301 research outputs found
Corso di Greco. Lingua e Civiltà. Lezioni 1 e Lezioni 2
No full textMateriali operativi per il Corso di Greco. Lingua e Civilta
Corso di Greco. Lingua e civiltà. Grammatica ( completata da una Guida per l'insegnante)
No full textL'impostazione del manuale è guidata dall'intento di coniugare due esigenze fondamentali: la scelta di privilegiare la tradizionale presentazione sistematica degli argomenti e l'intenzione di stabilire un contatto precoce e costante con il greco autentico, vale a dire con il testo degli autori. Un'attenzione particolare è rivolta al lessico e alla necessità della sua memorizzazione, attraverso una serie di interventi operativi orientati in una direzione produttiva e al tempo stesso economica
Guida per l'insegnante al Corso di Greco
No full textLinee metodologiche riferite al testo principale. Materiali didattici suppluementari per il docente
Olive mill wastewater degradation in soil
No full textOlive mill wastewater (OMW) is a by-product of olive processing for oil production. It consists of water initially present in the drupae (vegetation water), process water (added to improve oil separation during milling), and washing water of olives and milling plants. Olive milling causes a huge production of OMW: about 0.4-1.1 m3 of OMW are produced per 1000 kg of olives. This production takes place in a short time due to seasonal olive availability. Such large amounts cannot be disposed without any treatment in sewers or rivers because of the high COD (50000-200000 mg/L) and polyphenol content. Since the ’80s, different physico-chemical and biological treatments have been studied. Due to the high related costs, such treatments did not achieve wide diffusion except for demonstrative pilot plants. In Italy, the traditional solution of spreading OMW onto the soil continues to be applied according to the current regulation. In the case of OMW spreading onto agricultural soils, the high COD could be exploited to increase the organic fraction of poor soils. However, the phytotoxic and antimicrobial activity of OMW negatively affects such reuse. OMW toxicity has been ascribed mainly to the high polyphenol content (1.2-2.4%). Spontaneous remediation was observed with the spreading of moderate OMW amount onto the agricultural soil, probably due to reactions catalyzed by abiotic and biotic soil components. Indeed, the clay fraction of the soil generally contains iron and manganese oxides and adsorbs polyphenoloxidases contained in plants and fungi exudates. If too large amounts of OMW are spread on the soil, the natural remediation can be insufficient: the soil health is affected and OMW percolates down to the aquifer. In any case, the effects of prolonged OMW spreading on soil health are unknown, at the moment. In order to take full advantage of the OMW fertirrigating potential by preventing at the same time aquifer pollution, it would be interesting to develop a treatment that removes the polyphenols selectively, leaving unchanged the organic and salt content of the OMW. In this work, we propose to use the clay fraction of the agricultural soil as a catalyst for the reaction of humification of the polyphenols. The reaction would be carried out in a soil-OMW slurry in an aerated, stirred reactor to ensure optimal conditions for the oxidation reaction catalyzed by iron and manganese oxides and by polyphenoloxidases. The scope is a substantial reduction of free polyphenols concentration in the OMW without reducing the total organic load. Such a treatment, if effective, would combine simplicity and economy of realization by exploiting reagents and catalysts available in situ. The feasibility of polyphenol removal in soil has been assessed by experiments with model polyphenolic compounds and real OMW samples. Full conversion of low molecular polyphenols has been found in both cases. Experiments with model compounds have shown that the reaction is started by a preliminary oxidation by iron and manganese oxides and proceeds by further oxidation of intermediates by dissolved molecular oxygen. Final products are water-insoluble polymers. The treatment efficacy has been evaluated by the degree of polymerization of the polyphenols and by the reduction of phyto- and micro-toxicity. It has been found that phytotoxicity removal is marked with model polyphenols and only marginal with entire OMW. Therefore, in contrast with the common tenet, polyphenols do not seem to be the main cause of phytotoxicity in OMW
Olive mill wastewater: a source of microbial- and phyto-toxicity for soil.
No full textOMW are high phenolic content wastewaters produced during olive milling. In Mediterranean countries, where olive oil production is widespread, disposal of OMW is a serious problem because of their anti-microbial activity and phytotoxicity. Usually, OMWW are spread onto the soil and this practice is responsible of a continuous decreasing of soil quality and fertility. OMW are often stored in ponds for aging before spreading. In this case, however, soluble toxic compounds can permeate through soil and reach the groundwater table. Furthermore, long-term storage causes production of malodorous compounds due to anaerobic fermentation processes. Several treatments have been proposed for OMW but usually they are too expensive and not easy enough to be applied in low technology plants such as those where olive oil is produced. Generally, no tests are made to assess if the treated OMW can be used as water source for irrigation purposes. Target of this work is to assess microbial- and phyto-toxicity of OMW when spread onto the soil and to focus attention on reactions involving polyphenols and promoted by soil compounds. Phytotoxicity (measured by germination of Lepidium sativum) and microbial toxicity (tested on the growth of Bacillus cereus) of OMW are quite strong and a high dilution of the wastewater is needed to observe germination of the seeds or growing of bacteria. Oxidation of catechol and tyrosol, as models of phenolic compounds present in OMW, has been studied thoroughly in soil slurries. Final reaction products are high weight polymeric compounds whose structure is similar to that of humic and fulvic acids. The same reaction occurs when OMW are added to soil. Polyphenols contained in OMW are converted in 24 h, if oxygen is provided to the system. The measured reduction of phenolic compounds is bound to a slight decrease in phyto- and microbial toxicity. This indicates that reaction products are still toxic or other compounds in OMW are responsible of toxicity in the soil environment. Further studies will be devoted to assess the nature of these compounds and to find a possible treatment to reduce the damaging of soil quality when OMW are spread onto soil
Polyphenol Removal from Olive Mill Wastewaters by Catalytic Soil Components.
No full textOlive Mill Wastewaters (OMW) are one of the most common agricultural sources of pollution in the Mediterranean area. OMW are often disposed of by spreading onto soil for irrigation purposes. It should be noted that, in the countries of southern Mediterranean bank, water shortage is widespread. Furthermore OMW are also rich in organic and mineral compounds that could be usefully exploited as fertilizers. The high polyphenol content, however, can affect soil health because of the related microbial- and phyto-toxicity. Therefore, a detoxification treatment is mandatory before using OMW for agricultural purposes. The aim of this work is to test the feasibility of a simple treatment of OMW, with specific attention to the effects of spreading the treated wastewater onto the soil. The proposed technique exploits the natural catalytic activity of soil components towards polyphenol oxidation. The reactor used was an aerated stirred tank containing a slurry phase. Experiments were preliminarily performed on model phenolic compounds to check the soil capability to convert them, to elucidate the reaction mechanisms and, furthermore, to measure the residual toxicity of reaction products. Results obtained with model compounds were then compared with those achieved with the real OMW. Catechol and tyrosol were chosen as model compounds because they are widespread in OMW and they represent two of the main phenolic components detected in the OMW sample used. All phenolic content in OMW (hydroxytyrosol among the others) was monitored by reversed phase HPLC measurements. The experimental results indicated that soil is effective in converting phenols. As regards the model systems, complete conversion was achieved within 12 h, at room temperature, at the concentration detected in the OMW in either cases. These results were confirmed by experiments with OMW. Under the same experimental conditions, conversion of main phenolic compounds occurred in 24 h. In the short term, the observed reaction was found to be promoted by Fe and Mn-oxides contained in the soil. The experiments performed with model compounds suggested that reaction products are either polymers or polymeric aggregates. Indeed they were completely retained by filtration through 0,2 μm cut-off membranes. In the long term a reduction in overall TOC coupled with biomass growth was observed, thus suggesting that biotic mineralization occurred in the system, as well. Germination tests were performed with English cress seeds exposed either to the liquid or to the polymer containing solid phase from the slurry reactor. Tests indicated that the proposed treatment removes the phytotoxicity of the model compound solution and considerably reduces that of the real waste
Treatment of Olive Mill Wastewaters in Soil Slurry Reactors
No full textThe spreading of Olive Mill Wastewaters (OMW) onto the agricultural soil is widespread despite of their high phyto- and microbial-toxicity. In this work, a pre-treatment has been studied in order to make OMW more suitable to fertirrigation purposes. The treatment takes place in an aerated soil slurry and involves the same chemical and biological transformations that are responsible for the natural humification processes in agricultural soil. The suitability of treated OMW for fertirrigation has been evaluated by measuring residual toxicity with seed germination and microbial growth tests. The correlation between polyphenol content, salinity, pH and phyto/micro-toxicity has been investigated, as well
Didattica del greco: un'esperienza di insegnamento nella SSIS
No full textCon la sensibilità per la didattica maturata in anni recenti, è possibile misurarsi con maggiore consapevolezza con le difficoltà che comporta l'insegnamento linguistico ginnasiale. In questa ottica rappresentano punti di riferimento centrali ed ineludibili l'esigenza di uno studio ragionato della morfosintassi, la necessità di un approccio precoce al testo di autore e l'utilità della memorizzazione del lessico, opportunamente selezionato
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