The Arenas de Iguña facility in Spain was the the first MBR plant to use Huber's VRM 30 unit.
Click here to enlarge imageOperational performance has demonstrated the system's ability to meet the world's most stringent regulations, including California's Title 22 water recycling criteria.
Energy consumption for membrane air scouring is a significant operating cost for any membrane bioreactor facility. Huber's rotational design allows for a significant reduction of the amount of scouring air needed to prevent membrane fouling. In addition, the scouring air is introduced at only half the water depth which reduces the air pressure and thus the blower's power consumption. This design has proven to be reliable and has led to considerable savings in operating and maintenance costs.
Case Studies:Low Temperature Project
One of the first MBR plants using the VRM technology was a small plant at the Schwägalp valley railway station in Switzerland. It was designed for 780 residents and an average dry weather flow of 26,500 gallons per day. The treatment plant clarifies the wastewater of an alpine hotel, a cheese factory and a small guesthouse.
The rotating membrane unit (VRM 20) was installed in early 2002. During the summer season the plant has to handle up to 34,500 gallons of wastewater per day. Flows during the winter months can be as low as 1,300 gallons per day. Another challenge is the snow melt in the spring which leads to very low wastewater treatment temperatures.
Despite the enormous variations in flow and temperatures, plant operation is stable and reliable. Effluent is of a consistent high quality and membrane permeability is up to 12 gfd/psi. The plant operates with a membrane flux of 7.6 gfd, making sure that the membranes do not foul during the low temperature period.
The biological treatment stage achieves a COD reduction of nearly 97% and a total elimination of ammonium nitrogen. Maintenance for the MBR plant is minimal and is conducted by the operating staff of the railway company. Manual operator intervention is only necessary for excess sludge removal. The plant has been in operation for more than six years and only twice have the membranes required chemical cleaning. To date there has been no replacement required of any membrane modules due to failure or wear.
Protecting a Drinking Water Source
The new MBR plant for the small Spanish community of Arenas de Iguña, located near the coastal town of Santander, was put into operation in summer 2006. Until recently, the community had no sewage treatment plant at all even though drinking water for the region is taken from the river just a short way downstream from where the town's wastewater is discharged.
As problems with water contamination increased, it was decided in early 2005 to build a wastewater treatment plant with a membrane bioreactor. Huber received the order to supply the equipment for mechanical pretreatment, grit washing, the membrane bioreactor and sludge thickening.