FT-PRI-004
TECHNOLOGY FACT SHEETS FOR EFFLUENT TREATMENT PLANTS IN TEXTILE INDUSTRY
LAMELLA SETTLING SERIES: PRIMARY TREATMENTS
TÍTLE
LAMELLA SETTLING (FS-PRI-004)
Last update
June 2013
Last review
LAMELLA SETTLING
LAMELLA SETTLING (FS-PRI-004) Date
June 2013
Authors
Joaquín Suárez López Alfredo Jácome Burgos Pablo Ures Rodríguez
Reviewed by Amendments
Date
Amended by
Modification objective
FS-PRI-004
LAMELLA SETTLING
LAMELLA SETTLING (FS-PRI-004) Date
June 2013
Authors
Joaquín Suárez López Alfredo Jácome Burgos Pablo Ures Rodríguez
Reviewed by Amendments
Date
Amended by
Modification objective
FS-PRI-004
LAMELLA SETTLING
INDEX 1.- INTRODUCTION INTRODUCTION 2.- LAMELLAR AND TUBULAR CLARIFIERS 3.- DESIGN 3.1.- Design Parameters 3.2.- Design Criteria 4.- SLUDGE PRODUCTION 5.- PERFORMANCE 6.- PARTICULAR TECHNICAL CONSIDERATIONS 7. - SPECIFICATIONS SPECIFICATIONS OF TEXTILE INDUSTRY EFFLUENT TREATMENT 8.- PARAMETERS AND CONTROL STRATEGIES 9.- OPERATING PROBLEMS
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1.- INTRODUCTION Clarifier performance with flocculent sedimentation is mainly dependent on the hydraulic loading rate (HLR). Depth and hydraulic retention time are generally considered as second-order factors, according to the most common models of sedimentation processes analysis. One strategy to improve performance in clarifiers is the horizontal settling surface enlargement, involving directly a decrease in hydraulic loading rate at equal flow rate. This increase can be attained in different ways. One of the possibilities is the installation of different floors, which splits the flow supported by each horizontal surface.
Q
/ n
Sh Sh Sh
Figure 1. Analysis of the effect o f introducing levels or horizontal baffles in a settling tank. Where n is the number of false b ottoms and Sh is the true horizontal surface. The factor f does not grow just as n. "f " factor may vary between 0.5 and 1, being normally between 0.9 and 1. Occupied area and installation costs abatements are achieved by superimposing settling levels. The volume of building site with various levels clarifiers can be reduced to half. Different experiences in this way led to settling tanks with 3 to 5 levels. This arrangement creates problems sludge removal problems, so enhanced systems should be developed.
1
Flocculation tank SPLIT-ROLL entries 3 Sludge drainage 4 Manual controlled superior valve 5 COMBCET sludge extraction system (optional) 2
6
WATERINSE water cleaning system 7 Upper clarification level 8 Medium clarification level 9 Lower clarification level 10 Effluent weirs 11 Clarifier water channels
Figure 2. - "Multilevel" clarifier with parallel flow.
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Figure 3. – Multilevel settling tank with parallel flow on three levels.
An alternative to facilitate sludge removal would be to increase the steepness of the settling unit levels, in order to force the sludge to go down and deposit on a single surface, generating a single extraction system. This is the basic concept of the lamella or laminar plate clarifiers.
Q
/ n
Sh Sh d
Sh
Sh Q
/ n
Figure 4. – Diagram of a lamella clarifier basic operation.
Self-cleaning baffles are achieved with an inclination of 50 to 60 degrees. The spacing between lamellas is generally between 2.5 and 5 cm in drinking water facilities, and the order of 5 to 10 cm in wastewater treatment. The effective horizontal surface is the horizontal projection of each plate multiplied by plates number. This total projected surface value is used to calculate the hydraulic loading rate. An important factor to take into consideration is the critical scour velocity. The foregoing results in more compact equipment and with surface requirements considerably lower than in conventional circular and rectangular clarifiers. Laminar or tubular clarifiers are also called high rate settling units.
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Where SL = Plate surface
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Figure 5. - lamella settler basics sketch.
Figure 6. Analysis of the functional surface in a lamella separator.
2.- LAMELLAR AND TUBULAR CLARIFIERS Introducing parallel and inclined laminar plates (lamellas) inside a settling tank produces so-called lamella clarifiers. A system variant where plates are connected to each other results in tube settling clarifiers. Although the operation fundamentals are the same in this configuration, tubular units allow to work with greater structural rigidity modules as well as lower weight. There are two basic types according to the flow direction: if the water flows in the same direction as the sludge they are called co-current flow and the opposite direction is described as counter-current clarifiers.
Co-current systems: greatly facilitate sludge removal, but add the problem of the possible
creation of water short circuits. In this case the installation of baffles is required in order to allow water to pass through the plates. Water circulation through the plates can be increased, with the risk of settled sludge resuspension.
Counter-current systems: The collection of the clarified water is produced in the part where
the sludge concentration is lower, resulting in better clarified water. Reduces the risk of particle entrainment. Rising water tends to contact the upper plate, while sludge descend on the lower one.
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Figure 7. - Basic configuration of a lamella separator flow (co-current).
Figure 8. - Introduction of a lamellar module in a rectangular clarifier.
Figure 9. - View of lamellas upper side in a rectangular settler built in concrete without water.
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Figure 10. – Lamellar settler built in metal or fiberglass with counter-current flow configuration.
Figure 11. – SEDIPAC® Settler lamellar type.
A variant of the lamellar clarifiers are tubular decanters. The slope remains between 45° and 60°. This type of decanters have particle removal efficiencies around 10% higher than the counter-current lamellar decanters. Some disadvantages of this technology are the need for greater lengths to achieve a stable or laminar flow regime and higher pressure drop due to greater friction surfaces. Sedimentation and sludge slide on the tube wall causes a reduction of the effective area which involves a decrease in water flow and general performance.
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Figure 12. – Types of tubular modules
Figure 13. - View of the modules upper side in a rectangular clarifier built in concrete without water.
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Figure 14. - Example of plastic tubular modules.
Figure 15. – Lamellar clarifier with prior flocculation sketch
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Figure 16. - Disposition of the tubular modules inside a clarifier.
Figure 17. - Disposition of the tubular modules inside a clarifier and settled sludge accumulation scrapers system.
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Figure 18. - View of the upper side of a tubular settler and collection channels of clarified water.
Figure 19. - View of the lower part of a settler and tubular modules support.
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Figure 20.-Sketch DENSADEG system flows (Degremont).
Figure 21. – Floc characteristics at each DENSADEG stage (Degremont).
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Figure 22.- Sketch of ACTIFLO flows and elements in system configuration.
Figure 23.- Sketch of ACTIFLO flows and elements in system configuration.
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3.- DESIGN Basic requirements of a laminar or tubular clarifier: Laminar flow conditions must exist. The particle or floc that settles must do so without those interferences that would cause the turbulence of a non-laminar flow. The residence time must be long enough to allow a particle to complete the vertical distance between lamellas. The flow-through velocity between lamellas must not exceed a critical value since it would produce sludge scouring. Besides this, the volume between two plates should allow settled particles accumulation so that a change in the fluid regime does not occur due to the flow section change.
3.1.- Design Parameters
The most important parameters for the design of the lamellar settling are: Flow speed inside the tube or between lamellas: This is the speed determined by the geometry and will have a
similar slope direction as the module elements. Critical vertical speed in the tube or between lamellas: It is obtained as a water velocity projection on the lamella
vertical axis. It should be lower than the flocs (or the particles to be removed) fall velocity. Design hydraulic loading rate: It is obtained as the ratio between the effluent flow and the horizontal total
settling surface, obtained as the addition of all lamellas horizontal surfaces projection.
Where: HLR C = hydraulic loading rate (m/h) Q = primary effluent flow (m3/h) A = Settling horizontal surface decantation (total projected surface) (m 2) Global hydraulic loading rate: Is obtained by dividing the outflow from the horizontal area occupied by
the decanter (not including projections tubes or lamellae).
Where: HLR G = Global hydraulic loading rate (m/h) Q = primary effluent flow (m3/h) A = Settling horizontal surface (Settler horizontal occupied surface) (m2)
Hydraulic retention time: Related to water depth. A deeper water depth increases the probability of particles collision (flocculation), increasing the falling rate:
Where: H RT= hydraulic retention time (hours) h = water depth (m) V = settling effective volume (m 3)
Hydraulic load over weir: Corresponds to the effluent flow per linear meter of the outlet weir. The outlet
velocity is limited in order to prevent sludge entrainment.
Where: HLW = hydraulic load over weir (m 3/h/m) Lw = weir length (m)
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Reynolds Number: Used to characterize the flow within the tubes or lamellas. A laminar flow should be
maintained.
3.2.- Design Criteria Table 1.- Summary of design values lamellar/tubular clarifiers Parameter
Values
Confined flow velocity (m/d) NRe – Reynolds number HLR – Hydraulic loading rate (m/h) (with projections) HLR – Hydraulic loading rate (m/h) (without projections) HRT on the confined volume (minutes) HLW – Load over weir (m3/h.m)
≤ 15 ≤ 200 ≤ 1- 2 (1,2) ≤6 ≥ 6 – 10 ≤ 10
Other design criteria: AWWA (2005)
Distance from tubes top to collection channels: 0.6 to 1 meter. Separation between channels: Below 1.5 meters.
Kawamura (2000); cited by Montgomery Watson Harza, (2005)
Re-suspension of bottom sludge at HLR higher than: 18 m/h (0.3 m/min) In cold regions the maximum acceptable load would be 150 m/d for lamellar clarifiers. Hydraulic retention time in tubular clarifiers is usually lower than 20 minutes.
Arboleda, J. (2000); Teoría y práctica de la purificación del agua. McGraw - Hill. Tercera edición. (Colombia).
In page 271 it states that lamellar clarifiers have been designed in Latin America with 120-185 m/d, with removal efficiencies greater than 90%. When parallel collection channels are used the distance between them they must be separated in 2 times the tubular modules immersion depth, or even better 1.5 times. Camp formula to analyze the sludge entrainment inside the tubes.
Va 125 ∙ cosθ Ss 1 ∙ d
Where Ss is the specific weight of the particle and d is its diameter. Flocs between 0.2 cm and 0.01 cm in diameter with 1.01 specific gravity entrainment velocity are 2.8 and 0.625 cm/s.
Gutierrez, A.
Minimum lamellas immersion distance of 0.4 meters.
4.- SLUDGE PRODUCTION The amount of sludge purge from the primary settling (primary sludge) is given by the following expression: P f 1 º
Q
SS
R
10
5
Where: P f 1 = average daily production of primary sludge (SS kg/day) Q = average flow (m3/d) SS = average concentration of influent wastewater (mg/L) R = primary settling SS removal (%) If the sludge density is assumed to be that of water, the volume of primary sludge can be estimated by: Pf 1º V f ,1º 10 C Where: V f,1º = average flow of primary sludge (m3/day)
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C = concentration of primary sludge (%)
The concentration of primary sludge usually between 3 and 5%. The primary sludge usually generates odor, contains a large amount of microorganisms and is putrescible, because of the organic matter. Therefore, it normally requires stabilization. Besides, it commonly has drainage in drying beds, but is able to be mechanically dewatered.
5.- PERFORMANCE With a good sized study of the lamellas, the performance of the clarifier can be multiplied by 4.
6.- PARTICULAR TECHNICAL CONSIDERATIONS In the design of the clarifiers, the following aspects must be taken into account: In the case that their presence is expected, the clarifiers must be equipped with floating materials and foam skimmers and evacuation points, being extracted from the water line. Moving bridge should be easily accessible and h ave an automatic stop against obstacles. Special attention should be paid to sludge pipes arrangement, avoiding unnecessary distances, useless elbows, etc., and include the necessary number of flanges to facilitate installation maintenance. There should also be considered the access to all the sludge line, being desirable to avoid pipes to get buried. The design shall include connections for pressured water injection in areas considered as susceptible to clogging. Installation of a primary clarifier process bypass is contemplated. If there are more than one unit in parallel, each one of them should be able to be isolated. In the case of parallel units, a mixing chamber should be installed which hydraulic dimensioning must achieve an equal distribution of the range flows.
7. - SPECIFICATIONS OF TEXTILE INDUSTRY EFFLUENT TREATMENT
Caution with high temperatures and plastics deformability. Also attend materials degradation by high temperatures and pH. Care to modules flotation.
8.- PARAMETERS AND CONTROL STRATEGIES Control parameters for process efficiency assessment (MAGRAMA, 2012):
Concentration of solids in influent and effluent. Turbidity in effluent. Concentration of purged sludge. Scraper rotation velocity. Generation of bad odor. Excessive accumulation of floating materials in the clarifier surface. Abnormalities in civil works, which could lead to infiltrations. Pipes or space between lamellas clogging. Deformation of the lamellar modules or pipes. Discharge weirs leveling.
The sludge and floating materials which accumulate in the primary clarifiers need to be removed periodically. In case the sludge was not removed as regularly as required, anaerobic conditions will appear. This can result in gas generation which would carry part of the sludge until the surface of the clarifier, with the consequent decrease in the performance. It is important to periodically check if the frequency of excess sludge removal is correct, adjusting the frequency if necessary. Low solids concentration in the sludge purge will be sign of a higher purge frequency than required. On the contrary, the appearance of fermentation (bubbling), sludge rise and unpleasant odors generation are signs that the sludge is remaining in the bottom of the clarifier longer than recommended. The clarifier baffles and weirs should be cleaned by brushing where from time to time appear biomass growth.
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Maintenance and control activities (MAGRAMA, 2012):
-
Checking the operation of the bridge by starting and stopping the power and safety switch. Inspecting the operation of the central electromechanical gear motor (if circular clarifier). Grease level check. Noise, vibration and overheating motors or pumps assessment. Inspection and cleaning of possible clogging of the space between lamellas or pipes. Control of the operation of the primary clarifier Hydraulic loading rate (m/h) control, calculated according to the average (m 3/h) and maximum o (m3/h) operation flows of treated water and the surface of the clarifier (m 2). Operational hydraulic retention time (h) of the clarifier, calculated according to the average o (m3/h) and maximum (m3/h) flows of treated water and the effective volume of the clarifier (m 3). Load over weir (m3/h.m): calculated based on the maximum flow rate (m 3/h) and linear length o (m) of the discharge weir.
9.- OPERATING PROBLEMS The quality loss in effluent, mainly by the presence therein of particulate matter may be due to hydraulic overload or failure to proceed with the recommended frequency of sludge excess purge. In the first case it will be necessary to limit tributary flows and the second it is necessary to regulate the period of the sludge removal. The following table shows the main anomalies that can occur in primary sedimentation facilities, along with their possible causes and recommended solution (MAGRAMA, Table 2. Major abnormalities in primary clarifiers, causes and solutions.
Anomaly Low effluent quality due to high suspended solids concentration
Cause Hydraulic overload Low sludge purge period Floating substances accumulation
Low concentration sludge
Too frequent sludge extraction
Solution Limit wastewater flow Increase sludge purge Increase floatants removal frequency Decrease sludge purge frequency
Bubbling, bad odors and floating sludge High sand concentration in the sludge
Low sludge purge period
Increase sludge purge frequency
Improper degritter unit processing
Increase sludge purge frequency
Causes of lamella modules clogging (LamelaresTecnoConverting ):
On the walls of the thermoplastic lamellae adhesion of algae, mud, etc. It is common, sometimes due to various reasons. High concentrations of suspended solids. Chemical reagents as flocculants, coagulants... Uncontrolled spills (oil, grease ...) Existence of preferential flow between some lamellas. Bad sizing of the settling unit Improper lamellas maintenance.
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BIBLIOGRAPHY CEDEX (2010); "Curso sobre tratamiento de aguas residuales y explotación de estaciones depuradoras"; 2 tomos; Centro de Estudios y Experimentación de Obras Públicas; Gabinete de Formación y Documentación: Madrid. CRITES R. y TCHOBANOGLOUS G. (2000). “Tratamiento de aguas residuales en pequeñas poblaciones”. McGraw-Hill Interamericana, S.A.: Bogotá (Colombia). DAVIS, M. L. (2010). “Water and wastewater engineering. Design, principles and practice”. McGraw-Hill: New York (USA).
DEGRÉMONT (1979). “Manual técnico del agua”. Cuarta edición española. Grafo, S. A. Bilbao. GLUMRB (2004) “Recommended standards for wastewater facilities”. Policies for the design, review, and approval of plans and specifications. For wastewater collection and treatment facilities. A report of the wastewater committee of the Great Lakes – Upper Mississippi River Board. Published by: Heath Research, Inc., Health Education Services Division, Albany, N.Y. (USA). HERNÁNDEZ A. (1998). “Depuración de aguas residuales”. Paraninfo, S. A. Madrid (España). HERNÁNDEZ MUÑOZ A., HERNÁNDEZ LEHMAN A. y GALÁN P. (2004). “Manual de depuración Uralita. Sistemas para depuración de aguas residuales en núcleos de hasta 20.000 habitantes”. Paraninfo S. A.: Madrid (España). LIN S. D. (2007). “Water and wastewater calculations manual”. McGraw-Hill Companies Inc.: New York (USA). METCALF & EDDY (1995). "Ingeniería de Aguas Residuales. Tratamiento, vertido y reutilización”. McGraw-Hill – Interamericana, Madrid (España). METCALF & EDDY (2003). “Wastewater Engineering: Treatment and Reuse”, 4th ed., McGraw-Hill, Boston (USA). MOPU (1983). “Anteproyecto de modelo de pliego de bases técnicas para concursos de proyecto y ejecución de obras de estaciones depuradoras de aguas residuales. Centro de Estudios de la Dirección General de Obras Hidráulicas y Grupo de Tratamiento de Aguas de SERCOBE. Madrid (España). MAGRAMA (2010), “Manual para la implantación de sistemas de depuración en pequeñas poblaciones”; Ministerio de Medio Ambiente y Medio Rural y Marino Pº de la Infanta Isabel, 1, Secretaría General Técnica NIPO: 770-10-061-3; ISBN: 978-84-491-1071-9. NY-DEC (2004). Wet Weather Operating Practices for POTWs with Combined Sewers. New York State. Dpt. of Environmental Conservation. Documento de Transferencia Tecnológica. www.dec.state.ny.us/website/ dow/bwcp/ww_training.html RONZANO, E.; DAPENA, J. L. (1995); "Tratamiento biológico de las aguas residuales". Manual de PRIDESA; Ediciones Díaz de Santos, S. A.: Madrid (España). SAINZ J. A. (2007). “Tecnologías para la sostenibilidad. Procesos y operaciones unitarias en depuración de aguas residuales”. Fundación EOI: Gregorio del Amo 6, Madrid (España). SINCERO A. y SINCERO G. (2003). “Physical-chemical treatment of water and wastewater”. CRC Press LLC: Boca Raton (Florida – USA). SUÁREZ J., et al. (2008). Gestión de las aguas pluviales. Editado por CEDEX: Madrid. WEF - ASCE (1998). "Design of municipal wastewater treatment"; Vol. 2. Water Environmental Federation; Ameri can Society of Civil Engineering: VA (USA). WEF (2005) “Clarifier design”. Manual of Practice Nº FD-8. Water Environment Federation. Alexandria, VA (USA). VERNICK, A. S.; WALKER, E. C. (1981). "Handbook of wastewater treatment process"; Marcel Dekker, Inc.: Nueva York (USA).
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ANNEX 1.- SIZING CRITERIA COMPARISON Table A1.- Comparison of lamella and tubular sizing criteria Parameter
Units
KAWAMURA (2000) cited by Montgomery, 2005)
Hydraulic loading rateo ver tubular or lamella settlers with aluminum floc.
m/h
2,5 – 6,25
Hydraulic loading rate for tubular or lamella with heavy floc
m/h
Hydraulic loading rate (considering total horizontal surface) regarding aluminum floc Hydraulic radius
m/h
cm
2,5 – 4,0
2,5 – 4,0
Maximum flow velocity between lamellas or tubes, V0 HRT in tubular settlers
m/min
0,15
0,15
AWWA (2005)
ARBOLEDA (2000)
2,4 – 7,3
5,0 – 7,5
Wang, L. (2005)
TARGET TURBIDITY (JTU) (Tª agua) 1-5 3–7 5 - 10
ROMERO, J. (1999)
m/h
ESPERT, V. (1996)
SIZING CRITERIA PROPOSAL
3,75 – 7,5
6 m/h
General 2,5 – 12,5
6 7,2 9,6
Max. Bibliography 12.5
Tubular 7,5 – 12,5
3,8 – 7,5 1,0 – 2,0 (1.2)
1,0 – 2,0 (1.2)
min
6 - 10
3-6
HRT in lamella settlers
min
15 - 25
15 – 25
Load over weir
3
6 – 10
12
15
Max. Bib. 25 m /h.m
3,75 - 15
Aluminum sulphate light floc Aluminum sulphate heavy floc Softening floc
deg m/min
60º 0.05 - 0.13
Adimens.
<20000
Froude number
Adimens.
>10-5
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< 10,0
Max. Bibliografía 13
< 10,0
≤ 0,6 200 - 500
Floc particles NRe≤280 Discrete particles NRe≤600
Settling unit Reynolds number
7,6 ‐ 11
4 – 8
11,0 ‐ 13,0
Coagulation floc
Tubes or plates angle Average horizontal velocity Reynolds number between lamellas or tubes
6 ‐ 7,6
NRe ≤ 200
Max. Bibliography 600
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Kawamura (2000) / a) Antes de instalar las placas o los tubos. b) Puede ser mayor dependiendo de las características del flóculo y del tipo de placa o tubo utilizado.
Alberto (1999): Potabilización del agua. ALFAOMEGA. 3ª edición. (México, D.F.) Arboleda, Jorge (2000): Teoría y práctica de la purificación del agua . McGraw - Hill. Tercera edición. (Colombia). American Water Works Association (AWWA) y American Society of Civil Engineers (ASCE) (2005):Water treatment plant design . Handbooks. McGraw-Hill. Fourth edition.
(USA).
American Water Works Association (AWWA) (2002): CALIDAD Y TRATAMIENTO DEL AGUA. Manual de suministros de agua comunitaria . McGraw – Hill (quinta edición en
inglés). (Madrid)
Montgomery Watson Harza (MWH) (2005): WATER TREATMENT. Principles and design . Editado por John Wiley &Sons, Inc., (New Jersey- United States of America) Wang, Lawrence K. ;Hung Tung–Tse; Shammas, Nazih .(2005):Physicochemical treatment processes. Handbook of environmental engineering. Humana Press. (New Jersey-
United States of America)
Masschelen, W. J. ( 996): Processus unitaires du traitement de l´eau potable . CEBEDOC. (Belgium)
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Kawamura (2000) / a) Antes de instalar las placas o los tubos. b) Puede ser mayor dependiendo de las características del flóculo y del tipo de placa o tubo utilizado.
Alberto (1999): Potabilización del agua. ALFAOMEGA. 3ª edición. (México, D.F.) Arboleda, Jorge (2000): Teoría y práctica de la purificación del agua . McGraw - Hill. Tercera edición. (Colombia). American Water Works Association (AWWA) y American Society of Civil Engineers (ASCE) (2005):Water treatment plant design . Handbooks. McGraw-Hill. Fourth edition.
(USA).
American Water Works Association (AWWA) (2002): CALIDAD Y TRATAMIENTO DEL AGUA. Manual de suministros de agua comunitaria . McGraw – Hill (quinta edición en
inglés). (Madrid)
Montgomery Watson Harza (MWH) (2005): WATER TREATMENT. Principles and design . Editado por John Wiley &Sons, Inc., (New Jersey- United States of America) Wang, Lawrence K. ;Hung Tung–Tse; Shammas, Nazih .(2005):Physicochemical treatment processes. Handbook of environmental engineering. Humana Press. (New Jersey-
United States of America)
Masschelen, W. J. ( 996): Processus unitaires du traitement de l´eau potable . CEBEDOC. (Belgium)
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ANNEX 2 SURFACE REQUIREMENT ESTIMATION ESTIMATION OF SURFACE NEEDED FOR PRIMARY SETTLING
HYDRAULIC LOAD (m3/m2.h) Range Adopted value 3
Flow (m /h)
1 ‐1,5
4
6
REQUIRED SURFACE (m2)
5
1
1
10
3
2
20
5
3
30
8
5
40
10
7
50
13
8
60
15
10
70
18
12
80
20
13
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ANNEX 2 SURFACE REQUIREMENT ESTIMATION ESTIMATION OF SURFACE NEEDED FOR PRIMARY SETTLING
HYDRAULIC LOAD (m3/m2.h) Range Adopted value 3
Flow (m /h)
1 ‐1,5
4
6
REQUIRED SURFACE (m2)
5
1
1
10
3
2
20
5
3
30
8
5
40
10
7
50
13
8
60
15
10
70
18
12
80
20
13
90
23
15
100
25
17
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ANNEX 3 GRAPHICAL DESCRIPTION OF UNIT PROCESSES
Figure 1 Floating trouble in tubes module and clogging.
Figure 2 Lamella module on primary settling.
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Figure 3 Lamella plates module for settling unit with lateral inlet openings
Figure 4 Detail of tubular clarifier modules.
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Figure 5 Collection weirs on lamella clarifier.
Figure 6 General view of collection weirs in lamella clarifiers and scrapers bridge.
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Figure 7 General view of collection weirs in lamella clarifiers and scrapers bridge.
Figure 8 General view of lamella clarifiers.
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Figure 9 General view of collection weirs in lamella clarifier http://www.cend.es/Ejemplos-y-casos-ilustrativos/Decantadores-lamelares/
Figure 10 Example of description technical sheet of a tubular settler module.
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Figure 11 General arrangement of plate modules.
Figure 12 General arrangement of plate module.
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Figure 13 General scheme of late modules, flows and sludge purge.
Figure 14 Plastic settling unit tubular modules with elements breakage.
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