Proceedings

On an extremely constrained urban site, a step change in effluent quality required with tight timescales. Solution; the UKs largest BNR-MBR (Biological Nutrient Removal – Membrane Bio Reactor).   ?? WTW treats a flow of 42 MLD, the design combines a BNR ASP with a hollow fibre membrane plant to produce a denitrified, re-use quality effluent. The use of membrane technology significantly reduces footprint and allows for a high MLSS of up to 10000 mg/l in the biological stage giving further footprint reductions.   To achieve denitrification without carbon addition, design of the anoxic reactors is critical particularly the elimination of dissolved oxygen within the recycle stream.  Key design details, drawing on lessons learned from previous projects have ensured that the recycle system and anoxic lane design has been optimised to promote denitrification. Project timescales meant that the simultaneous commissioning of nutrient removal and membranes was required in order to meet regulatory dates, this posed particular challenges and reduced the filterability of the sludge initially impacting membrane performance.