| Scenario | Flow | Hours | Solids | Dose basis | Active | Solution | Product polymer | Solution volume |
|---|---|---|---|---|---|---|---|---|
| Municipal WAS | 50 m3/h | 16 h/day | 2.5% | 12 lb/metric ton DS | 100% | 0.25% | ~36 kg/day | ~14,400 L/day |
| Industrial mixed sludge | 200 gpm | 24 h/day | 1.2% | 6 g/kg DS | 40% | 0.30% | Depends on density and margin | Depends on strength and batches |
- Daily volume V = Qm3/h x hoursday
- Dry solids DSkg/day = Vm3/day x rho x (Solids% / 100)
- Dose mg/L Activekg/day = Dosemg/L x VL/day / 1,000,000
- Dose g/kg DS Activekg/day = (Doseg/kg / 1000) x DSkg/day
- Dose lb/ton DS Activelb/day = Doselb/ton x DSton/day; convert lb to kg
- Safety factor Activeadj = Active x (1 + Safety% / 100)
- Product mass Productkg/day = Activeadj / (Active% / 100)
- Solution volume SolutionL/day about Product / (Strength% / 100)
- Batches Batches/day = SolutionL/day / TankL
- Enter sludge flow, operating hours, solids percentage, and density.
- Select your dose basis to match jar test reporting.
- Enter polymer active content and add a safety factor if needed.
- Set your make-down strength and batch tank volume for mixing.
- Add the polymer unit price to estimate daily chemical cost.
- Press Calculate to view results above the form.
- Use Download CSV or Download PDF to store records.
1) Why polymer planning matters in dewatering
Polymer conditioning is a major driver of cake solids, centrate clarity, and equipment throughput. Plants typically evaluate dose during jar testing, then translate that number into daily consumption for the belt press, centrifuge, or filter. A small dose increase can stabilize capture, but it also raises chemical cost and make-down demand. This calculator converts your chosen dose basis into consistent daily mass and solution volume for practical planning.
2) Converting flow and solids into dry solids load
Dewatering demand is best compared on a dry solids basis. The calculator estimates daily dry solids using treated volume, sludge density, and influent solids percentage. For example, 50 m3/h for 16 hours at 2.5% solids and 1030 kg/m3 produces roughly 20,600 kg DS/day. That load is the anchor for dose normalization and for comparing different sludge sources across seasons.
3) Interpreting common dose units
Jar tests often report dose as lb per ton dry solids, g per kg dry solids, or mg per liter of sludge. Each unit is valid, but the operational meaning differs. Dry solids based dosing tracks capture performance when feed strength varies. Volume based dosing is useful for flow-paced pumps. The calculator back-calculates equivalent values in all three units after applying your safety factor.
4) Make-down strength, batching, and dilution water
Polymer is typically prepared at 0.1 to 0.5% strength to protect mixing equipment and improve activation. Solution strength directly sets make-down volume. At 0.25% strength, every 1 kg of product needs about 400 L of solution. The calculator estimates daily solution volume, dilution water, and batches per day based on your tank size so operators can schedule mixing without starving the feed system.
5) Cost control and practical verification
To support budgeting, the tool multiplies product mass by a unit price in kg or lb. Compare scenarios by adjusting safety factor, active content, and strength. Verify results by checking that solution volume aligns with pump capacity and that product per batch fits feeder limits. Track trends weekly; polymer demand commonly shifts with temperature, upstream process changes, and sludge age.
1) Which dose basis should I choose?
Use the same basis your jar test or vendor report provides. Dry solids based dosing is best for comparing sludges, while mg/L is convenient for flow-paced feed pumps and fixed hydraulics.
2) Why does active content change the result?
Active content converts required active polymer into product mass. Emulsions and solutions contain water and carriers, so a lower active percentage means more product must be purchased and prepared.
3) What does the safety factor represent?
It adds operational margin for variability in sludge, mixing, aging, and instrument drift. Many sites start with 5 to 15% and refine using weekly consumption and performance logs.
4) Is solution volume the same as dilution water?
No. Solution volume includes both polymer product and added water. The calculator reports makeup water separately as solution volume minus product mass, assuming about 1 kg per liter for solution density.
5) How do I size the batch tank?
Choose a tank volume that keeps batches per day manageable and matches operator coverage. Many facilities target 1 to 4 batches per day with stable mixing and aging time.
6) Can I use this for multiple dewatering trains?
Yes. Run separate scenarios for each train or blend by using the combined flow and solids. Export CSV to document each train and compare daily consumption and costs.
7) Why do my field numbers differ from the estimate?
Differences come from density assumptions, solids variability, polymer aging, overdosing for clarity, and equipment condition. Update density and solids with measured values and keep the same dose basis used in testing.