Investigation of filtration performance and phosphorus removal in an electric field controlled dynamic membrane bioreactor

Abstract

Dynamic membrane bioreactor (DMBR) offers several advantages over traditional membrane bioreactor, including cheaper costs, less resistance, and easier cleaning. Membrane fouling and poor phosphate removal performance restrict the application of DMBR. To address it, this study creatively combined electric field with DMBR and investigated the mechanisms. The results showed that applying an electric field significantly decreased membrane fouling rate in electric dynamic membrane bioreactor with Ti anode (E-DMBR-Ti). The median membrane fouling rate of E-DMBR-Ti was 2.28 kPa/h, which was 48.99 % lower than that of control group (4.47 kPa/h) during stable operation period. However, hydrogen bubbles formed on the cathode blocked membrane during membrane formation period. The enrichment of electroactive and denitrifying microorganisms (e.g., Lactococcus, Hydrogenophaga) in E-DMBR-Ti, which consumed electrons that would flow to the hydrogen evolution reaction, alleviated the negative impact. To address the issue of poor phosphorus removal efficiency of DMBR, based on the previous research, we replaced the titanium mesh of the anode with aluminum plates, and innovatively using the electrocoagulation technology which named E-DMBR-Al. At 2.4 A/m2 current density, E-DMBR-Al showed the highest phosphorus removal efficiency, with a median of 94.69 %, which was 37.69 % higher than that of DMBR. Furthermore, the enrichment of electroactive microorganisms (e.g., Lactococcus) and polyphosphate-accumulating organisms (e.g., unclassified_f__Comamonadaceae) on membrane contributed to the excellent phosphorus removal performance of E-DMBR-Al.