Page 59 - AQ242MP WW NO-CAL-2242-01-0519-water seminar

REVERSE OSMOSIS (RO)***
How it works: Considerations:
Water passes through a semi-permeable membrane as the • The expensive membrane needs to be replaced often
result of osmotic pressure. unless a mechanical filter is also installed
Usually requires several pre and post filters using other • Does not remove all organic and inorganic contaminants.
filtration technologies. For this reason most RO system include a carbon post
Efficiency: filter
• Removes nitrates, sodium, other dissolved inorganic and • Complicated installation – requires lot of space
organic compounds • Requires a storage tank which may need annual
• May also reduce the level of some pesticides, dioxins, disinfecting to prevent bacteria and slime growth
chloroform and petrochemicals • Requires frequent replacement of multiple pre-filters,
• Usually removes viruses and bacteria usually every 3-6 months
• Requires drilling a hole for separate spout
• Limited daily capacity due to slow processing – (50g/day)
• Produces 3-4 liters or more of waste water per filtered liter
***The Water Quality Association (WQA) cautions that, while RO membranes are reliable for treatment of a range of health contaminants, design
considerations such as tiny seal leaks or manufacturing imperfections may prevent a unit from offering foolproof protection against biological contaminants
for consumer drinking water systems. Therefore, WQA suggests that absolute disinfectant (a reduction of contaminants greater than 99.9 %) be
ensured with cyst-rated and certified products and post-disinfection systems.
WATER TREATMENT TECHNOLOGY

OZONE
How it works: Considerations:
Water passes through a chamber where it is injected with • Does not remove suspended solids so requires a
ozone to kill biological contaminants. secondary mechanical filter
Efficiency: • Dead microbes remain in the water unless filtered out by
• Kills viruses and bacteria but does not remove them the mechanical filter
from the water • Requires sufficient exposure time, usually a maximum
• Removes bad tastes and odors while retaining minerals flow rate of 0.5–1.5 g/min
• Requires electricity to operate, Requires drilling of hole in
countertop for installation of separate spout
• Must use with other filters for chlorine, lead, etc removal
ULTRA-VIOLET
How it works: Considerations:
Water passes by an ultra-violet light which produces • Water must be “clear” before it is exposed to the UV
UV-C radiation sterilizing the water, rendering biological light. This requires a mechanical pre-filter before the UV
contaminants inert. chamber.
Efficiency:
• Renders bacteria, viruses and cysts sterile so they can’t
reproduce, but does not remove them from the water
DISTILLATION
How it works: Considerations:
Heats water to the boiling point then collects the water vapor • Does not remove anything with boiling point higher than
as it condenses. water (typically 100º C or 212º F). This includes volatile
Efficiency: organic contaminants, certain pesticides, petroleum
• Removes chemicals with boiling point at or below water products, and volatile solvents
boiling point (typically 100º C or 212º F), including • Bacteria may colonize on the cooling coils during inactive
nitrates, sodium, hardness, dissolved solids, many periods
organic chemicals, lead and other heavy metals • Water tastes flat
• Kills viruses and bacteria but does not remove them • Removes natural minerals and dissolved oxygen

BOILING
How it works: Considerations:
Heats water to the boiling point for at least 1-3 minutes. • Concentrates contaminants such as nitrates and lead
Efficiency: with boiling point higher then water (typically 100º C or
• Kills viruses and bacteria but does not remove them 212º F)

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