Anaerobic Composting 101 : A Brief Guide

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In Brief: Anaerobic Composting

When it comes to composting, everyone thinks about oxygen. But what if we told you that organic matter can decompose and ferment without oxygen through the anaerobic method, which uses no oxygen? Here we look at the ins and outs of anaerobic composting to help you decide if it is the method for you and how to do it properly to ensure you create nutrient-rich, nutritious compost.

Composting is a great move if you want to reduce food waste, as well as improve the growing conditions for your plants.

If you would ask any keen gardener as to what is the most important ingredient apart from green and brown matter, the answer would be oxygen.

However, while the aerobic method is much more common, there are certain situations where composting anaerobically (without oxygen) is recommended.

Let’s take a look.

Why Use Anaerobic Composting?

Before we get into the benefits, as well as how to actually do anaerobic composting, let’s talk a bit about the basic principles of this method.

The Basics

The definition of anaerobic composting would be the decomposition of food waste/organic matter without oxygen.

The main principle is that you should never allow organic matter to putrefy under such conditions.

However, if you are looking to ferment the waste, then this option is quite effective.

If you are interested in how an anaerobic compost digester works, take a look at this video:


The idea is that, over the course of a couple of months, the green and brown matter decomposes and ferments while keeping almost the same physical volume.

The main issue with this method is that it comes with a very unpleasant odor.

That is why you will want to do this in a sealed trash bin/tumbler. Basically, anaerobic composting of green/brown matter is similar to pickling fresh food.

In What Situations Is Anaerobic Composting Required?

Because anaerobic composting doesn’t require oxygen, the heat that is created in the aerobic method is not the same, either. In the latter method, it is the higher temperature that kills weeds and harmful microorganisms.

With anaerobic composting, it all comes down to the acidic environment.

Two most common situations when people decide for this method are when it comes to generating energy, as well as managing food waste on a large scale.

Check this video out if you want to find out more about whether it is the right method for your needs:


How To Perform Anaerobic Composting

There are several anaerobic composting methods that you can choose between depending on the outside conditions, as well as how much organic matter you are planning to ferment.

First, we will go through the basic steps of this process. Then, we will present a few different types of anaerobic composting.

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Step-by-Step Guide

When it comes to the type of container you use for anaerobic composting, you should be a bit picky. Anything from a 5-gallon food bin to tumblers works well for aerobic composting.

However, when it comes to anaerobic methods, you are much better off with a digester bin or finding a non-toxic trash bin that is small/large scale depending on what your intentions are.

The most important thing is that you find a sunny spot to place the container. This means that you can’t rely on anaerobic composting when it comes to the winter season.

As oxygen is not used in this process, you will want to focus on the other two important elements – adequate temperature and moisture level.

For the first, the sunshine at the site will be more than enough.

When it comes to maintaining proper moisture, you should poke a couple of drainage holes. This is essential for keeping the microbes alive and busy.

The fact that anaerobic composting produces a lot of liquid is why those holes are so essential. Unless you are dealing with pet waste, we suggest putting the digester close to your plants.

This way, you will be both achieving optimal conditions for fermentation and nourishing your plants with the liquid that comes out of the digester.

The next step is especially simple. All it takes is you gathering all the kitchen waste you have and adding it to a strong bag. Also, you should mix a bit of brown matter, as well.

Keep in mind that, when it comes to anaerobic composting, it is all about digesting the food scraps. Too many leaves and twigs can disrupt the fermentation process.

Carry the bag to the digester site and simply place all the ingredients from it into the composting bin.

Depending on whether you want it to go through a full process or you want semi-digested compost, you should wait anywhere from 2 months to a full year.

A great thing about this method is that it requires much less effort than the common aerobic one. All it asks for is that, at a certain point, you stop adding more food scraps and mixing the ingredients.

In order for the fermentation process to go through, you will need to stop opening the lid and letting the oxygen in.

Thus, once the bin is 3/4 full, you should simply be patient and let the acidic environment do its thing. Is it worth the wait, though?

You can find that out by going through this detailed video:


One of the most popular variations of the anaerobic composting is stacking the food pile tightly.

As PlanetNatural suggests, providing at least 50% moisture, as well as leaving little to no space between the green matter, is going to speed up the anaerobic composting.

Keep in mind that you shouldn’t keep the bin open for two reasons.

First, the odor is incredibly strong. Secondly, it will slow down or completely end the process due to the oxygen that is flowing through.

Submerged Composting

Among the most innovative ways to perform anaerobic composting has to be submerging the container in water. What is so great about this is that you can then open the bin and not worry about the oxygen freely flowing through.

Behind the scenes, the high moisture level that goes up to 80% traps the gases, thus allowing the anaerobic environment to be created.

Source: Blogspot

Bokashi Composting

Last but not least, if you don’t have as much time and you want to have the fermentation process done within a couple of weeks go for Bokashi.

Find an air-tight container and put the food pile between a couple of newspaper layers.

Packing tightly and ensuring that no oxygen is flowing through will allow the microbes to feed and ferment the organic matter.

This process doesn’t take more than a couple of weeks, after which you should open up the lid and let the compost enjoy an aerobic environment for a couple of weeks more.

Here is a good video for bokashi composting beginners:



There are a couple of points that you should be focusing on. First, the material doesn’t go dry at any point. If you notice that this is becoming an issue, simply add more water.

The other issue may be too much high-carbon matter, such as wood chips and leaves. In order to prevent this from affecting the anaerobic composting process, we suggest adding more green matter or brown matter, such as grass clippings.

Lastly, you will want to keep the trash bin about 3/4 full. Make sure that the matter is tightly packed and that fruits, vegetables, and coffee residue make the majority of your compost.

Benefits Of Anaerobic Composting

The main advantage of deciding for anaerobic composting is that you won’t have to invest nearly as much effort as with the aerobic method.

If you decide to let it ferment for a whole year, then you will be able to use the organic matter straight out of the container.

On the other hand, if you go for the Bokashi method, you will need to let it sit a couple of weeks more in an aerobic environment, but that still isn’t as time-consuming as rolling the bag every couple of days would be.

The second great benefit/advantage is that you won’t have to worry about pests or other pathogens. First of all, these things can’t make their grand entrance due to the fact that the trash bin is tightly sealed when it comes to anaerobic composting.

Additionally, the acidic environment simply is not something that pests are looking for.


How Long Does Anaerobic Composting Take?

The answer depends on what you are looking to achieve. If you decide on the Bokashi method, which consists of tightly packing and sealing food piles in a trash bin, then you will need to wait for a couple of weeks. However, if you want optimal fermentation results, then we would suggest leaving the compost bin for a whole year.

What Is the Role Of Brown Matter In Anaerobic Composting?

The thing is, you shouldn’t use an excessive amount of leaves, wood chips, and shredded paper. These are high in carbon and can disrupt the anaerobic environment. The idea is that you ferment green matter, such as vegetable peels, fruit cores, coffee residue, and tea bags.

Should I Worry About Pathogens?

Absolutely not. As long as your trash bin is closed year-round, your organic matter will not be available for pests and pathogens.


Anaerobic composting comes with more than a couple of benefits, and it is certainly a great method if you are thinking about large-scale food waste management. In our opinion, you shouldn’t exclude either of the two methods (anaerobic and aerobic).

Instead, we would rather see you invest in two separate bins and maximize your composting potential. Good luck!