Two years of experience with semi-technical scale membrane bioreactor (MBR)
In wastewater treatment applications the MBR technology combines biological treatment and a membrane system to provide organic and suspended solids removal. Installation of low-pressure membranes within a biological reactor system replaces sedimentation, screening and media filtration as means of separating mixed liquor suspended solids (MLSS) from treated wastewater. This study is focused on experiments with ZeeWeed10™ MBR (Zenon GmbH) installed at the outlet of the main process line at Himmerfjärden WWTP, situated in Grödinge (south of Stockholm, Sweden). Results obtained for the MBR tests showed effluent water quality improvement in comparison with the full-scale plant performance with efficiency from 12 % removal efficiency
for total nitrogen to 100 % for MLSS. Additionally, Design of Experiments methodology (Modde 7), was applied for evaluation of fouling phenomenon in order to optimize the ZeeWeed10™ operation. 35 l m–2 h–1 of flux and 7 minutes filtration with 40s of backwash were found as the optimal effective permeation conditions for the MBR process. The permeation fouling rate (PFR) was chosen as the major criterion that illustrates the membrane fouling occurrence and shows the necessity for membrane cleaning procedure. Furthermore, the comparative studies of two membrane units (ZW500 and ZWNEW) were completed with an emphasis on fouling occurrence and indicated the ZWNEW as more fouling-resistant.