Step 1 of 8
Setup
Getting started
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This tool sizes and assesses hollow-fibre UF/MF membrane plants, pressurised or submerged. It gives guidance only. Work through the eight steps in order:
- Setup: design a new plant or assess an existing one, the membrane type and the plant identification.
- Configuration: trains, redundancy and module geometry, which set the membrane area.
- Operating: flows, temperatures, recovery and feed water.
- Cycles & Cleaning: backpulse, chemically enhanced backwash, clean-in-place and integrity test schedules, giving the in-service factor.
- Capacity & Redundancy: water balance, flux at each flow and the outage scenarios.
- Integrity (LRV), Fibre Repairs and Report & Save (Premium): pressure-decay LRV and DWQAR check, the repair log and map, and exports.
Pick a module template beside the model name, or under Settings, to fill in geometry and test pressures. Model basis, assumptions and references are in About this model.
Plant identification
Shown on the report and in file names.
Optional; shown on the report.
Optional, e.g. 2018.
Optional; for the record.
Pick a template to fill in geometry and test pressures, or type your own model name. Create and manage templates under Settings.
μm
MF about 0.1 to 0.2 µm; UF about 0.01 to 0.05 µm.
The pathogen group the integrity test protects against.
Live summary
New Plant
— enter configuration to see summary —
Clean start: fields are intentionally blank so you can enter your own plant.
Method timings (backpulse, chemical backwash and clean-in-place intervals) carry typical defaults you can change on the
Cycles tab. Membrane constants (surface tension, contact angle, pore factor) are under Settings.
Step 2 of 8
Configuration
Guide: using this tab
Define the physical plant: how many trains, the redundancy philosophy, and the module geometry
that sets total membrane area. The tiles show area per train, total area, and the flux your
configuration produces at design and peak flow so you can check it against the module's flux ceiling.
- Redundancy N+1 keeps full output with one train out; N+2 with two out.
- Layout depends on type. Pressurised is train → modules: modules sit side by side in the rack, so you set modules per train and how many rows they form. Submerged is train → cassettes → modules: cassettes are not side by side, so you set cassettes per train and modules per cassette. The repair map draws each accordingly. Membrane area follows from the effective modules per train × area per module.
Train layout
trains
Including standby trains, typically 2 to 12.
Trains kept spare, outside the duty count.
mod
Pressurised: modules per rack / train.
cass
Submerged: cassettes in each cell, typically 1 to 8.
mod
From the supplier, typically 16 to 64.
m²
From the supplier datasheet, typically 30 to 80 m².
rows
Pressurised only: how modules sit side by side in the rack (e.g. 2 or 4 rows). Drives the repair map layout.
L
Wetted volume per direct-integrity-test unit (submerged: usually one cassette).
Design limits
LMH
Supplier or approval limit, typically 40 to 100 LMH.
kPa
Supplier limit: submerged about 50 to 80 kPa, pressurised 150 to 300 kPa.
LMH/bar
Lowest acceptable permeability at 20 °C, typically 80 to 250 LMH/bar.Configuration summary
Trains in service
Amber and red flags are prompts to look, not instructions to act.
Step 3 of 8
Operating envelope
Guide: using this tab
Enter the flow, temperature and feed-water envelope. Minimum, average and peak flows drive the
flux scenarios; the temperature range feeds the viscosity normalisation to 20 °C. Feed
turbidity and solids are recorded as the fouling context for the plant. Recovery sets the volumetric
concentration factor used in the LRV calculation.
Flow & Recovery
m³/d
Lowest daily permeate flow.m³/d
Average daily permeate flow.m³/d
Highest daily permeate flow.%
Design overall recovery. Sets the concentration factor (VCF) for the integrity calculation. The Capacity tab computes the achieved net recovery from the cleaning regime.
Temperature & feed water
Condition
°C
Coldest feed water; used with peak flow.°C
Typical feed temperature; used with average flow.°C
Warmest feed water; used with minimum flow.NTU
Typical feed turbidity, e.g. 0.5 to 10 NTU.NTU
Highest event turbidity the plant must handle.mg/L
Blank = estimate from turbidity.
Treatment ahead of the membranes.
mg/L
Typically 1 to 10 mg/L.mg/L
Iron plus manganese, typically below 0.3 mg/L.Step 4 of 8
Cycles & cleaning
Guide: using this tab
Set the backpulse, chemically enhanced backwash, clean-in-place and membrane integrity test
schedule. The tool converts these into per-train downtime and an in-service factor, which reduces
net flux and available output on every other tab. Backpulse is triggered by elapsed time or by a TMP setpoint.
- Effect on production — this is what decides whether an activity is counted as lost output. Choose train offline (the usual case) when the train stops making water for the duration, so the time is subtracted from availability. Choose covered by standby only when a spare train picks up the flow, so the plant keeps producing and no output is lost. It changes the in-service factor, not the work itself.
- Chemically enhanced backwash — a short chemical dose during a backwash, between full clean-in-place events. Turn it off if the plant backwashes with water only.
Feed condition
Backpulse / backwash
min
Run between backpulses, typically 15 to 60 min.kPa
TMP that starts an early backpulse; for the record.sec
Typically 20 to 60 s.×
Backpulse flux divided by filtration flux, typically 1 to 2.sec
Typically 0 to 30 s.Nm³/h
Submerged only, per cassette; for the record.Membrane integrity test
/day
Per train. DWQAR requires at least 1/day.
min
Typically 10 to 30 min.
Choose “covered by standby” only if a spare train carries the flow, so plant output is unaffected.
Chemically enhanced backwash
Plant uses a chemically enhanced backwash
Turn off if the plant runs water-only backwashes between clean-in-place events. Suppliers use many names for this step (CEB, MC, maintenance clean, chemical wash) — they all mean a short chemical dose during a backwash.
hr
Typically 12 to 168 hr.min
Typically 15 to 60 min.
Caustic-oxidant is usually hypochlorite; its vapour corrodes plant-room metalwork.
Clean-in-place (CIP)
days
Typically 30 to 90 days.hr
Typically 4 to 8 hr.
Choose “covered by standby” only if a spare train carries the flow during the clean.
Downtime & in-service factor
Amber and red flags are prompts to look, not instructions to act.
Step 5 of 8
Capacity & redundancy
Guide: using this tab
Two linked questions in one place: how the plant performs at its design point, and whether it holds
output when trains drop out for cleaning.
- Water balance — daily feed, reject, cleaning volumes and net recovery.
- Flux & permeability — gross flux (while filtering, checked against the max) vs net flux (daily average delivered), and specific flux normalised to 20 °C, at the normal active-train count. Gross flux and redundancy both account for the in-service factor, so they tighten under the dirty-source condition (more backwashing and cleaning). The status column flags capacity limits and permeability loss; a key is shown under the table.
- Redundancy — gross flux (accounting for cleaning downtime) under simultaneous backwash, chemical backwash, clean-in-place and membrane integrity test outages at worst-case cold, with a pass/fail verdict against the flux ceiling. More frequent cleaning (dirty source) raises the flux and tightens the verdict.
Feed condition
Daily water balance
Flux & permeability: normal operation
At the active-train count for the selected redundancy. Gross flux is the flux while filtering (checked against the max design flux); net flux is the lower daily average actually delivered. Because the plant is offline for cleaning part of the time, gross flux rises as cleaning becomes more frequent — so it increases under the dirty-source condition. Specific flux is normalised to 20 °C for season-to-season comparison.
Reading the status:
- OK — gross flux and permeability are within your design limits.
- Near limit — gross flux is above 90% of the maximum design flux; little headroom for a turbidity event or a train outage.
- Flux > max — gross flux (while filtering, after allowing for cleaning downtime) exceeds the maximum design flux. This is a hydraulic capacity problem: add area (modules/cassettes), add a train, reduce the flow this case represents, or reduce cleaning frequency.
- Low perm. — the specific flux (flux per unit of TMP, normalised to 20 °C) has fallen below your minimum specific-flux floor. The plant may still pass the flux limit, but the membrane now needs more pressure than expected to make its flow. It points to fouling, incomplete cleaning recovery, or membrane ageing rather than a sizing problem — check the TMP trend, CIP effectiveness, and feed-water quality. If it persists at design flux, achievable capacity is being eroded and cleaning or replacement is due.
Redundancy: outage scenarios
Amber and red flags are prompts to look, not instructions to act.
Step 6 of 8
Integrity (LRV)
Guide: using this tab
Pressure-decay integrity testing to the USEPA Membrane Filtration Guidance Manual (LT2ESWTR). Enter
your test pressures and the measured decay rate; the tool returns the log-removal value (LRV) and, for
each target credit, the maximum allowable decay rate — your 4-log alert threshold. It
also back-calculates the smallest detectable defect and the test pressure needed for your target resolution.
- Vsys and Qp must be at the same physical level — both per test unit (e.g. per cassette) or both per train.
- Membrane constants (surface tension, contact angle, pore shape factor) are under Settings.
- The DWQAR 2026 (T3.PM) compliance panel below checks 3 µm resolution, daily testing, the claimed protozoa credit and the current pass/fail against NZ rules. (The rules call this a “direct integrity test”.)
Integrity test parameters
kPa
Applied test pressure, typically 50 to 250 kPa.kPa
Highest filtrate-side back pressure, typically 10 to 30 kPa.kPa
Operating TMP when tested, typically 20 to 100 kPa.°C
Water temperature during the test.μm
3 µm for protozoa credit (T3.PM.4c).log
Credit claimed, up to 4 log for protozoa.kPa/min
From the latest test, typically 0.05 to 0.5 kPa/min.min
Typically 5 to 10 min.m³/d
Blank = average flow ÷ active trains. Override to match the level at which Vsys is measured.
Integrity result
Alert thresholds
DWQAR 2026 (T3.PM) compliance
Amber and red flags are prompts to look, not instructions to act.
Step 7 of 8
Fibre repairs
Guide: using this tab
A running record of pinned or repaired fibres, with a visual map by train and module. Log each repair
as you make it; the map shades every module by the number of fibres repaired, so recurring damage stands
out at a glance. Pinned fibres are a small permanent loss of area and a common driver of gradual integrity
decline — tracking them supports your integrity programme and cleaning/replacement decisions.
Set your supplier’s repair limit per module under Settings; modules are flagged as they approach it and again once it is reached.
Log a repair
Day the repair was made.
Train repaired.
Cassette in that train.
Module position, counted from 1.
Fibres pinned or repaired, 1 or more.
How the fibre was sealed.
What found the leak.
Optional work order or technician.
Optional.
Repair map
Repair log
Amber and red flags are prompts to look, not instructions to act.
Step 8 of 8
Report & Save
Guide: using this tab
The single place to get data out of the tool. Choose the sections you want, then export a formatted
PDF report or a CSV of inputs and results. Save writes a JSON file of everything to
your downloads folder; Load restores it later. Nothing is uploaded anywhere — all
files stay on your device. To start again with a blank model, use Clear all at the foot of Setup.
Sections to export
Export
Save & Load
Save the full model — all inputs, settings and custom templates — as a JSON file you can archive or share. Load it back to pick up exactly where you left off.