How does Anaerobic Digestion Work?
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The process of anaerobic digestion is a sustainable process of recycling large amounts of food and animal waste
Anaerobic digestion is a complex biological process involving the breakdown of organic matter in the absence of air in large, sealed and insulated vessels with controlled heating and mixing.
Food waste enters a sealed building where it is processed into a liquid porridge, and then pumped into the anaerobic digestion plant. It is here that bacteria feed on the food waste and produce biogas. Biogas is captured and used as a fuel in CHP engines or sent through a gas filter and sent directly to the gas grid.
The digestate or biofertiliser produced undergoes pasteurisation to ensure that any pathogens are destroyed and is stored in large lagoons ready to be applied twice a year on farmland. The use of this high nutrient biofertiliser replaces the use of fossil-fuel derived fertilisers and ensures a complete loop of carbon and energy capture.
What is the Anaerobic Digestion process?
Once your food waste reaches one of our AD plants, it is booked in with our bookings team and weighed on one of our weigh bridges. Food waste is then sorted, separated and any packing removed by one of our specialised machines. Liquid and solid waste is then mixed together to create a ‘feed slurry’. The feed slurry is then pumped into one of our hydrolysis tanks to start its journey through the anaerobic digestion process.
The next stage is pasteurisation, in these tanks the liquid is heated to 70 degrees for one hour to destroy any pathogens. These tanks are heated using power from our CHP engines, the electricity that powers these is excess to requirements and used as part of this sustainable process. The pasteurised feedstock then enters the digesters, this is where the majority of the biogas is produced as the gas naturally rises to the top. The gas then flows into the gas holder, where it is regulated. Our CHP engines then use the regulated gas to generate electricity. This is then used to supply our plants, local businesses and excess goes to the National Grid.
Why recycle your food waste?
In the UK alone, we produce around 10 million tonnes of food waste annually, but only 1.8 million of this waste is recycled. Understanding the economic and environmental benefits of efficient food waste recycling can deliver huge benefits for business, the local environment and long-term sustainability.
Environmental Benefits
- Environmentally friendly process
- Renewable form of energy
- Low cost and high returns for businesses with the ability to save money
- Adhering to environmental credentials
- Reduced waste tonnage
Business Benefits
- Reduce landfill taxes through correct waste management
- Reduction of operational costs within the business
- Adhering to legal responsibilities
- Increased environmental awareness across the business
Is Anaerobic Digestion good for the environment?
Ultimately the environmental benefits of waste management are the most important factor to consider, closely followed by the positive influence the correct management of waste can have on a business from both a sustainability and financial perspective.
Businesses that take a robust approach to their waste management processes have a head start on those competitors within their field that don’t. Not only are there business improvements and cost savings, but there are also huge environmental long-term and sustainable benefits. Packaging and food waste can have a negative impact on the local environment and waterways as well as the human impact through increasing CO2 levels and emissions. It is important we see recycling and reusing as an important way of protecting our environment and reducing waste.
The benefits of dealing with business waste in the most appropriate manner:
By using correct waste management procedures
How do you generate renewable energy from the anaerobic digestion process?
As part of the anaerobic digestion process, food waste enters a sealed building where it is processed into a liquid porridge and then pumped into the digestion plant. It is here that bacteria feed on the food waste and produce biogas. Biogas is mostly methane (CH4) and carbon dioxide (CO2), with very small amounts of water vapour and other gases. Biogas is then captured and used as a fuel in CHP (combined heat and power) engines or sent through a gas filter and sent directly to the gas grid.
This is a great example of how methane is then converted into a source of green renewable energy. The digestate or biofertiliser produced as part of the anaerobic digestion process undergoes pasteurisation to ensure that any pathogens are destroyed and is stored in large lagoons ready to be applied twice a year on farmland. The use of this high nutrient biofertiliser replaces the use of fossil-fuel- derived fertiliser.
Other advantages
- It’s cheap to produce
- It can help improve the long-term health of soil
- It’s much quicker to make than compost
- Biofertilisers can be stored for longer than other forms of fertilisers.
Use of digestate and biofertilisers
The end product of the AD process is the generation of a nutrient-rich fertiliser that is used on fields and crops to sustain a longer-term growth and yield and has a better environmental impact than synthetic fertilisers. Creating healthy soil promotes good growth for plants and, in turn, is great for animal feedstock.
