Reverse osmosis system fault error message

An industrial reverse osmosis system malfunction with or without an error message regularly has typical causes, such as a lack of pressure and a lack of salt; no demineralized water is regularly produced for the duration of the fault.

The most common fault with a reverse osmosis system with a preceding softening system to replace the calcium and magnesium contained in the city water with sodium is regularly that the necessary salt for the softening system has been forgotten to add. It is also possible that the resin was filled in too late. After filling the salt into the salt dissolving tank of a water softener, your should allow at least 6 hours for regeneration of the water softener to be triggered. This is approximately how long it takes for a saturated salt solution to form, which is required for the ion exchanger regeneration of the strongly acidic cation exchanger in the softening system. Without the corresponding salt brine, the softening system is supposedly regenerating, but it is not regenerated. If the softening system does not supply softened water in this case, i.e. the ion exchanger is overrun, so-called hard water (i.e. still containing the hardness formers calcium and magnesium) is applied to the membranes of the reverse osmosis system and the membranes are often permanently damaged. Membrane cleaning is generally only advisable in large systems with more than 3000 l/h. To prevent this type of damage, reverse osmosis systems are often equipped with upstream hardness monitoring, e.g. in the form of a Limitron. The Limitron is a small, bulging resin bag that reduces its volume on contact with hard water and collapses, thereby triggering a reed contact. If the Limitron has collapsed, it can be regenerated overnight in a glass of brine from the softener’s salt solution tank (or from the canteen). It may then only be rinsed with softened or demineralized water and can then be reused in the industrial reverse osmosis system.

Another common fault or error message is a lack of pressure in the industrial reverse osmosis system. The main component of the reverse osmosis system is a high-pressure pump which is dependent on an inlet pressure of at least 2 bar in order to regularly increase this to 14 bar. A pre-filter, the softening system (or an antiscalant dosing device) and a fine filter are often installed in front of the high-pressure pump. A pressure loss of up to 2 bar may occur upstream of the high-pressure pump of the reverse osmosis system. A permanent minimum pressure of 4 bar from the municipal water network is therefore required. Experience has shown that this pressure can virtually never be guaranteed by the water suppliers, but is generally still present if no other consumers are connected to the municipal water supply of the specific operator. If the pre-pressure is available, the filter must first be changed to keep the back pressure at this point low. The problem will resolve itself when the pressure is restored. If there is too much decrease on this inlet water line, a pre-collector tank can also be used.

If the error message on the industrial reverse osmosis system is an increased conductivity value after the reverse osmosis system, this may be due to worn membranes, for example, or that these are not installed correctly and there is an internal leak between the permeate (the “good” water) and the concentrate (the concentrated “bad” water). If the membranes themselves are replaced, ensure that the membranes are handled with extreme care, as the outer polyethersulfone layer is only around 120 µm thick and can be easily damaged.

The formation of biology on the system is completely without error message. Biology can be formed, especially in systems that are not operated continuously but also have downtimes. The biology is regularly easily recognizable as a green film in the sight glass. UV radiation and/or high temperatures at the installation site accelerate the problem.

With regard to the concentrate of an industrial reverse osmosis system, it must be taken into account during the indirect discharge into the municipal sewerage system due to the concentration of the city water already at the planning It should be noted that for the discharge of concentrate there is an exemption limit of 10 m³/week for most parameters without a permit, but some parameters must also be complied with below this limit.

During maintenance, the typical and special problems of a reverse osmosis system can be regularly identified and eliminated before a malfunction occurs.

Do you have further questions about a reverse osmosis system and its maintenance? Please feel free to contact us.