Subsurface constructed wetlands for wastewater treatment and reuse in agriculture: five years of experiences in Sicily, Italy

The paper reports the results of an investigation on a H-SSF constructed wetland for tertiary treatment in a small community located in eastern Sicily, Italy. The system is designed to reuse wastewater for the irrigation of olive orchards covering about 150 hectares. From March 2001 to September 2005, wastewater samples were collected and the following chemical–physical parameters were determined according to Standard Methods: temperature, pH, EC, DO, TSS (105 °C), BOD₅, COD, TN, TP. The following microbiological parameters were also evaluated: total coliforms, faecal coliforms, Escherichia coli, faecal streptococci, Salmonella, helminth eggs. Mean removal efficiencies ranged from 77 to 92% (TSS), 37 to 72% (BOD₅), 51 to 79% (COD), 97 to 99.5% (E. coli). Removal efficiency of Salmonella and helminth eggs was always 100% in all samples; however, only 15% of total samples matched the limit of E. coli (<50 CFU/100 mL) fixed by Italian legislation for wastewater reuse.