Commercial RO System Guide: Design, Sizing, Operation

The CK-RO series covers 0.5–50 m³/h of permeate in single-stage configuration, with motor power rising from 1.5 kW to 70 kW. Recovery improves as the array becomes larger: a single-element 0.5 m³/h unit recovers about 50%, while a 50 m³/h array reaches 70–75%. Select by permeate flow at the design temperature, not by a round number on a brochure.

Model numbers describe permeate at the reference condition, not at every site. A CK-RO-5000L rated at 5 m³/h at 25 °C produces less at 15 °C and more at 30 °C, and the recovery printed in the table assumes a feed inside the stated limits. Ask for the design point, not only the model.

A single-stage system passes the water through the membrane once. It is the standard choice for drinking water, food service and general process water where 95–98% rejection is enough. A two-stage system passes the first-stage concentrate through a second array, raising overall recovery to 65–75% and reducing wastewater. RO+EDI adds electrodeionisation after the RO to reach ultrapure water without chemical regeneration.

A membrane is a precision element, not a filter. It needs water that has already been clarified, dechlorinated and stabilised. The limits below come from membrane warranty conditions and from the experience of systems that reach their expected element life. A design that ignores one of them usually fails on that one, not on the others.

Across the CK-RO range, recovery is 50–75%. At 50%, a 10 m³/h feed yields 5 m³/h of permeate and 5 m³/h of concentrate; at 75%, it yields 7.5 and 2.5. Permeate conductivity is at or below 10 µS/cm when the feed is at or below 300 µS/cm at 25 °C, corresponding to 95–99% salt rejection. Nitrate rejection is similar; boron rejection is lower, typically 40–80% at neutral pH, which matters for irrigation and some process uses.

Temperature moves both numbers. Permeate flow changes by roughly 3% per °C, so a system rated at 25 °C produces less in winter and more in summer at the same pressure. Recovery is limited by the solubility of the salts left in the concentrate, which is why the same skid is rated differently on a soft feed and a hard one.

Blending is a legitimate way to hit a mineral target: bypass 10–20% of the feed around the RO and the permeate picks up a controlled amount of hardness and alkalinity, which reduces corrosion in the distribution line. The blend ratio must be fixed by a valve and verified with a conductivity meter, not adjusted by feel.

Size on daily volume and the refill window, not on the instantaneous peak alone. A site that uses 20 m³ per day and can refill a 10 m³ tank over 10 hours needs 2 m³/h of permeate, not 20. Add 10–20% margin for fouling and cold water, and check that the RO runs at least 4–6 hours per day; short cycling wastes water through repeated flushing and wears the pump.

For process water, start from the equipment requirement: boiler make-up, humidification, ice machines, beverage dilution and rinsing each specify a flow and a quality. Where demand is spiky, a storage tank with a level switch and a booster set decouples the RO from the process, and the RO can run at its efficient point instead of following every draw.

Membranes typically last two to three years when pretreatment is right and cleaning is done on schedule. The cost drivers are replacement elements, pump energy, antiscalant or softening salt, cartridge filters and labour. Fouling appears first as rising differential pressure or falling permeate flow at constant pressure; scaling appears as falling rejection and rising conductivity.

Clean in place when the normalised permeate flow falls 10–15% or the differential pressure rises 10–15% from the commissioning baseline. Clean too often and you shorten element life; clean too late and the foulant becomes irreversible. Log feed pressure, permeate flow, concentrate flow and conductivity weekly so the trend is visible before a shutdown.

Yes. Systems from 4 to 25 m³/h can be built into a 20- or 40-foot container with pretreatment, RO, disinfection, controls and lighting, tested as a unit before shipment. The CK-RO containerized range covers 4–25 m³/h with 7–30 kW motors and 55–75% recovery. Containerized systems suit remote sites, camps and projects where civil works are slow or the plant may later be relocated; skid-mounted systems are the usual choice when a plant room already exists.

Every unit is pressure-tested and run before shipment, and comes with an installation manual, a wiring diagram, commissioning support and a 12–18 month warranty. Larger projects can include an engineer on site for commissioning and operator training on cleaning and consumable replacement.