Non-destructive approaches for assessing biofouling of household reverse osmosis membranes

Abstract

This study determined economic non-destructive methods to assess biofouling in point of use reverse osmosis (RO) membrane treatment systems. Three parallel household RO membrane units were operated under controlled feed water conditions to promote biofouling, inorganic fouling and a combination of both. Operational and biological parameters were monitored throughout the systems’ lifespan. Membrane autopsies assessed the degree and type of fouling. Statistical models determined statistically relevant parameters for fouling types that were validated with membrane autopsies. Permeate flow rates decreased differently with biofouling vs inorganic fouling. Large increases in permeate conductivity were noted in membranes suffering from biofouling and not in inorganically fouled membranes. The concentration of cell clumps from detached biofilm in the retentate increased in membranes experiencing biofouling and no increase was seen for inorganically fouled membranes. A combination of these methods could be used to conveniently assess the types of fouling experienced by RO systems.

Keywords:

• Reverse osmosis
• membranes
• biofouling
• detection

Acknowledgements

The research was funded by Unilever Safety and Environmental Assurance Centre and provided a MSc studentship to Stephen Markwardt. Special thanks are due to all the staff at the Center for Biofilm Engineering for their help and support throughout this project. Dr Al Parker is acknowledged for his assistance with statistics.

Disclosure statement

Authors Markwardt, Ronnie and Camper will gain no financial benefit from direct applications of this research.