Fat and grease from the slaughterhouse in Ringsaker caused severe problems in the municipal sewer system and wastewater treatment plant. A HUBER solution was selected for pre-treatment of the wastewater at the slaughterhouse. The wastewater is first screened and then treated in a dissolved air flotation process. Over 80 % of the particulate fat and greased are removed without the need for chemical pre-treatment. The removed fatty flotate sludge has a solids concentration of 6 to 8 %. Its volume is only 1 to 2 % of the wastewater flow. The flotate sludge is hauled to a rendering facility.
The slaughterhouse in Ringsaker, a town located about 80 km north of Oslo, has a capacity of 1,200 pigs and 120 cows per day. Its wastewater flow of 5,400 m³ per week contained about 270 mg/l free fat and grease, whish caused severe problems in the sewers and at the central wastewater treatment plant in Brumunddal. At the end of 2003 the slaughterhouse management made their decision to pre-treat their wastewater before it is discharged into the municipal sewer.
Our Scandinavian subsidiary HUBER HYDROPRESS provided the solution for this challenge. They supplied a 500 mm wide step screen SSM with 1.5 mm spacing for mechanical pre-treatment of the wastewater from the butchery. For mechanical pre-treatment of the wastewater from the animal truck washing hall, we supplied a tank-mounted ROTAMAT® micro-strainer Ro 9 with 1 mm wedge wire spacing and a screen basket diameter of 500 mm. Since only particulate matter needs to be removed, no additional chemical pre-treatment is needed in this case. Our dissolved air flotation unit HUBER HDF-10 efficiently removes free fat and grease.
HUBER's solution could easily meet and exceed the stated removal efficiencies of 80 % for particulate fat and grease as well as for total suspended solids, and of 30 % for BOD and COD. The volume of the flotate is about 1 to 2 % of the wastewater flow, and its concentration is 6 to 8 % DS.
Terje Grinden, the technical manager of the slaughterhouse’s maintenance department is very satisfied with our equipment and Reidar Larsen, the superintendent of the municipal wastewater treatment plant, confirms that their situation has magnificently improved since our slaughterhouse system has been in operation.
By Ole Alex Wetten, General Manager of Hydropress Huber AB, Norway