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galvis

Water treatment

R 1 = (total orifice

R 1 = (total orifice area / lateral flow area) in the previous example is R 1 = (32 x 0.785 (0.00635 m) 2 ) / (0.785 (0.0508 m) 2 ) = 0.001 / 0.002 = 0.5, which is just inside the range shown in table A2-1. R 2 = total lateral flow area / main flow area in the previous example is R 2 = (5 x 0.785 (0.0508 m) 2 ) / (0.785 (0.152 m) 2 ) = 0.01 / 0.018 = 0.55, which is inside the range shown in table A2-1. Diameter = 6.35 mm (1/4” ), separation = 0.12 m and flow velocity = 4.7 ms -1 orifices are inside the range shown in table A2-1 Alternative designs are also possible as long as a good flow velocity distribution is obtained. For example, it can be adopted 32 offices of do = 9.53 mm (3/8” ), 5 laterals of D L = 63.5 mm (2.5” ), and one main of 203 mm (8” ). The headlosses would be H fLn = 0.14m and H fLo = 0.20 m. The discharge of the main pipe can be placed at the bottom level of the unit or below if topographic conditions are favourable. In those situations in which the size of UGF units does not allow to follow previous guidelines or wherever a flat topography does not permit to place the fast opening valves low enough to obtain high drainage velocities, the false bottom option should be considered, as advised by CEHE (1999). References AWWA-ASCE. (1998) Water Treatment Plant Design. Third edition. McGraw Hill. USA Castilla, A. and Galvis, G. (1985). Diseño de Múltiples. Curso de Abasto de Agua para Poblaciones. Universidad del Valle, Facultadad de Ingeniería, Cali, Colombia. Fair, G.; Geyer, J. and Okun, D. Ingeniería Sanitaria y de Aguas Residuales.( 1987) Editorial Limusa, S.A. Versión española. México, D.F. Hudson, H.E. (1981). "Water Clarification Processes. Practical design and evaluation". Van Nostrand Reinhold environmental engineering series. McNown. J.S. (1954). "Mechanics of manifold flow". Trans. ASCE, 119 (Paper 2714): 1103. Vennard, J.K. and Dentoni, D.K. (1954). "Discussion to Mechanics on Manifold Flow". Trans. ASCE, 119 (paper 2714): 1136. CEHE (1999) Development and Integration of Small Scale Multistage Treatment for Drinking Water. Draft Version. England: CEHE, Centre for Environmental Health Engineering. R 5505C, pp. 1-142 A2-5

Annex 3: Information on analytical techniques A3.1. Spectrophotometric method for colour measurements The spectrophometric method is recommended for colour analysis in The Standard Methods, section 2120C (APHA et al, 1989). This method requires colour measurements at original pH and at pH 7.6 as well as to remove turbidity interference by centrifugation and filtration. In this study the pH of the water samples was normally at 7.4 and was not adjusted. Turbidity was removed only by centrifugation to avoid possible adsorption on the filtering medium, as recommended by Sawyer et al (1994). Spectrophotometer Shimadzu UV-120-01 was used to facilitate colour measurements. For high colour levels (in the range 10 to 100 PCU approx.), light absorbance readings at 455 nm of wavelength with a 1 cm light path were made using platinum–cobalt standards in the range 0 to 100 PCU. The calibration curve produced with these data (see figure A3-1) was used to facilitate colour measurements in samples taken from raw water, and effluents of DyGF and CGF stages from the MSF pilot system at Puerto Mallarino and some samples from full scale plants. For low colour levels (below 10 PCU approx.) a different calibration curve was produced by doing light absorbance readings at 455 nm of wavelength with a 10 cm light path using platinum–cobalt standards in the range 0 to 10 PCU. This calibration curve was used for colour measurements in samples taken usually from full-scale plants or the CGF and SSF stages from Puerto Mallarino. 0.3 0.25 Y = 0.0028X + 0.0022 R 2 = 0.9989 Absorbance 0.2 0.15 0.1 0.05 0 0 10 20 30 40 50 60 70 80 90 100 110 Concentration of platinum-Cobalt (PCU) Figure A3-1 Relationship between colour and absorbance readings with platinum-cobalt standards in the range 0 to 100 PCU. A3.2. Spectrophotometric and Gooch methods for SS measurements The Gooch method, a gravimetric technique is the recommended procedure to determine SS, suspended solids (Sawyer et al, 1994). However, this method is time consuming. In view of this limitation of Gooch method, Krawezyk and Gonglewski (1959) developed an alternative procedure based on spectrophotometric readings. This method was adopted in this study for low turbidity samples (below 20 NTU) to avoid processing large sample volumes. Several samples were collected from effluents of CGF units. The SS concentrations of these samples were measured by Gooch method, according to section 2540 D of Standard Methods (APHA et al, 1989). Sample water volumes varied between 750 and 3,000 ml, depending on sample turbidity values. These samples and their “ true” SS values (Gooch method) were used to calibrate the spectrophotometer shimadzu UV-120-01 at 810nm-wavelength and 10 cm light path, obtaining an absorbance reading for every “ true” SS value. Analyses were replicated three times and mean values were obtained for each sample and each analytical procedure. Calibration curves obtained with these mean values are shown in figure A3-2, based on samples taken from effluents of CGF units of both pilot and full-scale plants A3-1

  • Page 1 and 2:

    Development and Evaluation of Multi

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    ACKNOWLEDGEMENTS To my supervisor,

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    ABBREVIATIONS ABNT: Acuavalle: ACV:

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    SOCs: Synthetic Organic Chemicals S

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    u c V V f Vs uniformity coefficient

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    TABLE OF CONTENTS 1. INTRODUCTION 1

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    4 MULTISTAGE FILTRATION EXPERIENCIE

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    1 INTRODUCTION Water is essential f

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    Table 1.2 Access to WS&S in Colombi

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    Table 1.5 Safe drinking water cover

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    1.2 Multiple Barriers Strategy and

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    2 OVERCOMING THE LIMITATIONS OF SLO

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    adjustment, are among the technolog

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    On January 14, 1829, Simpson’s on

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    With increasing life expectancy, en

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    Table 2.2 Treatments steps recommen

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    In table 2.3, WHO guideline values

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    2.5 The Slow Sand Filtration Proces

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    When the particles are very close t

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    in which p 0 is the clean media por

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    Yao et al (1971) related the remova

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    compensate for the increase in the

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    can be applied, but intermittent op

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    Table 2.4 Comparison of design crit

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    Although accepted as indirect indic

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    50% when the temperature falls from

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    Figure 2.9 Flow diagram of the wate

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    ut higher running costs, since more

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    Headloss and flow control. Final he

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    Figure 2.13 Influence of flow condi

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    Operation and maintenance (O & M).

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    in parallel (Galvis, 1983; Smet et

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    cleaning simple, DyGF should behave

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    case of Dortmund (Germany), the HGF

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    Table 2.9 Data about three experien

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    Some points of discussion about HGF

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    and 600-800 NTU) and different filt

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    the HGF units of Aesch (see table 2

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    in spite of the low removal efficie

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    order to overcome the water quality

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    full-scale units. In this research,

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    3 MULTISTAGE FILTRATION STUDIES WIT

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    in the case of UGFL. Initially, it

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    • Bigger and better-instrumented

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    l Figure 3.7 Plan view of Cinara's

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    The present research work was divid

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    Table 3.1. Design parameters, grave

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    Figure 3.9. Piezometer distribution

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    were used to collect samples for DO

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    were poured into a funnel using fil

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    H 0 : H a : Treatment levels workin

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    3.2 Results and Specific Discussion

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    3.2.2 Dynamic gravel filtration (Dy

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    Mean faecal coliform removal effici

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    Table 3.10 Comparative analysis of

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    DyGF-A had flow reductions in the r

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    The experimental data used to produ

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    Previous observations were further

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    ates (figure 3.17 B). However, at t

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    Longer “initial-ripening” perio

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    Table 3.17. Descriptive statistics

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    100 Filtration rate = 0.3 mh -1 100

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    After the present experience, faeca

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    nature of the organic matter and th

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    Table 3.24 Comparative analyses of

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    3.2.4.3. Filtration run lengths and

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    deep bed filter (data not included

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    and operational considerations Pard

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    than in sand samples from other SSF

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    Step dose tracer tests were made at

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    for HGFS and from 3 to 5 for HGF. T

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    Constant and declining filtration r

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    The efficiency levels summarised be

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    Surface area of CGF and SSF units.

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    community based organisations and l

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    systems. All these systems were fed

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    Parts of the suburban settlements o

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    Figure 4.2. Layout of Retiro MSF pl

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    Traditionally, in the WS&S of Colom

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    Photo 4.10. Partial cleaning activi

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    Figure 4.3 Location of full-scale M

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    4.4.1.3 Main characteristics of mul

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    Figure 4.4 Layout of Restrepo MSF p

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    Figure 4.6 Layout of Javeriana MSF

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    Figure 4.9 Layout of Cañasgordas M

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    Figure 4.11. Layout of Ceylan MSF p

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    Table 4.4 Descriptive statistics fo

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    Water sources in the coffee region

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    Filterability results seem to under

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    Table 4.8 Mean removal efficiencies

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    The length of this ripening period

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    in Peru (Pardon, 1989) and Colombia

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    Photo 4.24 Drainage facilities in u

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    the Cauca Valley. This is not the c

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    Pardon (1989) reports similar evide

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    5. COST OF MULTI-STAGE FILTRATION P

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    ecame formally established as WS en

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    Models for assessing construction q

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    MSF system can then be calculated o

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    5.7 Cost Model for the Cali Area an

  • Page 206 and 207: Table 5.8. Annual labour costs due
  • Page 208 and 209: 5.8 General Discussion The followin
  • Page 210 and 211: systems. The differences between MS
  • Page 212 and 213: guideline for colour is < 15 PCU (W
  • Page 214 and 215: Table 6.1. Individual (at each trea
  • Page 216 and 217: Table 6.3. Individual (at each trea
  • Page 218 and 219: As shown in tables 6.1 and 6.3, col
  • Page 220 and 221: UGFL 0.45 UGFS 0.45 (32;51;85) (44;
  • Page 222 and 223: Table 6.4. An example of identifica
  • Page 224 and 225: MSF technology showed great flexibi
  • Page 226 and 227: In harmony with the new development
  • Page 228 and 229: epresents the risk the community ha
  • Page 230 and 231: The selection of MSF alternatives i
  • Page 232 and 233: scouring and transporting away prev
  • Page 234 and 235: REFERENCES ABNT, (1989) NB-592 Proj
  • Page 236 and 237: Craun, G.F., Bull, R.J., Clark, R.M
  • Page 238 and 239: Drinking Water Disinfection, ed. by
  • Page 240 and 241: Huisman, L. (1989) Plain Sedimentat
  • Page 242 and 243: Mendenhall, W. and Sincich, T. (199
  • Page 244 and 245: Ridley, J.E. (1967) Experience in t
  • Page 246 and 247: Visscher, J.T. and Galvis, G. (1992
  • Page 248 and 249: ANNEXES Annex 1: Accessories for Mu
  • Page 250 and 251: aw water. The red colour is used fo
  • Page 252 and 253: Annex 2: Design of Manifolds Manifo
  • Page 254 and 255: + q 2 Q1 (1.2 qn + qn) (2.2 qn) = =
  • Page 258 and 259: 0.30 0.25 0.20 0.15 0.10 0.05 0.00
  • Page 260 and 261: Table A.4-2 General notation for th
  • Page 262 and 263: Box A4-3. Sum of Square Error (SSE)
  • Page 264 and 265: Annex 5: Residence times in coarse
  • Page 266 and 267: Table A5-1 Percentage of incoming w
  • Page 268 and 269: Annex 6 Number and Type of Valves N
  • Page 270: Table A7-1. Descriptive statistics
  • Page 274 and 275: Tables A7-3 Removal efficiencies of
  • Page 276 and 277: Tables A7-5 Removal efficiencies of
  • Page 278 and 279: Construction quantities of DyGF com
  • Page 280: Net present value (US$) of MSF and