Selective memory


kiel
Human waste being collected in Kiel
Lubeck buckets
The waste was collected in buckets and sold to gardeners and farmers to use as fertiliser. This took place in Lübeck up until 1952.

lindley William Lindley (7 September 1808 - 22 May 1900) was a famous British engineer who together with his sons designed water and sewerage systems for over 30 cities across Europe, including Stralsund. In 1863 he began work on the sewerage system of Frankfurt am Main. Within 20 years the death rate from typhoid fell from 80 to 10 per 100,000 inhabitants. He used subsidence tanks for clarification and introduced sand-filtration, which was only adopted after the cholera epidemic of 1892- 1893. Lindley's designs were in demand across Germany and elsewhere, including St. Petersburg, Budapest and Moscow. In 1876 the Australian city of Sydney even asked him to design a sewer system for them, but he turned them down as he had just been commissioned by Warsaw.

sewers being dug up
The old wooden pipes are being replaced with new ones. Image taken in the center of Stralsund.

wooden pipe
Section of wooden pipe

During the period since the introduction of sewers in Stralsund in 1859 up until effective cleaning measures were taken in 1995 - a time-span of more than 100 years -  human and industrial waste has been released straight into the Baltic Sea. This has been, and in some places still are the way waste is being dealt with for cities around the sea. Being an almost enclosed and somewhat shallow body of water, the Baltic Sea is very sensitive to human intervention. A series of correlating events lead to a dramatic worsening of the maritime environment, the extent to which scientists only became aware of in the early 60'ies.

Field Trip to the Stralsund waste water plant
big waste
Solid objects such as CDs and other large items are the first to be removed in the cleaning process.
mechanical cleaning
This is followed by a process of mechanical  cleaning where the sediments settle over time.
bioclean
In the biological cleaning process air is pumped through the water, allowing perfect conditions for the growth of anaerobe bacteria and algae that further cleans the water.
cleaned water
By the final stage the water is 98% clean. It is then pumped into the Strelasund.

methanegas
The by-products from the water cleaning process are stored in large containers, where they create the methane gas that powers the entire sewerage plant.