Direct Osmosis High Salinity In Place Membrane Cleaning

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Direct Osmosis-High Salinity In place membrane cleaning.

eNPure utilizes exclusive patented (US Patent 7658852*) continuous cleaning technology that can be easily retrofitted and installed on existing Reverse Osmosis systems. This cleaning involves daily automatic membrane backwash and bacteria sterilization with periodic injections of high salinity table salt solutions into the feed stream. This process removes bio-films and other foulants, as well as reducing scaling of the Reverse Osmosis membrane, all without stopping the high pressure pumps.

How it Works:

In normal RO operations, feed water pump hydrostatic pressure is higher than feed water osmotic pressure, forcing permeate out through the membrane. Feed water bacteria, clay, silt, and other particles are deposited and held on the membrane by RO flow causing increased feed pressure, higher pressure drops, and more chemical cleanings. With Direct Osmosis-High Salinity (DO-HS) cleaning, fouling is backwashed from the membranes surface within a few seconds every day without stopping the feed pump.

In the clean-in-place tank, a 25% saline solution is added with an osmotic pressure of 2800 psi. For 10 – 15 seconds, this saline solution is injected into the feed water stream. The osmotic pressure of the saline solution is much higher than the hydrostatic pressure of the feed water pump, reversing the osmotic flow and back washing each membrane in succession like a vacuum cleaner.

As the saline slug moves through the pressure vessel, the process changes from reverse osmosis to direct osmosis in the area of the slug then reverts back to RO once it has passed. During Direct Osmosis, the permeate moves back through the membrane and into the saline water slug and local permeate up-flow provides intensive membrane backwash. The fouling is lifted from the membrane surface and is swiped out into the drain with reject water.

The fouling layer is affected by two cleaning forces simultaneously – up-flow from direct osmosis and cross flow shearing velocity. The slug not only draws water from the membrane, it also dewaters the micro-organisms exposed to the saline water slug. The micro-organisms affected include bacteria, algae, and fungi. Lastly, the saline slug has very high ionic strength and is able to dissolve microcrystals growing on the membranes, decreasing scaling.

View the video below about this technology.

REV: May-30-2018