Flottweg’s Xelletor passes the final stage of testing where it matters most

When Flottweg introduced its new Xelletor centrifuge system at the European Biosolids Conference last year, it was hailed as the most innovative and efficient product in its sector. However, admiring the product and learning about its performance capabilities at a conference setting is one thing. What really counts is seeing it in action, day in and day out.

Twelve months on, and thanks to early adopters in the UK and beyond, the wider industry has been able to do just that. Euroby has been working alongside Flottweg to help the manufacturer put its new product through an exhaustive 12 month acceptance testing programme. The results have just been published by Flottweg, and show that users are enjoying superior performance and reduced costs.

About the Flottweg Xelletor

The Flottweg Xelletor looks like nothing that has come before it with its tubular space frame construction and its open scroll body. It combines the functionality of both a decanter and a screw press and features the Flottweg Simp Drive®, which controls the differential speed between the scroll and the decanter bowl. Higher differential speed means optimum separation and more efficient cake compression.

To truly understand the performance credentials of the Xelletor, it is worth taking a step back and considering what users are looking to achieve. Wastewater treatment plants use a centrifuge for dewatering sludge as a faster and more efficient method that traditional filtration. Success or failure is assessed using three core metrics, which are cake dryness, polymer consumption and energy consumption.

Comparison testing

Flottweg arranged a series of comparison tests, comparing these three performance parameters from Xelletor units in regular use against a range of alternative solutions, including the previous Flottweg C-series machine, a comparable decanter built in the 1990s and a standard screw press. The data was impressive.

The Xelletor out-performed the others by 1.1 percent, 4.4 percent and 3.7 percent respectively in terms of cake dryness, and by 2.3 percent, 3.8 percent and 1.9 percent for polymer consumption.

Comparing power consumption was more of a challenge from the field data available, so instead, Flottweg used information from its test database, comparing the Xelletor’s power demands with those of figures from three similar Flottweg devices from the past 20 years. It is fair to say that the Xelletor swept the board, with power savings of between 10 percent and 50 percent.

UK Field testing

In May 2018, Euroby worked alongside Flottweg to put a Xelletor through its paces at a sewage treatment facility in the south of England, using thermally hydrolysed sludge as a test medium. Over a three day trial at flow rates of 10 to 15 m3/h, it achieved results of 35 percent dryness at a polymer dosing rate of 9 to 10 kg/tD.S. The plant ordinarily uses a belt press, which achieves just 30 percent dryness but with a higher polymer usage of 13 kg/tD.S.

Everyone at Euroby is excited to be so closely involved in the roll out of new technology that will be delivering such enhanced performance and reduced costs to our customers.