Biogas Yield Calculator
Find out how much biogas and electricity your industrial wastewater can generate. Enter your flow, COD, and anaerobic stage parameters to calculate daily biogas yield, electricity potential, and annual savings.
Enter Your Wastewater Parameters
Typical for high-strength industrial effluent with anaerobic treatment.
Turning Wastewater into Energy: The Biogas Opportunity
High-strength industrial wastewater from breweries, distilleries, dairy plants, and food processing units is a valuable feedstock for biogas production. When this effluent is treated in an anaerobic reactor — typically a UASB (Upflow Anaerobic Sludge Blanket) or CSTR (Continuous Stirred Tank Reactor) — the organic compounds (measured as COD) are converted into methane and carbon dioxide by anaerobic bacteria.
The theoretical yield is 0.35 m³ of methane per kg of COD removed. For a 500 KLD brewery with inlet COD of 3,000 mg/L and 65% anaerobic COD removal, this translates to over 340 m³/day of methane — enough to generate 1,200 kWh/day of electricity. At ₹9/kWh, that is over ₹39 lakhs per year in energy savings from waste that would otherwise need costly aerobic treatment.
Which Industries Benefit Most from Biogas Recovery?
Not all industrial wastewater is suitable for biogas recovery. The key criterion is COD concentration — biogas generation becomes economically viable when inlet COD exceeds approximately 1,500 mg/L. Industries with high-COD, readily biodegradable wastewater are the best candidates:
- Brewery & Distillery:BOD 1,500–8,000 mg/L. Excellent biogas potential. UASB is industry standard.
- Dairy:BOD 1,000–3,000 mg/L. Good potential, but fat content requires DAF pre-treatment.
- Sugar & Molasses:BOD 2,000–10,000 mg/L. Very high potential; UASB + biogas is mandatory in India.
- Food Processing:BOD 600–2,000 mg/L. Marginal to good depending on product.
UASB vs CSTR: Choosing Your Anaerobic Reactor
UASB (Upflow Anaerobic Sludge Blanket) reactors are the most widely used technology for industrial wastewater in India. They handle flows from 50 to 5,000+ KLD efficiently, achieving 60–80% COD removal at hydraulic retention times of 4–8 hours. UASB capital costs are moderate (₹5–10 lakhs per KLD) and the technology is robust and proven.
For very high COD loads (>10,000 mg/L) or effluent with high suspended solids, a CSTR (Continuous Stirred Tank Reactor) or Anaerobic Contact Reactor may be more appropriate. For maximum biogas yield from mixed solid-liquid streams (e.g., spent grains + process water), a plug-flow digester or two-stage system is preferred. Spans designs and supplies anaerobic systems across all these configurations.
Biogas Utilisation Options
Biogas generated from industrial ETPs can be utilised in three main ways: (1) Direct combustion for process heat — the simplest and most efficient option; (2) Electricity generation via a gas engine generator (35% efficiency), suitable where the plant has significant electricity demand; or (3) Compressed Biogas (CBG)— purified and compressed to CNG quality, which can be sold commercially or used as vehicle fuel. Spans offers complete biogas recovery systems including gas collection, scrubbing, storage, and utilisation equipment under our Compressed Biogas solutions portfolio.
Frequently Asked Questions
How much biogas can be generated from industrial wastewater?
Approximately 0.35 m³ of methane per kg COD removed. For a 500 KLD brewery at COD 3,000 mg/L and 65% removal, expect ~340 m³/day methane or ~524 m³/day total biogas.
What is a UASB reactor?
UASB (Upflow Anaerobic Sludge Blanket) is a high-rate anaerobic reactor where wastewater flows upward through anaerobic bacteria that break down organic matter and produce biogas. Industry-standard for brewery, dairy, and food plant ETPs.
Can biogas from an ETP power a generator?
Yes. 1 m³ methane produces ~3.5 kWh at 35% gen-set efficiency. A 1,000 KLD brewery ETP can generate enough biogas electricity to cover 40–70% of total ETP energy needs.
What COD removal is achievable in a UASB reactor?
60–80% for readily biodegradable wastewater (brewery, dairy, food). Below 25°C, performance drops significantly. Pharma/textile wastewater with refractory COD may only achieve 40–55%.
Does Your Plant Qualify for Biogas Recovery?
Not every ETP is configured for biogas capture. Let our team assess your wastewater profile, anaerobic potential, and the business case for adding a UASB or upgrading your existing anaerobic stage.