Fire risk in a waste sorting station. Why and what protection should be used?

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In 2019 alone, there were over 19,000 fires at landfills. Of course, this also includes fires of free-standing bins, but the most dangerous incidents concern sorting stations and waste management sites. According to the Headquarters of the State Fire Service, these fires could have been avoided if the system mentioned above was equipped with suitable fire prevention systems. Until now, these systems have been a rarity in the waste management industry. This is to be changed by the Regulation, which came into force on 3 April 2020.

One of the waste sorting stations fires of 2019

Sorting stations — an important recycling cell that generates huge costs in case of fire

First, it is worth saying why we are considering waste sorting stations today. The Regulation of the Ministry of the Interior and Administration mentioned above is only a consequence of the changes in our country in terms of recycling. The amended law on maintaining cleanliness and order in communes imposed a clear increase the required level in recycling. This year it is 50%. For this reason, municipal waste (both mixed and sorted) must be recycled at waste management sites.

These processes are carried out by adapted sorting stations, which most often form an integral part of the entire waste management plant complex. An exemplary sorting station line consists of:

  • Bag opener
  • Pre-segregation chamber
  • Rotating screen
  • Opto-pneumatic separator
  • Ballistic separator
  • Fe and ALU metal separator
  • Cleaning chamber
  • >300 mm fraction chamber
  • Balers

Za http://www.zgo.bielsko.pl/system-gospodarki-odpadami,technologia-przetwarzania-odpadow,18.html

The legislation requirements relating to the level of recycling make it necessary to set up new sorting stations where they were not yet built or retrofit existing systems to reach the required level.

But what happens when a fire burns down such a sorting station? Zakład Gospodarki odpadami S.A. in Bielsko-Biała saw it for itself in 2016. The fire, which was created in the waste containers, covered a large part of the hall together with the whole infrastructure used for sorting waste. The millions lost are not the only cost of the tragedy. Timely municipal services for residents still had to be provided, and at the same time, the waste collected had to be properly managed. Tomasz Ficoń, a spokesman for the town hall, even said that this is a problem of a waste collection company, sorting station and the town hall. We can elaborate on that by saying:

  • The sorting station will lose its profit because it will not be able to receive many waste fractions until the facility is rebuilt
  • Additional costs will be borne by the waste collection companies, which have to transport the waste to sorting stations located further away
  • Therefore, the costs of waste collection companies were probably renegotiated with the town hall, which also had to bear the costs of signing an agreement with a substitute sorting station that took over the burden of waste management from Bielsko-Biała

As can be seen, the effects of a fire at a waste sorting station do not only affect the owner of the system directly but also other companies and institutions.

Why are there fires in waste sorting stations?

Waste sorting stations, as well as other parts of the systems in waste management plants, are characterised by a high risk of fire. This is due to the following reasons:

  • Such systems have a high fire load density due to the accumulation of large amounts of combustible materials in a relatively small area
  • It is difficult to determine and control the composition of the waste and the gases emitted from it, which means that it is difficult to predict what will cause the fire and what material will be burnt. A common cause of fires, which is listed by the fire brigade, is the self-ignition of the gases released.
  • A large part of the problem mentioned in the above point is the problem of waste collection companies, which often hide one waste in another to “get rid of the problem”. This causes the sorting station to receive materials that pose a fire hazard, for which a given sorting line is not prepared.
  • Because of the above-mentioned variety of matter that starts to burn, these fires are violent and spread rapidly
  • When opening bags and shredding waste, there are frictional forces (the harder the materials, the higher the forces), or during metal shredding by shafts and blades in shredders. The resulting hot particles can be an obvious source of a fire.
  • Similar frictional forces leading to ignition can occur on conveyor belts or when transporting waste with loaders-excavators on sorting lines. The latter is risky not only because of the frictional forces but also because of the fire medium’s supply in the form of oxygen. Before sorting, it happens that the waste lies for a long time without being moved. If chemical or biological waste or, for example, damaged batteries are included, they start to generate heat, which, when the waste is moved, receives an inflow of oxygen, which makes ignition possible.

Of course, it is never possible to diagnose and fully eliminate the risk of fire. Sometimes a fire at waste treatment and storage sites starts in a completely unpredictable way. This was the case on 4 July 2020 in Przysieka Polska, when a cigarette butt was thrown out of a train travelling nearby, which started a 14-hour fire in a waste recycling company.

Sorting station fire

Fire caused by a cigarette butt thrown out of a train

What protection will work in the waste sorting station?

The previous fires in sorting stations and waste collection points showed very clearly how dangerous these objects are when a fire occurs. The fire spreads rapidly and quickly occupies a large area. A fire causes a large amount of poisonous smoke, which is always potentially dangerous to the surrounding environment. Due to the heterogeneous type of combustible materials, it is never known in which direction the fire will spread and whether there will be additional explosions. That is why it is so important to protect these systems with appropriate fire prevention systems. The question is which one to use?

  • Special spray systems, designed directly for extinguishing in storage halls, should be used.
  • Water extinguishing systems are ineffective in such conditions. The melting plastic, which is accumulated in waste sorting stations, forms a kind of “shell” on which water flows without getting into the waste heap.
  • The foam extinguishing is effective, however, and thanks to its “spilling” texture, it is good at reaching deeper layers of waste, where the fire often spreads.
  • The advantage of foam extinguishing is also less space required for the water tank. In this type of system, there is usually the maximum use of the area, therefore a smaller tank, which, at the same time meeting the fire prevention requirements, is often met with great approval by the investor

Appropriate smoke and temperature detectors, or even thermal imaging cameras, constitute important components for early detection of the danger. They will allow for a quick extinguishing reaction. However, with smoke detectors, there is a risk that dust and particulates accumulated in large volumes can often trigger false alarms.

What is worth checking while preparing for the retrofitting related to the fire prevention systems installation?

First, it should be stressed how important it is for a potential system contractor to visit the facility. Such a local visit allows the layout of the investor’s facility to be checked, making it much easier to propose dedicated solutions. Another advantage is the possibility of a direct conversation between the investor and the contracting company representatives, which often leads to the cementing of mutual trust, or causes the investor to distance himself from a company that does not inspire trust.

The second important issue for many companies is to check the complexity of the bid submitted by potential contractors. The installation of a fire prevention system requires a lot of work on the investor’s facility. This includes making the foundations for the tank and pumping station, supplying the tank and pumping station, routing the fire prevention network in the ground, supplying power to the tank, making the installation inside the hall, or work related to the automation of the system. It is always worth making sure that a potential contractor offers a comprehensive bid, or at some point, you will need to use the help of other contractors.

Photos: katowice.tvp.pl, Kościan 112

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