Kanes Foodsview Aquabio

Commissioned/installed date: 2001

The plant is an example of food effluent recycling with a sidestream pumped MBR based on Aquabio’s AMBR technology, and was commissioned in 2001. 80% of the flow is recycled.

The process treatment scheme comprises upstream screening, flow balancing, DAF treatment (for fine vegetable solids removal), the MBR itself and downstream treatment by reverse osmosis followed by UV disinfection. The permeate water is blended with mains water for use within the factory. The MBR comprises two 250 m³ bioreactors with four banks of crossflow membrane modules. The maximum MLSS concentration employed has been 20 g/L, but the bioreactor is generally operated at around 10 g/L resulting in food-to-micro-organism (F:M) ratios of around 0.13 kg COD/kg MLSS day.

Sludge production is calculated as being 0.14 kg DS/kg COD removed from a sludge age of over 100 days. Each membrane bank is fitted with four 200 mm diameter MT UF Norit membranes. The membranes operate at an average flux of 153 LMH normalised to 25°C. The permeate water has average TSS, BOD and COD concentrations of 4, 7 and 16 mg/L respectively. The UF permeate is passed to a two-stage reverse osmosis plant which achieves an overall recovery of 75−80%. The reject stream is discharged to sewer and the permeate, which typically has a conductivity of 40-100 µS/cm, is passed to the UV disinfection unit and then to the client’s water supply tank.

The plant has performed consistently in terms of biological treatment, membrane performance and final reuse water quality. For the majority of the time membrane performance has been better than design, allowing one bank to be maintained as a standby and so offering greater process flexibility and lower energy use. Occasional reductions in membrane flux have been linked to poor biomass health which has been rectified by closer management of the process.