The Use of Ultrafiltration Membrane and Pretreatment Processes in Wastewater Reclamation

The objective of the present study is to assess the feasibility of reusing ultrafiltration (UF) hollow-fiber membrane in the treatment of effluent of secondary domestic, industrial and pasturage wastewater. Simultaneously, kinds of pretreatment processes combined with UF were used to confer the removal efficiencies in term of turbidity, suspended solid, conductivity, inorganic matters and so on. Finally, collocate of backwash process with UF process was used as pretreatment to find the optimum operating conditions.
For the secondary domestic wastewater, the UF system was designed to operate at constant flux and the backwashing rate of 20 LMH and 0.1 m/s respectively. Wastewater was filtered through UF for 2 hours, and then backwashed for 1 min. From the results it is clear that the optimum operating conditions could be achieved when fiber filter was combined with UF process and backwash process.
For the secondary industrial wastewater, the UF system was designed to operate at a constant flux of 20 LMH with a backwashing rate of 0.1 m/s. Wastewater was filtered through UF for 90 min and followed by 1 min of backwash without any pretreatment. However, the results of transmembrane pressure (TMP) showed that this combination of processes could not decrease the membrane fouling effectively.
Since the concentration of suspended solid in the secondary pasturage wastewater was 50 mg/L which was over the standard value, granular activated carbon (GAC) should be used for pretreatment process. In this study, the UF system was designed to operate at a constant flux of 5 LMH and with backwashing rate of 0.1 m/s. Wastewater was filtered through UF for 15 min and followed by 1 min of backwash.
The results showed that the water quality of permeate for domestic wastewater treated by UF process was applicable to medium quality reuse. The water quality of industrial wastewater treated by UF process was not applicable to cooling water reuse. However, because the high concentration of turbidity and conductivity of wastewater from effluents of pasturage wastewater treatment, it is not suitable to use as the source of feedwater for wastewater reclamation.