Localized domestic wastewater treatment: part I - constructed wetlands (an overview)

Constructed wetlands (CW) are an alternative localized treatment technology suitable for reducing BOD, COD, NPK and pathogens to acceptable levels for subsequent use of treated water, especially for irrigation. Dissolved chemicals and heavy metals are also reduced to an extent. CWs are extensively used in developed countries for secondary and tertiary treatment of domestic sewage and treatment of surface run off as well as industrial effluents. But CWs are yet to be commercialized in developing countries. Also detailed mechanisms involved in the treatment, especially role of macrophytes and microorganisms, need to be understood. Precautions must be taken in the use of CWs to prevent proliferation of mosquitoes. This review presents prospects and problems in propagating CWs for different types of wastewater, with special focus on domestic wastewater treatment.