by
Sven-Olof Malmqvist
In my early career actually right after the university I worked with quite interesting projects. In hindsight we were really ahead our time.
At this time all the municipal waste water treatment plants were using mechanical and biological and to some extent chemical treatments. In particular for the phosphate removal. But using more tailored made flocculants one could reduce the biological phase which also were energy demanding and costly.
Suddenly there were lot of empty basins which should be utilised and someone came with the bright idea to farm fish in them. It could be profitable and of course kind of PR for having such a clean environment and water that you could farm fishes!
When cleaning waste water you get a solid part sludge which could be used as a fertiliser if the content of undesirables like heavy metals were low and if it was of the hygiene level one could expect, even today it is used partly as fertiliser.
Organic waste like sludge and manure from farming is a resource but also a problem if it’s not managed and distributed in a professional way.
And now we are coming to the brilliant idea to reduce the organic waste in sludge by letting earth worms treat the pile for a while. The obstacle was that we needed a special breed coming from the Philippines if I remember correctly, (eisenia fetida) these guys were not used the Swedish climate and during the winter they could die, anyway apart from that they were very speedy in their reproduction so if you started with a few you suddenly got a “farm”.
Read the full article, HERE.
In my early career actually right after the university I worked with quite interesting projects. In hindsight we were really ahead our time.
At this time all the municipal waste water treatment plants were using mechanical and biological and to some extent chemical treatments. In particular for the phosphate removal. But using more tailored made flocculants one could reduce the biological phase which also were energy demanding and costly.
Suddenly there were lot of empty basins which should be utilised and someone came with the bright idea to farm fish in them. It could be profitable and of course kind of PR for having such a clean environment and water that you could farm fishes!
When cleaning waste water you get a solid part sludge which could be used as a fertiliser if the content of undesirables like heavy metals were low and if it was of the hygiene level one could expect, even today it is used partly as fertiliser.
Organic waste like sludge and manure from farming is a resource but also a problem if it’s not managed and distributed in a professional way.
And now we are coming to the brilliant idea to reduce the organic waste in sludge by letting earth worms treat the pile for a while. The obstacle was that we needed a special breed coming from the Philippines if I remember correctly, (eisenia fetida) these guys were not used the Swedish climate and during the winter they could die, anyway apart from that they were very speedy in their reproduction so if you started with a few you suddenly got a “farm”.
Read the full article, HERE.
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