1,720,960 research outputs found
Rice waste streams as a promising source of biofuels: feedstocks, biotechnologies and future perspectives
Full text linkIncreased environmental concern over climate change due to higher oil usage has made human being to shift to cleaner and greener alternatives. The utilization of abundant agricultural waste streams as renewable feedstock for biofuels production can be a pivotal strategy. Among others, rice is one of the most largely grown crops, and more than 4.8% of the total production goes to waste. Although previous reviews are related to biofuels obtained from some rice waste, most of those are focused on lignocellulosic rice residues with much attention to thermo-chemical processes. The present paper, instead, reviews for the first time the biotechnological approaches to convert all rice wastes, like rice husk, rice straw, broken rice, discolored rice, unripe rice, into liquid (bioethanol, biobutanol, biodiesel), and gaseous (biogas, biohydrogen) biofuels through the use of pure or mixed microbial cultures. The global availability of each rice byproduct has been also investigated and the potential of rice waste as a ‘fuel farm’ has been estimated for bioethanol. The physical, chemical, enzymatic, or microbial pretreatments, which play a key role in making carbon available for hydrolysis and fermentation, are here discussed and evaluated. Despite the great promise of technologies so far developed, further research is still required for their up-scale and industrial commercialization. Moreover, future process integrations will open the landscape to biorefinery schemes where rice waste streams can be processed into biofuels and other added-value products, towards the full exploitation of the feedstocks and the economic and environmental sustainability of the overall process
Efficient production of hydrogen through bioaugmentation of the organic fraction of municipal solid waste by the newly isolated Clostridium sartagoforme SA1
No full textBio-hydrogen from organic waste holds promise as renewable energy. However, its large-scale production is limited by technical challenges, with low H2 yields and the absence of robust microbial strains being the major ones. To address these limitations, H2-producing microbes have been isolated from a full-scale anaerobic digestor treating complex organic waste. Clostridium sartagoforme SA1 was selected because of high H2 yields from glucose, soluble starch, and carboxymethylcellulose. The strain was then tested for H2 production from the Organic Fraction of Municipal Solid Waste (OFMSW), rich in starch and cellulose, with productions up to 55 mLH2 g/VS. Additionally, C. sartagoforme SA1 confirmed high H2 performances even in the presence of OFMSW's indigenous microflora, increasing the H2 yield by 38 % and highlighting its robustness in a highly competitive environment. This is the first report describing the efficient adoption of a C. sartagoforme strain for bioaugmentation of non-sterile OFMSW towards high H2 yields
Valorization of prosecco wine lees for sustainable polyhydroxyalkanoates production by Cupriavidus necator DSM 545 and Hydrogenophaga pseudoflava DSM 1034
No full textNowadays, in the agricultural and agro-industrial sectors, there is increasing attention on the wine industry. The environmental impact of wine production, particularly in terms of residues generation, is a growing concern. Among generated residues, wine lees, rich in organic matter, phenols compounds, and with low pH, pose environmental challenges due to their disposal requirements. Despite their usage for biogas production and extraction of compounds, such as antioxidants, tartaric acid and ethanol, their potential in bioplastic production, specifically polyhydroxyalkanoates (PHAs), remains largely untapped. This study aims to evaluate the potential use of wine lees as a medium sustaining bacterial growth and PHAs accumulation. Specifically, Cupriavidus necator DSM 545 and Hydrogenophaga pseudoflava DSM 1034, were cultivated in the liquid phase of wine lees obtained from the Prosecco winemaking. On pure distilled wine lees, after mild feedstock pre-treatments, C. necator DSM 545 reached a CDW (cell dry weight) of 2.97 g/L and accumulated PHAs was 1.27 g/L, pair to 42.90 % of CDW. On the same substrate, CDW for H. pseudoflava DSM 1034 was 3.96 g/L and PHAs reached values of 1.60 g/L and 40.42 % CDW. These results obtained on wine lees are similar or even better than those achieved in the control growths of the two strains on pure glucose. This is the first approach for the utilization of wine lees for PHAs production, highlighting their potential use in the PHAs industry, and offering a sustainable alternative for both residues management and bioplastic production
Coupling biogas upgrading with biopolymers accumulation through cyanobacteria CO2fixation
No full textBiogas, primarily composed of carbon dioxide (CO2) and methane, requires upgrading to biomethane by removing the CO2 to improve its usability, making it suitable for direct injection into gas grid and serving as a renewable alternative to fossil-derived methane. This study investigates the potential of the recently isolated cyanobacterial strain Synechocystis sp. B12, selected for its robustness and tolerance to high light intensity, in biogas upgrading. Synechocystis sp. B12 demonstrated exceptional tolerance to high CO2 concentrations as in the biogas, utilising it for photosynthetic growth without any detrimental effects from CH4 or other contaminants. This establishes it as a promising candidate for biogas upgrading applications. The strain successfully fixed over 99 % of the CO2 present both in synthetic gas mixture and industrial biogas. Moreover, Synechocystis sp. B12 converted the captured CO2 into polyhydroxybutyrate, a biodegradable bioplastic compound, achieving productivities of approximately 80 mg L-1. This approach provides the dual advantage of enhancing biogas quality while simultaneously transforming CO2 into valuable bioproducts
Harnessing the potential of Cupriavidus necator for CO2 capture from alcoholic fermentation and its bioconversion into poly(3-hydroxybutyrate)
Full text linkThe fermentation process in alcoholic beverage production converts sugars into ethanol and CO2, releasing significant amounts of greenhouse gases. Here, Cupriavidus necator DSM 545 was grown autotrophically using gas derived from alcoholic fermentation, using a fed-batch bottle system. Nutrient starvation was applied to induce intracellular accumulation of poly(3-hydroxybutyrate) (PHB), a bioplastic polymer, for bioconversion of CO2rich waste gas into PHB. Grape marc, another by-product of wine production, was evaluated as a low-cost carbon source for the heterotrophic growth of C. necator, which was subsequently used as an inoculum for autotrophic cultures. The effect of agitation, CO2 headspace composition, and nitrogen concentration was tested, obtaining a maximum PHB concentration of 0.69 g/L, with an average CO2 uptake rate of 1.14 +/- 0.41 mmol CO2 L-1h- 1 and 65 % efficiency of CO2 consumption. These findings lay the groundwork for developing carbon mitigation strategies in alcoholic fermentation processes coupled with sustainable biopolymer production
Efficient production of biohydrogen from African lignocellulosic residues
Full text linkBiohydrogen by dark fermentation using organic wastes is a promising technology towards energy transition and green economy. Unfortunately, H2 production is still limited as several parameters must be finely tuned. This study aims at the development of an efficient process to convert African lignocellulosic residues into H2. An alkaline H2O2 pre-treatment of coffee and pineapple skins, which are hugely produced as waste in many African countries, has been developed. The goal was to get simple sugars, under mild conditions, to foster H2 production. Once pre-treated, the feedstocks were converted by a heat-treated inoculum into H2 at two pH values (5.5 and 6.0). The results indicate that coffee and pineapple skins were efficiently transformed into H2 (up to 47.99 and 91.80 mL/gVS, respectively) at an optimal pH of 6 with a concentration of 1.25 % H2O2. These results proved that H2O2 pre-treatment and the fine tuning of pH can be the key drivers to boost H2 production of lignocellulosic matrices. This combined approach performed successfully and stands for a promising way towards the optimization of the H2-producing processing from waste streams also in African countries. This will contribute to the United Nation (UN)’s ‘Agenda 2030’ for green energy and sustainable economic growth
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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