Spiral wound membrane elements are a costly part of a dairy cheese and whey operation, if not maintained and cared for properly, a membrane investment could be a gateway for operational issues. Membrane applications in these facilities may include reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF) or a combination of these to achieve the desired end product. Complex feed streams can include whole milk, skim milk, sweet whey, acid whey, UF permeate, UF concentrate, and others. The systems are typically cleaned daily using a clean-in-place (CIP) procedure that is specific to the application and soils encountered. At times, these membrane systems may experience a decline in performance, such as high production pressures, reduced production flux rates, reduced clean water flux rates, low protein and/or salt rejection, or shortened membrane life. These are often complex issues to resolve in order to get the most out of your membrane systems.
Membrane Root Cause Analysis
If your membranes are not performing as expected, you should consider a basic 3-step root cause analysis:
- What are the issues?
- How did these issues occur?
- Initiate actions to resolve and eliminate.
To identify issues and determine how they occurred, a thorough assessment of the overall membrane process should include a review of the upstream unit operations as well as the membrane system itself. Consider upstream systems like the cheese milk membrane system, cheese-make process and the whey processes including storage silos, separator, clarifier, pasteurizer, fines saver, etc.
As you assess these systems, ask questions like:
- Are these units operating properly?
- Is the separator bypassed on occasion causing higher fat levels to reach the membrane system?
- Are there any changes to the feed stream that could impact membrane performance (pH, storage time, addition of defoamer, process aid, change in cheese making process)?
