Membrane CIP Considerations
CIP is your largest maintenance item when it comes to your membranes. To minimize membrane production fouling, take the following steps:
- Maintain product quality
- Maintain proper stage pressure drops (membrane crossflow velocities)
- Do not run too high of a baseline pressure
- Do not over concentrate
- Do not over feed — keep feed rate at membrane system design parameters
- Running outside of design parameters may cause irreversible fouling that cannot be removed by a standard cleaning program.
Normal production length for a dairy system is 20 hours, but this may need to be shortened if membrane productivity decline is greater than 15% or the feed pump reaches maximum capacity. Normal CIP runs are about 4 hours.
Cold processing is recommended for longer runs and maintaining product quality. Hot processing may require more frequent cleaning and/or membrane replacement. Bacteria can severely foul a membrane in 8 hours.
Membrane CIP Monitoring
CIP programs are custom-designed for each application. Monitor the pH of each wash cycle immediately after chemicals are added, 10 minutes after and throughout the whole cycle. Add more chemicals if necessary.
Monitor the temperature of each wash cycle.
Monitor and maintain “CIP Flush” cycle — take samples. The pH should be neutral and the sample clear to the drain.
Water Quality for Membrane CIP
Reclaimed water has inherent microbial risk (total organic carbon or TOC). It may require anti-oxidants and/or frequent CIP of storage tanks (every 1-2 days).
City water has chlorine, which must be removed first because it can damage RO membranes.
Clean Water Flux Test
This test determines the effectiveness of your CIP. The test should be done at the conclusion of every CIP cycle. Record permeation rate of the system at base temperature and pressure. Normalize temperatures and pressures outside of the baseline. Additional washes may be needed if not within 5% of the previous test. When you graph these tests, there should be a stable line.
A Better Process
Caloris is here to help if you are in need of assistance with your membrane systems. Contact us today to discuss your filtration needs. Call 410-822-6900 or send email to firstname.lastname@example.org to be connected to a membrane system specialist.
Stay tuned for the next article in our membrane system series — When to Replace Your Membranes.