Decision Question
Could a conventional anoxic zone design release more capacity in Battery C, or did its catchment and wastewater composition require a different solution?
Revealing catchment differences to inform anoxic zone design
Temporary Optimisers compared settled-sewage composition across two process batteries before moving to an existing anoxic zone. Minute-level trends showed that Battery C received less soluble carbon relative to ammonium and behaved differently from the reference battery, prompting the project team to reconsider a conventional anoxic zone design and take a wider systems approach.
Site / Asset Snapshot
Site Type And Scale
Large activated-sludge works.
Five process batteries, approx. 2.1 million PE
Project Context
AMP7 growth scheme
Nitrate management
Design Question
Existing Lane 18 anoxic zone assessed against a reference battery
Monitoring Scope
Two temporary Optimisers relocated across two one-week phases
Monitoring Strategy
The same Optimisers moved from catchment comparison to direct process assessment.
Week 1: Compare settled sewage
Battery B
Reference load profile
Battery C
Target load profile
Compare flow, dissolved COD and ammonium loading
Week 2: assess lane 18 anoxic response
Anoxic inlet
Anoxic outlet
Project Need
Primary Driver
Release more hydraulic capacity in Battery C while managing nitrate under a growth scheme
Evidence Gap
Existing data did not explain inconsistent denitrification or show whether Battery C matched the reference battery
Why it mattered
A conventional anoxic zone solution risked carrying the wrong design basis into investment decisions
BI-Zen Delivery, Evidence And Decision Informed
Minute-level evidence linked anoxic performance to catchment loading and available soluble carbon
Bi-Zen Delivery
Deployment
Two temporary Optimisers across Batteries B and C, then Lane 18 anoxic inlet and outlet
Measured
Dissolved COD and ammonium at one-minute resolution
Aligned With
Client flow data, process location and live dashboard trends
Service Provided
Rapid deployment, relocation, data checks, dashboards and engineering interpretation
Carbon source relative to ammonium loading
What Became Clearer
Battery C did not behave like the reference battery. Minute-level trends showed a different diurnal load profile and less soluble carbon relative to ammonium. Lane 18 monitoring also confirmed that denitrification was not consistently established. The evidence linked the weak performance to influent conditions and process configuration, rather than anoxic volume alone.
Decision Informed
The project team could not assume that a conventional anoxic zone design would work across Battery C. The evidence prompted a wider systems review before selecting the growth solution and reduced the risk of investing in capacity that would not address the underlying limitation.