Please enable JavaScript.

Coggle requires JavaScript to display documents.

Water Treatment (Filtration (Membrane Filtration (Flat Plate, Hollow Fibre…

- - - - Design
      - Type
      - Usage
        
        Preclarification
    - - Adsorptive capability - how much contaminants can be adsorbed
      - Selectivity - what type of contaminants adsorbed
      - High abrasion resistance
      - High thermal stability
      - Large surface area
  - - - 1st stage filtration
      - 2nd stage iron and manganese filtration
      - Adsorption
      - Combined filtration/adsorption
    - - Pre-treatment systems
      - Filter media - size, shape , hardness
      - Filtration rates 5-10m/h
      - Filter washing system (Backwash)
        
        Controlled by computer system
        
        Time (timer)
        
        Headloss - influent quality
        
        Filtrate quality - effluent quality
        
        Recipe
        
        Water only
        
        Separate air water (SAW)
        
        Combined air water (CAW)
        
        Combined air limited water (CALW) - collapse pulsing
      - Underdrain system
      - Performance monitoring
        
        Turbidity - online, continuous, coarse measurement
        
        Particle counting - fine measurement
        
        Head loss
        
        Runtime
      - Media arrangement
        
        Un-graded media
        
        Fine to coarse - size gradient
        
        Coarse to fine - size gradient
        
        Multi-media - e.g sand +carbon, sand + anthracite, multisand
  - - - High quality filtrate - doesn't require disinfection
      - Very efficient in cryptosporidium removal
      - Simple to operate
    - - Large footprint- 50-100x larger + slower than RGFs
      - Labour intensive cleaning process - but years between cleans (vs 24 h)
      - Requires local sand washing facilities
      - Delayed/slow start
      - Imperiled performance in cold weather
      - Waters with turbidity > 10 NTU require preliminary treatment
- - - - Water soluble polymers with surface charges along the chain
      - Neutralises surface charges
      - Positively charged sites along the chains are available for adsorption onto the negative colloidal particles
      - Stearic bridging mechanism forms floc
      - No effect on pH
      - Can be used alone or in conjunction with metal salts
    - - Alum
      - Ferric Chloride
      - Ferric sulphate
      - Polyaluminium chloride
  - - - pH
        
        Coagulant hydrolysis may affect water pH by consuming alkalinity
        
        pH correction may be required
        
        for optimal coagulant pH
        
        after coagulant use
        
        Optimal pH can be determined via jar tests
        
        Coagulant performance is pH sensitive and dependent on water characteristics.
      - Temperature
      - Alkalinity
    - - Jar tests
  - - - Mechanical devices
      - In-line blenders
      - Hydraulic methods
      - Air mixing
- - - - Medium to low pH - corrosive
      - Low SS
      - Low Alkalinity - not pH buffered
      - Low TDS - acidic
      - High Colour - dissolved organic matter
    - - Changing river channels
      - Rainfall/Flood conditions
      - Bacteria
        
        Pathogens
        
        Cryptosporidium
      - Summer/Winter conditions
        
        Low flow/algae
      - Pesticides - agricultural run off
        
        Nitrates
        
        Ammonia - plant/animal decomposition
      - High dissolved solids - hardness
  - - - Dissolved metals
  - - - Oils and Hydrocarbons
      - Colour - Tannins and Lignins
      - Organic Solids
      - Inert Solids - glass, dirt etc.
      - Heavy Metals
      - Biological Material
      - Hardness
      - Synthetics
      - Non-biodegradable materials
      - Dissolved gases
    - - Bacterial
      - Viral
      - Cyanotoxin
        
        Algae
      - Chemical
        
        Nitrates
        
        Can cause methemoglobinemia ("Blue baby syndrome") - prevents blood transferring oxygen, leads to anoxia
        
        Comes from sewage, agricultural runoff, leaky septic tanks, natural deposits, animal waste
      - Radiological
      - Protozoal
        
        Cryptosporidium
- - - - High-rate compared to conventional tanks (10-15m/h)
      - Sand ballasted (50-100m/h)
      - Design based on particle settling velocity
      - Shorter settling distance, which reduces surface area (footprint)
      - Shorter retention times (approximately 20 minutes vs. 2 hours for conventional tanks)
    - - Air micro-bubbles attach to the floc causing them to float to the surface forming a floating scum/sludge
      - Uses air saturated water (5-10% effluent recycle)
      - Advantages
        
        High loading rates
        
        Relatively thick sludge
        
        Polymer not required
        
        Very efficient for algae removal (settling resistant as has same density as water)
        
        Low footprint
        
        Good subnatant quality
      - Disadvantages
        
        Must be housed (rain)
        
        Mechanically more complex than conventional clarifier
        
        Not great for high turbidity waters
    - - Coagulated water flows up through a previously formed sludge blanket
      - Blanket acts as a "flocculation-filter"
      - Blanket depth of several feet is required
      - It requires uniform upward flow
      - Advantages
        
        Good for removal of turbidity, colour, tastes, organic matter, Fe and Mn
        
        High quality effluent
        
        Very high loading rates possible
      - Disadvantages
        
        Not good for algae
        
        Good for colloidal particulates but not for larger SS
        
        Sunlight might create thermal currents
        
        More complex
    - - Flash mix, coagulation, flocculation, clarification, solids recirculation and sludge removal in a single basin
      - Recirculation of settled solids to promote particle growth and improve solids removal
      - Up to 15 times influent flow recirculated
      - Particularly good for softening, turbidity and colour removal
      - Complicated civil and hydraulic engineering - more likely to go wrong, higher power requirements
      - Poor with weak flocs
      - Moderate effluent quality
    - - Widely used in water treatment
      - Shape
        
        Circular
        
        Rectangular
        
        Hopper-bottomed
      - Flow
        
        Horizontal
        
        Vertical
        
        Radial
      - Reduce flocculated turbidity from 2-10 NTU to <0.5-1.0 NTU
      - Design based on hydraulic loading rate (1.5-2 m/hr)
- - - - Can protect from pollution events in water source
    - - Sedimentation of solids
      - Pathogen Kill - UV disinfection
      - Mixing/Dilution
    - - Inflow/outflow rates and locations
      - Dimensions and profile
      - Wind conditions - can cause turnover due to surface drag
      - Can be prevented by aeration/mixing
      - Aeration used for control of algae and stratification
    - - If man-made - expensive, can cause population displacement
    - - Sedimentation
      - Runoff from deforestation