Sewage Treatment (Purification)

Methods for the reduction of the substances present in waste water by mechanical, biological and/or chemical processes. Sewage treatment is carried out mainly in (clarification) plants. The large detritus is removed in the preliminary sedimentation tank by means of grids and sand catchers. The Organic Compounds are removed with the help of micro-organisms in the biological clarification stage. Any remaining pathogenes can then be killed by subsequent disinfection of the Sewage, for instance by UV radiation. The rest of the sewage treatment process uses chemical methods to deposit or precipitate specific problem substances such as Phosphates or Heavy Metals. Clarification produces large quantities of Sewage Sludge, which must be digested (Biogas recovery) and then disposed of in a manner which does not harm the environment (e.g. by Sewage Sludge incineration) or put to productive use (Sewage Sludge can be used as a soil conditioner).