I. Water Supply Networks and Facilities Topic I.3. Sources for Water Supply - Surface Waters and Groundwater : Quality and Peculiarities - PowerPoint PPT Presentation

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I. Water Supply Networks and Facilities Topic I.3. Sources for Water Supply - Surface Waters and Groundwater : Quality and Peculiarities

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Title: I. Water Supply Networks and Facilities Topic I.3. Sources for Water Supply - Surface Waters and Groundwater : Quality and Peculiarities


1
I. Water Supply Networks and FacilitiesTopic
I.3. Sources for Water Supply - Surface Waters
and Groundwater Quality and Peculiarities
  • Water Quality
  • General classification of water quality
    parameters
  • Physical - temperature, transparency, turbidity,
    colour, smell, taste, conductivity, suspended
    solids
  • Chemical - dry residuals (total, soluble),
    hardness, alkalinity, pH, oxidability, gas
    saturation
  • bacteriological and biological - pathogens,
    coli-index, coli-test, etc. and hydrobionts,
    algae, fitoplancton, zooplancton, etc.

2
Water Quality
  • A. Physical Water Quality Parameters
  • Temperature
  • Rivers - 0o - 26o C
  • Lakes - relatively constant (equal to the mean
    air temperature)
  • Bulgarian State Standards (BSS) - 6o - 12o C
    (degree santigrade)
  • Transparency/Turbidity
  • Snelens type (symbol) - for transparency (30 cm
    according to the BSS)
  • Suspended solids concentration, SS (SS lt 2 mg/l
    according to the BSS)
  • Colour
  • Platinum-cobalt scale (solution of K2PtCl6 and
    CoCl2 in H2SO4)
  • Roubliovs scale (solution of K2CrO2 and CoSO4),
    degreeFor natural waters - 10 - 20 For
    drinking water lt 30 degree according to the BSS

3
Water Quality
  • Taste
  • Salty, sweet, bitter, sour (no any taste is
    permissible in drinking water)
  • Smell
  • Aromatic (pleasant), hydrosulfuric (H2S),
    phenolic, marsh, chloric (Cl2)
  • 5-grade scale (based on probe dilution) is
    applicable for smell detection smell lt 2 degree
    is permissible for drinking water according to
    the BSS
  • B. Chemical Water Quality Parameters
  • Dry residuals (DR)
  • DR lt 1000 mg/l is the standard limit for
    drinking water accord. to the BSS
  • Non-organic residuals (NOR)

4
Water Quality
  • Hardness
  • It is due to presence of Ca2 and Mg salts of
    carbonic acid (temporal hardness) and/or Ca2 and
    Mg salts of strong acids (permanent hardness)
  • Measures - mg-equiv./l, degree (German, French
    and English) 1o Germ. 10 mg/l CaO
  • According to the BSS, hardness gt 25o Germ. is
    not permissible for drinking water
  • Alkalinity
  • It is due to presence of HCO3-, CO32-, K2SO4,
    Na2SO4,KCl, NaCl
  • pH (active reaction)
  • H2O ? H OH-
  • H 10-7 mol/l - neutral
  • pH -logH -log(10-7) 7 - neutral active
    reaction

5
Water Quality
  • Oxidability
  • Measure - the mass of KMnO4, necessary for
    oxidation of the organic substances in a unit
    water volume, mg/l
  • Standard limit - 2,6 mg/l
  • Content of Fe2 and Mn
  • In groundwater Fe2 and Mn are usually in the
    form of Fe(HCO3)2 and Fe(HCO3)2 , respectively
  • On the surface 4Fe(HCO3)2 O2 2H2O 4Fe(OH)3
    8CO2
  • 4MnHCO3 O2 2H2O 4MnOH? 4HCO32-
  • The Fe(OH)3 and MnOH create a bitter taste and a
    black colour of water
  • Standard limits0,2 mg/l for Fe(OH)3 and 0,1
    mg/l for MnOH, respectively
  • Carbonic acid balance
  • 4HCO32- ? CO32- CO2 H2O
  • The above balance depends strongly on pH value

6
Water Quality
  • Dissolved gases
  • CO2 presents in natural water at pH lt 8,3
  • O2 concentration depends on water temperature and
    atmospheric
  • pressure
  • H2S (and/or its ions HS- and S2- in ratio,
    depending on pH and
  • temperature) present in some groundwater

7
Water Quality
  • C. Bacteriological and biological water quality
    parameters
  • Bacterial content
  • Bacteria general division pathogens (creating
    illness) saprophytes (non-
  • harmful)
  • Esherihia Coli - a saprophyte, accommodating at
    the human stomach and
  • faeces is an indicator for faecal pollution of
    water
  • Measures coli index - number of the
    coli-bacteria in 1 l water volume
  • Standard limit coli index lt 10
  • Biological content
  • General division Fauna - zooplancton
    (suspended), bentos (sediment),
  • hydrobionts (attached) Flora - phytoplancton
    (suspended), algae
  • (suspended, rooted)
  • Saprobility (symbioses) polysaprobe, mezosaprobe
    (? and ?) and
  • oligosaprobe

8
Water Supply Sources Peculiarities
  • A. Surface Waters Rivers
  • Source of feeding - atmospheric water and
    groundwater
  • Runoff regime - great variety of flowrates and
    water levels
  • Water intake Water level security,
  • category min max
  • I 1 97
  • II 3 95
  • III 5 90
  • Water quality - depends on geological, climatic
    and anthropogenic factors
  • Erosion and silt regime

9
Water Supply Sources Peculiarities
  • B. Surface Waters Lakes and Reservoirs
  • Stratification in depth
  • I zone (0 - 4 m) - higher temperature and
    pollution, low O2 concentration, plankton
    development
  • II zone (under 4 m) - lower temperature (1o C
    decrease in every 1 m depth), highest O2
    concentration
  • III zone (above the bottom) - lowest temperature
    and O2 concentration, high H2S, Fe2 and Mn
    concentrations
  • Water quality
  • It depends on geological features of the
    catchment and the lake bottom anthropogenic
    impact evaporation (increasing water salinity),
    euthrophication (phytoplankton blooming).
  • Silting
  • (The dead volume filling)

10
Water Supply Sources Peculiarities
  • C. Groundwater
  • General classification
  • I. According to the salinity (mineral salts
    content)
  • Fresh (sweet) water - up to 1 g/l dry residuals
  • Slightly mineral water - 1 - 3 g/l dry residuals
  • Average mineral water - 3 - 10 g/l dry residuals
  • Mineral water - 10 - 50 g/l dry residuals
  • Strong mineral water - above 50 g/l dry residuals
  • II. According to the temperature
  • Very cold water - about 4o C
  • Cold water - 4o - 20o C
  • Hot water - 20o -37o C
  • Warm water - 37o - 42o C
  • Very warm water - 42o - 100o C

11
Water Supply Sources Peculiarities
  • III. According to the hydrogeological conditions
  • Shallow aquifer (water-bearing stratum) -less
    than 10 m
  • Deep (10 - 30 m) non-pressurised aquifer - over
    impervious layer (clay)
  • Deep (10 - 30 m) pressurised aquifer - between
    two impervious layers
  • IV. According to water location
  • At the river terrace (send, gravel)
  • At the rock cracks
  • Springs - water coming out of pressurised or
    non-pressurised aquifers
  • Artesian water - coming out of pressurised
    aquifer and with
  • piesometric head above the ground level
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