Towards the Assessment of an Ecological Index for Quantifying Sustainability of Day Life. A Case Study of the Environmental Consequences of Dietary and Transport in a Standard Workday

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Carbon monoxide fermentation to bioplastic: the effect of substrate adaptation on Rhodospirillum rubrum

AbstractRhodospirillum rubrum is a gram-negative bacterium that naturally takes advantage of CO and which, in the presence of acetate, accumulates carbon and energy units as polyhydroxybutyrate (PHB). Since the conversion of CO depends on a large protein membrane complex that is expressed after the exposure to carbon monoxide, this study presents the effects of a CO-based acclimation in R. rubrum on the growth trend and on the production of PHB. The strain was cultured in two consecutive fermentation cycles on 15% of CO, and the behaviour of this species, in the presence of acetate or a reducing sugar, such as fructose, was compared. The exposure of R. rubrum to CO during the first adaptation phase led to the development of a metabolically active population characterised by a greater biomass growth. The supply of fructose ensured a shorter lag-phase and a higher biomass titre, but it also determined a decrease in the biopolymer accumulation. However, R. rubrum showed the best carbon utilisation in the absence of fructose, with a growth molar yield of 48 mg mol−1, compared to the 12 mg mol−1 obtained for fructose feeding

Thermodynamic optimisation of the biofuel production based on mutualism

Recently, we have introduced a new bioeconomic indicator in order to avoid the difficulties in evaluating the process and technologies for sustainability. In this paper, we wish to improve this new indicator for the analysis of sustainability. Indeed, the indicator has been based on the exergy analysis of dissipation and irreversibility, and it was proven in some social and technical application. In this work, a more general definition has been introduced in order to use it in any evaluation of sustainability. In particular, it has been applied to improve the biofuel production obtained by microorganisms, starting from the biophysical behaviour of the microorganisms themselves. Indeed, in industrialised countries, the management of CO2emissions represents one of the present compelling issues. In this context, the improvement of the energy efficiency, and its rational use, can be considered a fundamental economic strategy for the sustainable development of the industrialised countries. Our indicator takes into account all these requests for the development and sustainability, resulting a very interesting thermoeconomic quantity to be used by decision makers. Moreover, it is used to prove that mutualism can represent a new approach for the optimisation of biofuels production

Biofuels from abandoned mines: A starting point for future developments

Abandoned mines and quarries represent sites with the request of restoration due to their pollution. On the other hand, biofuels represent a response to the present request of sustainable energy, in order to reduce the CO2 emission, in transportation, but also in energy production and domestic use. However, biofuels production seldom requires lands for the biomass cultivation. In this paper, the use of the dismissed mines and quarries is suggested for the cultivation of algae, as biomass production. To support this approach, a theoretical numerical evaluation of a typical dismissed quarry is developed in order to highlight the feasibility of the approach itself

A short review of green extraction technologies for rice bran oil

Rice is one of the most important crops throughout the world, as it contributes toward satisfying the food demand of much of the global population. It is well-known that rice production generates a considerable number of by-products, among which rice bran deserves particular attention. This by-product is exceptionally rich in nutrients, since it contains a wide spectrum of macronutrients (proteins, fats, carbohydrates) as well as dietary fibers and bioactive compounds. However, rice bran is usually wasted or just used for the production of low-cost products. The lipidic fraction of rice bran contains an unsaponifiable fraction that is rich in such functional components as tocopherols, γ-oryzanol, tocotrienols and phytosterols. This lipidic fraction can be extracted to obtain rice bran oil (RBO), a high value-added product with unique health properties as a result of its high concentration in γ-oryzanol, a powerful antioxidant mixture of bioactive molecules. Conventional extraction methods employ hexane as the solvent, but these methods suffer from some drawbacks linked to the toxicity of hexane for humans and the environment. The aim of the review presented herein is to point out the new green technologies currently applied for the extraction of RBO, by highlighting reliable alternatives to conventional solvent extraction methods that are in line with the twelve principles of green chemistry and a circular economy

Catalysis in Diesel engine NOx aftertreatment: a review

AbstractThe catalytic reduction of nitrogen oxides (NOx) under lean-burn conditions represents an important target in catalysis research. The most relevant catalytic NOx abatement systems for Diesel engine vehicles are summarized in this short review, with focus on the main catalytic aspects and materials. Five aftertreatment technologies for Diesel NOx are reviewed: (i) direct catalytic decomposition; (ii) catalytic reduction; (iii) NOx traps; (iv) plasma-assisted abatement; and (v) NOx reduction combined with soot combustion. The different factors that can affect catalytic activity are addressed for each approach (e.g. promoting or poisoning elements, operating conditions, etc.). In the field of catalytic strategies, the simultaneous removal of soot and NOx using multifunctional catalysts, is at present one of the most interesting challenges for the automotive industry

A review on the catalytic combustion of soot in Diesel particulate filters for automotive applications: From powder catalysts to structured reactors

Abstract The current soot oxidation catalyst scenario has been reviewed, the main factors that affect the activity of powder catalysts have been highlighted and kinetic soot oxidation models have been examined. A critical review of recent advances in modelling approaches has also been presented in this work. The multiscale nature of DPFs lends itself to a hierarchical organization of models, over various orders of magnitude. Different observation scales (e.g., wall, channel, entire filter) have often been addressed with separate modelling approaches that are rarely connected to one another, mainly because of computational difficulties. Nevertheless, DPFs exhibit an intrinsic multi-scale complexity that is reflected by a trade-off between fine and large-scale phenomena. Consequently, the catalytic behavior of DPFs usually results in a non-linear combination of multi-scale phenomena