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Über dieses Buch

Chittaranjan Ray, Ph. D. , P. E. University of Hawaii at Mãnoa Honolulu, Hawaii, United States Jürgen Schubert, M. Sc. Stadtwerke Düsseldorf AG Düsseldorf, Germany Ronald B. Linsky National Water Research Institute Fountain Valley, California, United States Gina Melin National Water Research Institute Fountain Valley, California, United States 1. What is Riverbank Filtration? The purpose ofthis book is to show that riverbank filtration (RBF) isa low-cost and efficient alternative water treatment for drinking-water applications. There are two immediate benefits to the increased use of RBF: Minimized need for adding chemicals like disinfectants and coagulants to surface water to control pathogens. Decreased costs to the community without increased risk to human health. Butwhat,exactly, isRBF? In humid regions, river water naturally percolates through the ground into aquifers (which are layers of sand and gravel that contain water underground) during high-flow conditions. In arid regions, most rivers lose flow, and the percolating water passes through soil and aquifer material until it reaches the water table. During these percolation processes, potential contaminants present in river water are filtered and attenuated. If there are no other contaminants present in the aquifer or ifthe respective contaminants are present at lower concentrations, the quality of water in the aquifer can be ofhigher quality than that found in theriver. In RBF, production wells — which are placed near the banks ofrivers —pump large quantities ofwater.

Inhaltsverzeichnis

Frontmatter

Introduction

Introduction

Without Abstract
Chittaranjan Ray, Jüurgen Schubert, Ronald B. Linsky, Gina Melin

Systems

Frontmatter

Chapter 1. Conceptual Design of Riverbank Filtration Systems

Without Abstract
Henry Hunt, Jürgen Schubert, Chittaranjan Ray

Chapter 2. American Experience in Installing Horizontal Collector Wells

Without Abstract
Henry Hunt

Chapter 3. German Experience with Riverbank Filtration Systems

Without Abstract
Jürgen Schubert

Chapter 4. Riverbank Filtration Construction Options Considered at Louisville, Kentucky

Without Abstract
Stephen Hubbs, Kay Ball, David L. Haas, Michael J. Robison

Chapter 5. Operation and Maintenance Considerations

Conclusion
Numerous horizontal collector wells and vertical wells, employed at RBF sites in the United States and Europe, extract large quantities of water from alluvial aquifers along rivers. While the tendency in Europe is to use vertical wells, most utilities in the United States prefer the use of large-capacity horizontal collector wells. Most of these wells have been operating for decades. The successful operation of RBF wells depends upon both regularly maintaining the well screen and pumps and operating the system within design parameters. For the United States, the frequency of maintenance for most horizontal collector wells appears to be on the order of 10 years or longer. Most utilities using horizontal collector wells have backup wells or other means to continue water service during maintenance. This maintenance can usually be accomplished over a period of about 1 month, if necessary. In comparison, the maintenance cycles for horizontal collector wells and vertical wells are 7 and 15 years, respectively, at Düsseldorf, Germany, although this trend is reversed in the United States, where vertical wells tend to require maintenance more frequently than collector wells. Collector wells have other applications, including the development of groundwater for artificial recharge and aquifer storage and recovery programs. In addition, seawater collector wells can be used to produce high-quality saline or brackish water for cooling or desalination using the same hydraulic principles used for RBF.
Henry Hunt, Jürgen Schubert, Chittaranjan Ray

Contaminant Removal

Frontmatter

Chapter 6. Removal of Pathogens, Surrogates, Indicators, and Toxins Using Riverbank Filtration

Without Abstract
Jack Schijven, Philip Berger, Ilkka Miettinen

Chapter 7. Riverbank Filtration Case Study at Louisville, Kentucky

Summary
The results of NOM and disinfection byproduct precursor removal indicate that more than a 50-percent reduction in disinfection byproduct precursors can be achieved through the RBF process at Louisville with a filtration depth of 15 m. Biodegradation and the physical removal of particulate matter at the river/aquifer interface are the primary mechanisms for NOM and disinfection byproduct precursor removal. Adsorption may also play a role in further NOM reduction as the filtration depth increases. The results of turbidity, total coliform, HPC, total aerobic spores, and microscopic particulate analysis show that the RBF process is very effective in removing particles in surface water, suggesting that it is an effective water-treatment process for reducing the potential of microbial contamination in drinking water. The results also show that the removal efficiency increases with the filtration depth, with most of the removal occurring within the firstmeter of filtration. Data from total coliform, total aerobic spores, and microscopic particulate analysis suggest that a >2.5-log removal credit can be given to this RBF system.
Jack Wang

Chapter 8. Reduction in Disinfection Byproduct Precursors and Pathogens During Riverbank Filtration at Three Midwestern United States Drinking-Water Utilities

Conclusions
The three sites investigated during this project demonstrated the ability of RBF to effectively reduce a variety of microbial contaminants, TOC, DOC, disinfection byproduct precursor material, and total theoretical THM cancer risk. TOC and DOC reductions ranged from 35 to 67 percent for the closest wells at the three sites. Total THM FP and HAA FP reductions ranged from 57 to 73 percent and 50 to 78 percent, respectively. The higher reduction in disinfection byproduct precursor concentrations compared to TOC or DOC suggests a preferential removal of precursor material. In addition, a shift was observed upon RBF from the chlorinated to the more brominated disinfection byproduct species.
Further, it was demonstrated that RBF can provide reductions in TOC, DOC, disinfection byproduct precursor material, and theoretical cancer risk that match or exceed those provided by conventional treatment processes, even though the distribution of disinfection byproducts favors the brominated species in riverbank-filtered water. Total THM FP and HAA FP reductions upon simulated treatment ranged from 44 to 66 percent and 45 to 69 percent, respectively. Total THM FP and HAA FP reductions upon RBF ranged from 53 to 82 percent and 47 to 80 percent, respectively. Reductions in the theoretical cancer risk due to the THM FP concentrations ranged from 11 to 47 percent and 28 to 45 percent for the treated and riverbank-filtered waters, respectively. For two of the sites, ozonation of the riverbank-filtered water provided the largest reduction in theoretical cancer risk. As utilities respond to increasingly stringent regulations regarding disinfection byproducts and microbial contaminants, the water-quality improvements commensurate with RBF can help meet those regulations.
W. Joshua Weiss, Edward J. Bouwer, William P. Ball, Charles R. O’Melia, Harish Arora, Thomas F. Speth

Chapter 9. Occurrence, Characteristics, Transport, and Fate of Pesticides, Pharmaceuticals, Industrial Products, and Personal Care Products at Riverbank Filtration Sites

Conclusions
Organic compounds potentially can be transported from the river to riverbank-filtered water into public-water supplies. On a global scale, the total production of organic compounds, such as pesticides, pharmaceuticals, and personal care products, has increased during the last few decades. This increased production and load has increased the presence of these products and their degradates in rivers. On the other hand, the use of riverbank-filtered water is still increasing in many nations. For a long time, the interaction between the river and aquifer had not been recognized, but this interaction has received much more attention in the last two decades. People used to believe that aquifer media could filter out all potentially harmful components. As our knowledge about the occurrence, transport, and fate of organic compounds has increased over time and our analytical techniques have improved from parts per million, to parts per billion, down to parts per trillion concentrations, concerns about the presence of organic compounds in our drinking water and their effect on public health also have increased.
Nevertheless, the potential for the development of RBF worldwide as a pretreatment technology for drinking water is great and has been used successfully in the United States, Germany, and other countries for many years, decades, or even more than a century. If utilities develop effective monitoring networks and programs, have a good understanding of their hydrogeologic settings, including travel times and removal potential, and have an early warning system in place, RBF can be an effective tool to reduce the cost of alternative drinking-water treatment technologies, such as ultrafiltration, ozonation, and the use of activated carbon, for the reduction or removal of most organic compounds. As discussed in this section, a few organic compounds cannot be removed or can be partially removed by RBF. Several of these compounds, such as atrazine, alachlor ESA, EDTA, or selected pharmaceuticals, may be used as organic tracer compounds to evaluate contamination risks and the necessity of further protective actions. The organic tracer compounds also may be used to optimize the individual RBF process. If the occurrence of these compounds in drinking water is neither desired nor permitted by law, a multibarrier drinking-water treatment process may be necessary.
Ingrid M. Verstraeten, Thomas Heberer, Traugott Scheytt

Chapter 10. Effectiveness of Riverbank Filtration Sites to Mitigate Shock Loads

Without Abstract
Hans-Joachim Mälzer, Jürgen Schubert, Rolf Gimbel, Chittaranjan Ray

Chapter 11. Riverbank Filtration as a Pretreatment for Nanofiltration Membranes

Without Abstract
Thomas F. Speth, Till Merkel, Alison M. Gusses

Chapter 12. Water-Quality Improvements with Riverbank Filtration at Düsseldorf Waterworks in Germany

Conclusion
The Düsseldorf Waterworks supply drinking water to approximately 600,000 inhabitants. Since the Flehe Waterworks began operation in 1870, the City of Düsseldorf has depended on RBF as the main source of drinking water. For this reason, investigations and research on RBF and treatment are important in designing, constructing, operating, and maintaining the waterworks. Data show that RBF is an efficient treatment step in improving drinking-water quality. In addition, RBF is a stable process that not only does not produce residuals, but also helps decrease treatment costs.
Jürgen Schubert

Research, Needs

Frontmatter

Chapter 13. Infiltration Rate Variability and Research Needs

Without Abstract
William D. Gollnitz

Chapter 14. Siting and Design Issues for Riverbank Filtration Schemes

Without Abstract
Thomas Grischek, Dagmar Schoenheinz, Chittaranjan Ray

Chapter 15. Natural Organic Matter Removal During Riverbank Filtration: Current Knowledge and Research Needs

Without Abstract
Jörg E. Drewes, R. Scott Summers

Chapter 16. Research Needs to Improve the Understanding of Riverbank Filtration for Pathogenic Microorganism Removal

Conclusions
In summary, predicting pathogenic microorganism removal by RBF requires a sophisticated understanding of the flow and transport of biological particles within a porous media ecotope. The ecotope is biologically complex and difficult to study in the field. Similarly, the much more accessible schmutzdecke layer overlying a slow sand filter is poorly understood. Despite these problems, there have been significant recent improvements in understanding due to work in Germany, The Netherlands, and the United States. Nevertheless, more work remains necessary, in particular along the direction outlined in this chapter.
Philippe Baveye, Philip Berger, Jack Schijven, Thomas Grischek

Chapter 17. Organic Chemical Removal Issues

Without Abstract
Ingrid M. Verstraeten, Thomas Heberer

Backmatter

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