Cleaning Hard Water Scale From Reverse Osmosis Membranes

Complete Water Solutions was called upon to help with Cleaning Hard Water Scale From Reverse Osmosis Membranes. The powder coating industry and the metals finishing industry have found Reverse Osmosis to be beneficial to provide clean water to clean and rinse parts. Using Reverse Osmosis metal finishing industries have reduced water consumption and overall wastewater from high conductivity discharge. Some additional benefits include:

• Spot Free or Low TDS (Total Dissolved Solids) water for the final rinse. Some times in high-quality applications Reverse Osmosis may be followed up with De-ionized (DI) Water providing ultra-high purity.
• Reduction in scale and sludge formation on/in heat exchangers. Calcium and magnesium will precipitate out on heating surfaces over 105 Degrees F.
• Low TDS (Total Dissolved Solids) allows for reduction in chemical usage and dumping due to high conductivity. This reduces waste, water, heating energy and chemicals which provides an overall savings.

Reverse Osmosis systems in Metal Finishing is an important piece of equipment, so when our customers call and say they are down, we respond. Complete Water Solutions was called out due to low flow and high conductivity. The customer was running out of RO water needed for the Parts Washing Booth and thus forcing to slow production down or shut down all together.

Complete Water Solutions came out the same day and began to investigate.  We started at softeners. The softener system is composed of a two-tank unit. Fleck 2900 has 7 cubic feet of resin in each tank.

We first start by noting which unit(s) are on line and how many gallons are remaining. Unit #1 was on line with 5,687 gallons remaining and unit #2 in regen. The next step is to test the water both from the inlet and outlet of the softener. Inlet hardness was 26 Grains Per Gallon (444.6 PPM) and the outlet was 16 Grains Per Gallon (273.6 PPM)

The next step we do is to review the programming logging the current settings. Performing this on every service call provides a history of the last program. This is good for a few reasons, one it provides a written back up should the program be lost. If the controller needs to be replaced the program can be re-installed quickly without having to search far. Lastly, some times programs get changed, mostly by accident.

Next we waited for unit #2 to finish regeneration. During the refill process we noted that the brine tank only refilled 8″ of water. 8″ of water for brine is not enough. Before we begin to dig into the refill limitation we took down total flow processed by both softener vessels (this data is not available to get during regeneration)

To begin to understand the limited refill we begin to look at both the brine valve and the refill valve.

We cleaned the brine valve, brine piston, and the injector assembly

After cleaning these items we were able to successfully refill the brine tank to the correct levels. This also improved the brine draw rates allowing good brine saturation.

After the repairs we regenerated unit #1 again (after allowing some time) After the regeneration the softener tested at 0 GPG = Soft water

This hard water is what caused the RO System to have reduction in flow, increased pressure and increased conductivity. Before cleaning the Reverse Osmosis System we took down pre-data so we have a starting point. We also take data after cleaning to confirm the success of the cleaning along with having operational data should we need to look back.

Complete Water performed the cleaning use Avista Membrane Cleaning Products. We use the Avista products as they have been certified NSF approved for off-line cleaning. Because the membranes were scaled we only performed a cleaning using Low pH Cleaner

Avista P303 Low pH Cleaner – Data Sheet

After the first cleaning flows were up to 8 GPM. Past data shows flow at 10 – 12 GPM. So we performed a 2nd cleaning.

After cleaning the second time 11.4 GPM permeate and 3.9 GPM concentrate.