Holdenhurst Water Recycling Centre was identified by Wessex Water as being at high-risk due to solids loss from final settlement tanks (FSTs), compromising UV disinfection during storm-driven high flows. At flow-to-full-treatment the FSTs were at hydraulic and solids-loading limits. Another driver for low effluent TSS concentrations was the AMP7 requirement to achieve an effluent to total phosphorus limit of 1 mg/l, with the phosphorus contained in the TSS potentially necessitating the need for new infrastructure for tertiary solids removal. Reducing the mixed liquor suspended solids (MLSS) in aeration lanes would alleviate the stress on the FSTs however, risked impairing nitrification capacity of the plant. To overcome these issues the project adopted an asset-intensification strategy: retrofitting Integrated Fixed-Film Activated Sludge Membrane Aerated Biofilm Reactor (IFAS-MABR) modules to decouple nitrification capacity from suspended solids loading and maximise existing asset performance. A bespoke steel superstructure, designed by Mott MacDonald and installed by Trant Engineering, suspends 50 MABR modules within anoxic and selector tanks, allowing operation at MLSS ≈2,400 mg/L while avoiding additional footprint and a reduced net energy demand. Also, the retrofit includes 30 spare module positions for phased future expansion. Current operational data show ammonia removals up to 2.3x design targets, demonstrating resilience under variable and storm-impacted loads. Commissioned in July 2025 as the UK’s largest OxyMem MABR installation, Holdenhurst exemplifies asset optimisation to provide improved long term operational resilience while meeting tighter nutrient consents and future capacity demands.