When an Italian wastewater treatment plant required a solution for the measurement of two types of sludge with a single probe, water-monitoring expert Chemitec was approached to provide bespoke instrumentation.

The project, based at a site in Sant’Antonino Ticino just outside Milan, was being carried out by industrial plant specialist F.lli Bari on behalf of water services operator Alfa Varese.

The plant, which has been operational for 40 years, is responsible for the collection of domestic and industrial sewage from 25 municipalities – including Milan Malpensa Airport – and is designed to handle 5,500-6,000 m3 of wastewater per hour.

The operator was facing the challenge of having only a single collector for digested and excess effluent at the inlet of the sludge centrifuge.

Because these two sludges have different concentrations of suspended solids, optimal dewatering within the centrifuge could not be achieved and individual measurement was required.

Chemitec, with four decades’ experience designing and manufacturing instrumentation for global wastewater treatment processes, was commissioned to devise a customised solution.

The initial phase of the project saw the technical team from Chemitec visit site and perform a comprehensive assessment of the application alongside their counterparts from F.lli Bari.

Having considered the process’s unique requirements and challenges, Chemitec returned with a multi-instrument solution.

This included a dedicated S461ST suspended solids sensor, which was installed on the pipeline at the centrifuge inlet to allow the measurement of both the digested and excess sludge matrices.

Meanwhile, at the heart of the process was Chemitec’s intelligent 50 Series controller, which allowed the logic of the sensor to communicate with the operating logic of the centrifuge.

The 50 Series controller was cabinet mounted complete with a manual selector to enable recognition of the two sludge types, which the operator had the option of upgrading to automatic mode.

During system start-up, a calibration was performed with the two sludge samples taken and analysed on site to ensure optimal system performance.

The team at F.lli Bari were fully satisfied with Chemitec’s customised solution, the quality of the instrumentation and its integration with the existing system.

As part of Chemitec’s comprehensive after-sales service, the operator will continue to be supported with periodic probe calibration to ensure repeatable results over the long term.