Membrane fouling characteristics of PVDF membrane and nylon mesh in Anammox-MBRs

PVDF membrane was used in the early operation period (1~129d) and nylon mesh was used in the later operation period (220~360d) to analyze the nitrogen removal performance and membrane fouling characteristics of the two kind of membrane bioreactor (MBR) system. The MBR system was operated stably for 112d with the influent NH4+-N and NO2--N concentrations of 400~740mg/L and 460~790mg/L, respectively. During this period, the total nitrogen removal efficiency (TNRE) maintained at about 86%, and the nitrogen removal rate (NRR) was 0.61~1.08kg N/(m3•d). After 263days' operation, mixed liquid suspended solids (MLSS) in the reactor increased from 4918mg/L to 7230mg/L, and the corresponding mixed liquor suspended solids (MLVSS) increased from 2585mg/L to 4455mg/L, the highest special anammox activity (SAA) was 0.46g N/(d•g VSS). For both PVDF membrane or nylon mesh, the cake layer resistance dominates at the end of a membrane fouling cycle, but their fouling mechanisms was different. Compared with that of PVDF membrane system, nylon mesh maintained good anti-fouling performance, even operated under the same HRT to PVDF membrane. Considering the nitrogen removal performance and the membrane fouling cycle, nylon mesh with HRT=1.5h was preferred in this experiment. © 2020, Editorial Board of China Environmental Science. All right reserved.