WASTEWATER TREATMENT
Val Bisenzio
The Val Bisenzio treatment plants

In a process that began in 1997, the sewage treatment plants in the municipalities of Vaiano, Vernio and Cantagallo have become part of the system. They’re all located along the shaft of the Bisenzio River and treat wastes originating mainly from the textile industry. For these systems, the Company has, where necessary, carried out structural adjustments.

The Vaiano sewage treatment plant

The Vaiano sewage treatment plant (30,000 AE) has a weekday average of 8,000 m³/d, breaking down approximately 4,000kg/d of COD and a little less than 150 kg/d of surfactants. It essentially consists of stages for equalization, denitrification, biological oxidation, sedimentation and a final ozonation.
The sludge line consists of gravity thickening, aerobic digestion and mechanical dewatering by centrifugation. The sludge resulting from the treatment process amounts to about 2,000 t/a with 18% humidity.

The Vernio sewage treatment plant

The Vernio sewage treatment plant (30,000 AE) has a weekday average of 7,000 m³/d, breaking down approximately 4,000kg/d of COD and a little less than 100 kg/d of surfactants. It essentially consists of stages for equalization, biological oxidation and secondary sedimentation. The installation of a final filtration section for the reduction of suspended solids is in the works. The sludge line consists of gravity thickening, aerobic digestion and mechanical dewatering with belt presses. The sludge resulting from the treatment process amounts to about 1,500 t/a with 20% humidity.

The Cantagallo sewage treatment plant

The Cantagallo sewage treatment plant (35,000 AE) has a weekday average of 10,000 m³/d, breaking down approximately 4,000kg/d of COD and a little less than 100 kg/d of surfactants. It essentially consists of stages for equalization, denitrification, biological oxidation and secondary sedimentation. The unique feature of this plant is that it is entirely covered. The installation of a final section followed by ozonation for the removal of colour is in the works. The sludge line consists of gravity thickening, aerobic digestion and mechanical dewatering by centrifugation. The sludge resulting from the treatment process amounts to about 1,500 t/a with 20% humidity.