Anaerobic Digestion

Anaerobic digestion (“AD”) is a process by which organic material and waste is broken down by bacteria in closed bio-reactors creating a methane-rich biogas and nutrient-rich digestate. The biogas can then be further processed and distributed as natural gas or combusted to create electricity and heat. The digestate, which is high in nitrates and phosphates can be utilised as a substitute to artificial fertilisers.

The Anaerobic Digestion Process (Click on the image to enlarge)

The E-Invest team has developed an Anaerobic Digestion (AD) system that uses closed reactors to enhance the natural anaerobic bacterial process. The organic waste matter used as feedstock for the process is transformed into methane gas through three key stages:

1) HYDROLYSIS
The high weight organic molecules like proteins, carbohydrates, fats and cellulose are broken down by bacteria into smaller soluble molecules respectively amino acids, sugars, fatty acids and water.

2) ACIDOGENESIS AND ACETOGENESIS
The further breakdown of these smaller molecules into organic acids, carbon dioxide, hydrogen sulphide and ammonia occurs. Acetogenic bacteria complete this process to create acetate acid, ammonia, carbon dioxide and hydrogen.

3) METHANOGENESIS
Methanogenic bacteria break down the acetic acid to produce a biogas that consists of approximately 60% methane and 40% carbon dioxide.

By using this clean technology to convert organic waste to energy, E-Invest deliver an environmentally friendly solution that provides:

  • Safe recycling of difficult organic waste including liquids and animal by-products. If necessary a sanitation step is added.
  • Diversion of organic wastes from landfills that have a large environmental impact through methane gassing and leaching. This gives a large degree of control over greenhouse gasses currently released to the atmosphere.
  • Clean renewable energy (thermal, electrical or substitute natural gas (SNG) that can be used in vehicles or fed directly into the grid) contributing to solving the world energy supply and climate change problems. Energy from methane directly substitutes the use of declining fossil fuels.
  • A nutrient rich digestate ‘bio-fertilizer’ which can be separated into solid phosphate-rich compost and liquid nitrogen-rich natural fertilizer.

Links: Case-study Co-Fermentation