Constructed wetlands are on-site water treatment systems that use natural processes involving wetland vegetation, soils and their associated microbial assemblages to improve water quality.

On-site wastewater treatment in Shanghai, China Vertical flow constructed wetland, 80 m³/d

These low-cost technology was developed to be highly effective and suitable treatment systems for:
      Residential, municipal, industrial wastewater,
      Stormwater overflow
      Rainwater



Structure and function mode

In a first process step solids are extracted from the wastewater in septic tanks. The wastewater running off is piped by pumps or with a mechanical construction into the wetland field. Depending on installation type the wastewater flows through the constructed wetland in horizontal or vertical direction. The field consists of sands and gravel in special kinds of granulations, endemic plants like helophytes grow on its surface (and, by the way, offer a beautiful sight). The roots penetrate the gravel-sand-bedding, ventilates it and keeps it hydraulically permeable.

Benefits     High efficiency in purification     Sustainable solutions - low       costs for investment and       maintenance     Reduced impact on       municipal infrastructure     Few space demand       (not exeeding 1-3 m² per       inhabitant)     High life span       (renewable system)     Reuse for wastewater     Natural beauty     Individually designed

Treatment characteristics

Pollutants entering the wetland are removed from the water by microbes living on the surfaces of the gravel and plant roots. The plants provide oxygen to the bed and remove some of the nutrients. Other processes such as filtering, microbial decomposition, and attachment to particle surfaces also help remove pollutants.

COD removal    BOD removal    ammonia removal