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Über dieses Buch

This book identifies the key hydrologic and hydraulic factors which influence the performance of stormwater quality treatment systems such as constructed wetlands and bioretention basins. Mathematical relationships derived using conceptual models underpinned by fundamental hydraulic theory are presented to predict treatment performance. The key highlights of the book will include the identification of the linkages between influential hydrologic and hydraulic factors for constructed wetlands and bioretention basins to support more accurate prediction of treatment performance and effective design of these types of stormwater treatment systems. Furthermore, this book will showcase an innovative approach for using conceptual models to analyze stormwater treatment system performance.



Chapter 1. Storm Water Treatment

Urbanisation leads to changes in storm water quantity and quality due to the increase in impervious surface areas. While the quantity changes include increase in runoff volume and peak flow and decrease in the time to the peak, the quality changes are primarily due to the fact that a diversity of anthropogenic activities contributes a range of pollutants to the urban environment. These pollutants are washed off  by storm water runoff and transported to receiving waters. In this context, structural storm water treatment measures are commonly introduced to mitigate storm water quality degradation. This chapter presents reviews of typical structural storm water treatment systems used in urban areas, providing an overview of their design and the inherent treatment processes. The systems discussed include gross pollutant traps, vegetated swales/bioretention swales, detention/retention basins, infiltration systems, bioretention basins and constructed wetlands.
Isri R. Mangangka, An Liu, Ashantha Goonetilleke, Prasanna Egodawatta

Chapter 2. Creating Conceptual Models of Treatment Systems

The chapter discusses two conceptual models developed for replicating bioretention basin and constructed wetland behaviour. This discussion firstly outlines the development processes adopted including the theory applied, mathematical equations used and assumptions made, and then presents the model calibration procedure indicating model accuracy. A range of hydraulic parameters were selected to replicate the processes in the two treatment systems. These parameters were selected based on their ability to facilitate the analysis of the relationships between hydrologic and hydraulic factors and system treatment performance.
Isri R. Mangangka, An Liu, Ashantha Goonetilleke, Prasanna Egodawatta

Chapter 3. Assessing Bioretention Basin Treatment Performance

This chapter investigates the influence of hydrologic /hydraulic factors on the treatment performance of a bioretention basin using parameters generated by the conceptual model discussed in Chap. 2. The study outcomes showed that antecedent dry period is an important factor influencing pollutant removal efficiency. A long antecedent dry period will result in relatively low moisture content in the filter media which can enhance the runoff retention capacity and consequently improve treatment performance. This implies that planting vegetation with a high evapotranspiration capacity would enhance treatment efficiency. Additionally, it was found that pollutant leaching influences bioretention basin treatment performance , particularly reducing the ability for nutrient removal. This highlights the importance of the selection of appropriate filter media and its timely replacement.
Isri R. Mangangka, An Liu, Ashantha Goonetilleke, Prasanna Egodawatta

Chapter 4. Assessing Constructed Wetland Treatment Performance

This chapter presents the assessment of the constructed wetland treatment performance . The assessment was done by partitioning the inflow runoff hydrograph into ten segments and then investigating the treatment performance of each runoff segment within a constructed wetland. Accordingly, the hydrologic and hydraulic factors generated by the conceptual model were also appropriately allocated to the ten segments. The analysis outcomes showed that large and small rainfall events are differently treated in a constructed wetland. The pollutant load reductions for the initial sector of runoff from large rainfall events were relatively low, due to the rapid mixing taking place within the system. This highlights the need to establish an inlet pond prior to the flow entering the constructed wetland, so that the inflow will initially stabilise. This is also supported by the fact that the initial sector of runoff generally carries higher pollutant loads.
Isri R. Mangangka, An Liu, Ashantha Goonetilleke, Prasanna Egodawatta

Chapter 5. Implications for Engineering Practice

This chapter provides a consolidated summary of outcomes from the research study undertaken on the influence of hydrologic and hydraulic factors on bioretention basin and constructed wetland treatment performance , using the two conceptual models developed. The knowledge created is expected to provide practical guidance and recommendations for storm water treatment designers and hydrologic/hydraulic model developers. This chapter also briefly discusses key areas where currently there are significant knowledge gaps and areas for further investigation. These include, investigating other typical storm water treatment systems and pollutant behaviour in addition to what has been investigated in the research study. Additionally, the use of laboratory scale models to investigate the relationship between hydraulic factors and water quality treatment is recommended in order to validate the outcomes obtained by using the conceptual models.
Isri R. Mangangka, An Liu, Ashantha Goonetilleke, Prasanna Egodawatta


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