Calculator
Editable inputs
| Constituent | Feed mg/L | Your screening marker mg/L, optional | Projected mg/L | Marker reached at recovery | Marker status | Remove |
|---|---|---|---|---|---|---|
Calculated outputs
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About this tool
Pushing recovery from 80% to 90% doubles the concentration of anything that stays in the brine. Enter a feed flow, target recovery and your constituents to see the concentration factor, projected concentrations and the recovery at which each screening marker is reached.
Markers are your own values, such as a permit limit, a lab limit or a design target.
Method and equations
CF = 1 / (1 − R)C_conc = C_feed × CFQ_residual = Q_feed × (1 − R)R* = 1 − C_feed / C_markerAssumptions
- Each constituent is a conservative solute: it stays entirely in the concentrate and none passes to the product water.
- Recovery R is the fraction of feed water recovered.
- Thresholds are markers you choose, such as a permit value, a lab limit or a design target.
Limitations
- CF = 1/(1 − R) is the ideal path. Real species can precipitate, complex, volatilise or pass the membrane and deviate from it.
- A crossed marker is not a scaling limit. Only call it one if a project-specific, validated limit has been entered.
- No saturation index, scaling or corrosion claim is made.
Worked example
At 80% recovery the concentration factor is 1 / (1 − 0.80) = 5×. At 90% it is 10×, at 95% it is 20× and at 98% it is 50×.
- Sulfate at 5,000 mg/L in the feed reaches 25,000 mg/L at 80% recovery.
- With a 20,000 mg/L marker entered, the marker is reached at R* = 1 − 5,000 / 20,000 = 75% recovery.
- For a 100 m³/h feed, the residual flow at 80% is 20 m³/h; at 95% it is only 5 m³/h but four times more concentrated.
The curve explains why final recovery increments cost so much more than the first ones, and why a project-specific chemistry review is needed before choosing a recovery target.
The calculator above opens with these default values. Use Reset to defaults to return to them.
Frequently asked questions
Why does concentration rise so fast at high recovery?
Because the denominator (1 − R) shrinks towards zero. Going from 90% to 95% halves the remaining water and doubles the concentration of every conservative solute.
Is a crossed threshold a scaling limit?
No. It only shows that the ideal projected concentration has reached the number you typed in. Whether a mineral actually scales depends on speciation, temperature, pH, kinetics and antiscalant, which need a proper model.
Does this work for silica or calcium?
It shows the ideal concentration path for any conservative solute. Reactive species such as silica, calcium and carbonate often deviate, so treat their projections as upper-bound screening numbers.
What recovery should I target?
That is a project decision driven by feed chemistry, technology, disposal route and cost. This explorer shows the trade-off; it does not pick the number.
Related ZLD guide chapters
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Brine Consulting screening tool. Results are not a design guarantee, vendor guarantee, regulatory determination or detailed process design, and do not replace project-specific modelling, pilot testing or professional engineering review.