(Seah 2003, Daugherty 2005) More recently, there has been a move to replace
the conventional activated sludge and membrane filtration processes by a membrane bioreactor. (Tao
2008) In either case, as long as there is effective filtration of colloidal material from the in-coming
feedwater, and there is chlorine dosing to maintain a few parts per million (ppm) of chloramines, the
RO membranes can operate very stably. (Bartels 2003). Beyond this basic and successful approach,
there have been a number of new process improvements.