Clarification plant

Today I was at a clarification plant with my class. First we got a technical introduction and then we went out and were guided through area. So we saw a  big pump at the beginning where all the sewage water was pumped up from the canalization.

There were 3 of these screw pumps ,each of them is able to pump 800l per second and has a diameter of 2 m!

Next station was the aeration basin here bacteria are added to dissolve nitrite and nitrate ,because they are bad for the environment in such a high dose

looks pretty ugly at this stage. The brown color comes from the bacteria

this one is also aeration basin with bacteria in it , but air is pumped into it at the bottom  so the bacteria  can dissolve
other organic material

In the second stage water and the bacteria-mud get seperated in round sedimentation basins.

The basins are funnel shaped so the mud falls to the bottom
and can be exhausted

Then we went to another biological clarification method , the sprinkling filter ,here the dirty water is dropped onto 4m long plastic straps which are settled by algae.

At the end there are again some round sedimentation basins.The warter that leaves the facility is to 97-99% clean.The excess bacteria mud and the incoming organic material is later on collectedin huge digester towers 

to produce methane gas.

We even saw a fish in the last sedimentatin basin