[PDF] Pilot Scale Investigation Of Dissolved Air Flotation Performance For Drinking Water Treatment eBook

Author : James K. Edzwald
Publisher : McGraw Hill Professional
Page : 370 pages
File Size : 16,78 MB
Release : 2011-10-06
Category : Technology & Engineering
ISBN : 0071745637

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The definitive work on Dissolved Air Flotation Systems (DAF) for clarification of drinking water Dissolved Air Flotation for Water Clarification is a complete design and application source for the water industry divided into three parts: The first develops a fundamental basis for understanding how the process works, and might be adapted to work better. The second provides a reference for design engineers, water operators, and water managers regarding applications where DAF might be incorporated in an overall treatment scheme. The third develops the necessary DAF design concepts and to illustrate them by description of practical applications. Using DAF to remove particles is not only an important process for conventional drinking water plants, but may also be used as a pre-treatment process in membrane plants including reverse osmosis for water desalinization, and in water reuse applications. Dissolved Air Flotation for Water Clarification offers: Information on new applications of DAF in advanced water treatment, desalinization, water reuse, and industrial treatment in food, waste, and pulp and paper Detailed examples, including the world’s largest new DAF plant ever built – Croton, NY water treatment plant A single volume entirely devoted to DAF for drinking water clarification Coverage of conventional and pre-treatment processes SI and conventional units throughout

Author : H. Kiuru
Publisher : IWA Publishing (International Water Assoc)
Page : 228 pages
File Size : 20,35 MB
Release : 2001-04-30
Category : Science
ISBN :

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Dissolved air flotation (DAF) is an increasingly applied technology for particle removal in water and wastewater treatment. In DAF tiny air bubbles attach to the particles, which float to the surface, forming flocs which can be periodically removed to a sludge channel. The technique originated in the early 1900s, but has steadily widened its application across municipal and industrial water and wastewater treatment, earning a reputation for reliability, controllability and effectiveness. The aim of the Helsinki conference was to provide an opportunity for researchers and practitioners to examine and discuss current developments and applications of DAF technology in water and wastewater treatment. From the 58 oral and poster presentations, 26 papers have been selected for these proceedings. The papers have been divided into four themes: drinking water treatment, wastewater treatment, industrial and trade applications, theory and modelling.

Author : Babak Lakghomi
Publisher :
Page : 0 pages
File Size : 16,55 MB
Release : 2015
Category :
ISBN :

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The dissolved air flotation (DAF) process is known for its efficiency in the removal of low-density particles from water. The performance of the system depends, in part, on the hydrodynamics of the flow. Whereas experimental flow measurement methods for DAF can be very challenging due to the presence of bubbles and particles, computational fluid dynamics (CFD) can be applied as an alternative approach for improving the understanding of the hydrodynamics, but would still require validation. In this study, two-phase and three-phase analytical and CFD models of DAF were developed to evaluate the formation of stratified flow (back and forth horizontal flow layers in the separation zone) and its impact on bubble and particle removal. By including the effects of bubble aggregation and bubble-particle aggregation, the models were able to predict the formation of stratified flow under different air fractions, bubble sizes, and loading rates. The CFD model showed that stratified flow improved bubble removal as well as particle removal, demonstrating that up to 130% higher loading rates can be achieved in the presence of stratified flow. An increase in air fraction and bubble size was shown to improve bubble removal, but particle removal began to decrease when air fractions and bubble sizes increased beyond optimum levels. The CFD model was then validated with a pilot-scale DAF system by comparing measurements of residence time distribution (RTD), bubble layer position and bubble-particle contact efficiency. In general, the CFD model was able to represent the pilot-scale DAF flow at different loading rates with very good accuracy (R2 values higher than 0.75). Finally, the validated model was applied to evaluate the effect of the addition of different configurations of baffles in the separation zone. The results suggested that baffles in the separation zone can enhance stratification of the flow and allow up to 86% higher loading rates.

Author : K. J. Ives
Publisher : IWA Publishing (International Water Assoc)
Page : 380 pages
File Size : 40,16 MB
Release : 1995-05-31
Category : Science
ISBN :

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Author : Lawrence K. Wang
Publisher : Springer Science & Business Media
Page : 694 pages
File Size : 34,30 MB
Release : 2010-06-09
Category : Technology & Engineering
ISBN : 1588294943

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The past 30 years have seen the emergence of a growing desire worldwide that positive actions be taken to restore and protect the environment from the degrading effects of all forms of pollution – air, water, soil, and noise. Since pollution is a direct or indirect consequence of waste, the seemingly idealistic demand for “zero discharge” can be construed as an unreal- tic demand for zero waste. However, as long as waste continues to exist, we can only attempt to abate the subsequent pollution by converting it to a less noxious form. Three major questions usually arise when a particular type of pollution has been identi?ed: (1) How serious is the pollution? (2) Is the technology to abate it available? and (3) Do the costs of abatement justify the degree of abatement achieved? This book is one of the volumes of the Handbook of Environmental Engineering series. The principal intention of this series is to help readers formulate answers to the last two questions above. The traditional approach of applying tried-and-true solutions to speci?c pollution p- blems has been a major contributing factor to the success of environmental engineering and has accounted in large measure for the establishment of a “methodology of pollution control. ” However, the realization of the ever-increasing complexity and interrelated nature of current environmental problems renders it imperative that intelligent planning of pollution abatement systems be undertaken.

Author : Juan Pablo Gonzalez Galvis
Publisher :
Page : pages
File Size : 41,2 MB
Release : 2019
Category :
ISBN :

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The dissolved air flotation (DAF) has been used in drinking water treatment for its excellent algae and natural organic matter (NOM) removal. DAF drinking water treatability test are often conducted in a DAF jar test apparatus. Although, DAF jar test studies showed that they were able to predict NOM removals at full-scale facilities well, they have not always been successful in predicting the turbidity removals. One possible reason of the DAF jar test inaccuracy results could be associated to the small jar diameter, which may create wall effects. Therefore, the first two objectives of this research are: a) to develop and test a new, larger diameter and larger volume batch bench-scale dissolved air flotation system (LB-DAF) to better simulate turbidity removals in drinking water applications; b) to confirm these results by comparing the LB-DAF and full-scale DAF turbidity removals for two other source waters. The raw water characteristics of the three plants were quite different and the testing was performed at different times of the year. The development/optimization of the LB-DAF evaluated the impact of different variables (i.e., mixing intensity, water depth/tank diameter ratio, impeller shape, saturator pressure and recycle ratio). The results showed that the LB-DAF predicted well the full-scale DAF turbidity removals at three water treatment plants, and these predictions were better than those of DAF jar tests. For the LB-DAF design and operational variables evaluated had a limited impact on the turbidity removals. The LB-DAF predicted well DAF full-scale turbidity removals regardless of water temperature. This is an indication of the robustness of the DAF system. Ballasted sedimentation (BS) is a compact coagulation/flocculation and sedimentation process combination that has become very popular because it is very compact and because it can handle large variations in raw water turbidity and NOM. The literature survey did not initially identify studies on the BS treatment of algal impacted waters, for which DAF is considered particularly suitable. Thus, the third main objective of this dissertation was to compare the efficiency of BS with that conventional gravity settling (CGS), and that of DAF for the treatment of an algal impacted water via jar tests. These comparisons were performed at the Belleville Water Treatment Plant using Bay of Quinte water, one of the most eutrophic zones of Lake Ontario. Unfortunately, a change of weather prior to the testing resulted in raw water samples with relatively low concentrations of algae and cyanobacteria. The testing showed that DAF and BS had very similar NOM, cyanobacteria/algae (chlorophyll a and phycocyanin) removals.; however, the BS required microsand addition, polymer addition and a slightly higher alum dose. Only for turbidity removal the DAF was somewhat superior. It is suggested that these comparison experiments be repeated with waters that are more impacted by algae and cyanobacteria.