The headquarters of Consorzio Aquarno S.p.A.
The headquarters of Consorzio Aquarno S.p.A.
Tank at the treatment plant where Zenit's pumps and mixers were installed.
Tank at the treatment plant where Zenit's pumps and mixers were installed.

The Aquarno wastewater treatment plant in the municipality of S. Croce sull'Arno in Pisa, Italy has been treating wastewater from the local tannery district since 1974. The high polluting potential of the waste from leather processing businesses meant it was imperative to adopt more stringent industrial waste disposal measures. Zenit’s pumps and mixers played their part in a plan to optimise the purification cycle.

The wastewater treatment plant currently processes more than 30,000 m3 of urban wastewater a day, two-thirds of which is industrial waste from production plants and one-third is domestic wastewater from residential areas, with a treatment capacity in excess of two million population equivalent (PE).

Expanding infrastructure

Following an optimisation plan of the purification cycle and, as a result of its new, increased capability to collect incoming water in bad weather conditions, the Aquarno Consortium has expanded its infrastructure by constructing a further large tank with a capacity of over 30,000 m3, which is divided into six sub-sections into which pumps and mixers with modern, high-efficiency motors will be installed.

Increased efficiency

To improve system reliability and contain operating costs, Zenit engineers were asked to provide over 32 high-efficiency hydraulic Uniqa ZUG OC pumps with channel impeller fitting motors with power levels up to 37 kW in the Premium IE3 efficiency class for high performance and low energy consumption. Twenty-four ZMR series mixers fitted with high-efficiency 5.5 kW motors and 650 mm stainless steel propeller with self-cleaning profile were also installed in the first rain tanks.

The mixer installation structure is made from stainless steel for maximum durability, while the pumps were installed using DAC V bottom coupling systems allowing the machine to be easily separated from the system even when the tank is full.

Reliability & quality

Since the new Zenit machines were installed, there has been no need to shut down the plant for maintenance because of the reliability of the components and the high quality of the materials used. Additionally, the large free passage of the channel hydraulics has avoided problems of clogging and blocking even in severe working conditions. The use of high-efficiency motors made it possible to contain the costs related to energy consumption, and constantly maintain a high performance over long periods of time.

Today, the Aquarno Consortium has been able to reduce the polluting load of incoming wastewater by up to 98.5% and now the entire production of sludge resulting from the purification cycle can be recycled thanks to the reliability and efficiency of Zenit products.

This article was supplied and written by Michele Donà, Marketing at Zenit.