Baciacavallo sewage treatment plant

The core of the centralised treatment system is the Baciacavallo treatment plant, located in the southeast of the city, near the border with the Municipality of Poggio a Caiano. It converges the old Mazzoni, Bresci and Romita gores, along with the pressure collectors that drain the two new Macrolotto industriale located downstream. The plant’s first unit dates back to 1980.
In 1986 the treatment line was doubled with an almost mirror image.
In 1992 the ozonation plant was built for the removal of surfactants and colour. In 1999, the tertiary treatment of flocculation was doubled and, at the same time, the section for dewatering the resulting sludge was improved and modernised.

On weekdays the plant can treat up to 130,000 m³/d, breaking down up to 100,000kg of COD per day and 4,500kg of surfactants per day. It essentially consists of stages for equalization, primary sedimentation, biological oxidation, sedimentation, flocculation and a final refinement with ozone to remove colour and surface residues. The sludge line consists of gravity thickening, mechanical dewatering by centrifugation and sludge incineration.
This last stage uses a multi-level incinerator of 100t/d, supplied with post combustion, a wet scrubber tower for fumes, dust collector and continuous emission analyser. The sludge resulting from the treatment process can reach 30,000t/a with 75% moisture.