What are the shutdown concerns for Reverse Osmosis systems?
Let us have a look on the factors to consider for RO Shutdown
1) Flush brine with product water or feed water of adequate quality at low pressure to entirely displace brine from pressure vessels upon RO system shutdown.
2) Ensure that all membrane elements are maintained moist, disinfected, and/or frost-protected during shut-downs.
3) Ensure that the preservation water temperature and pH criteria are followed during shut-downs.
4) Make sure that following shut-downs, the product back pressure does not exceed 0.07 MPa.
(Product backpressure is calculated by subtracting product pressure from feed or brine pressure).
5) Special consideration must be made if RO trains are connected in parallel to a common permeate header and have time-shifted operating patterns.
6) Chlorine tolerance is restricted in composite polyamide RO membrane components. Under no circumstances should they be exposed to chlorinated water. Any such exposure might cause irreversible damage to the membrane, which is usually indicated by an increase in salt flow.
7) As a result, extreme caution must be exercised to avoid chlorine exposure as follows:
-Upstream of the membrane, disinfection of pipe or pre-treatment equipment;
-Cleaning or storage solutions preparation;
-Care must be taken to guarantee that the feedwater to the RO membrane elements contains no chlorine;
-If there is any residual chlorine in the RO feed, it must be eliminated using a sodium bisulfite (SBS) solution with enough contact time to achieve full de-chlorination.
Shut-down for a limited time
Short-term shut-down refers to when a RO plant must be shut down for more than one day but less than four days when the RO elements are still in-situ.
Prepare each RO train in the following manner:
1) Fill the RO section with feed water while releasing any gas that has built up in the system.
2) Close the valves when the pressure tubes have been filled.
3) Every 12 hours, repeat steps 1 and 2 above.
Shut-down for a Long Period of Time
Long-term shut-down refers to when a RO plant must be shut down for more than four days while the RO elements are still in situ.
Prepare each RO train in the following manner:
1) Contamination and fouling deposits on the membrane are removed from the system.
2) Circulate 500–1000 mg/l SBS solution as a preservation solution via the RO section (approx. 1 hour).
3) Once the RO section is entirely filled with this solution, seal all essential valves in order to keep the solution in the RO section.
4) With a new answer, repeat Steps 2) and 3)
- Every thirty (30) days if the temperature is below 80 degrees Fahrenheit (27 degrees Celsius).
- Every fifteen (15) days if the temperature is over 80 degrees Fahrenheit (27 degrees Celsius).
5) The preserved RO system's pH must be monitored on a regular basis to ensure that it does not go below pH 3.
6) The highest temperature during the shut-down time should not exceed 40°C, and the minimum temperature should be more than 0°C.
Technical assistance and guidance!
Netsol’s RO Plants offer both safe and environmentally friendly performance at a low cost. These machines may generate pure water outputs, depending on feed water quality and flow rates. Our technical team can design and build the precise equipment that meets or exceeds client quality standards.
Call us if you want the best water or wastewater treatment system for your home or business. Our services include Commercial RO Plants, Industrial RO Plants, STPs, ETPs, as well as a variety of useful after-sales services. Our professionals will check the customer's location first, then explain the available options and thus, allow you to select what is best for your property. You can always find useful information by liking and following us on YouTube and LinkedIn.
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