Decision question
How much nitrification headroom could the existing filters provide, and could a simple hydraulic change reduce the need for major capital work?
Testing what the existing filter works could achieve before committing capital
At a 2,826 PE biological filter works, BI-Zen monitored a controlled increase in recirculation and filter wetting using one-minute data at the humus-tank outlet. Live evidence exposed short morning ammonia peaks that periodic samples could miss and helped the project team test hydraulic options before assuming that a major media upgrade was required.
Site / asset snapshot
Asset context
2,826 PE biological filter works serving a growing catchment
Performance concern
Historical samples indicated borderline ammonia treatment
Intervention tested
Temporary increase in recirculation to raise filter wetting during summer low flow
Monitoring scope
One-minute NH4-N, NO3-N, turbidity, ph and temperature at the humus-tank outlet
Controlled change and live process evidence
The recirculation trial changed filter wetting while the optimiser tracked the combined biological response at the humus-tank outlet.
Inlet
Primary settlement
Biological filters
Recirculation loop
Humus tank
Final effluent
1 increased filter wetting via recirculation
2 monitored response at humus-tank outlet
Project need
Primary driver
Test installed process headroom before defining the capital solution
Evidence gap
Reveal short ammonia peaks and the response to recirculation that periodic samples could miss
Why it mattered
Avoid over-specifying a media upgrade if the main constraint was hydraulic or limited to short daily peaks
BI-Zen Delivery, Evidence And Decision Informed
One-minute monitoring separated short peak events from continuous loss of nitrification
Bi-Zen Delivery
Deployment
Temporary optimiser at the humus-tank outlet
Measured
NH4-N, NO3-N, turbidity, ph and temperature at one-minute intervals
Aligned with
Flow, current FFT and asset-capacity information aligned in a live dashboard
Service provided
Multi-week monitoring and wastewater process interpretation
Daily ammonia peaks that periodic sampling could miss
What became clearer
The works operated near its current FFT and showed a repeatable morning ammonia peak. Risk was concentrated into short periods rather than persisting all day. This directed attention towards peak-load control, hydraulic management and filter wetting instead of assuming that the filters lacked capacity at all times.
Decision informed
The team gained a stronger basis for targeting hydraulic changes and testing recoverable nitrification headroom before major upgrades. Recirculation was treated as a site-specific lever, not a universal answer. On split processes, parallel optimisers at individual humus-tank outlets could extend the approach by comparing units and targeting maintenance.