Decision question
Could the existing SBR and nitrifying filters support the future duty, and what was driving intermittent solids and ammonia loading?
Granular SBR monitoring identified a maintenance cause of solids breakthrough
To inform site rationalisation and future design, BI-Zen monitored crude-sewage loading and SBR outlet performance. Live, high-frequency evidence captured repeated solids breakthrough during specific decant cycles and focused investigation on a sealing valve letting by. The team could address the maintenance issue before considering larger process or capital changes.
Site / asset snapshot
Site context
20,000 PE works preparing to decommission an adjacent treatment stream
Main treatment
Carbonaceous SBR followed by downstream nitrifying filters
Project stage
Existing-asset assessment to inform rationalisation and future design options
Monitoring scope
Two temporary optimisers at the crude-sewage feed and SBR outlet
Process and monitoring points
Inlet and outlet monitoring captured changing load, SBR cycle behaviour and the duty passed to the downstream nitrifying filters.
Crude sewage*
Sbr feed
Sbr aeration**
Sbr settle
Sbr decant
Nitrifying filters
*incoming load
*SBR outlet performance and downstream filter loading
Project need
Primary driver
Inform closure of the adjacent works and define credible inputs for future design
Evidence gap
Periodic sampling could not capture cycle-by-cycle SBR behaviour or intermittent solids breakthrough
Why it mattered
A maintenance fault could be mistaken for inadequate process capacity and drive the wrong design response
BI-Zen delivery, evidence and decision informed
Live inlet and outlet evidence distinguished SBR performance from a correctable mechanical issue
Bi-zen delivery
Deployment
Two temporary optimisers at the SBR feed and outlet
Measured
COD, ammonia and turbidity, streamed through live dashboards
Aligned with
SBR operating and decant cycles, site flow and incoming load
Service provided
Rapid mobilisation, data assurance and wastewater process interpretation
Granular evidence: mlss breakthrough and sealing valve
Repeated outlet COD and turbidity peaks evidenced MLSS breakthrough during individual decant cycles.
What became clearer
High-frequency outlet monitoring captured repeated COD and turbidity peaks that conventional sampling could easily miss. The events aligned with individual decant cycles, showing intermittent solids carryover rather than a continuous loss of biological treatment. Inlet and outlet profiles also clarified the variable load reaching the downstream nitrifying filters.
Decision informed
The evidence focused the immediate response on the decanter sealing valve and associated maintenance before larger process changes were considered. It also strengthened the assessment of SBR performance, downstream filter duty and future design options for site rationalisation.