Domestic wastewater is one of the biggest sources of pollution that blends surface waters.

Municipal Wastewater Treatment is the process of removing of the harmful pollutants from wastewater. Domestic use is the main source of the pollutants. The pollutants are treated by various methods like Physical, Chemical, and Biological process.

Wastewater treatment plants have a high quality service requirement that involves tight control of sludge management, chemical management, energy savings and operating costs. In recent years, this has been facilitated by the introduction of advanced technological solutions such as automatic control centers in treatment plants. Setaş can include these technologies in plant designs in line with customer demands and needs, as well as integrate as part of the modernization of existing wastewater treatment plant.

Domestic wastewater treatment plants, are classified according to the number of people they serve. Mechanical, chemical and biological processes are used in wastewater treatment. In the mechanical-physical process, which is usually determined as the first step, undissolved suspended solids are removed from the waste water. Depending on the density, these particles are separated using pre-treatment steps such as screen, filtration, pre-settlement or dissolved air flotation. Light materials such as oil and grease float, high density materials sink. Components such as screen, sieve, grease trap, grit trap, flotation and pre-sedimentation are used for mechanical cleaning.

Biological treatment is a process, which nutrients and pollutants in wastewater are removed by microorganisms. While dissolved oxygen is required for the degradation of carbon compounds and ammonium (Nitrification) in wastewater, an oxygen-free environment is required for the degradation of nitrate (Denitrification).

The third step covers the removal of substances that are difficult or impossible to degradation, such as medicinal products, toxic substances and heavy metals, and especially phosphorus compounds, for those pollutants can be treatment using coagulation, flocculation and precipitation processes. In addition to these, disinfection is applied to the treated wastewater by methods such as UV radiation, ozonation and chlorination. In the final stage, adsorbable substances can be removed using an activated carbon filter.