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Commission the biogas digester and set up gas safety

A new digester needs time to build up its microbes, and the household needs gas safety rules before the first flame.

How

1. Fill with the starter slurry recommended by the manufacturer and feed daily as instructed.
2. Expect first gas after about 3 weeks in warm climates and up to 1.5 to 2.5 months in cold ones (one manufacturer's figures).
3. Do not overfeed: it drops the pH, raises carbon dioxide and gives no flame. Keep citrus, cooking oil, sand, soil, woody material and manure from animals treated with antibiotics in the past 5 days out of the digester.
4. Fit a hydrogen sulphide detector with an audible alarm in any enclosed space near gas parts. Ontario best practice sets the alarm at 10 ppm. Test and replace sensors as the maker says.
5. Teach everyone: no flames or smoking near the digester; if gas is smelled indoors, leave, close the valve and ventilate; never enter a pit or tank to rescue someone, call emergency services.
6. Post warning signs at the digester and digestate tank.

Safety: Do not rely on smell: hydrogen sulphide deadens the sense of smell at dangerous levels. Carbon dioxide and methane also displace oxygen in enclosed spaces.

Do these first

• safety-1

Sources

1. Biodigester user manual (B2C, 2021). Sistema.bio (manufacturer), accessed 2026-11
2. Hydrogen sulphide in agricultural biogas systems. Government of Ontario, Ministry of Agriculture, Food and Agribusiness, accessed 2026-11
3. Anaerobic Digesters and Biogas Safety. Farm Energy, Extension Foundation (eXtension), accessed 2026-11

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