In the technical sense, an urbanized area equipped with a community sanitation system consisting of one or several wastewater collecting systems (sewers) and one or more wastewater treatment plants, forming a coherent sewerage system. Under the meaning of the Urban Waste Water Treatment Directive, an area where the
All processes intended to render sewage sludge in compliance with environmental standards, land use regulations or other applicable quality standards for recycling or reuse. Primary, secondary and tertiary treatment is usually distinguished. These treatments not only reduce the volume of residues, but also stabilize and transform them into environmentally acceptable components and useful by-products. Tertiary treatment includes, for example, chemical conditioning, disinfection, pressure filtration, vacuum filtration, centrifugation and incineration. It is possible to classify wastewater treatment and sludge treatment in different categories, namely secondary treatment for wastewater and tertiary treatment for sewage sludge.
Treatment of (urban) wastewater which treats carbon suspended solids more advanced than primary treatment, according to a process by a process usually involving a biological treatment with secondary settlement or any other process resulting in a BOD reduction of at least 70% and COD of at least 75%. This treatment is required for agglomerations of over 2000 population equivalents.