From RO permeate to an impeccable and biologically stable drinking water


One of the challenges in achieving impeccable drinking water is bacterial regrowth. Reverse osmosis (RO) which is a known technology and mainly used for seawater desalination since it can remove dissolve solids from high salinity water. Although RO can remove ammonium up to concentration of 0.05-0.5 mg-NH₄+/L, we aimed to remove  ammonium in RO permeate to be less than 0.02 mg/L in order to lower the possibility of bacterial regrowth and the conversion to nitrite in the distribution. Ion exchange was chosen as an option to further removal of ammonium. AOC concentration is used as indicator for bacterial regrowth. Water can be considered as biologically stable if the AOC concentration is less than 10 µg L-1 acetate-C equivalents, depending on the residual chlorine in the system and other limiting nutrients. In this research, the biological stability of water produced by the RO pilot will be assessed by growth potential test. The growth potential test is basically performed by measuring the increase of bacteria cells (microbial biomass) in the water under a specific condition after certain duration.


– To investigate the efficiency of ion exchange resin in removing low concentration of ammonium.

– To investigate the growth potential of water treated by RO, after remineralization step.

Donor: Oasen
Duration: 8 months (2013)
IHE staff: Jan Schippers, Sergio Salinas, Maria Kennedy
Research fellow: Yuli Ekowati