Hollow fiber systems are commonly operated in a dead-end mode. All the
feedwater is directed across the membrane, leaving the filtered particles
behind on the membrane. Particulates are removed from the membrane
surface by means of a physical backwash that forces the particulates out of
the membrane pores and away from the surface of the membranes. The
backwash may occur every 20 minutes to every few hours, depending on the
system and the feedwater source. With the system operating in a dead-end
mode, operating pressures are generally low (commonly around 10-25 psi),
and there is no recirculation stream that would require extra pumping power.