Plusieurs raisons peuvent être à l’origine de la mauvaise performance d’une osmose inverse. Que ce soit relié à une mauvaise composante, l'entretien, un bris, ou des changements sporadiques dans l’eau, les osmoses inverses peuvent sous performer.
Without being exhaustive, here are some of the reasons that can affect the quality of the permeate of a reverse osmosis system.
Starting with the wrong selection of the system, membranes, pumps or any other key components of a reverse osmosis system. Take the example of membranes, some of them have chemical resistance, others have a better retention rate for seawater treatment or even a better coliform treatment capacity. There are so many types of membranes that it is very difficult to list them all. However, using the wrong membrane for your situation will significantly affect the quality of treatment offered.
D’ailleurs, si vous utilisez la chlorination comme technique de désinfection et que vos membranes ne sont pas résistantes au chlore, celles-ci s’abîmeront et laisseront passer des contaminants qui normalement ne passeraient pas.
Les changements inattendus
Water parameters may not be as expected, or fluctuations in water parameters may be experienced from time to time (e.g., seasonally). One of the factors that can greatly affect the quality of the RO treatment is the temperature of the water. The warmer the feed water, the lower the quality of the permeate.
Then there is membrane wear. When RO membranes are due for replacement, they are usually clogged with contaminants in the feed water. As the clogging increases, the pressure upstream of the membranes increases as the pressure required to allow water to pass through the membrane increases. The increased pressure allows some contaminants to pass through the membrane and end up in the permeate. This type of problem can also occur in the form of scaling in the system, which can cause more significant problems than just poor quality permeate.
L'usure
Comme préciser plus haut, plusieurs situations peuvent diminuer la qualité du perméat d’une osmose inverse. En ce qui a trait aux situations lorsque les membranes s’usent trop vite ou qu’elles se colmatent plus rapidement que prévu, on peut penser à un manque d’entretien préventif ou de surveillance adéquate. À titre informatif, une surveillance adéquate consiste généralement à trois étapes clés :
- Collecting operating data
- Evaluate the progress of the data over time
- Acting proactively to perform maintenance before performance exceeds allowable limits.
Poor pretreatment
Finally, the last of the precursors that can affect your RO system's water production is the system's pretreatment. If your pretreatment system is less efficient than expected and the TDS or TSS concentration is higher than estimated, not only will your membranes wear out faster, but the quality of treatment will be affected.
This summarizes the aspects that can affect the quality of the permeate offered by a Reverse Osmosis system. Obviously, other situations can occur, but knowing these will help you diagnose the most common situations.