The Importance of Choosing the Right Membrane System Arrangement

Caloris recently had an inquiry from a client that highlighted how important choosing the right membrane system arrangement was and to the success of the project. The client inquired about a Reverse Osmosis Polisher for two different sites.

At one site, the water stream was fairly clean, on the other site, in a potential failure mode, the water stream could contain solids that would foul the system. Although the client would have preferred two identical systems, in the end, the membrane arrangement selection drove the choices of our application engineers towards staged membranes for the application with a potential for solids in the water stream, while other application could use a more cost-effective array system.

Membrane System Arrangements

There are two types of membrane arrangements to consider:

  1. Staged Membrane Systems
  2. Array Membrane Systems

A staged membrane system assures good crossflow velocity, which is essential for proper cleaning and long production runs. This type of membrane system should always be used if the quality of your condensate is suspect or if the feed includes RO permeate, which is subject to membrane leaks that could quickly foul the RO polisher.

Staged membrane systems are usually the default design choice for new membrane installations, but they are not the only option to consider.

Array membranes are often not designed correctly, which can lead to fouling issues. There is significant cost savings possible with an array membrane system, however, if the flow dynamics are considered carefully before installation. While not easily standardized, an array membrane system does not require stage piping or a high-pressure recirculation pump. Those savings add up quickly (up to 15-25% compared to a stage system).

Clean condensate streams, where there are no concerns with product carryover issues, are the best case for using an array membrane system. Even then the flow dynamics can be tricky – without the proper crossflows, the RO will not be cleaned properly and quality issues will result.

The good news is that at Caloris, we have the know-how to determine if an array membrane system will work best for your facility and we can properly design the system to work efficiently and save you money.

If you are interested in learning more about the various types of membrane arrangements and what would work best in your plant, please send us an email at or give us a call at 410-822-6900.


About Caloris

Caloris transforms process systems design for the better with unexpected, future-focused solutions that solve real operational problems. We engineer efficient, dependable and productive solutions that also improve environmental sustainability where practical. Designed with the end user in mind to drive plant productivity. Caloris offers evaporation, membrane filtration and spray drying process systems for food and dairy industries, as well as for water reuse and wastewater treatment applications. Both Caloris’ custom and pre-engineered packaged systems are designed to meet our customers’ specific concentration/purification needs utilizing the most cost effective and energy efficient technologies available. Whether concentrating dairy, food or juice products at a high-volume production facility, or processing industrial wastewaters to reduce transportation and treatment costs and recover re-usable water, Caloris provides a range of options and technologies.