Process Description

The plant, receives pumped flows from two catchments and a gravity flow from a third area.

The influent enters an existing balancing tank and is pumped via an upgraded pumping station to an elevated inlet works. The inlet works comprises 3mm screening and grit removal. The hydraulic design of the plant then allows gravity flow through the MBR plant to the main outfall without the need for inter-stage pumping.

The MBR treatment plant has been constructed on the area of sludge drying beds from the existing works. This allowed the MBR plant to be constructed without requiring additional land area and allowed the existing works to remain operational with minimal modifications during the construction period.


The works can receive high and varying inlet ammonia concentrations. The plant has been designed to ensure that these fluctuations in concentration do not effect the discharged permeate standard.

The main membrane treatment structure, constructed in reinforced concrete, is divided into four membrane bioreactor tanks. The structure also comprises common flow split, permeate collection and sludge re-cycle tanks. This main treatment structure is 14.7m long, 7.7m wide and 4m high. To both minimise the visual appearance of the structure and to overcome ground condition issues, it is buried 2m in the ground.

Following treatment in the MBR plant, the permeate is discharged direct to the local watercourse.

Design data Population Equivalent Peak Flow: Average Flow: BOD load: Average Nitrogen load: Average Nitrogen Concentration: Peak Nitrogen Concentration:

1,471 1,555 m3/day 271 m3/day 90 kg/d 14 kg/d 50 mg/l 250 mg/l

Plant data Each Tank dimensions: No of membrane units: Membrane surface area:

5.3 x 3.4 x 4.0m 20 x 150 panels 2,400 m2