RO Booster pump

[copperglobe]

My RO system runs four SS bays and two in-bay automatics. I have 1,500 gallon RO tank underground that feeds these bays RO water. When we're really busy the RO machine runs quite a bit just to keep up. However, those days aren't all year long. Many times the RO machine will turn on and run for an hour or so and then be done for the day. The booster pump (Grundfos with Baldor motor- read expensive to replace and run) runs during these on/off cycles.

Recently I've been running the RO membranes without running the booster pump. Yes, the RO "runs" longer because the flow isn't as high without the booster pump but I'm able to keep up with the demand without the wear-and-tear on the pump/motor and the energy costs. I've tested the water (ppm) on "low pressure-city pressure" through the membranes and it's the same as with the booster pump. Seems to be working. Many times I can go weeks without the booster pump turned on and easily keep up. My product flow is 1 gpm without the booster pump and 2.25 with the pump.

Thoughts? Worries? Wonders?

 

[wash4me]

My booster pump has not worked for 2 years and I haven't seen any ill effects. You could do a little rewiring and add a second float that just kicks on the booster pump if you're below half on your reserve. Are you using your reject water in the automatics?

 

[copperglobe]

Yes, using the reject through the automatics. Wish I had a larger reject tank to store that water for the automatics though. I've thought about putting a second float deeper into the tank to turn on the pump if demand is high- turns on the booster pump. Thanks for the input.

 

[wash4me]

You could also turn off the ro production when your reject tank gets full. If it wouldn't keep up you could have an "emergency" float override where it turns on and runs reject to drain. I suspect it would keep up essentially making smaller quantities of water more often.

 

[MEP001]

Your system will run more efficiently at the higher pressure. If you're recovering and reusing all the RO reject, that doesn't matter, but you can make 1:1 reject to product with the pump running but you'd need 3:1 to keep the membranes from fouling without the pump.

 

[wash4me]

Water is dramatically different in different places. To get the real truth you probably need to experiment with your own log sheets. Water treatment companies and Carwash distributors have some knowledge but they don't pay the water bill so they're likely to have you dumping reject excessively to guarantee their settings were "right." Membranes have come down in price and it doesn't take that much water savings to pay for a fouled membrane. I've been running mine for over 2 years with no booster pump and I changed from 2:1 to 1:1 at the same time.