List the compounds you need PAC to remove. Pick from the library or add a custom one, then set the raw-water concentration (C₀) and your target (C target). The tool finds the PAC dose for each and the controlling (worst-case) contaminant drives the design.

Choosing C₀ (raw water): use a realistic event concentration — a bloom peak for cyanotoxins, a seasonal high for taste & odour, or your worst measured pesticide detection. If you don't have data, the library defaults are conservative typical values, not site measurements.

Choosing C target (treated water):

• Cyanotoxins & pesticides — set below the relevant health limit. Defaults use NZ provisional MAVs where they exist (e.g. microcystins ≈ 1.2 µg/L, cylindrospermopsin ≈ 1.0 µg/L, anatoxin-a ≈ 6 µg/L, atrazine/simazine ≈ 2 µg/L). WHO guideline values differ in places (e.g. cylindrospermopsin 0.7 µg/L). Design to a margin below the limit, not at it. Verify the current MAV against the Taumata Arowai / DWQAR 2026 schedule before use.
• Geosmin & 2-MIB — no health MAV; these are aesthetic. The target is set by human detection: sensitive consumers (super-tasters) detect both at roughly 5–10 ng/L. So aim for C target < 10 ng/L — the defaults use 5 ng/L to sit safely below the odour threshold.

Switch the concentration unit (mg/L · µg/L · ng/L) in ⚙ Settings. ng/L is the natural unit for taste & odour.

Turns the controlling dose into a practical design package: PAC mass flow, slurry feed rate, annual tonnage and cost, plus a dosing-point check.

• Design dose — controlling contaminant dose × safety factor.
• Mass & feed — converts dose and flow to kg/h and the slurry feed rate at your slurry strength, plus feed rate per mg/L of dose so you can size the metering pump across your operating range.
• Cost — indicative carbon cost per ML treated and per year. Excludes sludge handling and labour.
• Dosing-point check — flags whether the chosen point gives enough contact time to approach equilibrium.

Shows how a compound's required dose responds to the variables you can least pin down. Pick which compound to examine at the top (it defaults to the controlling one, but you can check any of them). The dashed crosshair marks the current operating point, labelled with its dose and value; hover any curve for point values.

• vs contact time — how much dose you save with more contact (the kinetic benefit).
• vs DOC — sensitivity to NOM competition; steep curves mean calibration matters most.
• vs % removal — cost of pushing to a tighter target.
• vs particle size — finer carbon vs dose trade-off.

Fit the Freundlich isotherm (K_f and 1/n) to your own jar-test data. Enter each jar's PAC dose, starting concentration and the residual measured after contact. The tool computes loading q = 1000·(C₀ − C_e)/D and fits the isotherm in log-log space.

• Two or more jars — fits both K_f and 1/n by regression and reports R².
• One jar — fixes 1/n at the assumed value and back-calculates K_f.

The single place to export, save and reload your work. Nothing is exported automatically — you choose what goes in.

• PDF report — opens your browser's print dialog. Choose "Save as PDF". For a clean output, turn off "Headers and footers" in the print dialog and leave margins at default.
• CSV — downloads the selected tables as comma-separated data for Excel.
• Save project (JSON) — writes every setting and result to a .json file in your downloads. Load project reads one back in to pick up where you left off.