Food waste has significant environmental consequences. When food is thrown away and ends up in a landfill, it decomposes and produces methane, a potent greenhouse gas which is a major contributor to climate change and has a much higher global warming potential than carbon dioxide. 

Rotting food waste is harmful to the environment because it also creates resource depletion, water pollution, loss of biodiversity, and soil and habitat degradation.  

What is anaerobic digestion?

Anaerobic digestion is a sustainable and environmentally friendly way of generating energy from organic waste. It diverts waste from landfills, reduces the volume of waste and produces a nutrient-rich fertilizer as a byproduct. 

The anaerobic digestion process consists of breaking down organic matter, such as food waste, without the presence of oxygen to produce biogas. Biogas is a mixture of methane (CH4) and carbon dioxide (CO2) that can be burned as a fuel source to generate heat and electricity. 

This process occurs naturally in the absence of oxygen and is carried out by microorganisms such as bacteria and archaea. These microorganisms break down the organic matter into smaller molecules that are then transformed into biogas. 

Through the construction and design of anaerobic digestion facilities, we can maximize the biogas production from organic waste through controlled and optimized conditions.  

The organic waste is first pre-treated, such as by grinding or chopping, to increase the surface area for microbial attack. The pre-treated organic waste is mixed with water to form a sludge, which is then fed into an anaerobic digester. 

Biogas upgrading

anaerobic digestion

The biogas produced during this process is then collected and processed to remove impurities such as sulfur dioxide, hydrogen sulfide, and moisture. The purified biogas can then be burned in a gas engine or turbine to generate electricity or used as a fuel source to generate heat. 

Biogas upgrading is the process of purifying raw biogas, which is a mixture of gases primarily composed of methane and carbon dioxide, to produce biomethane. Biomethane is a high-quality renewable fuel that can be used for a variety of applications, including heating, transportation, and electricity generation. 

This process typically involves removing impurities such as water, hydrogen sulfide, and other trace gases to produce a gas stream with a higher concentration of methane. There are several methods for upgrading biogas, including pressure swing adsorption, membrane separation, and cryogenic distillation. 

Once the biogas has been upgraded, it can be compressed and stored in tanks or pipelines for distribution and use. Biomethane can be used in place of natural gas and has a significantly lower carbon footprint, as it is produced from organic waste materials such as agricultural residues, food waste, and sewage. 

Biogas upgrading is an important technology for the transition to a low-carbon economy, as it enables the conversion of waste products into a valuable renewable energy source. It also helps to reduce greenhouse gas emissions and improve energy security by providing a reliable source of renewable energy. 

Benefits of anaerobic digestion

This process can be used as a solution for reducing food waste because it: 

  1. Treats a variety of waste: One of the main benefits of anaerobic digestion is that it can process a wide variety of organic waste, including food waste, manure, sewage sludge, and other organic waste streams.
  2. Diverts food waste from landfills: Anaerobic digestion can divert large amounts of food waste from landfills, where it would otherwise decompose and emit methane, a potent greenhouse gas. Diverting food waste to anaerobic digestion reduces greenhouse gas emissions and can help to reduce the amount of waste sent to landfills.
  3. Produces renewable energy: Biogas produced from anaerobic digestion can be used to generate electricity or heat, providing a renewable source of energy. This can help to reduce reliance on fossil fuels and lower carbon emissions.
  4. Produces nutrient-rich fertilizer: The digestate produced from anaerobic digestion is a nutrient-rich fertilizer that can be used to improve soil quality and promote plant growth. This can help to reduce the use of synthetic fertilizers, which can have negative environmental impacts.
  5. Creates economic opportunities: Anaerobic digestion can create economic opportunities for communities by generating revenue from the sale of biogas and digestate, as well as creating jobs in the construction and operation of anaerobic digestion facilities. 
  6. Plug and play anaerobic digestion: Anaerobic digestion facilities can be designed to be modular and scalable, allowing for the expansion of capacity as needed. 

Key challenges


The implementation of anaerobic digestion as a source of energy generation is not without its challenges. One of the main challenges is the high capital cost of constructing anaerobic digestion facilities. This can be a barrier to the widespread adoption of this technology. In addition, the operation and maintenance of anaerobic digestion facilities can be complex and require specialized knowledge and skills. 

Another challenge is the variability of the quality and composition of organic waste streams. This can impact the efficiency of the anaerobic digestion process, as well as the quality of the biogas produced. Therefore, it is important to carefully manage the organic waste streams and optimize the conditions within the anaerobic digester to ensure maximum biogas production. 

Anaerobic digestion is a promising and sustainable solution for the generation of energy from organic waste. While there are challenges to the implementation of anaerobic digestion, careful management of the organic waste streams and optimization of the anaerobic digester conditions can overcome these challenges and lead to a successful implementation of this technology. 

By Kristina Kinson