Vertical flow constructed wetlands for wastewater and sludge treatment represent a relatively new and still growing technology. Vertical Flow Constructed Wetlands is the first book to present the state-of-the-art knowledge regarding vertical flow constructed wetlands theory and applications. In this book, you will learn about vertical flow systems with information about application and performance. Vertical Flow Constructed Wetlands also includes information on how different countries are applying the technology, with design guidelines to illustrate best practices worldwide. A focus on water conservation through reuse of treated water showcases the benefit of vertical flow construction, which has greatly increased the attractiveness of the technology in recent years. - All state-of-the-art knowledge regarding vertical flow constructed wetlands gathered in one book - A review of various constructed wetland approaches, including information about applications and performance, helps clarify what is currently known about constructed wetland principles and design - Discussion of how to manage the treated wastewater leaving the vertical flow for increasing biodiversity, providing food and habitat for birds, and producing harvestable biomass or crops - Includes case studies of constructed wetlands in developing countries
This thesis describes in detail the background, methods, results, and conclusions of a three-year PhD research project - "subsurface flow constructed wetlands for the treatment of domestic wastewater", which was undertaken at Monash University between April 2008 and December 2010. The overall objective of the research was to discover the efficiencies of key pollutant removals (organics, nutrients, solids, and coliforms), when a medium-strength wastewater is treated in different types of subsurface flow wetlands, and how the pollutant removal should be modelled to reflect the biodegradation kinetics of the pollutants. The research was designed and carried out in four phases:In phase 1, a comparative experiment was carried out to understand how wetland media may affect the removal of organics and nitrogen; special focus was on studying the nitrification-denitrification process in hybrid wetland systems with an unconventional organic-containing wetland media (wood-mulch). The results indicated simultaneous nitrification-denitrification in vertical flow wetlands with organic mulch media, primarily due to greater oxygen flux in the wetland matrix and the supply of organic carbon from the media. In contrast, this unconventional media was found to be inefficient when it is applied in horizontal flow wetlands, as anoxic conditions caused excessive leaching of organics from the media. The monitoring of the performances of different wetland units, during this phase, allowed the selection of an effective hybrid wetland system for further experiments, to monitor pollutant removal stability in the next phase. In phase 2, experiments were carried out in three hybrid wetland systems that had identical configurations, plants (Phragmites australis), and media (including gravel, wood-mulch, and zeolite). The three systems were operated under different pollutant and hydraulic loadings, to monitor the removal of nitrogen and organics. The results demonstrated stable nitrogen and organics removal efficiencies within the range of hydraulic and pollutant loading variations. The media of wood-mulch and zeolite were found, or further confirmed, to enhance nitrogen removal in vertical flow wetlands, by enhancing simultaneous nitrification-denitrification and adsorption of ammonia. Horizontal flow wetlands with the traditional gravel media showed abilities to remove nitrate and the excess organics that was leached into the wastewater from wood-mulch media and, within the experiment range, the mass removals of nitrate and COD in the horizontal flow wetlands were found to increase with their loadings.In phase 3, kinetic models were developed to describe the biodegradation of nitrogen and organics removal in wetland systems. Reaction kinetics that were considered in the model development included first-order, Monod and multiple-Monod-kinetics; these kinetics were combined with continuous-stirred tank reactor (CSTR) or plug-flow pattern, to produce equations that link the inlet and outlet concentrations of each key pollutants across a single wetland. Using three statistical parameters, a critical evaluation was made to evaluate the suitability of five potential models for describing pollutant removals in vertical and horizontal flow wetlands. The results recommended the models that were derived from Monod kinetics for nitrogen and organics removal in both vertical and horizontal flow wetland systems.Finally, in phase 4 a simple MATLAB programme was established, based on the model studies in the previous phase, to provide a potential design tool for determining the surface area of a single subsurface (vertical or horizontal) flow wetland, when it is required to achieve a given pollutant removal target. The MATLAB programme can also be used to predict the performances of existing wetland systems.In order to assist readers to track the results of four phases of this research in its logic sequence, the thesis has been arranged to contain seven chapters. Chapters 1-2 describe the scope and objectives of the research and a literature survey on the technical development of subsurface flow wetlands for wastewater treatment. Chapters 3-6 describe in sequence the detailed methods and results of the four phases of the research. Overall conclusions are presented in Chapter 7. Four publications, including three ISI journal papers and one international conference paper, have been produced as a direct result of the research. The papers are attached in Appendix I, and all the original experiment records are attached in Appendix II.Overall, this research improved the current understanding of the removal of ammonia, nitrate, COD and BOD in vertical and horizontal flow wetlands. In addition, it produced kinetic models to describe the removal of these pollutants, potentially allowing model-based design of vertical and horizontal flow constructed wetlands for the direct treatment and reclamation of medium-strength wastewater.
With a sharp focus on environmental pollution and its impact on life and nature, scientists and engineers have studied the water treatment effect of natural wetlands for many years, resulting in the development of constructed wetlands (CWs) for treating wastewater. This informative new book provides current information and guidance on the construction, performance, operation, and maintenance of subsurface flow constructed wetlands of domestic and municipal wastewater. The focus of the volume is to evaluate the performance of horizontal subsurface flow constructed wetlands in treating domestic wastewater to establish the limit that can be safely discharged to agricultural drains. Two-step procedures were used for the preparation of this book. Using modeling and statistical analyses of treated water samples showed a significant difference between different media for the treatment of most pollutants. The authors went on to design artificial neural network models (ANNs) using Matlab software to simulate some of the experimental data and to anticipate the parameters of output concentration. The wetland systems have the ability to deal with various pollutants with different concentrations and to decrease the treated water to the standard limits. This volume presents the main role of emergent plants for treatment performance in the constructed wetlands and will be a very important resource for engineers in this field as well as for both undergraduate and graduate students.
Wetlands have been used for uncontrolled wastewater disposal for centuries. However, the change in attitude towards wetlands during the 1950s and 1960s caused the minimization of the use of natural wetlands for wastewater treatment (at least in developed countries). Constructed wetlands have been used for wastewater treatment for about forty years. Constructed wetland treatment systems are engineered systems that have been designed and constructed to utilize the natural processes for removal of pollutants. They 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 aim of this book is to summarize the knowledge on horizontal s- surface flow constructed wetlands (HF CWs) and objectively evaluate their treatment efficiency under various conditions. The information on this type of wastewater treatment technology is scattered in many publications but a comprehensive summary based on world-wide experience has been lacking. The book provides an extensive overview of this treatment technology around the world, including examples from more than 50 countries and examples of various types of wastewater treated in HF CWs.
