1,720,980 research outputs found
Decay of ozone in water : a review
No full textScientific publications on ozone decay kinetics in water report very wide result variations, depending on a multiplicity of factors, such as ozone concentration, pH, temperature, alkalinity, fluid-dynamic conditions, presence of UV radiations, and concentration of organic and inorganic carbon. This paper intends to provide an engineering-oriented review that summarizes and compares the main results reported in the recent literature so that the condensed information can guide the reader in getting operational indications to assist applications and research
The evolution of LCA in milk production
No full textThe comparison among different LCA studies is challenging. Analyzing 29 original articles selected among LCAs related to milk production, we evaluated their level of harmonization and the uniformation to the major standards currently available for the milk sector
A critical review of the recent evolution of Life Cycle Assessment applied to milk production
No full textLife Cycle Assessment (LCA) is one of the key tools for the evaluation of the environmental sustainability of the agricultural sector. LCA related to milk production has gained attention in recent years, but the results are often discordant and conditioned by the practitioners’ choices. This has made it difficult to clearly identify the most environmentally friendly way to produce milk. In the present paper, 44 milk LCA studies published after 2009 are reviewed, in order to evaluate the level of harmonization and comparability of methods and results, and to discuss emerging issues and hot topics that would be worth further investigation. Furthermore, the effects that the choice of functional unit and allocation rule could have on the results were statistically analyzed. The understanding of the current research direction of milk-LCA studies is useful to promote a more responsible and sustainable livestock production in the perspective of increasing animal protein demand. This review highlighted the difficulties encountered in comparing milk LCA studies, underlining the importance of practitioners’ choices in determining the results. Harmonization among LCA studies applied to the milk sector still represents a goal to be achieved. It appeared that future LCAs should investigate a broad range of impact categories, including biodiversity and water consumption; define one or more common functional units; improve transparency, giving a detailed description of system boundaries and reporting the method used for impact calculation; and systematically conduct a sensitivity analysis for a better understanding of the effects of the choices of method
Removal kinetics of copper from water by poliamidoamine hydrogels
No full textThe need for innovative and specific water treatment technologies explain the present study on a family of novel polyamidoamine (PAA) hydrogels and their effectiveness on the removal from water of inorganic contaminants. Batch kinetic tests were carried out in order to define the rate of the removal process and the factors affecting the reaction rate. Two samples of hydrogels, which differ for functional groups, were tested at three different solid/liquid ratios (1/150-1/300-1/600 g/mL) and in two different forms (powder -d<1mm- and grains -1mm<d<2mm-). The removal process was found to follow a saturation kinetic model and a comparison between the results obtained for the two different particle size enabled to define the influence of layer and pore diffusion on the overall rate of the process. As a function of experimental boundary conditions, equilibrium contact time ranged from 2 to 48 hours and copper uptake from 0.27±0.01 to 1.00±0.07 mgCu/gPAA, hence highlighting a strong dependence of the removal ability of PAA hydrogels on operating factors. A physical interpretation of the particle system is proposed and results point out the need for a deeper comprehension of the mechanisms of interaction between PAA hydrogels and water constituents (pH, complexes formation)
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