Part 1: A process approach to control and prevent biofouling in pressure-driven polyamide membrane systems

Majority of the fouling in membrane systems like polyamide membrane systems are accounted to fouling by microorganisms and associated soluble microbial products (SMP). Typically, bioformation involves the initial transport and deposition of the bacteria, adhesion or release from the surface, growth and replication, cell release and translocation and the formation of biofilm. The relatively high level of nutrients in the extracellular polymeric substance (EPS) explains the survival of bacteria in permeate water of industrial and municipal membranes systems. Once the initial deposition occurs an the EPS is produced, the multiple step process of bacteria growth and colonization throughout the water treatment system (WTS) becomes operationally difficult to control. Polyamide membrane system's operational performance and reliability relies pretreatment processes, membrane system design and characteristics. Pretreatment process is a critical component because it can remove microbiological activity from the feedwater, remove the nutrient source from the feedwater or a combination of both. Techniques commonly used to address the microbial activity and reduction of assimilable organic carbon include utilization of chemical residuals, ultraviolet disinfection, production of hydroxide radicals through generation of ozone, advanced oxidation processes and organic digestion followed by mechanical filtration.