Erillisviemärit

Erillisviemärit, which translates to separate sewers or separated sewers, refers to a wastewater management system where sewage and stormwater are collected and transported through distinct pipe networks. This approach contrasts with combined sewer systems, which carry both types of wastewater in a single pipe.

The primary purpose of separate sewers is to improve the efficiency and environmental impact of wastewater treatment. By keeping stormwater, which is generally less polluted, separate from sanitary sewage, the volume of water reaching treatment plants is reduced. This allows treatment facilities to operate more effectively and at a lower cost, as they do not have to process large volumes of rainwater. Furthermore, it helps prevent the overflow of untreated sewage into natural waterways during heavy rainfall, a common problem in combined sewer systems.

Implementing separate sewer systems involves constructing two separate underground networks. One network collects wastewater from households, businesses, and industries. This sewage is then directed to a wastewater treatment plant for purification. The second network collects rainwater runoff from streets, roofs, and other impervious surfaces. This stormwater may be directed to local streams, rivers, or lakes, or in some cases, it may undergo partial treatment before discharge.

While separate sewer systems offer significant environmental and operational advantages, their installation and maintenance can be more complex and expensive than combined systems, especially in existing urban areas where retrofitting can be challenging. Despite these challenges, many modern urban developments are designed with separate sewer systems to ensure better environmental protection and more efficient wastewater management.