Within our stomachs and digestive systems, there’s a whole community of friendly bacteria helping to break down food into nutrients; you’ll probably have seen adverts for supplements like Yakult that boost these essential microorganisms.

The same is true for anaerobic digestion (AD) plants. A varied cultivation of microorganisms, known as a microbiome, live within the digester. These good bacteria work hard to convert organic matter such as animal manure and sustainably grown crops into biogas. A by-product of the process is digestate, which farmers can use as a nutrient-rich natural fertiliser.

Types of AD-friendly bacteria

The AD process has four main stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Each of these stages is associated with a certain type of bacteria:

  1. Hydrolysis: hydrolytic bacteria break down the biggest molecules in feedstock, including carbohydrates, so they are available to the other types of microorganism.
  2. Acidogenesis: acidogenic bacteria convert sugars and amino acids into organic acids, alongside other chemical products.
  3. Acetogenesis: acetogenic bacteria convert the organic acids into acetic acids, alongside ammonia, hydrogen, and carbon dioxide.
  4. Methanogenesis: methanogenic bacteria convert the chemical products from the previous stage into methane and carbon dioxide. Methane is the desired component of biogas; carbon dioxide is an impurity that gets extracted in the clean-up stage.

Keeping the bacteria happy

The bacteria in the digester can be very particular! For example, they work best within a specific range of temperatures and pH levels. Therefore, we have to carefully monitor the process to make sure conditions are perfect, and that the bacteria can produce the maximum amount of green energy.

It’s also important that we add feedstock to the digester in precise amounts; different feedstocks will break down at different rates, and produce varying amounts of biogas. Our mechanical stirrers keep the whole mixture moving, so there is close contact between the bacteria and the organic material.

Encouraging microbiome research and innovation

The AD microbiome is complex and sensitive, making it a fascinating subject of study. We always welcome partnerships with researchers and innovators looking to optimise the generation of renewable energy. If you are interested in working with us on a project, please get in touch.