Feedwater Chemistry • Qualitative Treatment Guidance

Water Analysis & Treatment Selection

Enter the feedwater analysis once. The surface derives the parameters that do not need a model — hardness, cation–anion charge balance, TDS by summation, ionic strength — and, when the chemistry is complete, reuses the platform’s saturation-indices engine (LSI/RSI). The second panel maps observed water-quality drivers to candidate unit operations already built here; it is a starting point for verification, never a thresholded diagnosis.

Feedwater analysis

Optional fields only narrow the picture. Nothing is inferred from absent values — a field left blank simply skips the derivation it would enable.

TDS (mg/L) pH Temperature (°C) Calcium, Ca (mg/L) Magnesium, Mg (mg/L) Sodium, Na (mg/L) Potassium, K (mg/L) Bicarbonate, HCO₃ (mg/L) Carbonate, CO₃ (mg/L) Chloride, Cl (mg/L) Sulfate, SO₄ (mg/L) Calcium (as CaCO₃, mg/L) — for LSI/RSI Alkalinity (as CaCO₃, mg/L) — for LSI/RSI

Treatment selection ladder

Each driver is matched to the unit-operation surfaces already running on the platform, with the engineering step that must be verified (jar test, pilot, membrane projection, governing standard).

Elevated TDS / salinity on a brackish or seawater feed

Reverse osmosis separation

Brackish and seawater desalting is an RO application space. Confirm feed characterisation, recovery target and concentrate disposal route with the owning authority and a membrane projection.

Suspended solids / particulate fouling risk ahead of a membrane train

Ultrafiltration as upstream protection

Assemble UF ahead of RO in the treatment train, then verify SDI/turbidity performance with pilot or full-scale data and the membrane supplier.

CaCO3 / scaling tendency flagged by LSI or RSI output

Thermodynamic check and antiscalant dosing pathway

A scaling indication flags the need to manage the concentrate thermodynamics — antiscalant, acid or softening route selected against the actual salt system, not a rule-of-thumb.

Microbial / disinfection objective

Disinfection contact-time (Ct) accounting

Disinfection Ct workbook

Validate the disinfectant and its contact-time capacity against the governing potable water standard for the jurisdiction.

Trace organics or selective hardness removal

Nanofiltration or ion exchange separation

NF and IX are application-specific separations; confirm the target constituent and the resin/membrane specification with laboratory or manufacturer data.

Whole-plant configuration and water conservation

Plant-level mass balance and design path

Develop the plant-wide water and salt balance first, then iterate stage recovery and make-up against the verified feedwater analysis.

Method and references

Hardness = 2.497·Ca + 4.118·Mg (mg/L as CaCO₃) — the standard calcium/magnesium conversion factors.
Charge balance uses equivalent weights (Ca 20.04, Mg 12.15, Na 22.99, K 39.10 mg/meq; HCO₃ 61.02, CO₃ 30.00, Cl 35.45, SO₄ 48.04 mg/meq).
Ionic strength and LSI/RSI reuse the platform’s scaling-risk.ts / saturationIndices.ts engines — no constants are duplicated.
Cation–anion balance within ±5 % is a widely used acceptability guideline (e.g., Standard Methods practice for validating analyses); treat deviation as a trigger to re-check the analysis, not a quality verdict.
The treatment ladder points to genuine platform surfaces and carries no numeric cut-offs.

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