Agro-industrial Treated Wastewater Reuse for Crop Irrigation: Implication in Soil Fertility

Abstract

At the same time with population In many arid and semi-arid countries water is becoming an increasingly scarce resource and so it is fundamental to consider any sources of water including treated agro-industrial wastewater which might be used economically and effectively to promote further development. This study was carried out at Fiordelisi company (Stornarella; 41° 15’N, 15° 44’E; altitude, 154 m a.s.l.), which produces processing vegetables (i.e., tomato, broccoli, eggplant, zucchini, pepper) and is equipped with a wastewater treatment plant based on the following steps: screening, oil removal, equalization, activated sludge process (anoxic plus aerobic phases), chemically assisted sedimentation, sand filtration (preceded by chlorination), membrane ultrafiltration (Kristal 600ER -Hyflux - nominal pore size of 0.05 µm), UV disinfection (6 mercury- vapor lamps, 300W each). During the study three types of water (groundwater - GW -; secondary treated agro-industrial wastewater -SW - and tertiary treated agro-industrial wastewater -TW -) were used for irrigation of processing tomato and broccoli crops, to evaluate the main effects on plant nutrient contents of the soil. The experimental trials were carried out in open field over three growing seasons of the considered crops, from April 2012 to February 2015. Compared to GW, SW and TW were characterized by higher contents of plant nutrient, such as NH4-N,NO2-N, PO42-, K+, Ca2+, Mg2+, TSS and organic matter. On the contrary, GW showed higher NO3-N content. However, considering the seasonal irrigation volumes applied to tomato and broccoli crops, a significantly nutrients load in the soil was observed only for K+ and NO3-N.