The aim of this book is to present an overview of the state of the art with regard to the
function application and design of TWSs in order to better protect surface water from
contamination. Accordingly it also presents applications of constructed wetlands with regard
to climatic and cultural aspects.The use of artificial and natural treatment wetland systems
(TWSs) for wastewater treatment is an approach that has been developed over the last thirty
years. Europe is currently home to roughly 10 000 constructed wetland treatment systems (CWTSs)
which simulate the aquatic habitat conditions of natural marsh ecosystems roughly 3 500
systems are in operation in Germany alone. TWSs can also be found in many other European
countries for example 200 - 400 in Denmark 400 - 600 in Great Britain and ca. 1 000 in
Poland. Most of the existing systems serve as local or individual household treatment systems.
CWTSs are easy to operate and do not require specialized maintenance further no biological
sewage sludge is formed during treatment processes. As TWSs are resistant to fluctuations in
hydraulic loads they are primarily used in rural areas as well as in urbanized areas with
dispersed habitats where conventional sewer systems and central conventional wastewater
treatment plants (WWTPs) cannot be applied due to the high costs they would entail. TWSs are
usually applied at the 2nd stage of domestic wastewater treatment after mechanical treatment
and or at the 3rd stage of treatment in order to ensure purification of effluent from
conventional biological reactors and re-naturalization. New applications of TWSs include
rainwater treatment as well as industrial and landfill leachate treatment. TWSs are well suited
to these fields as they can potentially remove not only organic matter and nitrogen compounds
but also trace metals and traces of persistent organic pollutants and pathogens. Based on the
practical experience gathered to date and on new research regarding the processes and
mechanisms of pollutant removal and advances in the systems properties and design TWSs
continue to evolve.
