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Glossary

Wastewater Treatment

The term wastewater treatment covers all biological, chemical and/or mechanical processes that are used to reduce impurities found in wastewater.

Municipal and a lot of industrial wastewater sewage which predominantly contain organic impurities must be treated at least biologically. However, biological procedures are not sufficient if wastewater sewage is heavily polluted or if it is discharged into inefficient waters or lakes. The wastewater sewage must then be treated in “advanced wastewater treatment” plants. Wastewater is generally treated in sewage treatment plants. In the first stage 
 the mechanical cleaning  screen, grit chamber and sedimentation tanks or primary clarifiers are used to filter out coarse matter, sand and settleable solids. The second stage is biological wastewater treatment. The remaining, well-soluble wastewater components are exposed to microorganisms which live on the decomposition of organic matter and multiply in this process. With regard to the biological oxygen demand, the cleaning effect of such sewage treatment plants is usually 90 to 95 percent. The remaining five to ten percent and, in particular, the nitrogen and phosphorous compounds are removed in a tertiary treatment stage in modern plants. This final phase is referred to as advanced wastewater treatment or as an “end-of-pipe procedure” since this part of the treatment takes place after mixing all waters. When it comes to industrial wastewater treatment, concepts and technologies of production-integrated environmental protection are increasingly taking effect and guarantee sustainability.