Pneumatic transport of waste: innovation and environmental sustainability

Raccolta differenziata, Close-up Engineering
Rifiuti urbani, Close-up Engineering
Credits: MeC

Until a few decades ago, the idea of ​​traveling underground urban waste and dumping from somewhere else could certainly be interpreted as “science fiction”.  Today this idea has been realized taking shape as the possibility of eliminating the bins from the streets, making the garbage disposal an extremely low environmental impact, mainly due to reduced CO2 emissions caused by the movement of road vehicles.

The first system was born in Sweden in 1961, installed for the first time at the hospital Sollefteå. The first system was installed in the new residential district of Ör-Hallonbergen in 1965. Inventors of the system were four technicians in Sweden: Torsten Karefelt, Olle Genberg, Sten Olsson and Olof H. Hallström. The latter was the president of Centralsug (today Envac), which is still an important company in the industry.

Currently there are more than a thousand such systems installed in Europe, the Middle East, East Asia, North America. The cities that have seen the most successful in the use and management of these systems are Stockholm, London and Barcelona. In Italy, the units were designed in 2012 in the district of Varesine-Porta Nuova in Milan, born a new, home to about 400 families, by Envac with the aim of collecting plastic, paper, metal and moist. The Milan-based company Oppent has instead designed a system specifically for the building dell’Eurosky of Rome, a residential tower of 28 floors housing for the collection of paper, plastic and generic. The same pneumatic technology is in operation today at the headquarters of a Roman bank but only for the collection of the paper.

The installation of a system of pneumatic transport of waste may comprise both existing urban areas, both areas already built. For technical reasons it is not economically convenient to install systems of this type in the second case on said while instead it is substantially in the first case, by inserting already in the design phase the vacuum waste collection. However, the pneumatic transport system of the waste is cost effective compared to the traditional one as it is expected, however a depreciation calculated usually about 30 years.

So how operate a technological system of this type?

Trasporto pneumatico rifiuti, Close-up Engineering
Credits: Envac

The waste must be transferred from the points of production to a central collection through a network of underground pipes. The points of injection are constituted by load baskets or turrets placed directly in residential buildings or public areas at street level and enabling, in this way, to organize a collection of differentiated type, through automatic sorting systems. The cells are connected to valves provision of access to the transport network that are activated according to a preset program or filling to load the main pipes. In transfer piping main is produced a strong current of air in depression, manufactured through centrifugal compressors arranged in series. The separation of waste takes place downstream of the network through cyclones separation, followed by compaction systems of the masses (containers). Before coming into the atmosphere, the air used for pneumatic conveying is filtered and purified.

Advantages: the operating costs are reduced by approximately 20% compared to traditional requiring more labor-intensive; eliminated the odor problems are and improved the sanitary conditions; will reduce emissions of greenhouse gases produced by moving vehicles and driving mechanisms of loading / unloading of containers and compaction of the medium itself during the process of collection at each point of transfer; reduces the noise; eliminated odors and gases from truck and smelling waste; there is no more movement of heavy vehicles in residential areas; it has the elimination of dirt during the stages of harvesting.

Disadvantages: the handling of materials such as glass or metals could lead to a rapid deterioration of the pipelines by raising the costs of maintenance.

Companies operating such as the MeC and Envac work using advanced programs that take into account three fundamental relationships: environmental statement; study of environmental impact and economic feasibility study in accordance with the rules and regulations on the subject .