Membrane performance highly depends on the experimental conditions, such as solution pH, salt concentration, applied hydraulic pressure, and concentration polarization. These conditions often vary in many reports and can strongly influence membrane ionization and swelling behavior, membrane compaction, and transport modeling [1-7] . In addition, comparing data obtained from large module-scale systems to small bench-scale systems can be tenuous. Consequently, comparison of data from the OMD should beconducted with careful consideration of the data source.
We strongly encourage the membrane community to follow industry standard testing conditions for RO membranes (see Table 1) to avoid disparities in reporting that originate from the operational conditions. The standardization of membrane performance characterization will strongly facilitate comparison of the data and will allow more accurate derivation of membrane synthesis-structure-performance relationships and other meta-analyses.
|Testing condition||Seawater RO||Brackish water RO|
|Feed salinity (ppm NaCl)||32 000||2,000|
|Feed temperature (°C)||25||25|
|Hydraulic pressure (bar)||55.15||15.5|
Note: Standard testing conditions are based on industry-reported conditions found in product datasheets [8-10].