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8. Glossary of Terms
The following list includes terms and abbreviations used in this document.
Reverse Osmosis - A water purifi cation technology that uses a semi-permeable membrane to remove dissolved
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substances from the water. In reverse osmosis, an applied pressure is used to overcome osmotic pressure, forcing
water molecules to pass through the membrane while all dissolved solids remain in the feed water side of the
membrane.
Transfer Pump (Re-Press Pump) - A pump that delivers RO water to a wash, which is run by a command from the
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wash tunnel
Production Pump - VFD pump that matches the pump speed with municipal water pressure, to ensure the system
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delivers maximum RO water to the tunnel.
Thin Film Composite Membrane (TFC) - Thin Film Composite (TFC) membranes are a special type of RO membrane
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which offers high effi ciency, long life and resistance to most adverse water conditions.
The membrane material is very sensitive to free chlorine. If the feed water is chlorinated a chlorine pre-fi lter
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must be used to protect the membrane.
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Free chlorine must be controlled to 0.00 PPM level as even 0.1 PPM will damage membranes. The DOW/
Dupont membranes have a 1,000 hour life at 0.1 PPM free chlorine level in the feed water. Damage
accumulates proportional to the free chlorine level.
A failure in the carbon fi lter (chlorine removal) will quickly lead to a membrane failure which will require
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membrane replacement. Verifying that the carbon fi lter is operational is a critical maintenance check to avoid
damage or failure of the membranes.
Municipal Feed Water - The incoming water supply which is directed into the membrane for processing.
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This water must be pre-conditioned to meet the membrane manufacturer's water requirements to prevent
damage to the membrane.
Pre-treatments may include water softening, chlorine removal, sediment fi lters, and other chemical treatments
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based on the water analysis of the wash site.
Product Water (RO Product) - The purifi ed water that has been separated from the feed water stream by the
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reverse osmosis membranes.
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Recovery – The amount of RO Product water produced as a percent of the total amount of feed water.
Example: If the system feed fl ow is 20 GPM and the RO Product produced is 10 GPM, then the recovery would
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be 50%.
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This RO system has been designed for a maximum of 65% recovery. If the reject water is not being recycled
for other wash purposes, the recovery can be increased by replacing the 10 GPM fl ow orifi ce with a 6 GPM
orifi ce.
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Because the Reject water (or concentrate) is normally re-used in other wash operations the recovery is set to
50% to 65%.
Reject Water (RO Reject or Concentrate) – The portion of the feed water that does not pass through the RO
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membrane and is delivered to the Reject Tank.
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This water has a higher level of impurities than the municipal feed water and is captured in storage tank for
other uses in the wash system. This fl ow rate is set by a reject line orifi ce and does not require adjustment.
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Percent Rejection – The percentage of TDS removed from the feed water.
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Membranes typically reject greater than 99.5 % of the dissolved solids which are present in the feed water.
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Example: If the incoming feed water is 200 TDS, the RO water will measure approximately 1 ppm TDS.
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Glossary of Terms
Glossary of Terms
This change would reduce the maximum feed water rate to 16 GPM and increases recovery to 62.5 %.
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