A new high-pressure optical membrane module for direct observation of seawater RO membrane fouling and cleaning

A new high-pressure optical membrane module was developed to enable direct visual observation of bacterial deposition onto reverse osmosis (RO) membranes under practical seawater desalination operating conditions. The new optical membrane module withstands pressures up to 8.3 MPa (1200 psi) while allowing high transmission of UV and visible light. Computational fluid dynamic analyses of the optical module suggest practically relevant cross-flow hydrodynamic conditions exist through the viewing area of the optical window. Bacterial deposition rates and patterns were investigated for a live marine bacterium on two commercial seawater RO membranes operated at different permeate fluxes both with and without a commercial feed spacer present in the flow channel. These proof-of-concept results suggest the new device may prove valuable for laboratory studies designed to elucidate the effects of seawater RO membrane system parameters (e.g., permeate flux, cross-flow, membrane properties, spacer designs, etc.) on bacterial adhesion and removal. Future extensions of this innovation may include studies of novel seawater RO membrane materials, optimization of membrane cleaning, or using the device as an ex situ fouling detector at a full-scale seawater desalination plant.