Water and stone
A characteristic of the stone working industry is that it requires great quantities of water, resulting in a considerable environmental impact.
The COREFA consortium of Firenzuola (FI) – established by new companies that specialise in stone work – needed to recover, treat and redistribute the waste water in order to reduce demand from the water system.
Other essential requisites were: constant delivery pressure with variable water flow rates, since the companies did not all operate simultaneously and each of them required different water volumes according to the type of work and quantity of stone to be processed; easy and economic installation and management, as well as reliability and sturdiness.
The system, which handles the recovery and subsequent treatment and reutilization of the water, was set up by COGEDE di Fano, a company that specialises in this sector. It chose a LOWARA GHV40/100LM200UN3702 pumping unit in order to deliver a variable flow ranging from zero to 1,040 cubic meters an hour, with a constant pressure of 0.4 MPa (equivalent to 4 bar).
The unit, which consists of four electric pumps driven by 37 kW motors and controlled by four Hydrovar R frequency converters and four electronic pressure sensors, has proved to be the ideal solution, capable of satisfying the wide changes in demand, reducing power consumption and ensuring long life and easy maintenance.
The automatic on/off sequence control, the four reaction speed adjustment ramps, the automatic changeover and remote monitoring have enabled a considerable reduction of the power input at start-up and when the system does not require maximum flow rate, as well as the elimination of water hammer when the pump stops. Moreover, no by-pass lines or modulating valves are required.
The recovered water, which is very abrasive due to the presence of solids and suspended sediments, is collected and conveyed to the central treatment plant using lift pumps.
Source: Xylem Inc.
