The Historical Development of Constructed Wetlands for Wastewater Treatment

Abstract

Constructed wetlands (CWs) for wastewater treatment are engineered systems that are designed and operated in order to use all natural processes involved in the removal of pollutants from wastewaters. CWs are designed to take advantage of many of the same processes that occur in natural wetlands, but do so within a more controlled environment. The basic classification is based on the presence/absence of wastewater on the wetland surface. The subsurface flow of CWs can be classified according to the direction of the flow to horizontal and vertical. The combination of various types of CWs is called hybrid CW. The CWs technology began in the 1950s in Germany, but the major extension across the world occurred during the 1990s and early 2000s. The early CWs in Germany were designed as hybrid CWs; however, during the 1970s and 1980s, horizontal subsurface flow CWs were mostly designed. The stricter limits for nitrogen, and especially ammonia, applied in Europe during the 1990s, brought more attention to vertical subsurface flow and hybrid systems. Constructed wetlands have been used to treat various types of wastewater, including sewage, industrial and agricultural wastewaters, various drainage and runoff waters and landfill leachate. Recently, more attention has also been paid to constructed treatment wetlands as part of a circular economy in the urban environments: it is clear that CWs are a good fit for the new concept of sponge cities.

Constructed wetland as a green remediation technology for the treatment of wastewater from underground coal gasification process

“…CWs were initially used to treat municipal wastewater containing high concentrations of nutrients [ 32 , 33 ]. However, in recent years the evolution of CWs from simple to more advanced systems has evolved and various hybrid CWs have been applied to treat industrial wastewater from dairy and meat processing, the pulp and paper factory, brewery, tannery and olive mills [ 16 , 17 , 34 , 35 ].…”

“…CWs as nature-based processes remove pollutants from the water, avoiding the use of chemical products and the input of high amounts of external energy [ 33 , 48 , 49 ]. One of the positive characteristics of CWs is their work under controlled conditions such as the well-defined composition of media, plant types, flow patterns, controlled hydraulic pathways and retention time.…”

“…In the constructed wetlands the removal of pollutants is carried out by different physical, chemical, and biological processes like sedimentation, filtration, precipitation, ion exchange, adsorption, microbial processes for instance, nitrification, denitrification, sulphate reduction, carbon metabolization, and plant uptake. The activities of the processes are dependent on the interaction between plants, microorganisms, wastewater characteristics, media used and operation conditions [ 33 , 50 ]. Traditionally CWs have been used for urban wastewater, stormwater runoff and domestic wastewater treatment, but in the last two decades, the applications for industrial wastewater purification increased due to the development of the technology and the extended research in this field.…”

Mitigation of eutrophication from agricultural runoff: the case of the agricultural region of Moungo in Cameroon

“…CW are of two types: surface flow wetland and subsurface flow wetland. The efficiency of CW in P and N Removal is higher than the NW one 11 and. [12][13][14] Figure 4 Agricultural ditches; source: Yinfeng Xia.…”

Distribution of nitrogen-transforming bacteria in an artificial reservoir populated with aquatic higher plants

“…Почвенно-болотные системы с высшими водными растениями, созданные с использованием современной экологической технологии «constructed wetlands» (другое название -искусственный водоем с высшими водными растениями), могут использоваться для очистки сточных вод и являются одним из самых перспективных типов очистных сооружений ввиду низких затрат на капитальное строительство, простоты эксплуатации, высокой эффективности обезвреживания загрязненных вод и экологической безопасности. Constructed wetlands преимущественно применяются для очистки сточных вод на малых животноводческих фермах, в которых не требуется проводить сложное эксплуатационное и техническое обслуживание [1][2][3]. Многочисленные международные исследования свидетельствуют об успешном применении систем «constructed wetlands» для очистки сточных вод различного происхождения, в том числе для животноводства, где одним из главных загрязнителей выступают различные соединения азота [4][5][6].…”