How much electricity does a tannery effluent plant use for each kilogram of organic load it removes?

The European tanning reference document gives about 1 kilowatt hour (kWh) per kilogram of biochemical oxygen demand (BOD) removed by an oxidation ditch, and 0.3 to 0.5 for conventional activated sludge. A tonne of raw hide produces about 100 kilograms (kg) of BOD, so a rough check on a plant's power can be made from hide tonnes.

Three printed figures, per kilogram of BOD removed

• Oxidation ditch: about 1 kWh per kg of BOD (five-day test) eliminated. Retention time of at least 4 days; properly operated, it may discharge below 20 milligrams per litre of BOD.
• Conventional high-rate activated sludge: about 0.3 to 0.5 kWh per kg. Retention of six to twelve hours usually suffices.
• Extended aeration or low-load activated sludge, one to three days retention: more than 1 kWh per kg.
• The document adds that the electricity for biological treatment may be more than 50% of the whole effluent plant's energy.

How much load a tonne of hide brings

The document says one tonne of raw hide generates 15 to 50 cubic metres of effluent containing about 250 kg of chemical oxygen demand (COD) and 100 kg of BOD. Its input and output chart prints COD of 230 to 250 kg and BOD of about 100 kg.

At the ditch's reachable 20 milligrams (mg) per litre, 15 to 50 cubic metres leaves 0.3 to 1.0 kg of BOD in the discharge (20 grams per cubic metre x 15 to 50). So the amount eliminated is about 99 kg of the 100, and 100 kg is close enough for an estimate. That subtraction is my arithmetic.

Which scope

Electricity for your own effluent plant is already in your electricity bill, so it is Scope 2. Charges to a shared plant are a different line; see the common effluent plant page. Do not count the same kWh twice by adding an estimate on top of the bill.

Use it as a check, not a replacement

If the plant has its own meter, compare the meter with the estimate. A large gap usually means the load per tonne of hide at your tannery differs from the document's, or that the plant is run at a different retention time. The 100 kg is a figure for a conventional process from older work, not for your hides.

Example: 80 tonnes of raw hide a month

• Load: 80 x 100 = 8,000 kg of BOD
• Oxidation ditch at 1 kWh per kg: 8,000 kWh. Conventional activated sludge at 0.3 to 0.5: 2,400 to 4,000 kWh
• Emissions at 0.675 kilograms of carbon dioxide (CO2) per kWh for financial year (FY) 2025-26: 5,400 kg for the ditch, 1,620 to 2,700 kg for conventional

The 80 tonnes is an example. The document does not say whether pumping and sludge handling are included.

What Senseible does here

Senseible reads fuel invoices and electricity bills into records by billing period, so the effluent plant's electricity is in the bill you can compare with this estimate. It does not meter the plant or measure BOD.

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Sources: European Commission, Integrated Pollution Prevention and Control (IPPC) Reference Document on Best Available Techniques for the Tanning of Hides and Skins, February 2003 edition (filed by the publisher as superseded), CEA, CO2 Baseline Database for the Indian Power Sector, version 22.0, GHG Protocol Corporate Standard

Last reviewed 2026-11-06. Figures are from the February 2003 edition of the European tanning reference document, which the publisher files as superseded; its energy and effluent tables rest on European tanneries and on older studies. Check the current edition and your own records before you quote a number to a buyer.