Natural Sea Water Sources and PreTreatment

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Natural Sea Water Sources and Pre-Treatment

• Tony McEwan, Michael Farquhar and Jason Crichton

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Two Options for Raw Water

• Artificial sea water.
• Natural sea water direct from the sea.

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Survey Results Four Raw Water Systems Used

• Artificial sea water.
• Ship (Barge) raw sea water.
• Pump raw water from a well.
• Pump raw water directly from the sea.

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Barges
Barge information summary. (N5)    
 
1 1.20
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Wells
Well information summary. (N5)
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Direct Pumping
Direct pumping information summary. (N10)
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Advantages Disadvantages

• Lots available
• Cheaper.
• Not labor intensive.
• Complete chemical make-up.
• Good algae growth.
• Good for invertebrate tanks.

• Little control over pollution, nutrients,
  parasites.
• No control over salinity changes.
• No control turbidity causes.
• Bio-fouling.
• Some systems need to be (timed) tides.

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Flocculation Theory

• Increasing particle size by aggregation.
• Have to disrupt the colloid.
• Add chemical that overcomes repulsive forces
  between particles.
• FeCl3 is an inorganic electrolyte that disrupts
  charges.
• Fe3 ions attract small particles thus becoming
  larger that can either settle out or be trapped
  in a filter.
• pH dependant flocculation optimized pHgt5
• Good mixing.
• Sufficient time.

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Flocculation systems in Kuwait
Raw Water System
Recirculation System
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Experiment Results
Results of Ferric Chloride flocculation
experiment.
particles removed (filtrate wt raw water
filtrate wt after sand filter)/(filtrate wt raw
water)100
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Photographs of 1µm filter paper from FeCl3
flocculation experiment in Cape Town and Kuwait
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Protein Skimmer on Systems with and without
Ferric Flocculation System
With
Without
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Ideal System

• Pumping from a well system.
• Pre-filtered, safe from non dissolved pollution,
  not weather dependant, temperature can be more
  constant.
• Then have a sand filter and a method to sterilize
  water (Ozone or UV).
• Also have a line directly to sea for invertebrate
  tanks.