How do textile dyeing units count wastewater and ETP sludge sent to a common effluent treatment plant in Scope 3?

Effluent a dyeing unit sends to a common effluent treatment plant (CETP), and ETP sludge sent to a disposal facility, both go in Scope 3 Category 5. Build the line from three parts: methane from the COD you send, your share of the CETP's energy, and the sludge tonnes and trips on each disposal manifest.

The three parts of a dyeing unit's Category 5 line

Anything treated inside your own fence, such as a primary ETP before the CETP line, is Scope 1 and Scope 2, not Category 5.

• Effluent methane: from the organic load (COD) in what you send, at the CETP's treatment type. The method is on the linked CETP page; this page shows how it fits with the other two parts.
• CETP energy: your share of its electricity for aeration, pumping and, at zero liquid discharge plants, evaporators. The Scope 3 Standard puts a waste supplier's Scope 1 and Scope 2 in Category 5, and at a well run aerobic CETP this is often the largest part.
• ETP sludge: treatment or disposal emissions at the facility that takes it, plus, optionally, the tanker or truck trips that carry it if they are not already in another category.

Counting ETP sludge

Chemical sludge from textile ETPs is usually handled as hazardous waste under India's Hazardous and Other Wastes Rules, 2016, and goes to a treatment, storage and disposal facility (TSDF) or to a cement kiln for co-processing. Take the tonnes from each manifest. Chemical sludge holds little degradable organic carbon, so methane from a secure landfill is low; the larger items are often the transport and the disposal site's own energy. Use a factor for the specific waste type and route, and say where it comes from.

Splitting the CETP's energy to your unit

1. Ask the CETP society for its annual electricity and fuel use and its total inflow in kL.
2. Divide to get kWh per kL, then multiply by your kL from the CETP bills or your outlet flow meter.
3. If the CETP charges by pollution load as well as volume, ask whether its energy follows load, and use the same key it bills you on.
4. Apply the grid factor to the kWh, and keep the CETP's letter or report as the source.

When the CETP publishes nothing

Most CETPs do not publish their treatment stages or energy per kL. State your assumed correction factor and energy use, and show the line at a low and a high assumption so a reader can see how much the answer depends on them. Ask again each year; one real figure from the CETP narrows the range more than any default.

Worked example: one dyeing unit's full Category 5 line, as a range (assumed values)

• Effluent: 120 kL a day x 300 working days = 36,000 kL a year
• COD at outlet: 2,000 mg per litre = 2 kg per kL (assumed); organic load 36,000 x 2 = 72,000 kg COD
• Methane, low case (well run aerobic CETP, correction factor 0): 0 t
• Methane, high case (overloaded aerobic, factor 0.3): 72,000 x 0.25 x 0.3 = 5,400 kg CH4 x 27 (IPCC AR6, non-fossil methane) = 145,800 kg, about 146 t CO2e
• CETP energy at an assumed 4 kWh per kL: 36,000 x 4 = 144,000 kWh x 0.710 kg CO2 per kWh = 102,240 kg, about 102 t CO2
• Sludge trips: 180 t a year in 10 t loads = 18 trips x 300 km round trip = 5,400 km / 4 km per litre (assumed) = 1,350 L x 2.68 kg CO2 per L = 3,618 kg, about 3.6 t CO2
• Category 5 line: about 106 t (low) to about 252 t (high), before disposal-site emissions for the sludge

COD, the correction factor, kWh per kL and truck fuel use are assumptions. The disposal site's own emissions need a sourced factor for the waste type and route and are left out here.

What Senseible does here

Senseible keeps CETP bills that print kilolitres, and sludge transport invoices, as evidence in the Scope 3 trail, and reads your own ETP's electricity from your bills into Scope 2. The COD and methane arithmetic uses your lab data and the CETP's process details.

• Methane from an ETP you run yourself
• CETP effluent: which scope?
• Hazardous waste emissions from a manifest
• ZLD plant energy per kL

Sources: GHG Protocol Technical Guidance for Calculating Scope 3 Emissions (2013), Category 5, 2006 IPCC Guidelines, Volume 5, Chapter 6 (wastewater treatment and discharge), IPCC AR6 WG1, global warming potentials

Last reviewed 2026-10-17. The result depends on assumed CETP treatment and energy data; replace assumptions when the CETP publishes figures.