Sewage screens

Description

Hias IKS will alter a biological cleaning stage to a new biological phosphor removal process (the Hias process). The sewage at Hias RA is mechanically cleaned with cellular grates, then it goes through a sand/fat trap and finally primary sedimentation before it goes for biological treatment. The alteration will start after summer 2019 and will be completed in 2021. There is a need to procure a disk filter for this alteration. The process will be based on a biofilm on a carrying medium, and the water quality that will be treated in the disk filter will be comparable with the discharge from a traditional MBBR process. After the biological process, polymer can be added to the water, as well as flocculation before separation in a disk filter. Our experience is that our high SS load and use of polymer can, at times, give challenges with sludge blockages inside disk elements and in the discharge trough. We would, therefore, like systems with adaptations that are suitable for a high SS load and the use of polymer. What is to be delivered: delivery of a disk filter for separating biofilm sludge (equivalent to after an MBBR process). The disk filter is to be delivered without a tank, but with a cupboard for instrument termination, however without a control cupboard. A total filter area of 360 m2 (Q-max 200 l/s) is to be delivered, and an option for 540 m2 filter area (Q-max 300 l/s). The total for the facility, including the option, will be 900 m2 and Q-max 500 L/s. There will also be an option for a stand-by disk filter in addition to this. The disk filter can be maximum 9.5 m long and without an integrated overflow. It is to be delivered without a tank (tanks will be options). The pore opening on the filter disks must be 40 μm. The content of suspended matter in the inlet will vary between 150-400 mg/l. Hias would like an outgoing water quality with SS < 10 mg/l. The maximum available differential pressure above the disk filter is 28 cm, due to hydraulics in the facility. A decision as to whether to take up the option of 540 m2 total filter area will be depend on how the first installation handles a high SS load. The tenderer will be able to make adaptations to the first installation.