A blog from University of Borås

Tuesday, May 1, 2012

Waste sorting: Technology vs social solutions!

Waste is generally a mixture of valuable materials. However, people do not use it, since it is a mixed materials and most of us have no economically-feasible technology to use this material. However, if we succeed to separate it, then, we can have access to these valuable materials.

The global view on waste sorting into different fractions is an "impossible mission" or we, as engineers, usually look for an engineered technology to turn this impossible task to a possible one, and forget about the role of people in sorting and separation. Let's have a look on what we do:
1- In most of the countries in the world including industrial and developing countries: We have no solution, so lets dump it!
2- In some countries such as some European countries and Japan: Let's burn it altogether in an incinerator! They sometimes extract energy or sometimes not!
3- Let's separate the waste! But, we have a major question: Who should do it? Technology at waste stations? Scavengers? People at home?

In low wage developing countries, it is usually the scavengers who try to pick up valuable things among the wastes and then sell it. But, in more developed countries such as Sweden, there is no access to such people. In addition, it is just the recycling parts that the scavengers separate, and the rest remains.

Let's compare 3 methods to separate the wastes:

1- In Borås (Sweden): it is now many years that people separate wastes into black (biological wastes) and white bags (combustible wastes). It is easy to do and they close the bags and throw them together. They have one transporting system and then, machines separate the bags based on its color. They have done a huge investment on teaching people (social aspects) and the system works well. The black bags become biogas and the white bags become electricity and district heat via combustion.

2- In Göteborg (Sweden): The have recently started to separate the wastes into food wastes (paper bags) and other wastes (plastics bags). Then, there are two different transport system. The food wastes become biogas and the other wastes are combusted as in Borås, but different technology.

3- In Copenhagen (Denmark), they still burn the waste as mixed. But, they have different view of development. They forget about the social aspects, and put efforts in technology development to separate the "mixed wastes". They are testing in a pilot plants now (REnescience), in which the wastes are heated to less than 100 C, and then by enzymes, part of the wastes are dissolved into a slurry phase.

I belive, separation of wastes after the mixing is too costly and has low efficiency. If the politions and municipalities in the world invest more in developing social aspects in parity of technological aspects, we will have more economical solutions for converting "Wastes to Wealth"!

(An Indonesian Scavenger in Sulawesi)

(The technology used in Borås to separate black and white bags after collected together)

(Waste sorting in Göteborg, in which, the food wastes and other wastes are collected separately)

(The technology developing in Copenhagen for separating of mixed waste, still in pilot phase)

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