Development of Fouling-Control Strategy for Ceramic Membrane Bioreactor Applied in Partial Nitrification Process

A lab-scale ceramic membrane bioreactor (MBR) with active membrane-fouling control system was developed for the partial nitrification (PN) process. The in situ membrane cleaning method was applied to remove the contaminants on the surface of the membrane with no interruption of the wastewater treatment. The results showed that the device increased critical flux and reduced gel layer resistance (R-g) and internal resistance (R-i) of the flat-sheet ceramic membrane by inhibiting the formation of the cake layer. In long-term experiments, nitrite oxidizing bacteria (NOB) was successfully suppressed, and nitrite accumulation rate (NAR) was achieved at a high level, up to 90.09%; the effluent NO2--N/NH4+-N was maintained in balance dynamically with an average ratio of similar to 1.30, which would be beneficial to the proliferation of Anammox bacteria and the following autotrophic nitrogen removal (ANR) process. Moreover, with the assistance of in situ cleaning, energy input from aeration was significantly reduced, while over aeration was avoided for more stable PN performance.

Automated summary

A lab-scale ceramic membrane bioreactor (MBR) with an active membrane-fouling control system was developed for the partial nitrification (PN) process. The in situ membrane cleaning method was used for uninterrupted removal of contaminants on the membrane surface. The device increased critical flux, reduced gel layer resistance (R-g), and internal resistance (R-i) of the flat-sheet ceramic membrane by inhibiting cake layer formation. In long-term experiments, nitrite oxidizing bacteria (NOB) were successfully suppressed, achieving high nitrite accumulation rate (NAR) of up to 90.09%. The maintained balance between effluent NO2--N/NH4+-N ratios would promote the proliferation of Anammox bacteria and the autotrophic nitrogen removal (ANR) process. Moreover, in situ cleaning significantly reduced energy input from aeration and ensured stable PN performance by avoiding over aeration.