Biological and chemical wastewater treatment
The next stage of wastewater treatment is about biological aspects. Natural processes are mimicked to allow for efficient water purification. Experts speak in this context of the metabolization of organic substances. In biological sewage treatment plants, the supply of oxygen is used to accelerate the purification processes.
In the final step of wastewater treatment, chemical processes are performed. Typically, the previously clarified water is neutralized by the addition of caustic soda or lime. In this process, salts and colloids can precipitate. Depending on the size and nature of the wastewater treatment plant, various processes can be used in chemical wastewater treatment. In this context, mention should be made of ion exchangers, flotation or the membrane process. The water that finally leaves the treatment plant is – scientifically correct – clean, but not pure. Given the high demands on drinking water, it would be out of the question for consumption. However, some sewage plants use UV light to efficiently kill bacteria, germs and viruses. In other systems special filters are used for filtering. Only this ‘special treatment’ in wastewater treatment ensures unscrupulous drinking water quality.