Planning Tool
Sludge Dewatering Polymer Cost per Dry Ton Calculator
Enter your sludge data and the polymer dose from your jar test or plant records to calculate polymer cost per tonne of dry solids and monthly chemical spend. Dose is never supplied by this tool — it must come from your site-specific operating data.
Formulas
Dry solids fraction = dry solids % ÷ 100
Dry solids (t/day) = wet sludge (m³/day) × density (kg/m³) × solids fraction ÷ 1,000
Polymer consumption (kg/day) = dry solids (t/day) × dose (kg/t DS)
Daily chemical cost = polymer (kg/day) × price (currency/kg)
Chemical cost per t DS = dose (kg/t DS) × price (currency/kg)
Monthly polymer cost = daily cost × operating days/month
Intermediate calculations retain full precision. Displayed values are rounded. Blank and zero inputs are always treated as distinct.
Your inputs
* Required. Polymer dose must come from your jar test or actual plant operating records — this tool does not recommend a dose.
Worked example
A plant receives 100 m³/day of sludge at 1,020 kg/m³. Dry solids are 2%. Operating data shows 5 kg polymer per tonne of dry solids. Polymer is priced at 3.20 USD/kg. Plant runs 30 days/month.
Dry solids = 100 × 1,020 × 0.02 ÷ 1,000 = 2.04 t DS/day
Polymer = 2.04 × 5 = 10.2 kg/day
Daily cost = 10.2 × 3.20 = USD 32.64/day
Cost/t DS = 5 × 3.20 = USD 16.00/t DS
Monthly cost = 32.64 × 30 = USD 979.20/month
The dose of 5 kg/t DS in this example comes from illustrative plant operating data. Your actual dose must be determined by jar test on your sludge.
Reading your results
Dry solids (t DS/day)
The mass of solids your dewatering system must handle each day. This is the basis for all polymer and cost calculations.
Polymer consumption (kg/day)
The amount of dry polymer required each day at your entered dose rate. Use this to plan procurement quantities.
Cost per tonne dry solids
The normalised polymer chemical cost independent of your sludge volume. Useful for comparing quotes at different price points or when your sludge volume varies.
Monthly polymer cost
The total polymer chemical spend for the month at your operating days and entered price. The most relevant figure for budget planning.
What this cost estimate includes and excludes
Included
- Polymer chemical cost only
- Calculated from your entered dose and price
Excluded
- Freight and import duty
- Labour and equipment
- Sludge disposal or transport
- Cake-solids performance guarantee
- Process-side savings or avoided costs
Validating your dose before you order
The dose you enter here should come from a jar test on your actual sludge or from current plant operating data. Applying an unvalidated dose risks over-dosing (cost) or under-dosing (poor dewatering). Common dose validation failures include:
- Using a dose from a different sludge type or feed concentration
- Extrapolating from a single data point without a jar-test curve
- Ignoring seasonal or upstream process changes that shift the optimal dose
- Changing polymer grade without re-running a jar test
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