Abstract:
Reverse osmosis (RO) is awidespreadwater treatment process utilised in water reuse applications.However, the
improper discharge of RO concentrate (ROC) containing organic micropollutants such as pharmaceuticals into
the environment may cause potential health risks to non-target species and particularly those in aquatic environments.
A study was conducted using a submergedmembrane-filtration/granular activated carbon (GAC) adsorption
hybrid system to remove organicmicropollutants from a water treatment plant ROC by initially adding 10 g
GAC /L of membrane reactor volume with 10% daily GAC replacement. The percentage of dissolved organic carbon
removal varied from 60% to 80% over an operation lasting 10 days. Removal of organic micropollutants was
almost complete for virtually all compounds. Of the 19 micropollutants tested, only two remained (the less hydrophobic
DEET 27 ng/L and the hydrophilic sulfamethoxazole 35 ng/L) below 80% removal on day 1, while
five of the most hydrophobic micropollutants were detectable in very small concentrations (b5–10 ng/L) with
N89%–N99% being removed. High percentages of micropollutants were removed probably because of their
high hydrophobicity or they had positive or neutral charges and therefore they were electrostatically adsorbed
to the negatively charged GAC.
