Most of us regard household waste handling as nothing more than a practical necessity, not something to give a lot of thought. It’s pretty simple: we sort, pack and carry our rubbish bags out to the bin, where a lorry picks them up. The early-morning din of banging trash cans is simply part of the urban soundscape for many of us. To be sure, rubbish lorries are generally cleaner and quieter than they once were, but getting all that waste from our homes to the tip takes a lot of trips through crowded streets. This system, based mainly on manual labour, hasn’t changed much for at least a century.
But with new technology making inroads even in garbage collection, the Swedish company Envac has staked out a position as an international leader in automated waste management. Envac’s solution transports rubbish in sealed underground pipes, cutting out the need for surface transportation in lorries. Call it the “rubbish vacuum”.
Everything to the right place
Occupants of homes and offices served by the Envac system still sort their waste for recycling, just as most of us do anyway. The difference is that sorted rubbish bags are deposited into different inlets connected to underground tubes.
How does separated trash stay sorted as it moves through the system? Beneath each inlet is a vertical shaft for temporary storage above a closed valve. Although the shafts for paper, glass and metal all lead to the same horizontal tube for transport, a control system sees to it that they take turns, with valves opening and high-pressure fans creating a vacuum to empty the shafts at regular intervals. Sorted waste is delivered to a reception facility, with separate containers for different waste fractions. The waste is compressed in sealed containers for transportation by lorry to another facility for recycling, burning, composting or disposal. Particles and odours are filtered out of the transport air before it is released.
This closed system eliminates the need for on-site or street-side rubbish storage, with inevitable problems from odours, vermin and hygienic risks. No one need come into contact with anyone else’s trash bags or bins.
Suitable for old and new neighbourhoods
Of course, it’s easiest for urban planners to include an automated waste handling system before construction begins. Underground transport frees precious space on the surface for other uses, improves hygiene and comfort for residents, and reduces noisy, polluting vehicle traffic in crowded areas.
But older neighbourhoods perhaps have the most to gain. Crooked, narrow streets may be charming, but they’re often highly impractical for lorry traffic and for placement of source separation containers. A waste transport system hidden underground can solve these problems.
In addition to stationary vacuum waste management systems, the principles can be applied in a variety of ways. Some examples:
Mobile systems: Waste bags are deposited into an inlet, indoors our outdoors, where they are temporarily stored in a sealed tank. These tanks are connected at docking points via a network of pipes. The docking points are placed for easy access by collection vehicles, for instance to avoid the need to drive into courtyards. The dimensions of the system are matched to pre-determined collection intervals. As with a stationary system, the waste is compacted and odours and particles are filtered from the transport air before release.
MaxiVac: This system is designed for handling, transportation and storage of food wastes. The primary market is large catering kitchens that are in use around the clock, for instance in airports, where there is a need to quickly dispose of large amounts of waste generated both on incoming planes and in restaurants. While details of the system may vary, certain characteristics are standard:
- Waste is deposited in inlets placed to serve various steps in the food preparation process. The most common approach is for trays to travel along a conveyor belt, with food waste automatically vacuumed up or manually deposited into the inlet.
- The inlets are connected to a waste storage room via a sealed pipe system. Waste is sucked into the pipes by vacuum pressure, transported to a separator and finally deposited in containers.
Other applications are found in offices and hospitals.
Published in January 2009