Although membrane bioreactors (MBRs) have been developed as a key treatment technology for wastewater reuse and recycling during the past 20 years, application of this technology is still limited due to high membrane costs as well as high energy consumption. The aim of this study was to develop a low-cost MBR by using used non-woven modularized membranes. A bench-scale MBR system was developed with the membrane module. It was found that a dual-media structured module can achieve excellent permeate quality (turbidity <1.5 NTU and SS <3 mg/L) with a permeate flux of 1.5 m³/m²day, under a daily backwash condition. The maximal operation MLSS level was identified as not greater than 5,000 mg/L under the above operation conditions. When the F/M ratio was 0.18 g COD/g MLSS/day and the sludge age was 45 days, the system can remove 90 % COD and 88%...[ Read more ]

Although membrane bioreactors (MBRs) have been developed as a key treatment technology for wastewater reuse and recycling during the past 20 years, application of this technology is still limited due to high membrane costs as well as high energy consumption. The aim of this study was to develop a low-cost MBR by using used non-woven modularized membranes. A bench-scale MBR system was developed with the membrane module. It was found that a dual-media structured module can achieve excellent permeate quality (turbidity <1.5 NTU and SS <3 mg/L) with a permeate flux of 1.5 m³/m²day, under a daily backwash condition. The maximal operation MLSS level was identified as not greater than 5,000 mg/L under the above operation conditions. When the F/M ratio was 0.18 g COD/g MLSS/day and the sludge age was 45 days, the system can remove 90 % COD and 88% ammonia. The permeate of the non-woven MBR technology developed in this study satisfies the wastewater reuse requirement for urban uses.

In addition to the MBR application, the developed non-woven membrane module is also applicable in secondary effluent polishing. This study showed that the effluent SS and turbidity of an activated sludge process can be reduced from 25 to 2.3 mg/L and 10 to 2.1 NTU, respectively, when the MLSS in the aeration tank was 3,000 mg/L. In this application, no aeration for membrane fouling prevention was provided and the backwash frequency was reduced from daily to a monthly basis. These enabled effluent reuse with the developed low-cost membrane to become much more cost-effective compared to conventional effluent polishing technologies.

Keywords

Low-cost membrane, non-woven memebrane; memebrane bioreactor; effluent polishing; wastewater and effluent reuse.