| This research details the effects of ozone pretreatment on flux for a reverse osmosis system. Ozone at concentrations of 0.15 mg/L, 0.30 mg/L, and 1.5 mg/L were compared against the baseline dose without ozone. The effects of solid and organic removals were studied and showed that using ozone at low concentrations reduced turbidity and COD for a simulated surface water. These initial tests showed that the best reduction was at 0.30 mg/L of ozone. Also total suspended solids in the size range of 2.00-4.99 microns were reduced by 16.5% at this dose.; Next, a series of bench scale tests were run for 62.5 hours using a standard reverse osmosis system with the three pre-ozonation doses and a no ozone baseline. Temporal models were developed using the flux data from these tests to determine the effects of operating hours and ozone dosage. It was found that the laboratory data was not linear and followed power law models.{09}Statistical analysis was used to determine the significance of each ozone dose on the four developed models. The change in flux over the 62.5 operating hours with an ozone dosage of 0.30 mg/L showed the lowest flux change. Also, using an ozone dosage of 0.30 mg/L results in a better overall efficiency for the RO system with longer operating times to reach 90% efficiency.; Lastly, the models were tested using Hermia's filtration models and resistance versus time data to determine the type of membrane fouling that existed. It was concluded that the major fouling was pore blockage.; This work demonstrated that ozone pretreatment is effective prior to use with reverse osmosis since it shows a better solid and organic removal rate as well as decreased flux and resistance changes over time. |
