Müllheizkraftwerk Ulm, Germany
The multi-stage process for the treatment of very acidic effluent was dimensioned in such a way that the contaminants can be separated as “pure products”.
 
1^st stage: Separation of particles and activated carbon powder
The acidic effluent is treated by a membrane filter press. Before emptying the press, the cake is washed in order to eliminate the acids. This process step allows the separation of white gypsum in the following stage.
 
2^nd stage: gypsum recovery
In the gypsum precipitation stage, the effluent is partially neutralized to pH 2 by adding lime and caustic soda. The addition of lime is controlled by a continuous measurement of calcium and sulphate. The gypsum separated in the following sedimentation is dewatered and washed with a vacuum belt filter so that “pure” gypsum is recovered.
 
3^rd stage: Ammonium stripping and recovery
The effluent which is still acidic is afterwards adjusted to pH 11 by using caustic soda. The steam-stripping is carried out in 2 columns, and after condensation the recovered ammonia is recirculated to the incinerator where it is used in the DENOX stage.
 
4^th stage: Precipitation of heavy metals
The heavy metals still contained in the waste water are finally neutralized and precipitated with the help of precipitation and flocculation chemicals. The hydroxide sludge is separated in a clarifier and finally dewatered in a chamber filter press. The effluent is finally polished over 2 sand filters.
 
5^th stage: Evaporation for salt recovery
The effluent is finally evaporated in order to get a pure salt solution. This stage was not delivered by EnviroChemie.

Dimension of the waste water treatment plant:

2 m3/h

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