Optical waste sorting system

There are many waste sorting systems in the world — here is one of them —

waste sorting by machine identifying the colors.

Here is one example from Eskilstuna, Sweden. Every household get free color bags from the post box — by puting one color bags hanging in the post box meaning they need more of those color bags (e.g. green for organic waste, orange for plastics…), then they will get a few more. Therefore this service is available at houses at the moment — not apartments or corridors, which makes it easier to manage the system as apartments and corridors are hard to track their usage condition and responsibility household in case of misusage. But they think this could be promoted further in the future.

Everyday the delivery truck go and empty the garbage bins from household with mix colored garbage bags and empty the truck into the loading zone as below.

As you can see from the picture, not all bags are colored bags, some are mixed with garbage bag from supermarket. That means they will not be sorted and will end up in the mixed waste.

Then all incoming waste go onto the conveyor belt, where they will be seperated by optical sensors.

If they match the color by the optical sensors, they will be pushed down by a rubber plate brush down to the sorted color bins.

Waste will then either be transported to where it will be further process — e.g. biogas plant, or processed with bags removed at the spot. Collected plastics will be compressed and shipped to Germany because these is no plastic processing companies yet in Sweden. There will be one coming soon though.

But what happens to the miscellaneous waste? There are 5 workers there to manually sort out the waste (in the house on the left).

They have now a food waste storage tank ready to use so then they don’t have to deliver those food waste everyday, but can store up to a month there before sending out. but a small part of the food waste will turn to protein by fly larvae, which is restricted to be used as protein in only certain fishery and poultry rising as feed.

The above is the story about the optical waste sorting system. And now let’s think about whether this is sustainable or not.

Well, it is easy to use for handlers and household, which makes it easy to spread around. this is very practical and important, because you can easily design something very idealistic and perfect but no one wants to use it. then it doesn’t mean anything.

At the same time, maybe you would ponder, then aren’t we using extra plastics to try to ‘save’ other resources? Does that make any sense? It is true that it will cost extra energy. But if it helps all waste to go to the right places, and nutrients get recycled, wouldn’t it be better than everything just mix up together? Which might even be more detrimental for the environment?

At this stage, this system is not applicable for all the household yet. Because even with the easily identified colors, people still make mistakes, which then not benefiting the system. So the person who pickup the garbage will have random check on whether the right things are in the right bags, if they aren’t then the house will get a notification. And if they continue doing so, then some persuasive staff will go and ‘educate’ them. People are quite satisfied with this system because it is easy to handle. So far, it works quite well this way.

Who knows, I guess no one method fits the diverse of population, combination of various ways of waste management might work together the best.

Something off topic:

Last but not least, in the same community, they have a very nice recycling mall called ReTuna. Very recommended to visit.

The first floor are the recycling items from the community that people donate and they sell them for very cheap prices. Plus, they hire people who can’t find jobs. The second floor is commercial companies selling either new but old-school, recycling, vintage…stuff. They will have to have a theme and get it approved by the mall management system. Some of them are super cool and have very nice innovative way of showing recyling stuff! One would be trash in a bin but could be treasure in another places~