Interactive Calculator · 2026
Sludge Generation Calculator
Estimate how much sludge your sewage treatment plant produces. Enter the flow, inlet and outlet BOD and a sludge yield — get the dry sludge in kg/day, the number every sludge-handling and disposal plan starts from.
Dry sludge mass (kg/day) vs wet sludge volume (m³/day)
Your plant
Average daily flow treated by the STP.
Raw sewage strength entering the plant.
Treated effluent BOD — CPCB norm ≤ 10 mg/L.
Sludge produced per kg BOD removed — typically 0.5–1.0 by process.
Dry mass vs wet volume
The plant produces 23.2 kg of dry solids a day, which at ~1% solids fills 2.3 m³ before dewatering.
Dry sludge is the true solids load your handling train must stabilise and dispose of. Wet volume is what you actually pump and store before thickening and dewatering.
Dewatering to 20–25% solids shrinks that wet volume roughly twenty-fold — the single biggest lever on disposal cost and transport.
How this is calculated
- BOD removed = flow × (inlet BOD − outlet BOD) ÷ 1000 = 100 × (300 − 10) ÷ 1000 = 29 kg/day.
- Dry sludge = BOD removed × yield = 29 × 0.80 = 23.2 kg/day.
- Wet sludge volume = dry sludge ÷ 10 (≈1% solids, 10 kg/m³) = 23.2 ÷ 10 = 2.3 m³/day.
Indicative sludge estimate for concept planning. Actual production varies with process type, sludge age, inert solids and primary settling — confirm with a qualified consultant before sizing sludge handling.
Related Guides — Deep-dive reading
Sludge Generation Estimation in STPs: How Much Sludge Will Your Plant Produce?
Every STP that cleans water also makes sludge — and the biosolids you forget to plan for become the operating headache you cannot ignore. Here is how to estimate sludge generation, understand the yield concept, and size dewatering before you build.
Sewage Treatment PlantsSTP Sludge Removal & Disposal: A Practical O&M Guide for Operators
How to waste sludge on schedule, dewater it on drying beds or a filter press, dispose of or reuse it safely, and keep the compliance records that inspectors ask for — written for the people who actually run building STPs in India.
Sewage Treatment PlantsHow to Size an STP: A Step-by-Step Method (With Worked Example)
The complete sizing methodology for a domestic sewage treatment plant — from headcount and LPCD to sewage generation, peak flow and tank-by-tank volumes — worked end to end with an Indian apartment example.
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