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The analysis of the rheological properties of the sludge produced in biological purification plants is paramount for the design of equipment (pumping, mixing, conditioning, aeration, filtration, etc.) and the management of these plants. In particular, solid content in the sludge plays a significant role in the rheological quantities. In this study, an investigation of the sludge rheology produced in different sectors of an activated sludge plant (aerated sludge, recirculation sludge, and thickened sludge) has been performed. Specifically, for each sludge sample, various physical-chemical parameters have been analyzed, and rheological tests have been performed at different temperatures (10°C, 20°C, 30°C, and 40°C ± 0.1). The sludge was considered as a non-Newtonian Bingham fluid. Viscosity and critical stress were determined, and their dependence at different temperatures, on some physical parameters, such as solid content and settling solids, has been studied. Results evidenced that viscosity and critical stress increase with increasing solid concentration. Moreover, at the same concentration, as the temperature increases, the viscosity decreases, whereas the critical stress decreases until temperature values of about 30°C and then increases again. PRACTITIONER POINTS: An investigation of the sludge rheology produced in different sectors of an activated sludge plant has been performed. For each sludge sample, various physical-chemical parameters have been analyzed, and rheological tests have been performed at different temperatures. Viscosity and critical stress were determined, and their dependence at different temperatures, on some physical parameters, has been studied. Results evidenced that viscosity and critical stress increase with increasing solid concentration.

In this study, the equivalent dose rate of natural radionuclides ( H T ) in 99 spring water and surface soil samples was determined using an alpha, beta, and gamma high sensitivity detector up within a Geiger-Muller tube and with an external probe NaI (Tl). The samples were collected in the Crati basin (southern Italy), and during sample collection, water quality parameters were detected in situ and at the University of Calabria laboratories. A Pearson correlation coefficient analysis was applied to identify and clarify the relationships between water physical-chemical properties and soil and water radioactivity. Results show that the mean H T for spring waters is 97.07 μSv/h. Furthermore, the mean H T for surface soils is 97.92 μSv/h, thus evidencing higher mean H T values than worldwide ones reported in a previous literature. Low correlation coefficients were detected between water H T and conductivity and pH. On the contrary, a reasonable correlation was found between H T in spring water and in soil. This relationship is associated with some rocks of the Sila Massif and of Coastal Chain, i.e., plutonic and metamorphic crystalline rocks. Finally, the estimation of the health risk was calculated: results did not evidence serious dangers for people living in the studied environment. The results from this survey for the H T evaluation provide an extensive assessment of the background exposure levels in the investigated area.

Knowledge of bioclimatic comfort is paramount for improving people&rsquo, s quality of life. To this purpose, several studies related to climatic comfort/discomfort have been recently published. These studies mainly focus on the analysis of temperature and relative humidity, i.e., the main variables influencing the environmental stress in the human body. In this context, the present work aims to analyze the number of visits to the hospital emergency department made by the inhabitants of the Crati River valley (Calabria region, southern Italy) during the heat waves that accompanied the African anticyclone in the summer of 2017. The analysis of the bioclimatic comfort was performed using the humidity index. Results showed that greater the index, the higher the number of accesses to the emergency department, in particular by the most vulnerable population groups, such as children and the elderly.

In this work, we present an experimental study on the re-aeration of a biological effluent coming from a wastewater treatment plant located at sea level. The oxygen transfer efficiency has been calculated for a hydraulic structure characterized by three different weirs jumps (Bazin type). The experimental results have been compared with those obtained by two (and well known) empirical equations (Avery-Novak equation (Avery and Novak, 1978) and Thene equation (Thene, 1988)). These equations did not allow a well fitting of the experimental data. We proposed a modification of the Thene equation by inserting of the Weber number of the jet. By this new correlation, we obtained a good fitting of re-aeration data obtained for the studied hydraulic structure.

The characterization of the spatial variation of geochemical parameters in spring waters, especially the ones used for drinking purpose, is essential to identify potential risks to humans. In this work, results of a qualitative analysis on 190 samples of spring waters collected in the largest catchment of the Calabria region (southern Italy) are shown. Several physical and chemical parameters were analysed and the Langelier-Ludwig diagram was built to evaluate the hydrochemical facies of the sampled waters. Additionally, the relationships between water temperature and altitude and electric conductivity (EC) and altitude were assessed. Geostatistical methods were used to map the physical and chemical parameters. Results showed a good quality status of the spring waters in the Crati basin, with a predominant Ca-Mg-type hydrochemical facies. Then, a connection between EC and temperature with elevation has been detected in some area of the basin. Finally, the spatial analysis allowed identifying the distribution of the concentration of the several parameters.

This work aims to improve the knowledge of nutrient exchanges between soil and atmosphere through a comparative analysis of the contribution coming from atmospheric depositions and their release in water runoff. The study has been realized on a mountain catchment, crossed by Bonis stream, tributary of Cino river and located in Sila Greca plateau (Calabria, Southern Italy). This experimental basin, laying on a basement formed by inclusive and plutonic rocks, extends for an area of 139 hectares, spreading from 975 m a.s.l. to 1301 m a.s.l. The catchment is forested for about 95% of its surface area with the main presence of Pinus laricio Poiret populations differentiated for age, density, tree canopy cover and stand characteristics within an area without human settlements and pollution sources. The basin has been instrumented, since 1986, to measure the main abiotic features in inflow and outflow discharges. These chemical and physical parameters, as N-NH4, N-NO2, N-NO3, P-PO4, S-SO4, Cl, pH and conductivity, have been analyzed on a fortnightly basis. From collected data, it has been estimated, for each nutrient, its annual and monthly mean weighed concentrations to value the basin resilience after external inputs and its rolling action after some events, as acid depositions. In conclusion, the monitoring of mountain catchments could supply useful data about the global changes of atmospheric chemistry and, as a consequence, on the variability in quality control of surface waters, considering that mountain catchments supply most of water resources of a good quality level for mankind.

We present the results of high-resolution electron energy loss experiments on (CO/O)/Ni(1 0 0) and (CO/H)/Ni(1 0 0) systems. Oxygen and hydrogen interact differently with Ni(1 0 0) surface, nevertheless, both species do not affect to a great extent the vibrational properties of CO. A phase of CO molecules weakly bonded to the surface and unaffected by coadsorbed oxygen and hydrogen, is found. Coverage of 0.5 ML of predosed oxygen chemically passivates the Ni(1 0 0) surface and inhibits any CO adsorption at room temperature. CO sites are unambiguously determined for each predosed Ni(1 0 0) surface.

IL TROFISMO DELLE ACQUE LENTICHE: UN CASO STUDIO NELL'INVASO DI TARSIA SUL FIUME CRATI (CALABRIA) 1Ernesto Infusino, 2Giovanni Callegari, 2Nicola Cantasano 1Università della Calabria, Dipartimento di Ingegneria per l'ambiente e il territorio, Arcavacata di Rende (Cs) 2Consiglio Nazionale delle Ricerche, Istituto per i Sistemi Agricoli e Forestali del Mediterraneo I.S.A.FO.M.- UOS Rende (Cs) La direttiva 2000/60/CE istituisce un quadro per l'azione comunitaria in materia di acque evidenziando la necessità di "integrare maggiormente la protezione e la gestione sostenibile delle acque nelle politiche comunitarie". In tal senso, "una politica delle acque efficace e coerente deve tener conto della fragilità degli ecosistemi acquatici" al fine di impedirne il loro deterioramento ed estendendo tale protezione, anche, agli ecosistemi direttamente dipendenti da quelli acquatici. Pertanto, la direttiva suggerisce ai paesi membri che i corpi idrici, ed in particolare i laghi, debbano essere classificati in base al loro "stato ecologico", ottenuto in base a monitoraggi con cadenze prestabilite, in funzione della pressione antropica, dei parametri biologici (fitoplancton, macrofite, fitobentos e macro-invertebrati bentonici), limnologici e trofici. Tra i più importanti parametri chimico-fisici, individuati dalla direttiva, vi sono: la trasparenza, la salinità, l'acidificazione, le condizioni termiche, il contenuto di ossigeno ed il livello dei nutrienti. La Direttiva stabilisce, infine, l'obiettivo del raggiungimento dello stato ecologico "buono" delle acque entro il 2015, indicando come strumento prioritario la riduzione delle pressioni antropiche presenti nel bacino idrografico. A tal fine alcune Regioni, ai sensi dell'art. 91 del D.lgs. n. 152/2006, hanno individuato i principali bacini drenanti dei rispettivi territori, le misure per la prevenzione e riduzione dell'inquinamento nelle zone vulnerabili e le relative aree sensibili aggiornando, così, le rispettive leggi regionali in materia di acque. In Calabria, pur mancando una legge regionale di recepimento della predetta direttiva, il bacino del lago di Tarsia, area protetta regionale e sito SIC della Rete Natura 2000, è stato inserito nella fase di caratterizzazione del Distretto Idrografico dell'Appennino Meridionale. Ai fini di una corretta redazione del Piano Regionale di Gestione delle Acque e secondo le norme espresse nella Direttiva 91/271/CEE e nell'articolo 106 del citato D.lgs. n. 152/2006 si prevede che, per il risanamento dell'invaso di Tarsia, il cui bacino scolante subisce rilevanti pressioni antropiche da aree urbane limitrofe, sia necessario l'abbattimento minimo del 75% del carico complessivo dei nutrienti derivanti dalle acque reflue. In generale, l'autodepurazione delle acque lentiche è influenzata da numerosi parametri ed in particolare dalle concentrazioni di fosforo ed azoto. Elevate concentrazioni di tali nutrienti favoriscono, infatti, la transizione da comunità "climax" ad ecosistemi caratterizzati da un'elevata produzione primaria che, in alcuni casi, possono evolvere verso forme eutrofiche ed ipertrofiche. In particolare, le acque lentiche artificiali, rispetto a quelle naturali, hanno un comportamento alquanto diverso presentando una minore suscettibilità nei confronti dei fenomeni eutrofici per effetto del prelievo di acque ad uso irriguo e/o potabile e grazie ai periodici scarichi dalle prese di fondo che tendono a rinnovare la massa idrica invasata. Infine, un caso specifico è rappresentato dagli invasi stagionali, presenti soprattutto nelle aree vallive, in cui il rinnovamento è totale, come nell'invaso di Tarsia sul fiume Crati, oggetto del presente studio. La stagionalità dell'invaso consente l'utilizzo dei modelli di simulazione dei processi trofici e auto-depurativi su una scala temporale ristretta a differenza degli invasi naturali o a lento ricambio.

Questo studio si propone di valutare lo stato di salute ecologica e la funzionalità ecosistemica del bacino idrografico del fiume Crati attraverso l'applicazione della nuova versione dell'Indice di Funzionalità Fluviale (Siligardi et al., 2007) ai sensi del D.Lgs.152/99 e della Direttiva Quadro sulle acque 2000/60/CE. I risultati evidenziano il buon grado di funzionalità fluviale del bacino idrografico in esame sebbene alcuni tratti nella zona di deposito siano compromessi nelle loro componenti biotiche ed abiotiche a causa della presenza di numerose captazioni e derivazioni idriche utilizzate anche a scopo irriguo ed agricolo. L'applicazione del metodo consente di individuare le criticità ambientali emergenti alle quali la sensibilità politico-amministrativa può porre rimedio se interviene in una direzione non più antropocentrica ma ecosistemica, così come suggerito nel metodo proposto. Questa sperimentazione, in forma estesa, del metodo IFF in Calabria conferma la notevole versatilità del nuovo indice e la grande valenza territoriale nell'ottica di una visione globale e sintetica degli ecosistemi fluviali.