The optimal MBR configuration: Hybrid versus stand-alone — Comparison between three full-scale MBRs treating municipal wastewater Original Research Article

Construction or modernization of a wastewater treatment plant (WWTP) with membrane bioreactor (MBR) technology requires the selection of an optimal configuration and design. The objective of this paper is to evaluate a stand-alone MBR in comparison to a hybrid MBR, i.e., a combination of a conventional activated sludge (CAS) process and an MBR. This paper evaluates two different hybrid MBR configurations, i.e., in series and in parallel, and a stand-alone MBR. The impact of these MBR configurations on operation, performance, energy consumption and economy is evaluated. A hybrid MBR operated in series provides certain operational flexibility, ensures more stable conditions for the activated sludge leading to a more stable MBR operation at energy and cost efficient conditions. Nevertheless, determination of the optimal plant configuration depends on the particular local situation such as the presence and condition of old infrastructure, availability of equalization tanks and space requirement.