ETP Sludge from Solids, Coagulant and Biomass

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. The 11 inputs are read from the form on every keystroke: Effluent Flow, Suspended Solids In, Suspended Solids Out, COD In, COD Out, Coagulant Dose, Coagulant Sludge Factor, Biological Yield, Cake Moisture, Disposal Cost and Daily Fabric Production.
2. Each value is checked against the accepted range in the input table below. A value outside its range stops the calculation rather than producing a misleading figure — the results blank out and a message appears.
3. The validated values are substituted into the expression above, which resolves Wet Cake Generated together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Suspended Solids Removed, Coagulant Dosed, Chemical Sludge, COD Removed, Biological Sludge, Total Dry Solids, Removed Solids as a Share, Dry Sludge per m3 Treated, Dry Sludge per Tonne of Fabric, Disposal Cost and Disposal Cost per Tonne of Fabric — come from the same pass, so they always describe the same case as the headline figure.
5. Results are rounded for display only. The full-precision value is used throughout the chain, so reading a rounded intermediate figure back into the tool by hand can shift the last digit.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

The tool loads with this case already solved — the Wet Cake Generated shown above is its answer. Change one value and the difference from this baseline is the sensitivity of the result to that variable.

How to use it

1. Work through the input groups in order — Effluent and Treatment. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Wet Cake Generated in the dark results panel — that is the headline figure, expressed in t/day.
4. Check the supporting rows underneath (Suspended Solids Removed, Coagulant Dosed, Chemical Sludge, COD Removed, Biological Sludge, Total Dry Solids, Removed Solids as a Share, Dry Sludge per m3 Treated, Dry Sludge per Tonne of Fabric, Disposal Cost and Disposal Cost per Tonne of Fabric) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Process planning — establishing Wet Cake Generated before a trial is booked, so machine time and material in Sustainability, ETP & Utilities are committed against a calculated figure rather than an estimate.
• Costing and quotation — Wet Cake Generated is an input to the cost sheet, and quoting from a worked number rather than a remembered one is what keeps a margin intact.
• Troubleshooting — when the floor result drifts from plan, entering the measured values (starting with Effluent Flow) shows how much of the gap in Wet Cake Generated each variable explains.
• Teaching and study — the accepted ranges bracket normal Sustainability, ETP & Utilities practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Assumptions and limits

• The biological yield is quoted per kilogram of COD removed, which is the convention in textile effluent work and slightly overstates growth because part of the COD removed is stripped or adsorbed rather than metabolised; where the plant has a long sludge age, endogenous decay reduces the net yield substantially and the figure should be lowered rather than the model changed. A plant running extended aeration will generate materially less sludge than this default suggests, and that is one of the main reasons to run it. The coagulant sludge factor covers the metal hydroxide the coagulant precipitates as and not the coagulant mass itself; it varies with the product and with pH, and alum, ferric and polyaluminium chloride are not interchangeable in it. Cake moisture is the single largest lever on the number that gets paid for: moving from 78 to 72 percent cuts the wet tonnage by more than a fifth without changing a gram of dry solids, which is why press performance and conditioning polymer are worth more attention than they usually get. Nothing here addresses sludge classification, which in most jurisdictions is what actually sets the disposal cost - a sludge carrying heavy metals from a dyestuff or a fixing agent is a different waste stream at a different price.
• Every input is bounded to the range normal practice occupies (Effluent Flow 10 to 20000 m3/day, Suspended Solids In 10 to 5000 mg/L and Suspended Solids Out 0 to 500 mg/L, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Questions people ask