Waste collection and sorting in the urban environment is an important component on the road to the circular economy. Cities and boroughs deal with collection in different ways. In Prague, Štěrboholy is currently testing multi-commodity collection of sorted waste, which includes metal, plastics and tetrapack packaging. In the territory of the city districts of Prague 5, 6 and 7, the collection of gastro-waste takes place, which is subsequently used for processing in biogas plants. Radim Polák, head of the waste department, told us more about the project.

Can you introduce your project to us in your own words? What do you think is its biggest benefit?

The pilot project for the collection of gastro-waste from households is the first of its kind. So far, it has only taken place at canteens and restaurants in the trade waste regime. Prague is aware that this waste segment has considerable potential, for example due to further use in biogas plants. It would be possible to produce biomethane in them, which can be further used, for example, as a drive for public transport buses or Prague services vehicles. This would also be advantageous because CNG vehicles have lower emissions and operating costs than diesel vehicles. We are currently researching how much it would be worthwhile to implement a similar step, and we are conducting a pilot project in the city districts of Prague 5, 6 and 7. Multi-commodity collection of sorted waste is taking place in Prague Štěrboholy, where we test a new way of collecting several types of waste in one container in connection with the planned construction of a new line with an optical sorting system, which is able to sort individual packaging components according to customer requirements. In the event of its introduction, this new form of collection could save Prague considerable funds for the collection of sorted waste in the future. In addition, there would be a reduction in traffic load and emissions.

What exactly does “multi-commodity collection” mean? What is the main difference from conventional mixed waste bins?

Multi-commodity waste collection means the collection of several components of sorted waste in one container. In our case, it is paper, plastics, beverage cartons and metal packaging. These commodities are collected together and their sorting takes place later on the sorting plant.

At what stage is the project currently? Is it already running or is it just being planned? Where and when should it start?

Both pilot projects are currently underway and we already have ongoing results. For both the gastro-waste collection project and the multi-commodity collection of sorted waste, we perform an analysis of mixed municipal waste in order to have data on how the percentage of individual components changes during the projects, or what effect the projects have on its composition.

New optical sorting should be part of the “multi-commodity collection”. Can you tell us how it should work? Is this the first similar device in our country, or would we find it elsewhere?

The construction of an optical sorting line is not directly part of the project, but the results of the project could significantly support the argumentation for its construction. Currently, optical sorting is used mainly in Germany, Austria and other EU countries.

What can be thrown into the new gastro-waste collection containers and where would we find them? For example, is it possible to get rid of used vegetable and animal fats and oils?

This project is intended primarily for apartment buildings with a place for separated waste in household equipment. For the purposes of this pilot, special brown containers with an orange lid with a volume of one hundred and twenty liters were chosen for the collection of gastro -waste. They store kitchen scraps of both plant and animal origin in these household containers. This is mainly biowaste from kitchens, such as bones, meat, leftover meals, past food or even leftover fruit and vegetables.

What happens to animal waste next? Where does it end and how is it used compared to the usual disposal in a mixed waste container?

The collected material is transported to the biogas plant, where it is weighed, monitored and crushed at the entrance. Waste with a higher water content is suitable for BPS, ie food that has already undergone some processing process – such as cooked meals, expired food, confectionery and the like. Furthermore, waste of animal origin such as fats, waste from milk processing, meat or used drinks. Precisely due to the higher water content, it is not appropriate to dispose of this waste in incinerators or waste-to-energy plants, as they reduce the calorific value.

Is Prague the first in the approach to gastro-waste treatment, or do similar activities take place in other cities? Possibly abroad?

Processing of gastro-waste in biogas plants is common, but according to available information, no municipality in the Czech Republic offers the opportunity to sort gastro-waste to its citizens. So far, all production is within the scope of trade activity. On the contrary, abroad, gastro-waste sorting is a common part of the waste management system. Our projects were inspired by cities such as Milano or Bristol, which are similar in size and population to Prague.

What does participating in the E.ON Energy Globe mean to you?

It is an opportunity to present our projects to the public and raise awareness of waste issues in the capital. Furthermore, thanks to the competition, we can inspire other cities and municipalities to implement similar projects, and thus contribute to improving the environment.

What all belong in scrap metal containers and where exactly would we find these containers?

Metal waste collection has long been part of the municipal waste management system. Metal collection containers are part of separate collection stations in the city streets. In the multi-commodity collection project, metals appear only as one of the collected commodities.

What volume of waste has already been sorted out within the Pilot Project of Multi-Commodity Waste Collection in the Prague Štěrboholy District?

In the first phase of the pilot project of multi-commodity collection of sorted waste – ie in the period from 14 June 2019 to 30 May 2020, 263 kilograms of metals, 2,613 kilos of plastics and 953 kilograms of beverage cartons were sorted in this way. After sorting, these impacts are included in the further processing and sale of secondary raw materials. Now the project continues in the second phase.

And gastro-waste?

The project to collect gastro-waste from households began in December 2019. During the entire duration of the project, 25.35 tonnes of gastro-waste was collected. All gastro-waste is processed at the biogas plant in Přibišice near Benešov. The resulting product is methane and digestate, which is used as a fertilizer.

And a little dream at the end. Imagine winning in our competition… Where do you see yourself in a year? What is your vision that the competition could help you with?

Of course, if our projects won the E.ON competition, we would be very happy. But most of all, we would like the general public to find out about the issue of waste and the possibilities of its use. We would like to motivate citizens to also be actively involved in projects. Looking ahead, we would like these projects to be extended to the entire city and become part of the waste management system in the capital city of Prague.

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