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.
In fact, if you use chlorination as a disinfection technique and your membranes are not chlorine resistant, they will be damaged and allow contaminants to pass through that would not normally get through.
Unexpected changes
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.
Wear and tear
As mentioned above, there are several situations that can affect the quality of the permeate from a Reverse Osmosis system. For situations where the membranes wear out too quickly or clog up faster than expected, one can think of a lack of preventive maintenance or adequate monitoring. For your information, proper monitoring generally consists of three key steps:
- 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.