Drinking Water Treatment, Volume 2, Chemical and Physical Elimination of Organic Substances and Particles E-Book
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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
Today, hundreds of millions of people drink contaminated water without knowing it. Yet water treatment technologies can effectively eliminate contamination and can supply urban and rural populations with safe drinking water in a secure way. For almost two centuries, the huge number of treatments available to guarantee water quality has grown alongside technological progress, the strengthening of industry norms and the reinforcement of consumer expectations. New treatment methods have been developed according to the advancement of knowledge and new sanitary regulations. This five-volume book sets out to clearly present the variety of treatments available along with their performance, limitations and conditions of use as well as ways to combine them to produce safe drinking water, which is a basic need essential to everyday life. The author shares his expertise acquired at Veolia, a company that is a world leader in water services and sanitation, desalination of sea water and the recycling of wastewater. Founded in France in 1853 to bring safe water to populations and to protect them from waterborne epidemics which ravaged cities, its history is intertwined with that of water treatment.
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Table of Contents
Cover
Title Page
Copyright Page
Chapter 7. Removal of Natural Organic Matter
7.1. Natural organic matter: humic substances
7.2. Methods of quantification and assessment of organic substances in water
7.3. Conditions for the removal of NOM
7.4. NOM removal techniques
7.5. Adsorption on activated carbon
7.6. Ozonation
7.7. Biological treatment
7.8. Treatment of ion exchange resins
7.9. NOM removal by high-pressure membranes
7.10. References
Chapter 8. Filtration
8.1. Rapid filters and very high-rate filters (TGV)
8.2. Multimedia filters
8.3. Direct filtration
8.4. Pressurized filters
8.5. Filtration mechanisms.
8.6. Implementation parameters
8.7. Sizing parameters: filtration rate and material height
8.8. Operating parameters
8.9. Veolia filtration technologies: general information
8.10. Regulation systems
8.11. Recycling and microbiological risks
8.12. Monitoring the operation and performance of filters
8.13. References
Chapter 9. Adsorption on Activated Carbon
9.1. Activation processes of activated carbon
9.2. Physicochemical properties of activated carbon
9.3. Transport process in activated carbon: mass transfer
9.4. The different forms of conditioning of activated carbons
9.5. Adsorption reactors on activated carbon: removal process
9.6. PAC reactors: description of PAC reactors
9.7. Veolia technologies: treatment process with PAC reactors
9.8. Micrograin activated carbon reactors
9.9. Fixed bed reactors – GAC filters
9.10. Pressurized GAC filters (Opacarb
™
filters)
9.11. References
Index
Summaries of other volumes
End User License Agreement
List of Tables
7. Removal of Natural Organic Matter
Table 7.1. DOC characterization results
Table 7.2. Emission and excitation wavelengths used in fluorescence for the characterization of molecules present in natural organic matter
Table 7.3. Estimation of DOC removal according to water alkalinity
Table 7.4. Performance of conventional coagulation and advanced coagulation
Table 7.5. Relation of SUVA to the efficacy of aluminum-based coagulants
Table 7.6. Equivalent dosages of coagulants
Table 7.7. Comparison of DOC and turbidity removal efficiency with Al
2
(SO
4
)
3
and FeCl
3
Table 7.8. Operating and control parameters for water containing NOM
Table 7.9. Parameters that are applicable to the model
Table 7.10. Application of the first model to various Veolia sites
Table 7.11. Application of the second model at various Veolia sites
Table 7.12. Freundlich parameters for various PACs with respect to DOC removal
Table 7.13. Characteristics of tested powdered activated carbons
Table 7.14. Performance results on DOC removal according to PAC dosage (Aquasorb MP23)
Table 7.15. Characterization of surface functions with and without in situ ozonation
Table 7.16. Bromate formation in various ozonation tests
Table 7.17. Freundlich parameters for DOC for some GACs
Table 7.18. Freundlich parameters for DOC with micrograin activated carbon
Table 7.19. Operating PAC parameters in the Opaline
®
B process
Table 7.20. Operating parameters of submerged membranes
Table 7.21. Main sizing parameters
Table 7.22. Operating parameters that affect the effectiveness of resins with respect to NOM removal
Table 7.23. Relationship between inlet DOC, treatment rate and resin concentration
Table 7.24. Operating parameters of a treatment unit
Table 7.25. Characteristics of NF and OIBP membranes with respect to DOC (*for 90% removal)
Table 7.26. Nanofiltration and low-pressure reverse osmosis performances
8. Filtration
Table 8.1. Maximum acceptable turbidities for different types of filters (TGV = very high-rate filters; H = hours)
Table 8.2. Characteristics of various filtration materials
Table 8.3. Examples of H/d
10
ratio for different types of filters
Table 8.4. Parameters for pressure loss calculations
Table 8.5. Example of the calculation of the interstice diameter/d10 ratio of the material
Table 8.6. Calculation of the retention capacity of sand filters
Table 8.7. Equations to calculate the minimum fluidization rate and the washing rate
Table 8.8. Cleaning conditions for single-media and dual media filters
Table 8.9. Main parameters involved in filter design
Table 8.10. Choice of the Veolia filter type according to its application
Table 8.11. Removal log of microorganisms during filtration under turbidity conditions of filtered water
Table 8.12. Some recommendations to implement according to the problems encountered
9. Adsorption on Activated Carbon
Table 9.1. Pore characteristics
Table 9.2. Methods of analysis of functional groups
Table 9.3. Main characteristics of some activated carbons
Table 9.4. Log Kow of micropollutants: drugs, endocrine disruptors, industrial products, pesticides, disinfection by-products, etc.
Table 9.5. Physical and chemical adsorption parameters
Table 9.6. Advantages and disadvantages of GAC filters
Table 9.7. Equations characterizing the fluidization and expansion speeds
Table 9.8. Size characteristics of micrograin activated carbon
Table 9.9. Concentration of micrograin carbon and d
60
according to reactor heights
Table 9.10. Comparison of granular, powdered and micrograin activated carbon
Table 9.11. Sizing parameters
Table 9.12. Operating parameters
Table 9.13. Sizing parameters
Table 9.14. Performance of the chemical parameters of the La Bergerie plant (France)
Table 9.15. Characteristics of some powdered activated carbons used in PAC reactors
Table 9.16. Characteristics of the micrograin activated carbons used
Table 9.17. Washing conditions of GAC filters according to their place in the treatment system and according to the configuration of the material filters
Table 9.18. Characteristics of Mangaflo (MnO
2
)
Table 9.19. Characteristics of some granular activated carbons used in drinking water installations
List of Illustrations
7 Removal of Natural Organic Matter
Figure 7.1. Vegetation–decomposition and water pollution. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.2. Characteristics of humic substances. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.3. Humic acid (a) and fulvic acid (b) model
Figure 7.4. Monomer of humic substances
Figure 7.5. Classification of natural organic matter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.6. Some functional groups of humic substances. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.7. Methods of NOM quantification. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.8. Fractionation of total organic carbon. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.9. Total organic carbon concentrations in different types of water. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.10. Concentration of humic substances on some surface waters (France and Africa). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.11. UV 254, color, DOC and SUVA. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.12. SUVA and coagulation efficiency. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.13. Typical chromatogram of a natural surface water sample. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.14. Distribution of organic matter in terms of DOC (mg·L
−1
) and DOC %. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.15. Chromatogram for OCD (DOC). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.16. Chromatogram for UVD (UV 254 nm). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.17. Chromatogram for OND (UV 220 nm). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.18. DOC removal according to alkalinity. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.19. Change in the TTHM/DOC ratio. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.20. TTHM formed according to the residual SUVA DOC. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.21. DOC removal based on SUVA for aluminum sulfate. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.22. Overall mechanism of NOM removal with aluminum salt coagulant. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.23. NOM removal efficiency according to pH and aluminum sulfate dosage. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.24. Control of NOM removal with ferric chloride. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.25. Percentage of DOC removal based on SUVA for ferric chloride. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.26. NOM removal efficiency according to coagulant dosage (FeCl
3
) and pH. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.27. LC-DOC on raw water and decanted water with FeCl
3
. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.28. FeCl
3
efficiency (42%) at different pH values (Veolia France site). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.29. Fe(OH)
3
(a) and Al(OH)
3
(b) flocs. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.30. Evolution of SUVA between raw water and decanted water on a plant, including FeCl
3
coagulation (Veolia site). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.31. Comparison of DOC removal with Al
2
(SO
4
)
3
and FeCl
3
at different dosages. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.32. Comparison of DOC removal with Al
2
(SO
4
)
3
and FeCl
3
at different dosages. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.33. Evolution of organic matter removal (FeCl
3
coagulant: 70–90 g·m
−3
, pH 5.5–6). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.34. The effectiveness of various coagulants against TOC (3.3 mg·L
−1
) on the Urne River. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.35. Efficiency of ferric chloride for the removal of organic matter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.36. SUVA relation according to the dosage of metal/DOC removed. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.37. Evolution (LC-DOC chromatograms) of organic matter over the course of a year (source: Veolia site, western France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.38. Evolution of the composition of organic matter over a year (source: Veolia site, western France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.39. Influence of the type of coagulant used for DOC removal. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.40. Mechanism for removal of NOM and turbidity. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.41. Mechanism of NOM removal in an acidic medium. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.42. Mechanism of NOM removal in a basic medium. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.43. Mechanisms of NOM coagulation. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.44. Mechanism for removal of NOM and turbidity. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.45. Choice of the coagulation method to be used in the presence of natural organic matter and turbidity. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.46. Decrease in pH according to the coagulant dosage. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.47. Precipitation of fulvic acid according to pH with FeCl
3
. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.48. Simplified diagram of organic carbon fractions removed by coagulation–flocculation–decantation (or flotation). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.49. Example of DOC/TOC ratio according to turbidity. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.50. Efficiency zone of activated carbon for DOC removal after advanced coagulation. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.51. Adsorption of various substances in the pores of activated carbon. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.52. Comparison of adsorption of DOC on two types of PAC (Veolia site). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.53. Injection of PAC into raw water before coagulation. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.54. Performance of various PACs with regard to DOC removal. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.55. Injection of PAC in raw water to improve DOC removal (Veolia site). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.56. DOC removal in two decanters in a row: Actiflo
®
in the first stage and Actiflo
®
Carb in the second stage. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.57. Influence of the PAC contact time on the reactor performance. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.58. LC-DOC characterizing the different organic substances removed by Actiflo
®
(coagulation) and Actiflo
®
Carb (activated carbon). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.59. Illustration of DOC removal with the two stages: coagulation and PAC reactor. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.60. Removal of organic substances (UV 254) on two Actiflo
®
Carb operating in parallel. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.61. DOC removal according to PAC dosage. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.62. Weight and hydraulic balance of Actiflo
®
Carb. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.63. Functional groups on the inner surface of the activated carbon
Figure 7.64. Example of surface functions on the internal surface of micropores
Figure 7.65. Adsorption isotherm results with PAC and ozonated PAC in situ. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.66. Operating diagram of the combination O
3
in situ + PAC reactor. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.67. Example of the link between humic substances and surface functions
Figure 7.68. LC-DOC of samples treated with Actiflo
®
Carb with and without activated carbon ozonation. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.69. Mesopore volume versus adsorption capacity for NOM. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.70. Evolution of DOC at outlet of GAC filter (Aquasorb 2000) for a contact time of 12 min. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.71. Evolution of DOC at a GAC filter outlet (Aquasorb 2000) for a contact time of 30 min. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.72. UV 254 chromatogram on raw water and preozonated water. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.73. Characterization of NOM fractions in raw water and after ozonation. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.74. Effect of preozonation at alow mg O
3
·mg
−1
DOC ratio on the coagulation efficiency of NOM. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.75. BDOC/DOC ratio according to ozone dosage. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.76. Influence of interozonation on DOC and UVA. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.77. Treatment process including the Opaline
®
B process. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.78. Simplified diagram of the adsorption-biodegradation passage. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.79. DOC and BDOC removal with the Opaline
®
B process. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.80. Evolution of the permeability according to the operating time
Figure 7.81. Preozonation performance in relation to BDOC removal in Opaline
®
B. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.82. Treatment process including an O
3
-GAC stage. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.83. Principle of the primary mechanism depending on the age of the activated carbon. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.84. Example of the operation of an O
3
-GAC association (Veolia site, Australia). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.85. Outlet DOC after biological GAC filter versus different contact times (Veolia site, France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.86. Evolution of the BDOC at the O
3
-GAC water outlet during one year of operation, with a contact time of 10 minutes on the GAC filter (Veolia site, France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.87. Bacteria grown on a biological GAC filter
Figure 7.88. Mechanism of NOM removal by the resin. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.89. Selectivity diagram of an anionic resin
Figure 7.90. Position of the Opalix
®
process in the treatment chain. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.91. Treatment unit equipment. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.92. Relationship between the treatment rate and the DOC concentration of treated water. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.93. Natural organic matter fractions removed by high-pressure membranes. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.94. Influence of pore diameter on DOC removal. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 7.95. TOC in water upstream and downstream of nanofiltration membranes. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
8. Filtration
Figure 8.1. Operating principle of a filter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.2. Clogging depth between a rapid sand filter and a TGV sand filter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.3. Diagram of the different types of filters: single-media, dual media and three-media. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.4. Single-media filter and dual media filter, in both filtration mode and wash mode. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.5. Direct filtration with coagulation, with or without flocculation. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.6. Particle retention mechanisms on a filtering material. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.7. Detachment mechanism under the action of shear forces. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.8. Cumulative distribution curve of the diameters of sand grains (d
10
: 0.70 mm and d
10
: 1.00 mm). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.9. H/d
10
ratio for sand filters
Figure 8.10. Turbidity evolution profiles according to material diameter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.11. Filtered water production rate depending on the filtration rate. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.12. ΔP/H obtained for different effective sand sizes and at different filtration rates. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.13. Changes in filtered water quality and pressure loss. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.14. Development of negative pressure losses in a filtration cycle. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.15. Evolution of pressure losses in a filtration cycle. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.16. Characteristics of different heights in a filter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.17. Estimation of the turbidity of filtered water in relation to the speed and height of filtration. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.18. Interstices of sand grains saturated with retained particles. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.19. General diagram of how the filters operate. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.20. Backwashing rates versus ES for different media at 15°C. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.21. Expansion percentage versus different backwashing rates. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.22. Layout of the filter walls against media losses during the air/water phase. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.23. Air/water washing. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.24. Desructuring and removal of particles (air/water phase). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.25. Example of the evolution of SS concentration in dirty water during backwashing with water alone (dual media filter). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.26. First phase of air scouring (a) and second phase of washing (b) (air/water). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.27. Different types of Veolia filters. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.28. Single-media filter in filtration mode (a) and backwash mode (b). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.29. Some layouts of the Filtraflo
®
F after an Actiflo
®
or in direct filtration. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.30. Filraflo
®
F. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.31. Filtraflo
®
F washing procedure. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.32. Filtraflo
®
F installed in (a) Yaoudé (Cameroon), (b) Annet-sur-Marne (France), (c) Omerli (Turkey) and (d) Rennes (France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.33. Floc diffusion diagram in a rapid filter and an F-TGV filter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.34. Treatment process with filters on material for the F-TGV filter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.35. Rapid particle attachment mechanisms and F-TGV filters. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.36. Filtraflo
®
F-TGV. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.37. Filtraflo
®
F-TGV in operation and in wash mode. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.38. Filtraflo
®
F-TGV in (a) Chengdu (China) and (b) Huachipa (Peru). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.39. Turbidity recordings of filtered water on Filtraflo
®
F-TGV for 2 months (January and March) at the Chengdu plant (China). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.40. Filtraflo
®
SV operating diagram. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.41. Filtraflo
®
SV in filtration mode and cleaning mode. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.42. Filtraflo
®
SV (China). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.43. Filtraflo
®
DC description. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.44. Filtraflo
®
DC cross-section. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.45. Quality of filtered water at the Tibitoc plant (Colombia). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.46. Anthracite-sand Filtraflo
®
DC. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.47. Rapid Filtraflo
®
DC in Villefranche, France (a), and TGV type in Woronora, Australia (b), Oslo, Norway (c) and Tibitoc, Colombia (d). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.48. Filtraflo
®
TC description. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.49. Filtraflo
®
TC cross-section. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.50. Example of a Veolia pressure filter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.51. Veolia pressure filters. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.52. Recycling of dirty water from filters. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.53. Filter with mud balls (a) and example of mud balls in a plant in India (b). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 8.54. Presence of sand at the bottom of the filter due to the deterioration of the strainers. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
9. Adsorption on Activated Carbon
Figure 9.1. Crystal structure of graphite. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.2. Pore size observed on activated carbon. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.3. Main functional groups of the activated carbon surface
Figure 9.4. Surface functions in micropores
Figure 9.5. Different surface functions distributed on the surface of the activated carbon
Figure 9.6. Origin and manufacturing method of activated carbon
Figure 9.7. Porous distribution and adsorbability of some organic molecules. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.8. Different stages of adsorption on a grain of activated carbon. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.9. Classification of isotherms. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.10. Adsorption of a contaminant with powdered activated carbon in an integral mixing reactor
Figure 9.11. Schematic diagram of adsorption modes. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.12. Adsorption isotherms with Freundlich and Langmuir models. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.13. Powdered activated carbon made from date pits
Figure 9.14. Example of the particle size of a micrograin activated carbon
Figure 9.15. Electron microscope views of the Microsorb 400 R
Figure 9.16. (a) Picabiol activated carbon with a plant base (Jacobi) and (b) F400 (Chemviron) with a coal base
Figure 9.17. PAC reactor and equilibrium kinetics. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.18. Influence of the parameters: mass of carbon or dosage, particle diameter or agitation. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.19. Operating diagram of the integral mixing reactor. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.20. Injection of PAC in a contact tank or in line in the coagulation tank. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.21. Process with PAC recirculation. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.22. PAC reactor located in the second stage. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.23. Evolution of the adsorption front and of the outlet concentration during an operating cycle. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.24. Adsorption on GAC filter with breakthrough (Cp) or concentration limit curve (CL). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.25. Principle of natural organic matter (NOM) removal in a GAC filter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.26. How a GAC filter works
Figure 9.27. Expansion of Microsorb 400R according to flow speed at 15°C (source: Veolia). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.28. Experimental results and theoretical equations. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.29. Variation in the porosity during expansion (20°C)
Figure 9.30. Integration of powdered activated carbon in the treatment process. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.31. PAC injection in a Multiflo
®
. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.32. How Multiflo
®
Carb works. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.33. Multiflo
®
carb with contact tank (a), flocculation tank (b), settled water (c). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.34. Evolution of turbidity according to the stops (2 min) and immediate restarts of Multiflo
®
Carb. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.35. Concentration of PAC sludge in Multiflo
®
Carb
Figure 9.36. Evolution of turbidity in settled water. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.37. Multiflo
®
Carb photo, L’Haÿ-les-Roses plant (France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.38. Operating principle of the Actiflo
®
Carb (source: Veolia). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.39. Hydrocyclones for the separation of sand and PAC. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.40. (a) PAC contact tank and (b) Actiflo
®
Carb settled water. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figures 9.41. Actiflo
®
Carb in the (a) Lucien Grand and Moselle plant and (b) Madon plant. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.42. Actiflo
®
and Actiflo
®
Carb in series for the removal of turbidity, color, algae, organic matter and micropollutants. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.43. (A) Turbidity and (B) UV 254 nm at the Actiflo
®
Carb outlet. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.44. TOC and water quality with the Actiflo
®
Twin Carb mode. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.45. Photos of plants with Actiflo
®
Carb: (a) Lucien Grand, (b) Montlucon, (c) Cholet (France) and (d) Zhejiang Fuyang (China). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.46. Packaged solutions with Multiflo
®
and Actiflo
®
. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.47. Packaged solution (Actiflo
®
Carb and filter) for the Moselle and Maddon plant (France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.48. Operating diagram of the Opacarb
®
MF process (source: Veolia). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.49. La Bergerie plant (Donville, France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.50. Installed mechanical filtration equipment. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.51. Operating principle of the Opaline
®
C process. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.52. Ultrafiltration membrane workshop in the Clermont–Ferrand plant (France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.53. Ultrafiltration membrane workshop in the Alcay plant (France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.54. Integration of μgrain activated carbon in the treatment process. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.55. (a) Operating principle of the Filtraflo
®
Carb and (b) fluent view of the speed distribution. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.56. UV absorbance 254 nm removal on Filtraflo
®
Carb and UV254 versus DOC correlation. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.57. Metaldehyde removal on Filtraflo
®
Carb. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.58. Filtraflo
®
Carb from the Craon plant (France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.59. (a) Gahard plant and (b) Barregant plant model. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.60. Operating principle diagram of the Opacarb
®
FL process. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.61. Opacarb
®
FL with optional deflector lamellas. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.62. Opacarb
®
F with in situ ozonation option. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.63. Expansion percentage according to the ascension speed
Figure 9.64. Microscopic view (a) and porous sieve (b). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.65. Porous sieves installed in the contact tank. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.66. Application example with Opacarb
®
MG and Actiflo
®
downstream. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.67. TOC removal on Opacarb
®
MG (source: Veolia). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.68. Integration of the GAC filter in a treatment system. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.69. Description of a GAC filter. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.70. GAC filter floor under construction. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.71. Structure of (a) picabiol (Jacobi) activated carbon and (b) Filtrasorb FTL (Chemviron) activated carbon. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.72. GAC renewal by hydroejector. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.73. GAC filters in Iver (UK) (a), Moulins-lès-Metz (France) (b), and Epernay (France-Pays de champagne) (c). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.74. GAC filters in series. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.75. Operating diagram of the GAC filters in series. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.76. Different implementation modes of GAC filters. For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.77. Dual media filter (Picotalen – la Montagne noire, France). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Figure 9.78. Opacarb™ GAC filters at the Champigny-les-Langres plant (a) and in South Africa (b). For a color version of this figure, see www.iste.co.uk/gaid/watertreatment2.zip
Guide
Cover Page
Title Page
Copyright Page
Table of Contents
Begin Reading
Index
Wiley End User License Agreement
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Drinking Water Treatment 2
Chemical and Physical Elimination of Organic Substances and Particles
Kader Gaid
First published 2023 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.
Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:
ISTE Ltd 27-37 St George’s Road London SW19 4EU UK
www.iste.co.uk
John Wiley & Sons, Inc. 111 River Street Hoboken, NJ 07030 USA
www.wiley.com
© ISTE Ltd 2023 The rights of Kader Gaid to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s), contributor(s) or editor(s) and do not necessarily reflect the views of ISTE Group.
Cover illustration: © imageBROKER.com/Matton Images
Library of Congress Control Number: 2022942618
British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN 978-1-78630-784-2
7Removal of Natural Organic Matter
7.1. Natural organic matter: humic substances
Organic matter can be divided into three categories: particulate matter, colloidal matter and dissolved matter. In general, zooplankton, phytoplankton and most bacteria are included in particulate matter. Dissolved matter is defined as matter whose compounds pass through a filter with a porosity of 0.45 μm.
Humic substances (HS) are the main organic constituents of soils and sediments. They are described as polymers with a molecular weight (MW) of 1,000–350,000. HS are formed by the decomposition of plant and animal tissues, and by chemical and biological processes that tend to produce complex chemical structures that are more stable than the parent material from which they are derived. Dissolved organic substances encompass a wide range of compounds, including HS, amino acids, fatty acids, phenols, sterols, carbohydrates and porphyrins.
There are two sources of natural organic matter (NOM): allochthonous NOM and autochthonous NOM. Allochthonous NOM (known as HS) is derived from decaying plant material. Soil humus, plant litter, microbial biomass and root exudates contribute to allochthonous NOM. They typically have a high molecular weight (>1,000 Daltons; 1 Dalton = 1 g·mol−1) and are hydrophobic.
Autochthonous NOM is derived from algae, phytoplankton and materials present in wastewater discharges. They are hydrophilic.
Figure 7.1.Vegetation–decomposition and water pollution.
If allochthonous inlets are high, such as in colored springs or during precipitation/snowmelt events, the proportion of autochthonous NOM is generally low. Conversely, if allochthonous inlets are low, such as in clear springs or during drought periods when there is very little runoff, the proportion of autochthonous NOM is generally high.
In surface waters, dissolved HS originate from soils that come from plant weathering, chemical polymerization or microbial synthesis.
The identification of organic matter requires a fractioning step of these constituents.
This separation is based on the solubility of the molecules in water according to the pH level. HS are generally divided into three fractions (Figure 7.2) based on their solubility in acidic and alkaline solutions:
– humic acid, brown or black, soluble in a basic medium and insoluble in the acidic pH range (pH < 2);
– fulvic acid, yellow in color, soluble in water regardless of the pH value. It is the humic fraction that remains in acidified aqueous solutions and is soluble in bases and acids. It has a lower molecular weight than humic acid but has more hydrophilic functions than humic acid or humin. Their average length is 60 nm, and their average diameter is 2 nm;
– humins, which are black in color, are composed of bitumen, fatty acids and humic acids. They represent the insoluble humic fraction of soils that cannot be extracted by either an acid or a base.
Figure 7.2.Characteristics of humic substances.
The elemental analysis of HS shows that they are composed of carbon (C), hydrogen (H), nitrogen (N), sulfur (S) and oxygen (O). The major constituents of humic and fulvic acids are carbon and oxygen. The presence of carbon and nitrogen is higher in humic acids than in fulvic acids. Conversely, the fulvic fraction contains more oxygen. The O/C ratio makes it possible to differentiate humic acids (O/C = 0.5) from fulvic acids (O/C = 0.7). The H/C ratio is inversely proportional to the aromaticity or the degree of condensation.
Proteins and polysaccharides are grouped together under the term biopolymers. They can have both negatively and positively charged sites. Their net charge depends on the pH of the water. They are large molecules with high molecular weights in the range of a few hundred to several tens of thousand Daltons.
Figure 7.3.Humic acid (a) and fulvic acid (b) model
More globally, NOM is mainly composed of humic acids, fulvic acids, hydrophilic acids, carboxylic acids, amino acids, carbohydrates and polysaccharides.
HS are dark in color, mostly made up of aromatic acids (containing one or more benzene rings [C6H6]) and hydrophilic acids (polar molecules with an affinity for water), with molecular weights ranging from a few hundred to several thousand Daltons. They contain phenolic OH and carboxylic groups, with a lower number of aliphatic OH groups.
Carboxyl, phenol, alcohol, carbonyl, quinone and methoxyl groups are the main functional groups of HS. Ether, ester and ketone groups may also be present. The total acidity of fulvic acids is higher than that of humic acids.
Figure 7.4.Monomer of humic substances
R1 = -COOH or -COCH
3
or -OH
R2 = -H or -OH or -COOH
R3 = -H or -OH or -OCH
3
or -COOH
R5 = -H or -OH or -OCH
3
R6 = -H or -COOCH
3
n = 14 and n = 15 for the AH and n = 14, 15, 16 and 18 for the AF
Humic and fulvic acid particles vary in shape and size depending on the pH. They tend to aggregate into long fibers or fiber bundles at low pH. However, at high pH, they disperse, and the molecular arrangement becomes smaller but better oriented. Humic acids are more aromatic and have a higher molecular weight than fulvic acids. Ozone tends to react more readily with humic acids. Fulvic acids are slightly more biodegradable than humic acids. Biodegradable organic matter is more hydrophilic than non-biodegradable matter.
A common approach to its characterization is to divide the mixture into hydrophilic and hydrophobic fractions. The hydrophilic fraction includes, for example, carboxylic acids, carbohydrates and proteins, while the hydrophobic fraction includes HS.
Figure 7.5.Classification of natural organic matter.
The analysis methods of the functional groups show a great diversity of functions in HS, such as carboxylic, phenolic, alcoholic, quinone and hydroquinone groups. The relative distribution of these groups varies according to the types of substances. The total acidity of fulvic acids is higher than that of humic acids. Fulvic acids have more oxygen atoms per unit weight than humic acids, which coincides with a greater number of carboxyl groups COOH, hydroxyl groups OH, aldehydes and ketones C=O. The reactivity of HS is partly due to the presence of oxygen in the carboxylic, phenolic or alcoholic functional groups. Moreover, among the groups contributing to the acidic character of HS, carboxylic acids (-COOH) are more important than alcoholic functions (-OH). The charge of the HS is always negative or null, of variable intensity according to the pH of the medium, and comes from the dissociation of the functional groups. In general, the color of the surface water is attributable to the organic matter.
Figure 7.6.Some functional groups of humic substances.
One of the most important characteristics of HS is their ability to form water-soluble and insoluble complexes with metal ions and hydrated oxides, as well as interact with clay minerals and various organic compounds such as alkanes, fatty acids and other organic substances such as pesticides. The formation of water-soluble complexes of HS with metal ions is of particular interest because complexation can increase the concentrations of these ions in natural waters.
The types of interactions that occur between metal ions and organic acids found in natural waters range from complexation reactions to colloid formation. Many complexes between HS and metals are chelates.
Thus, the quantity, character and properties of NOM differ from one water to another in the same region and depend on the biogeochemical cycles of the elements in its environment.
In addition, the various molecules that make up NOM vary seasonally within a site due to, for example, precipitation, runoff from melting snow, flooding, or drought. Floods and droughts are the primary impacts of climate change on water availability and quality. It is suggested that these climate changes may be causing an increase in the total amount of NOM in surface waters.
The consequences of the presence of organic matter in treated water include the following:
– effects on the organoleptic qualities of the water, such as color, odor and taste;
– reactions with chemical disinfectants, therefore controlling the demand for disinfectants;
– reactions with metals, inducing their precipitation;
– the formation of disinfection by-products, such as trihalomethanes and halogenated acetic acids;
– a contribution to corrosion in the distribution networks;
– a contribution to the development of biofilm in the distribution networks;
– a reduction in the life span of activated carbons, requiring frequent renewal.
7.2. Methods of quantification and assessment of organic substances in water
Methods for quantifying and assessing NOM generally include:
– total organic carbon (TOC) and dissolved organic carbon (DOC);
– UV absorbance at 254 nm;
– specific UV absorbance (SUVA);
– liquid chromatography to qualitatively assess the distribution of different organic substances in a water sample;
– fluorescence.
Figure 7.7.Methods of NOM quantification.
7.2.1. Total organic carbon
HS represent approximately 60–80% of the organic carbon in surface waters. They are found in highly variable concentrations in natural surface waters but are much less concentrated in groundwater.
The main elements of NOM are carbon, oxygen, nitrogen, sulfur and hydrogen. Carbon is the dominant element in terms of weight, accounting for 40–50% of the weight of NOM. For this reason, NOM is quantified by TOC analysis. TOC can be fractionated into particulate organic carbon (POC) and DOC. The separation (Figure 7.8) between these two forms is performed by vacuum or pressure filtration (0.45 μm porosity filter). DOC is the portion of organic carbon that is completely dissolved in water. To measure DOC, the particulate portion of the organic carbon must be removed before analysis.
DOC is characterized by a biodegradable dissolved organic carbon (BDOC) and a fraction that is resistant to biodegradation (RDOC).
Figure 7.8.Fractionation of total organic carbon.
BDOC can also be fractionated into a rapidly biodegradable fraction and a slowly biodegradable fraction. The rapidly biodegradable BDOC is available as a source of carbon and energy for microorganisms. It represents approximately 5–30% of the DOC. Slowly biodegradable BDOC is more likely to be found in the distribution system when it has not been degraded or eliminated in the treatment process. Assimilable organic carbon (AOC) is similar to BDOC in terms of availability to microorganisms, but the analytical methods are different. BDOC represents the fraction of DOC that can be mineralized by heterotrophic microorganisms, whereas AOC is a portion of DOC that can be converted to biomass and expressed as carbon concentration.
Figure 7.9.Total organic carbon concentrations in different types of water.
BDOC also presents problems for the quality of distributed water. Specifically, when the temperature is favorable and the residual chlorine concentration is low, it becomes a nutrient-rich source for many bacteria and promotes biofilm formation in the system.
Biofilms can contribute to the survival of pathogens that have successfully penetrated drinking water treatment barriers or directly entered the distribution system due to a breakdown in pipe integrity. The most important elements in controlling bacterial growth in distribution systems are maintaining a residual concentration of disinfectant, limiting BDOC and controlling corrosion. A BDOC concentration of less than 0.2 mgC·L−1 is recommended for treated water to be considered biologically stable and not conducive to bacterial growth.
Most natural waters contain TOC and DOC. TOC concentrations in waters vary from resource to resource, as illustrated in Figure 7.9.
Seawater has a lower TOC content than most lakes and rivers, except in a few special cases where treated wastewater is discharged not far from the water inlet.
Groundwater most often has TOC concentrations <1 mg·L−1. HS in groundwater are mainly derived from the leaching of humic matter from soils or from the leaching of fine organic particles that were deposited together with the sediments that make up the aquifer rock. They can be contaminated by surface water infiltration.
River waters are contaminated by the degradation of plants, while estuary waters are mostly polluted by wastewater discharges. Generally, more than 70% of DOC constitutes humic and fulvic substances. However, this percentage varies according to the geographical area and the manner in which the plants decompose.
7.2.2. Absorbance of ultraviolet light at 254 nm (UV 254)
Ultraviolet spectroscopy is a spectroscopic technique that measures the light absorbed by compounds in solution in water in the ultraviolet range. This is in the wavelength range of 200–400 nm. When molecules in solution in water are subjected to radiation in this wavelength range, they undergo one or more electronic transitions. They absorb light at certain frequencies that represent the exact energy required to excite an electron to a higher energy state. Since light absorption is essentially related to electron density, compounds with electron-rich functional groups will absorb more light than compounds without such groups. The electronic spectrum depends on the light intensity absorbed by the sample, analyzed according to a given wavelength, known as UV absorbance. This provides correlations with the concentration of the compounds present in the water.
UV 254 is the amount of light, with a wavelength of 254 nanometers, that a sample will absorb. The principle of this method is that UV absorbing constituents, such as humic or fulvic acids, absorb UV light in proportion to their concentration. UV 254 samples must be measured in water that does not contain any oxidants or disinfectants. This is necessary because oxidants react with organic compounds and cleave the double bonds that absorb UV 254. Samples for UV 254 must be filtered to remove particulates. UV 254 is representative of the existence of unsaturated carbon bonds, including aromatic compounds, which are generally resistant to biodegradation. For the same amount of DOC, a decrease in UV absorbance at 254 nm usually results in an increase in the biodegradability of NOM.
Figure 7.10.Concentration of humic substances on some surface waters (France and Africa).
7.2.3. Specific UV absorbance
SUVA is an indicator of the aromatic fraction of NOM that contains chromophores (groups of atoms with one or more carbon double bonds). The SUVA parameter is an indicator of the humic content of water.
It is a calculated parameter that is equal to the UV absorption at 254 nm (measured in cm−1) divided by the DOC (measured in mg·L−1).
Waters with low SUVA values mostly contain non-humic matter that is difficult to remove with advanced coagulation. On the other hand, the TOC present in waters with high SUVA values is generally easier to remove by advanced coagulation.
The equation to calculate the SUVA value is:
Generally speaking, organic compounds with high SUVA values have low biodegradability due to the increased presence of aromatic groups and other unsaturated configurations.
Figure 7.11.UV 254, color, DOC and SUVA.
SUVA is a judging parameter for deciding between conventional and advanced coagulation. The general rule is that the DOC of water with an SUVA of less than 2 L·mg−1·m−1 is mainly composed of non-humic (and lower hydrophobicity) substances with low molar weights. This indicates that a large fraction of the matter is hydrophilic and non-humic, with a low UV absorbance, low chlorine demand and low potential for THM formation.
A SUVA greater than 4 L·mg−1·m−1 indicates that the DOC is predominantly made up of HS with high molar weights. In this case, we are in the presence of hydrophobic aromatic HS associated with a high UV absorbance, a high chlorine demand and a high potential for THM formation.
A SUVA that is between 2 and 4 L·mg−1·m−1 indicates a DOC consisting of a mixture of non-humic hydrophilic matter and humic hydrophobic matter with a medium UV absorbance, higher chlorine demand and higher potential for THM formation.
The different NOM fractions have different properties in terms of treatability by coagulation, adsorption with activated carbon, chemical oxidation, reactivity to chlorine and ozone, and potential for the formation of disinfection by-products.
Figure 7.12.SUVA and coagulation efficiency.
SUVA is a quantitative measure of the unsaturated bonds and/or aromaticity of organic matter in water. Overall, an increase in SUVA reflects a greater humification, aromaticity and hydrophobicity of the NOM, which leads to a lower biodegradability.
7.2.4. Liquid chromatography
DOC, UV 254 absorbance, pH, turbidity and color are common water quality parameters assessed in drinking water plants.
However, they do not give accurate information on the character of the NOM, such as molar weight (MW) or hydrophobicity.
The liquid chromatography-organic carbon detection (LC-OCD) technique has been developed for the characterization of NOM contained in surface waters. The organic fractions described below are usually found in surface waters.
The qualitative determination is based on the separation of hydrophilic molecules according to their hydrodynamic molecular size, performed by the size exclusion chromatography (SEC). High molecular weight molecules, which do not penetrate the pores of the column material, appear first on the chromatogram, while smaller molecules are eluted after.
The quantification is based on the determination of TOC in the Gräntzel reactor. The device is equipped with three detectors: an organic carbon detector (organic carbon detection [OCD]), a UV detector at 254 nm and an organic nitrogen detector ( organic nitrogen detection [OND]). Figure 7.13 shows the specific chromatogram of a natural surface water (water from the Seine river). The separation principle (SEC) and triple detection (OCD, UVD, OND) allow the LC-OCD system to determine the nature of the different organic fractions present in the sample to be studied, as well as their quantification. It should be noted that in UV light, some peaks are not visible in OCD because some molecules do not have chromophore groups and are therefore not visible in UV light (such is the case of polysaccharides). The peak elution between 60 and 75 min for OND corresponds to the oxidation of low molecular weight nitrogenous materials into nitrates and to mineral species. The quantification limit of LC-OCD is 0.1 mgC·L−1 per compound. All samples were analyzed with an SEC HW-50S column for an analysis time of 150 min. The main organic matter fractions for a natural water sample are as follows.
