Can osmotic membrane bioreactor be a realistic solution for water reuse?

Abstract

A growing emphasis on water recycling resulted in intense research activity, aiming to develop and validate reliable and high-quality water treatment processes at lowest cost. In parallel, significant advances in the field of osmotically driven processes have been obtained in the past decade. While the combination of membrane bioreactor (MBR) and reverse osmosis (RO) has become the preferred choice for water reuse, the osmotic membrane bioreactor (OMBR) has begun to be considered as a promising alternative. Based on the current state of knowledge, this paper critically asses the potential for OMBR to be implemented for water reuse application and highlights challenges to reach full scale operation. The initial vision of an energy-free osmotic gradient process is not realistic and its low fouling behaviour is still to be properly assessed. However, OMBR demonstrated unique features such as high rejection of contaminants and an absence of RO brine stream that can support its implementation, especially in the context of high end (potable, industrial) water reuse. However, to become a viable and effective technology for water reuse, significant research and development is still required. Tackling the salinity build-up, developing membranes and modules adapted to OMBR, evaluating long term performance and economics, validating removal of contaminants and developing design, maintenance and automatic control systems constitute critical topics to be considered in future research.