What is Anaerobic Digestion

It has been recorded that there is around 9.5 million tonnes of food waste a year in the UK. This takes into account any food wastage from food manufacturers, wholesale and retail sectors, hospitality and food industries and UK households. 85% of this comes directly from households and food manufacturers. This accounts for an overall value of £19 billion per year! Overall, this equates to over 25 million tonnes in greenhouse gases. This is why it is incredibly important for food waste to be recycled and be put to good use.

What is Anaerobic Digestion and how does it work?

Anaerobic Digestion is when organic matter is broken down such as food or animal waste and subsequently produces biofertiliser and biogas. This will happen when oxygen is removed from a tank and this is an anaerobic digester which is an oxygen-free tank.

What are the Anaerobic Digestion process steps?

There are four main steps to the Anaerobic Digestion process which ensure that the end result means that the gases made can be used for other more useable purposes:

    Step 1: Take away any contaminants by firstly screening organic fuel. The fuel used can be anything that has biodegradable materials.

    Step 2: When the fuel has been screened it needs to be treated so that it ends up having a smooth texture. The fuel will then be put into the Anaerobic Digestion unit so that the microorganisms break it down.

    Step 3: A digestion unit is either Thermophilic or Mesophilic and these operate at different temperatures and a choice is made dependant on which is best for particular microorganisms to work in.

    Step 4: There are four different stages of the breakdown of organic materials including Hydrolysis, Acidogenesis, Acetogenesis and Methanogenesis These are chemicals that will turn matter into biogases that can be used.

What are the product gases of Anaerobic Digestion?

    Hydrolysis – carbohydrates and proteins will be broken into amino acids and sugars. This process will break them into single molecules rather than long-chain chemical compounds.

    Acidogenesis – the molecules of sugar and amino acids are broken into fatty acids and ethanol. At this point, carbon dioxide is produced as well as hydrogen sulphide.

    Acetogenesis – The fatty acids and ethanol are then turned into acetic acid, carbon dioxide and hydrogen.

    Methanogenesis – Here is when the microorganisms turn the last of the acetic acid and hydrogen into methane and more carbon dioxide.

How does temperature affect biogas production?

Mesophilic units are between 20-45°C these are usually used because they are cheaper to maintain and set up as they have a lower operational temperature. Whereas thermophilic units work at a higher temperature usually between 50-60°C.

The temperate will render various organic material biodegradability that in turn influence the biogas production quality and amount.

What happens in an Anaerobic Digester tank?

The digester has a system in which to produce biogas and other coproduces that are split into solid and liquid coproducts. Solids can include; fertiliser, soil and compost and liquid can be concentrated fertiliser or flush water.

Why is Anaerobic Digestion important?

Anaerobic Digestion is important because it has a number of benefits including;

Digesting solids: these solids can be recycled and used for soil and bedding for farms.

Reducing greenhouse gas emissions.

Producing nutrients for plants: The nutrients for plants are transformed and conserved throughout this process. Ammonium is created from manure proteins and if injected into the soil it can help increase plant growth.

Reducing odours: The digester liquid waste is more stable than the raw manure and contains less strong odours. Therefore when it is applied to land such as on a farm the smell is not as strong.

What is the end product of Anaerobic Digestion?

Anaerobic Digestion created biogas and that biogas can be used for heat and electricity, transportation fuel and flare excess which destroys any excess gas and using primary gas instead.

Do Anaerobic Digesters smell?

Yes, the process, in general, has a bad smell. However, if the digester is kept concealed then there is no reason that this bad smell should escape and produce a foul odour.

Is Anaerobic Digestion carbon neutral?

Although anaerobic digestion can result in producing greenhouse gas emissions because of methane of the biogas the effect of this is zero-sum. Therefore it is considered to be carbon neutral.

What is the range of retention time during Anaerobic Digestion?

This could be anywhere between 2 to 6 days dependent on the temperature.

How many Anaerobic Digestion plants are there in the UK?

There are now 579 fully operational anaerobic plants running in the UK, with a further 331 ones planned to be implemented in the future.

How much does it cost for an Anaerobic Digestion plant?

An anaerobic digestion plant can cost anywhere from £1.2 million upwards.

Food waste recycling bins and collections

Food waste bins and containers are specifically designed to ensure any leftover food waste is stored in a hygienic manner and a helpful way to do food recycling. They come with biodegradable bin liners that will ensure that odours are reduced and there is a lack of interaction from flies and other vermin. You can place any type of food waste into a dedicated food recycling bin, apart from any liquid drinks or waste foods such as fat, gravy, milk or oils.

We provide free food recycling bins and can collect from any business location in the UK. We are here to provide all the knowledge that you need to know to get started.

Call us today on 0800 211 8390 or fill out a web form. We look forward to hearing from you and helping you make the first steps with your food recycling journey.

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