With over five and a half million inhabitants, New York City prepared itself to overtake London to become the largest city in the world after the First World War. It was already the most modern city, but it still had to dispose of over 1,000 tonnes of horse manure every day, not to mention human waste. Then, in 1922, the magazine Science and Invention developed ideas that included a city-wide centralized vacuum system that would dispose of these huge quantities waste.
Proven since 1961
This great idea came slightly too early but was not entirely unrealistic, as demonstrated not long afterwards in 1961. During that year the hospital in Sollefteå, Sweden, installed the first central waste disposal system operated with a vacuum. Four years later Ör-Hallonbergen, also in Sweden, followed with the first system that was responsible for waste collection for a residential area. Today it is estimated that over 1,000 such systems are used worldwide, and this upward trend shows no sign of abating.
Operating a waste disposal system of course requires distinct infrastructure. The vacuum is generated in a central station where the suctioned waste is also collected for further treatment. It travels there through an underground pipe system at speeds of up to 70 kilometres per hour. Receiving units are located at the other end of the pipes. The waste is deposited in these, similarly to how it would be thrown into a refuse bin.
Advantages of centralized waste disposal
Vacuum technology offers a number of benefits over conventional waste disposal using plastic bins and refuse collection vehicles. For example, trucks are no longer needed to collect waste. This eliminates the associated noise and CO2 emissions, and reduces the amount of traffic. The centralized systems also significantly improve energy and ecological footprints.
In addition, there is no overfilling at waste disposal stations, as an installed sensor recognizes when a certain fill level has been reached. A valve then opens and the contents are sucked out. The whole system is also hermetically sealed, preventing hygiene problems from arising in the first place.
This aspect is particularly important for commercial kitchens and the food industry. Large amounts of organic waste accumulate there every day, such as vegetable waste, fruit peelings and seeds, or blood and unusable parts of animals in meat processing. Using a vacuum enables these waste products to be hygienically and quickly transported to a collection point through a pipe system.
Less waste water and better recycling
Water is often used during conventional disposal to remove this type of waste residue. The tremendous amount of waste water that is generated in the process can be greatly reduced using vacuum technology, which also significantly lowers disposal costs. Concentrated organic waste can then be better utilized – such as through incineration, conversion to biogas or as raw material for nutrient-rich fertilizers.
Apart from industry, the benefits of centralized vacuum systems already in place can be seen in particular in densely populated residential areas and larger facilities such as hospitals, airports or shopping centres. They are also a key component of many ambitious city planning projects, for example in China and the United Arab Emirates, but also in many cities in Europe. Experts in this field agree that centralized vacuum systems will play a crucial role in the disposal technology of the future.
Busch has supplied vacuum technology for disposal systems in many countries since the 1980s.
Advantages of centralized waste disposal
Why invest in a vacuum system for waste disposal, when existing conventional disposal systems with roadside plastic bins and refuse collection vehicles works perfectly well? There are many advantages, according to manufacturers of this type of system, and any investment in vacuum systems will pay dividends through the savings made.
At present, overfilled bins and litter baskets in public areas are the exception rather than the rule; sensor-controlled emptying at disposal stations will put an end to that. Lorries for waste collection become unnecessary; noise and pollution are reduced; and city centres and historic neighbourhoods in particular benefit from the improved traffic situation. The centralized systems also significantly improve energy and ecological footprints. Waste sorting is also possible, for example by using different coloured rubbish bags that can be automatically detected and sorted.
Using vacuum processes for removal of organic waste is particularly beneficial in food processing. For this application, only small pipes are required, which can also be installed in existing systems. The vacuum ensures waste is quickly and hygienically transported to a collection point. This process requires no additional rinsing water, and also means that vermin can't feed on waste that is awaiting collection.
The collected food waste can be used for combustion, converted into biogas or bioethanol in fermentation systems, or it can undergo a process of hydrothermal carbonization (HTC) and be transformed into brown coal. Furthermore, the nutrients from concentrated organic waste can also be used to produce animal feed, or as raw material for nutrient-rich fertilizer.