IAS SpA Priolo Associated Biological Plant for Domestic and Petrochemical Wastewaters in Priolo (Italy): Experience and Results after 5 Years' Management

Priolo Associated Biological Plant, designed and constructed for the treatment of 1200 1/s ± 20% (about 4300 m3/h) of industrial and domestic wastewaters, occupies a site of about 40 000 m2 near Siracusa (Italy), It is very important in the Siracusa Industrial Area where, within the space of about 20 years, uncontrolled industrialization occurred. The main users of the plant are the big petrochemical factories of the area (Montedison, Enichem, and Exxon) and small towns such as Melilli, Priolo, and Belvedere. The wastewaters are transported to the plant via a glass fibre reinforced plastic (GRP) pipe 40 km long, laid in a north-south direction. The treated effluent is discharged into the sea through a submerged outfall 1600 m long and 35 m deep. The plant is provided with large waterproof basins (75 000 and 25 000 m3) were toxic and harmful wastes can be held. Plant management is carried out by IAS SpA (Siracusa Water Industry), a company which is both public and private. This paper gives some data on the characteristics of the treated wastewater, tests performed, process efficiency, type of management, and running costs. The results of research conducted using a pilot plant are briefly discussed. From May 1987, this research has enabled the biological plant to treat about 14 tons per hour of untreated sulphuric soda effluent sent directly from a petrochemical plant. The constant research activities implemented by the management have given the users of the plant the opportunity of reducing their highly expensive pretreatments to a minimum.