide, MBS and MBF remain largely unexploited, such that this study highlights some of the current researches and future development priorities
LONG TERM EXPERIENCES IN USING MICROALGAE IN WASTEWATER TREATMENT UNDER SUBOPTIMAL CLIMATIC CONDITIONS
No full textEnvironmental deterioration, resource depletion and climate change are forcing the water industry to find cost-effective and low-energy solutions able to remove pollutants while recovering most of the resources contained in wastewater. In such challenge, microalgae-based technologies are promising as they rely on phototrophic microorganisms which remove nutrients (nitrogen and phosphorus) by assimilation, supply oxygen for the aerobic bacteria, therefore decreasing the energy demand of the plant and fix CO2 which could be provided by flue gases. Also, the microalgal biomass can be used for the recovery of resources such as energy, biofertilizers, feed, biopolymers, pigment, etc. In this study, a comprehensive evaluation of microalgal applications integrated into conventional engineered technologies such as municipal and agro-industrial wastewater treatment and biogas production is presented. Data were gathered during several projects (MICROGATE, IMAP, Polo delle MICROALGHE) with the aims of designing, implementing, and operating different configurations of microalgal based systems. The bioreactor park included bench (up to 1 L), laboratory (up to 10 L) and pilot scale raceway ponds (4-6 m2) and bubble columns (70 L). Their performance and efficiency were determined and monitored using a multidisciplinary approach consisting of well-established analytical methods, innovative tools assessing the photosynthetic efficiency, tailored respirometry protocols and advanced molecular methods. The biomass obtained was then chemically and microbiologically characterized for the definition of the best valorization pathway. Finally, all the information obtained were used for the development of mathematical models
Comparison of the performance and microbial community structure of two outdoor pilot-scale photobioreactors treating digestate
No full textThis study aimed at examining and comparing the nutrient removal efficiency, biomass productivity and microbial community structure of two outdoor pilot-scale photobioreactors, namely a bubble column and a raceway pond, treating the liquid fraction of an agricultural digestate. Bacterial and eukaryotic communities were characterized using a metabarcoding approach and quantitative PCR. The abundance, composition, diversity, and dynamics of the main microbes were then correlated to the environmental conditions and operational parameters of the reactors. Both photobioreactors were dominated either by Chlorella sp. or Scenedesmus sp. in function of temperature, irradiance and the nitrogen compounds derived by nitrification. Other species, such as Chlamydomonas and Planktochlorella, were sporadically present, demonstrating that they have more specific niche requirement. Pseudomonas sp. always dominated the bacterial community in both reactors, except in summertime, when a bloom of Calothrix occurred in the raceway pond. In autumn, the worsening of the climate conditions decreased the microalgal growth, promoting predation by Vorticella sp. The study highlights the factors influencing the structure and dynamics of the microbial consortia and which ecological mechanisms are driving the microbial shifts and the consequent reactor performance. On these bases, control strategies could be defined to optimize the management of the microalgal-based technologies
Digestate treatment with algae-bacteria consortia: A field pilot-scale experimentation in a sub-optimal climate area
No full textThis paper addresses the efficiency of a microalgae-based agricultural digestate treatment at pilot-scale in an outdoor raceway pond (880 L, pH-dependent CO2 dosage) and in a bubble column (74.5 L, air-bubbling). Specifically, nitrogen removal, evolution of the algae-bacteria consortium, and the actual process applicability in the Po Valley climate are discussed. The performance of the two reactors varied seasonally. The average algal productivity in the raceway was 32.4 ± 33.1 mg TSS·L−1·d−1 (8.2 ± 8.5 g TSS·m−2·d−1) while in the PBR it was 25.6 ± 26.8 mg TSS·L−1·d−1; the average nitrogen removal was 20 ± 29% (maximum 78%) and 22 ± 29% (maximum 71%) in the raceway and in the column, respectively. Nevertheless, nitrification had a key role as 61 ± 24% and 52 ± 32% of the nitrogen load was oxidized in the raceway and in the column, respectively
Piggery wastewater treatment with algae-bacteria consortia: Pilot-scale validation and techno-economic evaluation at farm level
No full textThe efficiency of an outdoor pilot-scale raceway pond treating the wastewaters generated by a large-scale piggery farm in Northern Italy was evaluated. The biomass productivity over 208 days of experimentation was 10.7 ± 6.5 g TSS·m-2·d-1, and ammoniacal nitrogen, orthophosphate, and COD average removal efficiencies were 90%, 90%, and 59%, respectively. Results were used to perform a comprehensive techno-economic analysis for integrating algae-based processes in farms of different sizes (100-10000 pigs). The amount of N disposed of on agricultural land could be reduced from 91% to 21%, increasing the fraction returned to the atmosphere from 2.4% to 63%, and the fraction in the biomass from 6.2% to 16%. For intensive farming, the release of 110 t N·ha-1·y-1 contained in the digestate could be avoided by including algae-bacteria processes. The biomass production cost was as low as 1.9 €·kg-1, while the cost for nitrogen removal was 4.3 €·kg N-1
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