Paul Cohen-Tannugi

Waste 101: Intro to Composting

What and How to compost at Mediamatic

Starting in December 2019, we have adopted a new waste management policy targeting the separation of organic (bio) materials produced in the kitchen, at the bar and office, using it to build an on-site composting facility, and to better close our waste cycle. 

This article will introduce you to our compost facility and teach you step-by-step how to turn waste into black gold.


step 1. Collect food scraps 

step 2. Ferment the food scraps using bokashi

step 3. Transform bokashi into compost

step 4. Use the compost in the garden

What is compost?

A compost is a living pile of organic materials decomposing, in a controlled-environment with materials such as: vegetable/fruit food-scraps and leftovers; coffee-grounds/tea; paper napkins, as well as plant clippings from our gardens.

The bulk of the decomposition process is made possible by a synergy of macro-organisms (Earth, humans, worms, insects), micro-organisms (microbes, yeast, fungi), and the environment (temperature, moisture). All are part of digesting and breaking down the materials to regenerate a rich, bio-diverse humus that can be used in the gardens for growing more plants and food. 

Types of composts being used at Mediamatic: 

  • Bokashi fermentation compost (green-bins) in the kitchen patio (located between the Aroma Lab and the Kitchen), dedicated for all organic waste produced on-site (kitchen scraps, food, coffee/tea). 
  • An outdoor compost and vermicompost located next to the Clean Lab using earthworms to eat the food-waste. This is ultimately where the bokashi ends up, as well as any garden clippings.

The main difference between the two types are:

  • Bokashi is an anaerobic fermentation process whereby a starter is sprinkled on top every-time food is added to the bin. The benefits are multiple, including the preservation of the food, and lack of CO2 or greenhouse gas emissions. 
  • A vermicompost is a regular aerobic compost (requires oxygen), but with worms added into it, which speeds up the process, and creates a bio-diverse system that improves it’s effectiveness as a natural fertiliser.

Photo by Craik Sustainable Living from Flickr



Vermicompost-redwrigglers -

A Waste Odyssey: a journey from waste-to-food


Step 1. The White Bucket


The first step in the heroic journey of food-waste recycling starts with waste separation of organic materials.

Use White buckets available in the kitchen and at the bar for biodegradable materials including: food scraps (vegetables and fruits), paper napkins, coffee-grounds and tea leaves.

For instance, during Lunch cooking, dispose of food-scraps in the white bucket. After Lunch is over, discard all food-waste directly into the bucket behind the kitchen counter to separation more efficient. After cleaning dishes, transfer white bucket content into the green bin and follow the instructions below.

All non-recyclable materials should be thrown the regular trash (e.g., plastics), or in their respective bins (glass; cartons/cardboard; oil in the blue-drum).

Do not store those bins in the Patio. Refer to FAQ below for more information.

Step 2. Green Bin Bokashi


The next step in the journey is the transfer of the white bucket into the green bins located at the kitchen patio.


  • Add one scoop for every 5cm-thick layer of food-waste.
  • Use a plunger to press down the food from the top to evacuate air from the pile.
  • Make sure the bins are closed tightly by pressing down on the sides. This is important to keep the bins air-tight, minimizing the risk of interference with the fermentation process.

Fermentation duration: 

fermentation can take anywhere from a week, up to 2-weeks depending on conditions like temperature, moisture and materials

  • Ideal temperatures for bokashi fermentation are 25ºC~40ºC taking approximately ≤7 days
  • At room temperature (15ºC~25ºC) it may take up to 1 week.
  • Below room temperature, it will still ferment but will take longer, up to 2 weeks. 

Keep in mind, the effective microorganisms (EM) will only become active with enough moisture (60-70%).

If the pile looks dry, add water. Conversely, if it feels too wet, or soggy, drain the liquids using the bottom tap. 

This “compost juice” is a powerful cleaner for pipes due to its acidity, as well as a natural fertilizer for plants by dilluting with water 1:100 (Tea-Water ratio).

A sign of successful fermentation will include pickled fragrance, and exhibit white mycelium mold spread over the food.

Maintenance duties:

Because we only have four green-bins available, proper rotation is key for effectiveness. Once a bin becomes full, it should be kept closed and left to ferment. Once the fermentation is done, the bin has to be emptied into garden compost pile.

Ideally, you want the contents fermented before emptying. However, you may need to empty a bin due to lack of available space, especially during the Winter when fermentation takes longer. This is okay, and fermentation will still proceed inside the compost pile.

Or alternatively, it can be added directly in the soil for gardening use (refer to page 2 of this guide for details)


Important: The following online form helps keep track of our bins to know which ones are in-use; are full, or empty. 

Please fill in the questionnaire everytime a bin becomes full, or after it has been emptied.

You can also scan the QR Code located below, and on the bins with your phone to access the form effortlessly.

*Tracking results are automatically uploaded onto this excel sheet

Feel free to make improvements to it if you’re excel-savvy!

Resources on Bokashi:

Step 3. Compost & Vermiculture


Once fermentation is achieved, the bins need to be emptied in the outdoor compost-pile.

it may be a good idea to have one pile dedicated to the bokashi for the benefit of worms (As of December 2019, the middle pile is reserved for bokashi)

How: Tip the bin over the wooden fence to empty the content.  

Be aware that a full bin is heavy. Ask for help when needed. 

Finally, rinse the bin and metal plate with water, so it’s clean and ready for to be used again.

Here is an explanation of vermiculture by CGIAR on Climate Change Agriculture and Food Security (CCAFS):

Vermiculture involves using earthworms to turn organic residues into nutrient-rich compost materials that can fertilize soil. Vermiculture is one method of creating organic fertilizers that can be used instead of inorganic products. The liquid, vermijuice, can be extracted from the compost material and turned into bio-pesticide. The earthworms, after nourishing the soil, can be fed to fish or poultry. The reuse and recycling of these farm resources leads to increased soil health and agricultural productivity. (source: CGIAR)

While we do not yet use the worms to purposely feed animals at the moment (although you may notice more birds around), it may be an idea for the future (i.e, aquaponics).

The bottom line is: Keep the worms happy, make the soils and plants happy. 

Tips to create good environments for worms:

- Add layer of wet shredded paper; newspaper or cardboard on top of the food. This bedding layer allows worms to lay their eggs for reproduction.

- Acidity: Although worms are quite tolerant of acidity, if it's too hostile, they will leave the pile and not eat the food. To bring up the pH, add a layer of wood-ash from the pizza oven on top of the food. This is a great way to use the ashes produced at the Bar.

- Keep compost moist (but not too wet). If you hold a handful of compost, squeeze it and water drips out, it's too wet, in which case you can add some dry materials to compensate.

- Cover food with a layer of materials: soil, yard waste, dry leaves to avoid exposure to air which may exhibit smell.

 If for any reason, you find the compost is not working as expected, it may be a good idea to transfer the piles from one bin to the other (check image instruction below). This will ensure proper aeration of the pile.

 Don’t forget to fill-in the Compost Tracker form so we can keep track of the progress.

*For safety and hygiene, gardening gloves and tools are available in the aquaponics.



It may happen that all the green bins are full, and some need to be emptied before the fermentation has fully succeeded. In this case, empty the bin that has been sitting for the longest, into the outdoor compost. 

This will happen especially during the Winter, when colder temperatures will slow-down fermentation cycle. Fortunately, the fermentation will continue in the compost pile, and benefit the latter. 

Maintenance duties:

Compost Cleaning and Maintenance duty should be a shared responsibility from all staff at Mediamatic. Therefore, I am suggesting that it should be part of one's Cleaning Shift duties to check if bins need to be emptied, and proceed when required. 

This is an important part of our responsibility towards the environment, as well as ensuring that waste is properly disposed of for gardening-use. Every little step matters. 

 For more details on compost duties and maintenance, check this composting fact guide by Permaculture North Beaches, Australia

Gardening Use (Part 4/4)

Extraction & Put to Good Use

After a few months of digestion and fermentation by various organisms, the compost should finally be ready for its final destination: the Garden. Finished compost should be look like black soil with fine particles. If you notice large particles such as wood, sticks or even plants, then you will need to sift the compost before adding it to the soil.

Before you do anything however, it’s a good idea to have a plan of action ahead of time. For instance, calculate roughly how much soil you will need for your project. Or use a plastic sheet to avoid leaving behind a mess. If it's a big project, you can talk to the boat people and let them know that you will be using that space for some time (to avoid any miscommunication).

You will need the following tools to extract compost for your garden:

  • Pitchfork and shovel to extract compost; sifter (check aquaponics for tools)
  • Wheelbarrow for sifting and transportation (next to the compost pile)
  • Large plastic sheet on the floor to avoid leaving a mess behind.
  • Helping hands: the more the merrier. It will make the work much easier, and pleasant. 

First, unfold the plastic sheet over your work area. This will make cleaning easier at the end.

Place the wheel-barrow next to the compost fence. Position the sifter on top of the wheel-barrow.

Use a pitch-fork, or shovel, to dig into the pile, and place it on the sifter. 

With a forward-backward movement, shake the sifter to filter large particles from the finished, fine humus that will slip underneath. Large particles can go back into the compost for further decomposition. 

Empty the wheelbarrow  into an empty area on the plastic sheet for later use. 

Application of compost on the garden: 

Any tools required are either in the aquaponics or in the barn. Make sure to properly return any items you take out, and don't leave a mess behind, as this is a communal area.

Tips: Compost harvest is intensive work, and it will be much easier to have one person shoveling the pile, another one sifting and emptying the wheel-barrow. Take your time. Take breaks, and enjoy the process of reaping the rewards of all the hard-work. 


Thank you for your attention, and together, we can close the waste cycle to grow more plants (and food!)


FAQ (frequently asked questions)

- How long does it take from start to finish?

Vermicomposting [VC]: It varies. During the Winter when temperatures are down, worms may cluster in the middle, taking more time to decompose food, 3-4 months. For this reason, it is best to start composting in the Fall after the harvest and before Winter starts, to have a beautiful compost ready by the next Spring. Patience is key for compost.

Also, while heat is generally a good sign in a compost, worms may not necessarily enjoying cooking at too high temperatures. So be aware of the nitrogen content, and try to separate bokashi and garden-yard-waste for more effectiveness. 

For Bokashi Compost [BC]: 1 to 4-weeks. Refer to Part 2 above.

-Whose duty is it to clean/empty the green-bins?

Refer to Part 3 above. 

- The compost smells bad. What should I do? 

VC: This is usually a sign of anaerobic decomposition (rotting). Solution: You can try and aerate the pile (by using a pitch-fork to turn it around); you can also add ashes, or coffee-grounds on top to absorb the smell. 

BC should have a distinct sweet-sour smell, similar to sauerkraut or pickles. However, it should not have a "puky" rotten smell.  If that is the case, you have couple options:

  1.  You can cover the pile with a few scoops of ashes (from the rocket stove/pizza oven) and/or add shredded newspaper.
  2. Add more starter on the top. This will absorb the smells and help with the fermentation. Also, make sure to drain liquids from the tap every week.

- Ran out of starter. Where can I find more?

There is more Bokashi starter in the dry storage at against the wall, bottom shelf in a box, on your right from the entrance. If running low of supplies, let someone in the office know to order more. This is the type we currently use (2kg bags)

- What is the blue container next to the kitchen area?

The blue drum in the patio is used to store cooking oil. Our supplier is ROTI. Contact them for an appointment to collect and dispose of the oil properly. They turn the collected oil into biodiesel, reducing reliance on fossil fuels. Win-Win!

- Compost is great but.. what else can we use the waste for?

Great question! There are many other methods that either include composting (or not) that can benefit us. 

Protein Production: For instance, calorie-rich food waste makes for excellent feed to breed and harvest Black Soldier Fly larvae (Hermetia Illucens), which in turn, makes great feed for animals rich in proteins and other minerals. This is a great way to turn biomass into protein.

Bio-gas Production: A Bio-digester is like an enclosed compost which harvests gas (e.g., methane) from organic materials decomposition (especially manure), which can be used for local energy production. Useful for cooking, heating, or sterilising substrates (to grow mushrooms!) or all three combined.

Biochar Production: Biochar is essentially charcoal made using a process called pyrolysis (low-oxygen burn) from any carbon source (e.g., corn stalks; coconut stalks; wood/tree pruning..). The resulting coals can be used in a variety ways, with cascading benefits (adding value to each step). For example, charcoal is a great water filter, deactivating harmuful bacteria and pathogens (benefitting context: sceptic system; farm effluents). This is the same system as used in commercial Brita water filters. 

Afterwards, those micro-organism "charged" coals can then be added to a compost to giving valuable housing to microbes, and stabilising pathogens. Finally, when deposited on soil, this EM-charged (effective microorganisms) coal enriches and adds to the soil carbon layer. More information on biochar at

Heat-Production (Biomeiler): Since good compost releases heat in the process of decomposition, heat recovery is made possible by using a biomeiler, sandwiching a coiled metal element, or water pipe within it, that can provide free-heating to households

Further biomeiler resources from Cornell University:


Thank you for your contribution to reduce waste, and may the gardens grow bountiful while regenerating the ecosystem!