Download of ROPRO 8.06 was on the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The program belongs to Education Tools. We recommend checking the downloaded files with any free antivirus. The actual developer of the free software is KOCH Membrane Systems, Inc.
From the developer:
The ROPRO software program is a tool for estimating the performance of spiral wound RO membrane elements manufactured by Koch Membrane Systems, Inc. The program predicts the effect of various system process design choices including: single pass, single pass with recycle, two pass with or without interstage pumping, and two stage concentrator.
You may want to check out more software, such as KMS ROPRO, which might be similar to ROPRO.