Constructed Wetlands for Wastewater Treatment
Constructed wetlands for wastewater treatment are wastewater treatment systems that encompass a plurality of treatment modules including biological, chemical and physical processes, which are all akin to processes occurring in natural treatment wetlands. Although initially designed and used for domestic wastewater treatment, through the efforts of research and operation for over fifty years, they have now been successfully extended to the treatment of a wide variety of wastewaters which include, but not limited to industrial effluents, urban and agricultural stormwater runoff, animal wastewaters, leachates, sludges and mine drainage. The basic classification of constructed wetlands is based on the type of macrophytic growth, but a more popular classification is that based on the water flow regime, i.e. horizontal or vertical flow.
In recent times, a more pragmatic approach to constructed wetland design has led to the development of Engineered Wetlands. However, while all engineered wetlands can be regarded as constructed wetland systems, not all constructed wetlands can be regarded as engineered wetland system. Engineered wetlands are special, advanced kinds of constructed wetlands in which operating conditions are more actively monitored, manipulated and controlled than is the norm with ordinary constructed wetland systems. In these systems, some of the multiple reactions and operating processes that are carried out in single cells in constructed wetlands are optimized in individual cells in series in engineered wetlands. However, irrespective of the type of constructed or engineered wetland system, the elimination principles for pollutants are the same.
Constructed and/or engineered wetland systems are capable of removing and/or converting a wide range of wastewater pollutants through a vast array of processes that include complex physical, chemical and biological interactions between water, substrate, filter material, macrophytes, litter and detritus and micro-organisms. In particular, engineered wetlands have evolved as an effective means of advanced wastewater treatment including nutrient removal. For efficient engineering design to achieve optimal removal efficiencies, a good knowledge and understanding of the complex mechanisms involved is very essential in order to maximize the particular removal mechanism. The systems are considered as thin film natural biological reactors using selected substrata, plants, and engineering configurations and they should be designed using sound engineering practice to ensure the effectiveness of the wastewater. In general, these systems have proven to be an effective low cost treatment system which utilizes the interactions of emergent plants and microorganisms in the removal of wastewater pollutants.
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This article was written by:
Dr Akintunde Babatunde (BSc,MEngSc,PhD,MIEI)
Centre for Water Resources Research,
School of Arch.,Landscape and Civil Engineering,
University College Dublin,
Links
A. O. Babatunde and Y. Q. Zhao. Water Science & Technology—WST Vol 60 No 2 pp 483–489, Phosphorus removal in laboratory-scale unvegetated vertical subsurface flow constructed wetland systems using alum sludge as main substrate, IWA Publishing: 2009
Y. Yang, Y. Q. Zhao, A. O. Babatunde and P. Kearney, Water Science & Technology—WST Vol 60 No 12 pp 3181–3188, Two strategies for phosphorus removal from reject water of municipal wastewater treatment plant using alum sludge, IWA Publishing 2009.
