Separate Sewers

Separate sewerage consists in the separate collection of municipal wastewaters (blackwater from toilets, greywater and industrial wastewater) and surface run-off (rainwater and stormwater). The separate collection prevent the overflow of sewer systems and treatment stations during rainy periods and the mixing of the relatively little polluted surface run-off with chemical and microbial pollutants from the municipal wastewater. The design of the sewers and the (semi-) centralised treatment stations thus needs to consider the volume of the wastewater only and the surface run-off and rainwater can be reused (e.g. for landscaping or agriculture) after a simplified treatment.