Biowaste

As a result of microbial activity, natural organic substances, primarily composed of carbon, hydrogen, and oxygen, are converted into compounds or gases that are easily absorbed by plants, such as methane gas, which is a natural energy source and can be used similarly to natural gas. However, for these processes to occur and the prepared biomass to be utilized, a relatively clean raw material is required – free from unwanted impurities. While the average amount of organic waste in household waste reaches 30-40%, which should not be a cause for concern, the main issue in the current waste management situation is the sorting and separation of clean biomass.

Waste management companies that were the first to start collecting organic waste separately encountered significant problems – residents showed little interest in this type of waste, as its collection is not economically viable, and residents are unaware of what happens to this waste, where it goes, and why it should be separated from the rest of the household waste.

There are several key conditions to consider when starting the separate collection and recycling of organic waste:

1. Organic waste accounts for ~40% of household waste – it is wet and dense. As a result, even a small volume of this waste is heavy and affects the cost of waste disposal at landfills, which is determined by the weight of the waste brought in.

2. Organic waste decomposes relatively quickly, forming various compounds, including those with strong odors. Therefore, its removal must be regular, at least once a week, and the waste should be stored in specialized containers with air gaps that allow drying and oxidation, thus reducing odor formation. To ensure the containers do not smell, the waste management company must also regularly wash them.

3. During the recycling process, with proper air supply and humidity control, organic waste naturally forms compost, which provides the essential nutrients for plants – primarily carbon, nitrogen, and phosphorus, as well as micronutrients.

4. On the other hand, when organic waste is processed without air supply, methane gas is produced, which can be used, similarly to natural gas, for heat and electricity production.

5. Microorganisms, which are the main agents in these processes, are living organisms whose activity is threatened by heavy metals and other waste type impurities. They require a balanced diet with a specific ratio of carbon, oxygen, and phosphorus, as well as moisture, and in aerobic processing – air.

Overall, the process of separate collection of organic waste is not simple, and when starting it, all of the above-mentioned factors must be taken into account. Initially, residents may find sorting organic waste unnecessary and burdensome, but it is important to note that unseparated large amounts of organic waste, when buried in landfills, not only lose their potential as a valuable agricultural raw material but also, during the decomposition process, produce combustible gases, which, if not collected, can cause dangerous fires. Meanwhile, at landfills, only about ~30% of the theoretically possible gas volume is actually collected, which could be generated if the waste was processed in methane gas reactors. The waste biomass in reactors can be used as an alternative carbon source, for example, to replace corn, which is currently widely cultivated in Latvia.

On the experience of separate collection of biological kitchen waste on Anniņmuiža Street

After the initiation of separate collection of biological kitchen waste in the residential building on Anniņmuiža Street 20, the pilot project results showed that, regardless of ethnicity or economic status, families actively participated in sorting biological waste when it was explained why it is done (by distributing informational materials and explaining) and when a contract was signed with the building manager for participation in the sorting collection.

The distribution of small bins with lids, intended for the collection of specialized biological waste, also encouraged sorting, while simultaneously signing contracts with each household. The price of the bin (6 or 10 liters) with labeling is ~9 EUR. Purchasing them from the building management funds helps ensure the planned sorting and attracts residents.

Of course, along with the contracts and the small bins for biological waste collection, there must also be a specialized container for the collection of organic waste in the yard or at the designated sorting waste container station, and regular removal of this container ensures the utilization of the collected organic waste mass.

We encourage all multi-apartment building managers to listen to these recommendations and successfully begin managing organic waste. Meanwhile, we invite single-family home residents to start sorting and recycling organic waste, including kitchen and garden waste, by composting in their households. This not only reduces the costs of waste management but also provides necessary fertilizer for garden plants. By purchasing composting bins (examples shown in Figures 1 and 2), almost all natural organic waste can be transformed into soil fertilizer – compost – within six months.

1., 2. Image. Garden composting bins – 1.2 m³ and 1 m³ (photo: LASA archive)

To ensure that the organic waste mass being composted is recorded and that the fee for household waste collection is reduced according to the respective amount, single-family home residents who have started composting sign an addendum to their existing waste management contract with the waste management company, indicating that they are composting in their household in a composting bin of a specified volume (specifying the bin volume). This not only reduces the amount of waste to be disposed of but also provides an opportunity to have the unsorted waste container collected less frequently.

Recycling organic waste must become part of our daily routine, with everyone participating – by collecting sorted kitchen waste, garden waste, and either handing them over for further recycling or starting composting in single-family households. This is one of the key conditions to ensure that by 2035, only 10% of the current waste mass is buried in landfills.

Image by Freepik