RoDisc® Rotary Mesh Screen: an innovative low-cost alternative

The trickling filter plant with separate secondary clarification tank on STP Vorra was built in 1982 and had to be redesigned in 2006 to meet ATV-DVWK A281 standards. It was necessary to build a new bigger secondary clarification tank with a volume of 350 m³. Taking into account the conditions on site (soil properties, high groundwater level) the costs for building this new clarifier (including sheet pile, unwatering, distribution structure, inlet/outlet line, secondary clarification tank) were estimated to amount to approximately € 525,000.

In search of low-cost alternative solutions plant manager Mr. Sauerbrey contacted HUBER SE in 2007. Within a very short time we came to the conclusion that the desired improvements could be achieved with the use of a RoDisc® screen. It was the wish of the municipal council to run tests at first to be sure about the actual operating efficiency of our screen. The test unit achieved the requested results for all parameters.

Test results:

• Inlet AFS = 22 mg/l  -> Outlet AFS = 8 mg/l
• Inlet COD = 51 mg/l  -> Outlet COD = 37 mg/l

After thorough investigation of technical options by the engineering office Siegle it was decided in 2009 to have another design proposal prepared that should include the alternative of a disc filter system for installation downstream of the existing secondary clarification tank. The total costs for this measure were now estimated to amount to approximately € 330,000. Additionally, another € 50,000 could be saved with execution planning. So, compared to a conventional solution (building a new secondary clarification tank), the investment costs could be reduced by approximately € 250,000 and also the required parameters can be fully met.

After placement of the order for the supply and installation of the HUBER RoDisc® screen at the end of 2011 the screen was commissioned already in June 2012 and has since operated to the full satisfaction of the plant operators.

HUBER SE would like to take this opportunity to thank everyone involved in the project for their cooperation and confidence in our products and services, in particular the customer (municipality of Vorra), the operating staff on site, plant manager Mr. Sauerbrey, and the engineering office Siegle from Nuremberg.