Effects of fertigation with purified urban wastewater on soil and pepper plant (Capsicum annuum L.) production, fruit quality and pollutant contents

Abstract

The effects, in greenhouse conditions, of Purified Urban Wastewater (PW) from Almería (Spain), in the fertigation of pepper (Capsicum annuum L.) on sandy mulch soil, were evaluated. Primary, secondary (active sludges) and tertiary (Chlorination + ozonation) purification treatments were applied to wastewater. Irrigation treatments applied were PW, natural Ground Water (GW), Fertilizer PW (FPW) and Fertilizer GW (FGW). The vegetal biomass, yield and fruit quality were controlled. Heavy metals (Cr, Cd, Pb, Ni, Mn, Cu and Zn), arsenic (As) and Polycyclic Aromatic Hydrocarbons (PAH) in water, soil, leaf, and fruit were analysed. The PW presented heavy metal, As and PAH contents acceptable for its use in drip irrigation. In the soil, fertigated with PW, the concentration of heavy metals and As did not increase, whilst the PAH concentration decreased. The PW treatment supplied enough nutrients to obtain yield and fruit quality equal to that of GW with fertilization. A significant saving on N, P and K fertilizers (37%, 66% and 12% respectively) was achieved by using PW. The Cd, Pb and As contents of the fruit did not show risk for human consumption. The total PAH concentrations in the fruit were low, the highest of which was phenathrene, with no carcinogenic signification.