Providing a second-chance to organic waste
Annually, 2.01 billion tonnes of municipal solid waste is produced worldwide, where organic waste, such as food and greens, represent 44% of the total. Additionally, 37% of all generated litter is still disposed of in some form of landfill. However, the disposal of organic waste to landfills severely impacts the environment because as the discarded items rot, methane, a greenhouse gas 84 times more harmful than carbon dioxide, is released.
Nowadays, a variety of habits can be adopted to avoid throwing food to the landfills. From supporting circular businesses, such as Too Good to Go, to efficiently plan meals or to properly store fruits and vegetables. Among these practices, composting is a complementary solution, which can be carried comfortably at home.
But what is composting?
Composting is a recycling process, where the decomposition of organic matter, such as leaves, flowers, wood or food scraps, generates a fertilizer abundant in nutrients that can be used to nourish soil and improve the growth of plants.
Even though composting is not a standardized process, there are some steps that should be kept in mind in order to start composting at home, which include:
1) Choose a location and a composting method, to arrange the perfect bin
There is a variety of places and composting methods to pick on.
|Method/Location||I have time and live in an apartment||I don’t have time and live in an apartment||I have time and have a garden||I don’t have time and have a garden|
Even though digesters are associated with a wide range of types of containers and systems, in this article, this term is used to mention bins that include a section underneath the soil.
One example is the green cone, where the base must be dug into the ground, where the compost will be digested by the bacterias present on the ground. The remaining structure is located above the floor, with the top right under the sun, to heat up the bin. Even by requiring some digging, this approach takes all types of food, including cooked food, is pest proof and a carbon-nitrogen ratio is not needed. In other words, digesters are an amazing solution for people who simply want to get rid of kitchen trash without any inconveniences.
- Insulated bins
This outdoor type of container is ideal for hot composting, due to the ability of maintaining higher temperatures, even during winter. In other words, it is perfect for users who desire to compost rapidly, without large amounts of scraps.
Tumblers are excellent for aerobic practices*, because it facilitates one of the hardest parts of fast composting: the aeration process, just by making turn the compost easier. In addition, most tumbler bins are now designed to avoid pests and to handle all food waste
*Aerobic method require the right amount of oxygen in the compost. To achieve the ideal flow, it is fundamental to turn the compost regurlarly and the bin should be open or have holes on the lid.
- Fermenters (Bokashi)
Fermenters are optimal for anaerobic* procedures, and can be used inside the home, for example in the kitchen or in a balcony, and also outside, like in a private garden. Another advantage is that it can handle cooked food, dairy and raw meat. In this category, Bokashi, a method that combines bacteria and fungi to ferment organic matter, is very popular, because it is one of the easiest fermenter bins to implement in a kitchen or in a balcony. On the indoors, start by buying or building a small bin. It is necessary to buy a specific bokashi bran, to add to the compost with the scraps. This is an air-tight technique, so every time you add materials, add bran, squeeze the pile, and close the bin very well with the respective lid. Keep in mind: the pile can not be mixed, the materials must be disposed of in layers and the container’s lid must fight properly and tightly, in order to keep the air out. A disadvantage of bokashi is that it does not generate finished compost, so the results must be buried or added to a hot composter.
* Anaerobic procedures, do not require air flow, and can be practiced in close bins without necessity of turning the pile;
- Other Bins
For indoor composting, it is recommended to use lidded containers, in metal or plastic, in order to avoid attracting insects. These bins are often used for aerobic composting, and they can be placed either on the kitchen or in the balcony, in a shady spot. Therefore, it is necessary to mix the pile once in a while and the bin should have evenly spaced holes in the lid, to guarantee sufficient oxygen. For diy aerobic bins, drill by yourself five holes in the lid.
Furthermore, many more bins are available, besides the indicated above, such as wooden, wired or plastic bins, etc.
In this process worms turn the organic waste into compost. Vermicomposting is also one of the easiest methods to apply indoors, in the kitchen or on a balcony. This method can only process small amounts of materials, depending on the bin size. However, worms require a certain amount of attention and care, for example, for an outside placement, the worms bin can not be in a location of direct sunlight, preferably a shady spot. Indoors, the container should be kept in a zone with consistent temperature and moisture level. So places near the oven, heater or air conditioner should be avoided. If you decide to build a diy bin do not forget to drill evenly spaced holes in the lid, since vermicomposting is an aerobic method.
- Trench composting
This system is based on digging a hole on the ground, adding the sourced scraps and burying them. This technique avoids bad smells and provides nutrients to plants right in a critical zone, the root area.
If buying a bin is not possible, composting is still possible with these solutions:
– Trench Composting, as previously mentioned;
– Built a Do It Yourself bin, either by reusing a container or any other materials available at home;
– Register and attend a workshop of Lisboa A Compostar, a composting education project, that offers a domestic compost bin to attendees that have space to install it at their home. Participants can also choose to get a code to access a communitary bin, instead of receiving a domestic one.
Some links to bins, Lisboa A Compostar and how to build a DIY bin are available at the end of the article.
2) Source your scraps
All composting methods require two key elements:
– “Browns” to provide carbon, in order to keep decomposers “alive” while waste breaks down. This includes materials such as dead leaves, paper, card, and sawdust.
– “Greens” to provide nitrogen, to guarantee a rapid growth and reproduction of decomposers. This includes materials such as fruit and vegetable scraps, flowers, eggshells and coffee grounds.
– Some composting may need water or air, depending on the method and if the “greens” are ensuring enough moisture.
One of the most practical methods to source greens materials, is collecting the food waste you produce daily, such as used tea leaves, or fruit and vegetables peels, to a different container, in order to separate the organics from other recyclable materials and non-compostable waste. If possible reuse the container and don’t forget that the container can only be added to the composting if manufactured with compostable materials. Regarding brown materials, gather newspapers, cardboard from boxes or dead leaves and tree branches. Insider’s tip: smaller pieces break down faster, so chop food scraps and shred paper, leaves and card, into tinier bits.
But at crucial moments, there is a question that always arises: what can really be composted or not?
So in addition to some of the materials already mentioned, and in order to tackle some future doubts, here is a list of what is compostable or not:
|Can Be Composted||Can Not Be Composted|
|Coffee grounds and filters (in paper)||Non-biodegradable materials (plastic,glass,etc)*|
|Grass clippings (without pestice treatments)||Coal or charcoal ash**|
|Plain wooden chopsticks||Diseased or insect-ridden plants**|
|Hair and fur||Pet feces**|
|Old herbs and spices||Cigarette butts|
|Old wine and beer (in small quantity)||Medication|
|Fireplace ashes||Cooked foods (with oils or grease)*|
|100% cotton or wool rags||Black walnut tree leaves or twigs|
*Do not decompose
**May be harmful to plants, and spread diseases, bacterias and other pathogens to humans
Even though, raw meat, dairy, and some other cooked foods are biodegradable, specialists tend to discourage their addition to compost piles, since it can carry harmful pathogens that might survive the composting process and also attract bad odours or pests, such as flies, rats or raccoons. In addition, only specific methods can handle these substances, which are anaerobic procedures, more specifically digesters, fermenters and bokashi bins. However, plain rice and spaghetti cooked without any oils or grease can be added more safely, since breaks down relatively quickly.
Considering this information it is only recommended to add these ingredients, if there is already a good level of expertise concerning compost practices.
3) Fill with scraps and stir
Lastly, start adding all the materials you source into the bin. For aerobic compost methods, mix the contents minimum once a month, to effectively aerate.
To learn more about composting and get access to a bin (lisbon only): https://lisboaacompostar.cm-lisboa.pt/pls/OKUL/f?p=178:15
How to build Diy bins: https://www.thespruce.com/compost-bin-plans-4769337
Tumbler composter: tinyurl.com/3pswzern
Home bin: https://tinyurl.com/4bwnnxp5
Wood compost bin: https://tinyurl.com/pm9khs
Green cone vs. Green Johanna: https://www.mazeproducts.com.au/wp-content/uploads/2018/01/GGS-Leaflet.pdf
How to Make Vermicompost at Home: https://krishijagran.com/agripedia/how-to-make-vermicompost-at-home-check-step-by-step-process/
Kaza, S., Yao, L., Bhada-Tata, P. & Woerden, F. V. (20/09/2018). What a waste 2.0. Available at: https://openknowledge.worldbank.org/handle/10986/30317
EDF (N/D). Methane: A crucial opportunity in the climate fight. Available at: https://www.edf.org/climate/methane-crucial-opportunity-climate-fight
EPA (N/D). Composting at Home. Available at: https://www.epa.gov/recycle/composting-home
Hu, S. (20/07/2020). Composting 101. Available at: https://www.nrdc.org/stories/composting-101
Compost Magazine (N/D). Which type of compost bin is right for you? Available at:
Rishell, E. (2013). Backyard Composting. Available at: https://web.archive.org/web/20180920170413/http://pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/HORT/HORT-49/HORT-49-PDF.pdf
Raabe, R. D. (N/D). The Rapid Composting Method. Available at: https://vric.ucdavis.edu/pdf/compost_rapidcompost.pdf
USDA Natural Resources Conservation Service (April 1998). Composting. Available at: https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs144p2_014870.pdf
Pavlis, R. (N/D). Bokashi Composting Myths. Available at: https://www.gardenmyths.com/bokashi-composting-myths/