The Case for Full Vacuum System at Changi International Airport Terminal 3

Nexaldes is the only supplier in the world that can offer both the gravity and full vacuum systems. The STREAM Full Vacuum System is most suitable for commercial areas such as Transport Terminals, Hotels and Retail Malls where food & beverage outlets are in abundance. In these kitchens; high volumes of food are generated on a regular basis. Cleaning professionals who are tasked with disposing the organic waste from these areas typically use large industrial sized garbage bags to store and transport the garbage.

These bags when filled would be very heavy, bulky and sometimes it leaks, leaving a trail of garbage juice all over its path. When used in a Gravity Vacuum System these large bags frequently get stuck due to its density.

Why? Each full bag can weigh anywhere between 10kg to 20kg each. The first problem is that the size of these bags will not fit into a typical Gravity Vacuum load station hopper door (400mm x 400mm). Secondly, it will have difficulty sliding down the refuse chute (ND400mm vertical pipe), un-assisted by vacuum suction, because of the expanded condition of the garbage bag. Finally, as the bags stack up in the temporary storage section just above the discharge valve (see photo), it creates a plug syndrome that becomes difficult to disengage because the bags have become compacted. (Vacuum suction in a Gravity Vacuum System is mainly from the bottom of the discharge valve to the container bin).

However, in a Full Vacuum System, the entire chute is under vacuum (see Full Vacuum video). The vacuum forces the garbage bag through a computer controlled inner door.

Typically, waste is moved at very high speeds, so much so that as the cleaner is about to throw the second bag into the load station, the first bag that he threw a few seconds earlier has now travelled several hundred meters down the pipe - heading straight towards the sealed container. That is why plug syndrome does not occur in a Full Vacuum System.

This was the major observation point that the representatives from the Changi Airport authorities noted in our Full Vacuum System installed in Maju Junction Kuala Lumpur (see World Class Projects) before deciding to choose the Full Vacuum System over the Gravity Vacuum System. They realized that they would face regular blockages and operational deficiency had they decided to use the Gravity Vacuum System in Terminal 3.

Their decision to use the Automated Waste Collection System instead of conventional method was triggered by their concern over security measures because originally, the airport planners wanted to allow conventional garbage trucks to collect garbage from a refuse collection room located directly beneath the terminal building. When the tragedy of 9/11 struck, the planners questioned this decision. The Automated Waste Collection System was the answer. Today, the STREAM Full Vacuum System transports garbage from 13 load stations in the terminal to a central waste handling facility located approximately 1.2 kilometers away.