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Storage reservoirs are a key element in wastewater treatment trains for agricultural reuse; however, there is a need for further research on design criteria and operation rules for such reactors. The percentage of fresh effluents (PFE) is an important parameter for the design of perfectly-mixed reactors. PFE correlates better than mean residence time with the performance of the reactor. It allows for estimation of the removal of pollutants in non steady-state systems, such as seasonal wastewater storage reservoirs, and for forecasting the quality of the effluents released for irrigation. However, calculation of PFE is a difficult process requiring complex computer algorithms. A simplified analytical approach is developed to calculate the PFE for n days. The formulation is discussed, describing the relationships between the hydraulic variables, and then applied to a non-steady-state continuous-flow wastewater reservoir in Eastern Sicily (Italy). [ABSTRACT FROM AUTHOR]

This paper presents the results of an experiment carried out in Southern Italy (Sicily) on the estimation evapotranspiration (ET) in pilot constructed wetlands planted with different species (Chrysopogon zizanioides, Myscanthus x giganteus, Arundo donax, Phragmites australis, and Cyperus papyrus). In the two monitored growing seasons, reference ET0 was calculated with the Penman-Monteith formula, while actual ET and crop coefficients were measured through a water balance and the FAO 56 approach, respectively. The highest average seasonal ET value was observed in Phragmites australis (17.31 mm d−1) followed by Arundo donax (11.23 mm day−1) Chrysopogon zizanioides (8.56 mm day−1), Cyperus papyrus (7.86 mm day−1), and Myscanthus x giganteus (7.35 mm day−1). For all plants, crop coefficient values showed different patterns in relation to growth stages and were strongly correlated with phenological parameters. Myscanthus x giganteus and Arundo donax showed a water use efficiency values significantly higher than those observed for the other tested species. Results of this study may contribute to select appropriate plant species for constructed wetlands located in semi-arid regions, especially when the use of reclaimed water and/or the use of aboveground biomass are planned. [ABSTRACT FROM AUTHOR]

This investigation was under taken to evaluate the groundwater resources contamination due to intensive agricultural practices (particularly greenhouses). The study-area is located in the coastal area of the Ragusa province (South-East Sicily), where numerous existing greenhouses may cause the contamination of groundwater systems (unconfined and confined aquifers) beneath the cropped land. The pollution risk is mainly related with the seepage process of macro-elements nitrogen (N), phosphorus (P), potassium (K), held in the irrigation water and the massive use of fertilizers and pesticides, that may pass through the unsaturated zone of the soil profile. Moreover, the area is characterized by the presence of several wells (about 15 wells/km²) for agricultural use that cause the aquifer overexploitation and the consequent risk of seawater intrusion. The agriculture practices adopted in the study area (irrigation volumes, fertilizer concentrations, use of pesticides…) were monitored since February 2009; moreover, the pollution risk of the aquifers was evaluated through the analysis of groundwater water samples collected (monthly) in the monitoring wells; in particular, nitrogen compounds, soluble phosphorous (PO₄²⁻), potassium, as well as the main pesticides commonly used in the study area, were measured.The results show that electrical conductivity and chloride concentration values can cause reduction of production and leaf damage problems, respectively, for most of the monitored farm systems. The high nitrogen compounds concentrations observed in the monitored wells can cause health and environmental problems. Moreover high pesticide contamination of groundwater was found in two of the five monitored wells.